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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/9-77-036
December 1977
ALGAE AND WATER POLLUTION
An Illustrated Manual on the
Identification, Significance, and Control of
Algae in Water Supplies and in Polluted Water
C. Mervin Palmer
Illustrations in color by Harold J. Walter
and Sharon Adams
Edited by Ronald L. Lewis
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
For sale by the Superintendent of Documents, U.S. Government
Printing Office, Washington, D.C. 20402
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research Laboratory,
U.S. Environmental Protection Agency, and approved for publication. Approval does not
signify that the contents necessarily reflect the views and policies of the U.S. Environ-
mental Protection Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
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FOREWORD
The Environmental Protection Agency was created because of increasing public and gov-
ernment concern about the dangers of pollution to the health and welfare of the Amer-
ican people. Noxious air, foul water, and spoiled land are tragic testimony to the deteri-
oration of our natural environment. The complexity of that environment and the inter-
play between its components require a concentrated and integrated attack on the prob-
lem.
Research and development is that necessary first step in problem solution and it in-
volves defining the problem, measuring its impact, and searching for solutions. The Mu-
nicipal Environmental Research Laboratory develops new and improved technology and
systems for the prevention, treatment, and management of wastewater and solid and haz-
ardous waste pollutant discharges from municipal and community sources, for the pres-
ervation and treatment of public drinking water supplies, and to minimize the adverse
economic, social, health, and aesthetic effects of pollution. This publication is one of the
products of that research, a most vital communication link between the researcher and
the user community.
As part of these activities, this illustrated manual was prepared to aid those people con-
cerned with water supply and pollution control, to prevent or control problems caused
by undesired algal growth, and to help them create conditions suitable for beneficial use
of algae for pollution control.
Francis T. Mayo, Director
Municipal Environmental Research Laboratory
HI
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PREFACE
A manual on this general subject entitled Algae in Water Supplies was published in
1959. Approximately fifty thousand copies have since been printed by the U.S. Govern-
ment Printing Office, divided among eight printings. In 1962, the Agency of International
Development of the U.S. Department of State arranged for the translation of the manual
into Spanish and for its printing in Mexico from where it was distributed throughout Latin
America. This Spanish edition included a special bibliography of technical papers in
English, Spanish, French, German, Portuguese, and other languages dealing specifically
with algae in Latin America. It was printed for distribution, in part, by Centro Regional
de Ayuda Tecnica. Agencia para el Desarrollo International (AID), Mexico, and in part,
by Editorial Interamericana. S.A.
In 1964, the late Dr. Kuwahara, who had previously spent some time at the Robert A.
Taft Sanitary Engineering Center in Cincinnati, Ohio, translated Algae in Water Supplies
into Japanese and had it printed serially in seven issues of the journal of Water and Waste
(Japan) beginning with Volume 6, Number 7. Color plates of the English language edition
were included in black and white.
Color plates were also included in the twelfth through fourteenth editions of Standard
Methods for the Examination of Water and Wastewater published by the American Public
Health Association, American Water Works Association, and Water Pollution Control Fed-
eration.
The U.S. Environmental Protection Agency, National Environmental Research Center,
Cincinnati, Ohio, in 1973 had enlarged posters of the six color plates printed for distri-
bution.
This present manual is primarily an enlargement of the previous manual but with
greater emphasis on algae associated with water pollution. New chapters include "Algae
in Streams," "Algae and Eutrophication," "Algae and Pollution — Estuarine," "Algae as
Indicators of Water Quality," and "Algae in Sewage Stabilization Ponds." Additional ma-
terial has been added to all of the other chapters and many more algae have been in-
cluded in the completely revised Key in the Appendix. The chapters and color plates
have been rearranged.
Grateful acknowledgment for aid and encouragement is given particularly to Dr. Rob-
ert Bunch, Chief, Treatment Process Development Branch, Wastewater Research Division,
Municipal Environmental Research Laboratory (Cincinnati, Ohio), U.S. Environmental Pro-
tection Agency. Persons responsible for negotiating the contract to revise the manual, and
with responsibilities for seeing that it was carried out satisfactorily, are James W. Geiser,
Contracting Officer, Dr. Ronald F. Lewis, Project Officer, and E. M. Hennessey, Contract
Negotiator. Credit for producing the colored illustrations of algae goes to Sharon Adams
for Plates V and VI and to Harold J. Walter for the others. All new photographs and line
drawings were furnished by the writer. The writer expresses his indebtedness to these
co-workers listed above and to others for their aid in preparation of the new manual.
C. Mervin Palmer Ronald L. Lewis
Aquatic Biologist (Retired) Biological Treatment Section
Interference Organisms Studies Treatment Process Development Branch
Wastewater Research Division
Present address: Municipal Environmental Research Laboratory
Kendal at Longwood, Box 220 Cincinnati, Ohio 45268
Kennett Square, Pennsylvania 19348
IV
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CONTENTS
Foreword iii
Preface iv
I. Introduction 1
II. Significance of Algae 3
III. Identification of Algae 6
IV. Algae in Streams 18
V. Plankton Algae in Lakes and Reservoirs 22
VI. Attached Algae 26
VII. Algae and Eutrophication 31
VIII. Clean Water Algae 34
IX. Algae and Pollution—Fresh Water 36
X. Algae and Pollution—Estuarine 40
XI. Algae as Indicators of Water Quality 42
XII. Algae in Sewage Stabilization Ponds 46
XIII. Taste and Odor Algae 52
XIV. Filter and Screen Clogging Algae 57
XV. Additional Problems Caused by Algae 60
XVI. Additional Uses for Algae Found in Water Supplies 68
XVII. Procedures for Enumeration of Algae in Water 75
XVIII. Control of Algae 78
Appendix
Key to fresh water algae common in water supplies
and in polluted waters 98
Bibliography 111
Glossary 119
TABLES
Number
1 Comparison of the Four Major Croups of Algae in Water Supplies 13
2 Algae in Water Supplies. A List of the More Important Species 13
3 Recent Changes in Names of Algae 17
4 Common Algae, Except Diatoms, of Streams 21
5 Plankton and Other Surface Water Algae 24
6 Attached Algae 29
7 Algae Affecting Operation of Canals 30
8 Predominant Algae in Oneida Lake, 1961 33
9 Phytoplankton in Lake Erie, 1951 - 1952 33
10 Clean Water Algae 35
11 Pollution Algae - Algae Common in Organically Enriched Areas 39
12 Algal Genus Pollution Index 45
13 Algal Genera in American Sewage Ponds 50
14 Algae Most Abundant and Widespread in Sewage Ponds 50
15 Various Conditions of Sewage Oxidation - Stabilization Ponds 51
16 Taste and Odor Algae, Representative Species 55
17 Odors, Tastes, and Tongue Sensations Associated with Algae in Water 56
18 Filter and Screen Clogging Algae 59
19 Additional Problems Caused by Algae in Water Supplies 66
20 Uptake of Cesium-137 by Algae 66
21 Maximum Concentration Factors for Isotopes in Columbia River Organisms 67
22 Relative Concentration of Radioactive Material in Various Types of Organisms.... 67
23 Other Uses for Algae in Water Supplies 72
24 Relative Toxicity of Copper Sulfate to Algae 81
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ILLUSTRATIONS
Color plate
I Plankton Algae in Lakes and Reservoirs 82
II Attached Algae 84
III Clean Water Algae 86
IV Fresh Water Pollution Algae 88
V Estuarine Pollution Algae 90
VI Sewage Pond Algae 92
VII Taste and Odor Algae 94
VIII Filter and Screen Clogging Algae 96
Figure
1 Accumulation of algae floating on the surface of water 4
2 Water net, Hydrodictyon reticulatum 7
3 Spirogyra ellipsospora 7
4 Spirogyra varians 7
5 A blue-green alga, Desmonema wrangelii 7
6 A green alga, Pediastrum boryanum 7
7 A desmid, Cylindrocystis brebissonii. 7
8 Anacystis cyanea (formerly M;crocyst/s aeruginosa) 7
9 Agmenellum quadriduplicatum (formerly Merismopedia glauca) 7
10 Phytoconis botryoides (formerly Protococcus viridis) 7
11 Haematococcus lacustris (formerly Sphaerella lacustris) 7
12 Colonies of indefinite form in Oocystis novae-semliae 9
13 A simple filament, Anabaena constricta 9
14 Threads are grouped into erect cones in Symploca muralis 9
15 Filament with alternate branching in Microthamnion strictissimum 9
16 A branching, tubular, nonseptate alga, Botrydium granulatum 9
17 Cells embedded in a gelatinous tube in Hydrurus foetidus 9
18 Mature and young portions of Compsopogon coeruleus 9
19 M/croco/eus pa/udosus, showing a single thread and a group of threads
surrounded by a sheath, under high and low magnification 12
20 Scenedesmus quadricauda, showing spine-like extensions on the terminal cells . 12
21 Lateral flagella in Merotrichia capitata 12
22 Anterior flagella on cells of Pleodorina illinoisensis 12
23 Posterior and lateral views of anterior flagella on Conium sociale 12
24 Two spore-producing cells on filaments of Trentepohlia aurea 12
25 Enlarged terminal reproductive cells on filaments of Audouinella w'o/acea 12
26 Terminal cells specialized for sexual reproduction in Vaucheria arechavaletae ... 12
27 Thick-walled zygospores formed during sexual reproduction in Zygnema normani 12
28 True branching in the blue-green alga, Nostochopsis lobatus 12
29 Anacystis (Microcystis) 20
30 Anabaena 20
31 Oscillatoria (two sizes) 20
32 Oocystis 20
33 Actinastrum 20
34 Scenedesmus (reproducing) 20
35 Ankistrodesmus falcatus 24
36 Cloeotrichia natans 24
37 Plankton diatoms, showing distinctive shapes of cells and colonies 24
38 Vaucheria geminata 27
39 Vaucheria sessilis 27
40 Pithophora oedogonia 27
41 Schizomeris leibleinii 27
42 Stigonema hormoides 27
vi
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43 Tetraspora 27
44 Calothrix 27
45 Enteromorpha 30
46 Oedogonium 30
47 Stigeoclonium (immature) 30
48 Calothrix parietina 35
49 Ulothrix zonata 37
50 Osc/7/ator/a limosa 37
51 Oscillatoria tenuis 37
52 Oscillatoria princeps 37
53 Phormidium uncinatum 37
54 Synedra and Nitzschia 44
55 Melosira (indicator alga) 44
56 Pandorina (indicator alga) 44
57 Eug/ena (indicator alga) 44
58 Kirchneriella subsolitaria, the alga used in the Vermont test 44
59 Achnanthes, a sewage pond diatom 48
60 Some flagellate algae producing tastes and odors 54
61 Pulses, over a four year period, of three taste and odor algae in a water
supply reservoir 54
62 Closterium lunula 61
63 Lyngbya majuscula 62
64 Nodularia spumigena 63
65 Scenedesmus bijugatus 70
66 Trachelomonas hispida 71
67 Scenedesmus obliquus 71
68 Pediastrum duplex 71
69 Chlorogonium euchlorum 71
70 Nannoplankton counting slide 76
71 Typical form of algal plankton record 76
72a Experimental testing of a potential algicide: Applying the algicide to a
blanket of algae 79
72b Experimental testing of a potential algicide: Result of the test: Blanket of
algae has disappeared 79
VII
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CHAPTER I
INTRODUCTION
Since the quality of water affects our lives in many ways,
water must be of good quality if its aesthetic value in the
scenic environment is to be appreciated. Polluted water
can be the reason for the closing of both commercial and
sport fishing areas and restricting the recreational use of
bodies of water. Water quality can have a great influence
on the ability of aquatic plants and animals to exist and
grow in a stream, lake, pond, or bay. Water used to manu-
facture many industrial products must be of good quality
to prevent a reduction in the quality and value of the
manufactured product. Water of poor quality costs more
to be treated for use as a community water supply. Poor
water can affect our health since it can carry disease agents
and toxic chemicals and it may have an unpalatable taste
or a disagreeable odor. The temperature, clarity, and
color of the water can affect the quality of the water.
As population and industrial demands increase and
groundwater supplies become inadequate, more and more
cities and villages are turning to lakes, streams, or reser-
voirs for their water supplies. This change from ground
to surface source of supply has created many new prob-
lems for those engaged in the procurement and treatment
of water for domestic and other uses. Groundwaters are
essentially free of organisms which may complicate the
provision of potable water. Some problems are odor and
taste, the clogging of filters, growths in pipes as well as
in cooling towers and on reservoir walls, surface water
mats or blooms, infestations in finished waters, and tox-
icity.
Pollution of surface water has become one of the more
important problems about which to be concerned. It re-
quires consideration and action by individuals, civic
groups, city, state, and national sanitary and health de-
partments, and by industry.
Algae are involved in water pollution in a number of
significant ways. Pollution may bring about an enrichment
of the algal nutrients in water and this may selectively
stimulate the growth of a few types, producing massive
surface growths or "blooms" that in turn reduce the water
quality and affect its use. Certain algae are able to flour-
ish in water polluted with organic wastes and to play an
important part in "self-purification" of the body of water.
The selective types of algae that exist in polluted water
also are being used as indicators of pollution. Polluted
water algae may frequently include certain forms toxic to
man or animals drinking the water or living in it. Since
algae constitute part of a chain of aquatic life in the water,
whatever alters the number and kinds of algae affects all
of the other organisms, including fish. Thus it requires a
continuous monitoring and study of algae existing in
waters of various quality in order to determine what con-
trols, what changes, or what uses can be instituted for the
benefit of man and for conservation of water and desir-
ible aquatic life.
The number and kinds of algae and other organisms
which grow in surface waters depend on environmental
conditions. Fertilizing materials such as sewage and or-
ganic wastes from milk plants, canneries, slaughter houses,
paper mills, starch factories, and fish processing plants
greatly increase the productivity of the waters and their
crops of algae and other plankton organisms, many of
which produce problems when they become abundant.
In muddy streams such as the Missouri, turbidity limits
light penetration sufficiently so that few problems occur
from algal growth. When impoundments are built in such
a stream, they create settling basins in which the water
clears and algal growths develop, producing tastes and
odors or other nuisance conditions. The extensive im-
poundment program which has been underway for 40
years can create many water supply problems which did
not exist previously in these waters.
Pool size, shape, depth, amount of shore line, extent of
shoal areas, character of the bottom, physiography and
soils of the watershed, amount and rate of precipitation,
sunlight, and the quality of the water are all factors in-
fluencing the growth of algae in a reservoir. A narrow,
deep reservoir having no shoal areas, a minimum of shore
line, little wind mixing, an unproductive watershed, and
soft water low in dissolved solids will have less algae than
a wide, shallow, irregular reservoir located in an area of
rich soil where the incoming water is rich in dissolved
materials and there is complete wind mixing. In many
areas the best reservoir sites have already been utilized.
New reservoirs will have to be built in less favorable sites
where productivity of algae will be greater. In the Great
Plains area and in several other parts of the country, res-
ervoir sites for water storage are usually wide and shallow
and favorable for the development of plankton growths.
In view of these conditions, problems caused by nuis-
ance organisms will become more widespread and of
greater importance. In several areas they are now the
number one problem of water works operators. Attempts
to control nuisance algae with chemicals has a long his-
tory.
Studies have been made to improve methods of using
existing algicides and to find better or more specific ma-
terials. Specific algicides would be of considerable eco-
1
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/ALGAE AND WATER POLLUTION
nomic benefit, as smaller amounts of material could be
used to control only undesirable forms without affecting
the others. This is very important from the standpoint of
fisheries management, as algae constitute much of the
base of the food pyramid on which all the higher forms
of aquatic life depend. Furthermore such a procedure
provides a form of biological control. The application of
very toxic materials in large dosages which will kill prac-
tically all the algae is undesirable. When much of the
population is destroyed, the weed species come back
first, and since there is little competition, in great abund-
ance. If selective algicides can be discovered, their use
will control the problem species, while the desirable
forms can increase so that the undesirable species are less
likely to come back in large numbers.
Algicidal and/or biological controls are feasible in lakes,
small streams, or reservoirs where most of the water is
used. They are economically unsuited to large lakes or
rivers where only a portion of the water is used by the
water plant. In such situations some other method of
treatment must be provided in the water plant. It is be-
lieved that materials causing odor or taste are present in
very small amounts. If the taste and odor materials pro-
duced by so-called nuisance organisms are known, it may
be possible to treat or change them by additives to ren-
der them innocuous. Investigations have been conducted
to recover, isolate, and identify odoriferous materials pro-
duced by algae and other organisms in water supplies.
Studies of attempts to control algal problems in water
works, sewage ponds, and polluted waters have revealed
hit-or-miss procedures, little coordination of effort, and
only occasional systematic recording of essential data. The
great majority of water and wastewater treatment plants
are not staffed for making studies to determine the cause
of their trouble, to identify the organisms responsible, or
to detect their development. The value of continued sur-
veillance of algal populations has been proven by studies
in several of the larger water plants, sewage ponds, lakes,
and streams. There has been a need for some time for a
planned and uniform approach to these problems and for
placing information in an understandable and useful form
into the hands of those who need it. This manual is an
attempt to meet this need in appraisal of algae in relation
to water pollution problems and to furnish information
for remedying some difficulties.
It is realized that very few operators or members of
treatment plant staffs have had training in aquatic
biology or in the identification of algae. However,
if growths of algae are to be detected and controlled,
stimulated, or left undisturbed, continued surveillance of
plankton populations and identification of the organisms
are essential. This manual presents a simplified identifica-
tion key limited to species of importance in water sup-
plies and associated with pollution. Terms and structures
used in this key are defined and illustrated. The most im-
portant species of algae are illustrated in three-dimen-
sional drawings in color which show both external and in-
ternal structures. The drawings are based on actual speci-
mens and on descriptions from a large number of texts.
It is believed that with these drawings and the key any
person who applies himself diligently will be able to
identify at least the most important forms. As experience
is gained it should be possible to detect the development
of troublesome algae so that control measures can be ini-
tiated before real trouble develops. In addition to the
key and plates, the manual deals with the ecology and
significance of algae and presents concise and pertinent
information on filter-clogging and mat-forming algae, at-
tached forms, algicides, and algal control, algae associated
with pollution (both fresh water and estuarine), various
uses of algae, algae of rivers and lakes, eutrophication, al-
gae as indicators of pollution, methods of recording algae,
and the use of algae in waste stabilization lagoons for the
treatment of domestic and/or industrial wastes.
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CHAPTER II
SIGNIFICANCE OF ALGAE
Algae are common and normal inhabitants of surface
waters and are encountered in every water supply that is
exposed to sunlight. While a few of the algae are found in
soil and on surfaces exposed to air, the great majority of
them are truly aquatic and grow in the waters of ponds,
lakes, reservoirs, streams, and oceans. Operators of water
treatment plants are aware of the ability of algae to pro-
duce odors and tastes and to clog sand filters. In addition,
algae are recognized as important in water supply in many
other ways, including their capacity for modifying the pH,
alkalinity, color, turbidity, and in relation to the radioac-
tivity of the water. Some types are undoubtedly the most
troublesome of the various nuisance organisms, but others
can actually be put to good use in improving a water
supply.
One of the principal reasons for the importance of algae
is their ability to give rise to very large quantities of or-
ganic matter in the water. It has been estimated, for ex-
ample, that more than 130 tons of algae/day flow into
Fox River, Wisconsin, from Lake Winnebago (1). Plankton
algae in the Scioto River, Ohio, has reached a maximum
of more than 8,000 ppm (2). Algal counts for Lake Mich-
igan water at Chicago nave at times reached over 4,000
organisms/ml (3), and the White River in Indiana has rec-
ords of counts exceeding 100,000 algae/ml (4). Such large
quantities of algal material can always be counted on to
cause serious difficulties in water treatment plants.
Small numbers of particular kinds of algae may also be
troublesome. The diatoms Tabellaria, Synedra, and Me/o-
s/ra almost invariably reduce the length of filter runs. The
brown flagellate, Synura, even in small numbers, is a no-
torious taste and odor producer. Comparatively low con-
centrations of most of the algae, however, are often an
asset rather than a liability in raw waters.
Unattached, visible, and sometimes extensive accumula-
tions of algae at or near the surface of the water are des-
ignated as blooms, mats, or blankets (fig. 1), the last two
terms generally being applied when the algae are in the
form of threads or filaments. Many of the algae attached
to submerged rock, wood, soil, the surface of trickling
filters, filter beds, or coagulation basin walls may form
continuous carpets of growth. When the water becomes
turbulent, fragments of the algal carpet may be detached
and subsequently carried away. These massive growths
of algae can be troublesome in clogging screens, in the
production of slime, and as a source of tastes and odors
particularly if anaerobic decomposition occurs. The
blooms and surface mats can be the cause for complaints
by persons using the body of water for recreational pur-
poses. They may also be one cause of fish kills by acting
as a barrier to the penetration of oxygen into water under
the algae. Algae that are dispersed and not in blooms or
mats normally would have just the opposite effect.
The algae that collect and grow on the surface of a
slow sand filter as a gelatinous slimy film may be respon-
sible for gradually reducing the flow through the bed, but
they also perform a useful service by adding oxygen to
the water, which permits the bacterial decomposition of
organic matter within the filter to remain aerobic. Anaer-
obic activities in the sand bed would tend to render the
filtrate less palatable. The slimy mass of algae and other
aquatic plants and animals at the surface of a slow sand
filter is called the filter skin and has also been referred to
under the German name of Schmutzdecke.
Unattached microorganisms that are dispersed individ-
ually or in colonies in water are designated collectively
as plankton. Included are the plankton algae, which con-
stitute most of the phytoplankton (meaning plant plank-
ton), and the planktonic animals or zooplankton. When
the water supply comes from a large, deep reservoir or
lake, the planktonic algae are likely to be of much more
significance than the attached or benthic algae. Many
water treatment plants, therefore, keep records of the
plankton but not of the benthos. In some treatment plants
it has been a general practice to apply an algicide to the
raw water whenever the concentration of planktonic algae
approaches a count of 500 areal standard units/ml (5).
All surface waters contain dissolved and suspended
materials. Some of these serve as nutrients and support
the growth not only of algae but of many other kinds of
aquatic life, the numbers of which are governed to a great
extent by the amounts and kinds of nutrients available.
Some of the aquatic plants and animals are large, the fish,
turtles, cattails, and water lilies, for example, but there
are also immense populations of small forms, many of
them microscopic. The microscopic organisms in addition
to algae include bacteria, actinomycetes, minute worms,
and mites. More recently, sub-microscopic viruses have
been found to be common in water, and some of them
prey on algae (6). Many of these aquatic organisms may
play a major part in affecting the quality of the water and
have to be dealt with in the process of preparing water
for domestic and industrial use. The present account deals
primarily with the algae, but it is obvious that the activi-
ties of one group of organisms are closely associated with
those of other organisms present in the same environment.
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ALCAE AND WATER POLLUTION
Figure 1.—Accumulation of algae floating on the surface of water.
PHOTOSYNTHESIS
Algae differ from the other groups of small or micro-
scopic organisms in possessing an internal green pigment
called chlorophyll, sometimes hidden or partially masked
by other pigments, which enables them in the presence of
sunlight to combine water and carbon dioxide to form
starch or related substances, and to release oxygen into
the water. This process, known as photosynthesis (7), is
absent in all typical bacteria, actinomycetes, fungi, yeasts,
protozoa, and Crustacea. In general it is not characteristic
of animals but is common to all types of green plants.
Respiration, on the other hand, is a process carried on by
all plants and animals and the gaseous exchange is the
opposite of that in photosynthesis, i.e., oxygen is absorbed
and carbon dioxide is released. However, in algae and
other green plants the rate of photosynthesis is normally
faster than that of respiration. These organisms, therefore,
release more oxygen than they use and absorb more car-
bon dioxide than they release, while animals and other
non-photosynthetic organisms release carbon dioxide and
absorb oxygen from their environment. For this reason, the
amount of oxygen and carbon dioxide in an environment
such as water often depends to a large degree upon the
relative rates of photosynthesis and respiration being car-
ried on collectively by the algae, bacteria, and other or-
ganisms in that area.
Some aquatic pigmented forms containing chlorophyll
are able to swim or crawl, although most of the typical
algae are not capable of self locomotion. Many of these
pigmented swimming forms have whip-like structures
called flagella and have been classified by some workers
as protozoan animals rather than as algae. However, it
seems best in this document to classify them as algae (8).
The algae make possible important chemical changes
and metabolic activities in the water through their release
of oxygen during daylight hours. The oxygen is made
available for respiration that is carried on by all types of
animals from fish to the smallest forms. Oxygen helps to
prevent foul or septic conditions by favoring the activities
of aerobic rather than anaerobic bacteria. The algae con-
stitute the primary source for continuous daytime renewal
of this essential element in most bodies of quiet water.
Oxygen release by algae and oxygen uptake by reaeration
are the two primary sources for renewal of oxygen in
flowing streams and turbulent water.
Another important chemical effect of algae is the con-
tinuous removal of carbon dioxide from the water during
the daylight hours as a result of photosynthesis. This proc-
ess brings about an alteration in the relative amounts of
soluble (unbound) carbonic acid, intermediately soluble
(half bound) bicarbonates, and the nearly insoluble
(bound) monocarbonates, often causing some of the lat-
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Significance
ter to precipitate. All of this produces a change in the
total hardness of the water. Vigorous growths of algae
have been known to reduce the water hardness by as
much as one-third.
These changes in carbon dioxide and hardness also
tend to change the pH of the water. The pH rises as the
algae increase their photosynthetic activity during day-
light hours. The pH then decreases at night when the al-
gae are not carrying on photosynthesis but are releasing
carbon dioxide in respiration. These changes in hardness
and in pH must be taken into account at the water treat-
ment plant, since they may require changes in the dosages
of chlorine, alum, and other chemicals used in treatment.
Corrosive activity of the water is also often increased
as a result of algal growth. This can have far-reaching
effects on the pipes in the distribution system and on
many industrial processes where water is in contact with
the machinery. In California, algae attached to the metal
walls of sedimentation tanks caused deep pits to be
formed in the metal as a result of the depolarizing action
of the oxygen produced by the algae. Algae in contact
with submerged concrete blocks have caused complete
disintegration of the concrete (9).
The substance produced by algae in photosynthesis is
primarily a carbohydrate which may either be used in res-
piration or in construction of cell substances or stored,
generally as starch or in some cases as an oil. Since
aquatic organisms lacking chlorophyll are unable to manu-
facture carbohydrates or oils from inorganic matter, they
are dependent upon algae and other green plants, directly
or indirectly, for their source of these organic substances.
Algae represent an essential and basic part of the cycle
of living organisms. Live algae serve as food, especially
for small aquatic animals, which in turn serve as food for
larger forms. The remains of dead algae are utilized by
bacteria and other scavengers.
Increasing attention is now being paid to algae that
produce toxic organic substances causing the death of
many kinds of wild and domestic animals. There are rec-
ords of algae that are toxic to humans, and some have
several times been looked upon with suspicion as the
possible cause of certain outbreaks of gastro-intestinal dis-
orders among persons using a common water supply.
Algae problems which relate to providing suitable water
supplies, together with the use of some algae in water
supply and sewage treatment improvements, clearly indi-
cate a need for more knowledge of the environmental
requirements of these organisms, their life cycles, growth,
and nutrition.
Reports have been published for various parts of the
continent which summarize the importance of algae and
other interference organisms in water supplies and to
water quality. The regions that have been covered in-
clude New England (10), the Chesapeake area (11), Indi-
ana (12), Ohio (13), Pennsylvania (14), Virginia (15), West
Virginia (16), Canada (17), California (18), and the South
Central United States (19).
REFERENCES
1. Current pollution investigations and problems in Wisconsin. K. M.
Mackenthun. In Biological Problems in Water Pollution, ed. by
C. M. Tarzwell. Dept. Health, Education, and Welfare, Public
Health Service, Robert A. Taft San. Eng. Center, p. 179-183. 1957.
2. A study of pollution and natural purification of the Scioto River.
R. W. Kehr, W. C. Purdy, J. B. Lackey, O. R. Placak, and W. E.
Burns. U.S. Public Health Service, Public Health Bull. 276, 153 p.
1941.
3. Quantitative study of the phytoplankton of Lake Michigan at Evans-
ton, Illinois. K. E. Damann. Butler Univ. Bot. Stud. 5:27-44. 1941.
4. Plankton populations in Indiana's White River. J. B. Lackey and
E. R. Hupp. Jour. Amer. Water Wks. Assn. 48:1024-1036. 1956.
5. Comprehensive survey of taste and odor problems. H. N. Lendall.
Water Wks. Eng. 99:1237-1238. 1946.
6. Virus diseases in blue-green algae. R. S. Safferman. Chapter 21 in
Man and the Environment, D. F. Jackson (ed.), Syracuse Univ. Press,
Syracuse, N.Y., p. 429-439. 1968.
7. Photosynthesis in the algae. R. W. Krauss. Indust. and Eng. Chem.
48:1449-1455. 1956.
8. Suggested classification of algae and protozoa in sanitary science.
C. M. Palmer and W. M. Ingram. Sewage and Indust. Wastes
27:1183-1188. 1955.
9. Biological corrosion of concrete. E. T. Oborn and E. C. Higginson.
Joint Rept. Field Crops Res. Branch, Agric. Res. Service, U.S. Dept.
Agric, and Bur. Reclamation, U.S. Dept. Interior. 8 p. Jan. 1954.
10. Algae and other interference organisms in New England water sup-
plies. C. M, Palmer. Jour. New England Water Wks. Assn. 72:27-
46. 1958.
11. Algae and other organisms in waters of the Chesapeake area. C.
M. Palmer. Jour. Amer. Water Wks. Assn. 50:938-950. 1958.
12. Algae and other interference organisms in Indiana water supplies.
C. M. Palmer and H. W. Poston. Jour. Amer. Water Wks. Assn.
48:1335-1346. 1956.
13. Algae in water supplies of Ohio. C. M. Palmer. Ohio Jour. Sci.
62:225-244. 1962.
14. Algae in relation to water quality in Pennsylvania. C. M. Palmer.
Proc. Pa. Acad. Sci. 41:73-85. 1967.
15. Biological aspects of water supply and treatment in Virginia with
particular reference to algae. C. M. Palmer. Va. Jour. Sci. 18 (New
Series No. 1):6-12. 1967.
16. Algae and associated organisms in West Virginia waters: problems
and control measures. C. M. Palmer. Castanea 32:123-133. 1967.
17. Survey of water purification practice in Canada. D. H. Matheson
and A. V. Forde. Jour. Amer. Water Wks. Assn. 49:1522-1530.
1957.
18. Algae and other interference organisms in water supplies of Cal-
ifornia. C. M. Palmer. Jour. Amer. Water Wks. Assn. 53:1297-1312.
1961.
19. Algae and other interference organisms in waters of the South
Central United States. C. M. Palmer. Jour. Amer. Water Wks. Assn.
52:897-914. 1960.
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CHAPTER III
IDENTIFICATION OF ALGAE
Several of the large groups of algae are recognized by
their common names, such as the diatoms, desmids, ar-
mored flagellates, euglenoids, greens, blue-greens, yellow-
greens, browns, golden-browns, and reds. Included in
these groups are numerous individual kinds which prob-
ably total more than twenty thousand. A few of the less
specific kinds of algae have common as well as scientific
names, for example, "water net" for Hydrodictyon (fig. 2),
"green felt" for Vaucheria, "sea lettuce" for Ulva, "water
silk" for Spirogyra, and "stone wort" for Chara. Each one
of these is known as a genus (plural, genera) and is com-
posed of specific kinds known as species (plural also is
species). Two species of the genus Spirogyra, for example,
would be Spirogyra ellipsospora (fig. 3) and Spirogyra var-
ians (fig. 4). For the great majority of algae, however, only
scientific names are available, no common names having
as yet been applied to them.
Experience in water and sewage treatment plants has
demonstrated that there is considerable difficulty in rec-
ognizing the various algae and in determining which of
the many present are really important. In this manual the
algae are considered and displayed according to their
significance to sanitary scientists and technicians, rather
than with regard to their evolutionary relationship as bot-
anists would normally classify them (1). Obviously only
a fraction of the total number of algae can be included,
but many of those omitted are comparatively rare types
or relatively unimportant in water supplies.
For convenience, most of the algae of importance in
water supplies and water pollution may be categorized
into four general groups, the blue-green algae, the green
algae, the diatoms, and the pigmented flagellates. This is
a simplification of the grouping which is used in more
extensive treatises on the classification of algae. As might
be expected, there are a few miscellaneous forms which
do not fit into these four groups, brown, red, and yellow-
green algae, for example. Desmids are a subgroup of the
green algae. The blue-green algae include such forms as
Osdllatoria (pis. IV and VIII), Anacystis (Microcystis) (pis.
VII and VIII), and Desmonema (fig. 5). As the name im-
plies, many of the specimens have a blue-green color.
They are surrounded by a slimy coating. Their form and
internal structure are comparatively simple. The green al-
gae are exemplified by Chlorella (pis. IV and VIII), Ped/'as-
trum (fig. 6), and Spirogyra (pis. IV and VIII). Their most
common color is grass-green to yellow-green, and the pig-
ment is localized in plastids. Reserve food is generally
starch. The desmids (fig. 7) are a subgroup of the green
algae. The diatoms are represented by the genera Cyc/o-
te//a (pis. Ill and VIII) and Navicula (pis. Ill and VIII). They
have a rigid wall containing silica which is sculptured
with regularly arranged markings. Their plastids are
brown to greenish in color. Within the category of pig-
mented flagellates are placed all of the swimming algae
which have flagella. Euglena (pis. I and IV) and Synura
(pi. VII) and representatives of this group. A comparison
of the more significant characteristics of the four groups
of algae is summarized in Table 1.
A total of almost 500 genera and species of the most
important algae is included in the next 11 chapters of this
manual, being considered according to their occurrence
and significance under the general titles of algae in
streams, algae in ponds, lakes and reservoirs, attached al-
gae, algae and eutrophication, clean water algae, algae
and pollution—fresh water, algae and pollution—estua-
rine, algae as indicators of water quality, algae in sewage
stabilization ponds, taste and odor algae, and filter and
screen clogging algae. In Table 2, these algae are listed
alphabetically, together with their group, the title under
which they are discussed, and the plate or figure where
they are illustrated. A key for identification of the fresh
water forms is included in the Appendix. A number of
additional algae are referred to briefly in Chapters XV and
XVI but are not included in the key. More extensive man-
uals on both marine and freshwater algae would be re-
quired for their identification (2-8, 10-13).
Authorities have changed the names of several of the
better known algae. The list of these changes which in-
volve any algae referred to in the manual is given in Table
3. Most of the changes involve genera and species of
blue-green algae and were reported by Drouet and Daily
in 1956 (4). For example, Microcystis (fig. 8) is changed to
Anacystis, Coelosphaerium is included under Comphos-
phaeria, and Merismopedia (fig. 9) becomes Agmenellum.
The name of the green alga Protococcus (fig. 10) is changed
to Phytoconis (9). The pigmented flagellate Sphaerella
(fig. 11) is now recognized as Haematococcus (2). More
recently, changes have been suggested for names of fila-
mentous blue-green algae, but these are not followed in
this manual (14, 15).
Eight plates of illustrations in color together with photo-
graphs, line drawings, the key, and descriptions are in-
cluded for use as aids in the identification of the signifi-
cant forms. Six of the color plates of important algae are
the work of artist-biologist Harold J. Walter, and were
done under supervision of the author (16, 17). The orig-
inal six paintings are on display at the U. S. Environmental
Research Center in Cincinnati, Ohio. Plates V and VI were
-------
Identification
Figure 2.—Water
net, Hydrodictyon
reticulatum.
Figure 7.—A desmid, Cylindrocystis brebissonii.
Figure 3.—Spirogyra ellipsospora.
Figure 4.—Spirogyra varians.
Figure 5.—A blue-green alga, Desmonema wrangelii.
Figure 8.—Anacystis cyanea (formerly
Microcystis aeruginosa).
Figure 9.—Agmenellum quadriduplicatum
(formerly Merismopedia glauca).
Figure 10.—Phytoconis botryoides
(formerly Protococcus viridis).
Figure 6.—A green
alga, Pediastrum
boryanum.
Figure 11.—Haematococcus
lacustris (formerly Sphaerella
lacustris).
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ALGAE AND WATER POLLUTION
painted by Sharon Adams from drawings made by
the author. The line drawings which are included as fig-
ures throughout the manual were made by the writer and
published previously in two taxonomic papers (18, 19).
The eight plates of algae in color represent four gen-
eral areas of concern for plant operators; namely, water
pollution, water treatment, sewage treatment, and water
reservoirs. Taste, odor, and filter clogging are the most
troublesome problems faced by many operators in water
treatment plants. Representative algae associated with
these conditions are illustrated on plates VII and VIII. In
connection with water pollution, natural stream purifica-
tion, and sewage treatment, the significant algae are those
whose growth or survival is closely related to the amount
and composition of sewage and other organic wastes in
the water. Plates III and IV illustrate the contrasting fresh-
water groups of clean water and polluted water algae. In
the reservoirs and settling basins of water supply systems
are encountered the drifting, swimming, and attached
growths of algae which can become troublesome in the
raw water and can cause nuisance conditions in the treat-
ment plant. Plates I and II illustrate respectively the plank-
tonic and mat-forming algae of surface waters and the
algae attached to the sides of reservoirs and settling bas-
ins. Algae in water of high organic content are illustrated
in plates IV, V, and VI, the fourth and fifth contrasting the
algae associated with pollution of fresh and estuarine
waters.
The algae as illustrated on the plates are not shown in
actual or relative size. Some of the forms illustrated are
so minute as to be visible only under very high magnifi-
cation of a compound microscope. Other forms are large
enough to be seen under lower magnification or even
with the unaided eye. Chlorella on plates IV and VIII,
and Chrysococcus on plate III, are good examples of mi-
nute, microscopic algae while Lemanea on plate III, and
Chara on plate II, are large forms often growing to a length
of several inches. Thus, rather than having the same draw-
ing scale for all of the algae, each is enlarged sufficiently
to make clear its own particular characteristics. The mag-
nification for each drawing is given with the species name
in the list accompanying each plate.
The eight color plates contain illustrations of 174 of the
algae referred to in this manual. Drawings and photo-
micrographs of some other forms are also included in the
manual as noted earlier. The paintings and the drawings
were prepared in such a way as to emphasize the char-
acteristics most helpful in the identification of unstained
material in water samples.
While illustrations may be a real aid in recognizing the
various kinds of algae, an identification key is essential for
distinguishing the many genera and species encountered.
An original key, limited to the algae selected as most im-
portant in water supplies, has therefore been prepared
for this manual. Since many other algae may be associ-
ated with these forms in the water, the supplementary use
of additional treatises on algae would help to assure the
greater accuracy in identifying the specimens.
When acquainted with the nature of an identification
key, an observer can make direct use of the device in de-
termining the name of a particular form whose essential
characteristics have been determined through study under
a microscope. It is necessary, therefore, to know the es-
sential characteristics which must be observed in any
specimen before the key is used for its identification. The
essential characteristics are considered under the follow-
ing headings: 1, gross structure of the alga, including
shape, size, and cell grouping; 2, cell structure; 3, spe-
cialized parts of cells; 4, specialized parts of multicellular
algae; and 5, measurements.
CROSS STRUCTURE
The cells of algae may be isolated units with each uni-
cell behaving as an independent organism. Hundreds of
genera of algae are unicellular. Examples illustrated in-
clude Tetraedron, Euglena, and Comphonema on plate IV.
In many other algae the cells are grouped together into
various shapes of colonies such as are illustrated by As-
terionella, Hydrodictyon, Anacystis (Microcystis), Dino-
bryon, Vo/vox, Pandorina and Synura on plate VII and
Oocystis in figure 12. The colony of cells may have a def-
inite, distinct shape, as in Vo/vox, or it may be indefinite
and irregular, as in Anacystis. Colonies in the form of
threads (filaments) where the cells are arranged in a simple
linear series or chain are distinctive and very common
(fig. 13). The threads may be isolated, or obviously
grouped together as in Symploca (fig. 14); they may be
unbranched (simple) or branched. The branches may be
attached to the primary thread singly (alternate), in pairs
(opposite), or in groups of more than two (whorled). Ana-
baena, Spirogyra, Osdllatoria, and Arthrospira, on plate
IV are simple filaments. Microthamnion (fig. 15) and Au-
douinella (pi. II) have alternate branching; Stigeodonium
(pi. II) has, in part, opposite branching; and Chara (pi. II)
has whorled branching. Chaetophora and Phormidium
on plate II have filaments grouped together into larger
growths.
In a few cases the alga may be in the form of a con-
tinuous, sometimes branching tube with no cell walls to
divide the material into distinct units or cells. The tube is
described as being nonseptate (having no transverse walls).
Botrydium (fig. 16) and Vaucheria on plate II have this
type of structure. In others such as Hydryrus (fig. 17) and
Tetraspora on plate II, the whole gelatinous mass in which
numerous cells are embedded is tubular in form.
A few freshwater algae have cells forming dense, mas-
sive strands, the strands being from a few to many cells
thick and with central and marginal (peripheral) cells
which differ from one another. Lemanea on plate III and
Compsopogon on plate II and in figure 18 are examples
of specialized strands. Finally, a limited number of algae
have cells arranged to form a flat or bent membrane, as
indicated by Hildenbrandia on plate III.
In summary, the gross structural forms encountered
among the algae include the unicell, colony, filament,
tube, strand, and membrane.
-------
Identification
Figure 12.—Colonies of indefinite form in Oocystls novae-semliae.
Figure 16.—A branching, tubular,
nonseptate alga, Botrydium granu-
latum.
Figure 13.—A simple filament, Anabaena
constricta.
Figure 14.—Threads are
grouped into erect cones in
Symploca muralis.
Figure 15.—Filament with alternate branching in
Microthamnion strictissimum.
Figure 17.—Cells embedded in a gelatinous tube in
Hydrurus foetidus.
Figure 18.—Mature and young portions of Compsopogon coeru/eus.
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10
ALGAE AND WATER POLLUTION
CELL STRUCTURE
The three main parts of many algal cells are the proto-
plast, the cell wall, and the outer matrix. Within the
protoplast, one or more separate bodies of green, yellow-
green, brown, or some other color may be present. These
are known as plastids or chromatophores. In the blue-
green algae (Myxophyceae) the pigments are not localized
in plastids but are distributed throughout the whole proto-
plast. Some of the protoplasts may contain bodies other
than plastids, such as nuclei, crystals, starch grains, oil
droplets, called sap vacuoles, and spherical pyrenoids
around which minute grains of starch collect. Pyrenoids
are generally inside the plastids, as shown in Chlorella on
plate VIII and Oocystis and Scenedesmus on plate I. The
nucleus of the cell is present in all but the blue-green al-
gae but seldom referred to in the manual, because it is
colorless and difficult to observe without staining or other
special treatment of the material.
The walls of algal cells are commonly a thin, rigid mem-
brane which is in contact with the outer edge of the proto-
plast and completely surrounds it. Some of the swimming
algae, such as Euglena on plate I, do not have a rigid wall
and their protoplasts are therefore somewhat flexible,
making them changeable in form. In the green algae the
cell wall is semirigid and composed of cellulose. In dia-
toms the wall is very rigid and composed principally of
silica that is sculptured with a regular, even pattern of
lines and dots as illustrated by Diatoma and Nevicula on
plate VIII.
The outer matrix, when present, tends in most cases to
be flexible, colorless, gelatinous material which has been
secreted through the cell wall. It often changes with age
to become pigmented, to show stratification, and to de-
velop a semirigid surface membrane. In most cases it as-
sumes a form and structure characteristic for the particular
alga of which it is a part. In Botryococcus (pi. I) its brown
color partially hides the green plastids within the proto-
plasts. In Gonium (pi. I) it forms a sphere. Dinobryon
and Trachelomonas on plate VIM have a specialized outer
matrix called a lorica which is rigid and^ of definite form.
Lyngbya and Tolypothrix on plate II and Microcoleus (fig.
19) have an outer matrix in the form of a semirigid tube-
like sheath.
SPECIALIZED PARTS OF CELLS
Certain additional cell parts may be charcteristics use-
ful in identification. Some cells have a gelatinous stalk,
one end of which is attached to the cell and the other to
some other object. Gomphonema and Achnanthes on
plate II are shown with stalks. In many cases the cell may
become detached from the stalk very readily. Gompho-
nema on plate IV is illustrated without the stalk, although
it is generally present in this genus.
Knobs or spines may be found extending from the cell
wall, or the cells may have sharp spine-like ends. Micrac-
tinium on plate I has true spines while Ankistrodesmus on
plate III and Scenedesmus (fig. 20) have spine-like tips.
Knob-like swellings on the cell wall are shown on the
large cell of Chlorococcum on plate IV.
Swimming (motile) cells are often supplied with one,
two, or occasionally more than two flexible, whip-like
hairs known as flagella, extending from the front (anterior),
side (lateral), or back (posterior) of the algal cell. Lateral
flagella are found in Merotrichia (fig. 21) while anterior
flagella are shown in Pleodorina (fig. 22), and in two views
of Gonium (fig. 23). A reduction in the illumination of
the microscope field may help in making the flagella
(singular, flagellum) visible. Swimming cells may also con-
tain a single, small, red or orange body called an eye
spot in the protoplast. This eye spot is generally located
near the anterior end. Carter/a and six other motile algae
are illustrated on plate IV.
Several special terms are required in the description of
a diatom cell. The wall (frustule) of the diatom is com-
posed of two approximately equal halves, the one, like a
cover (epitheca), fitting with its edge over the edge of the
other (hypotheca). When the cell is lying in the micro-
scope field so that these overlapping edges are visible,
the diatom is said to be presenting its girdle view. If the
cell is lying so that the top of the epitheca or bottom of
the hypotheca is visible, the diatom is said to be present-
ing a valve view. In Gomphonema on plate II the left
hand cell is in girdle view and the right hand cell is in
valve view. These views are shown together in Gompho-
nema on plate IV. When diatom cells are fastened to-
gether into a filament or ribbon, it is the valve surfaces
which are attached together, so that the diatoms in the
colony are always seen in their girdle view. Thus, the
two attached cells in Diatoma on plate VIII present the
girdle view while the isolated cell to the left is shown in
valve view.
In diatoms the wall markings and partial partitions, par-
ticularly those visible in the valve view, are important in
identification. The many fine lines or lines of dots (punc-
tae) extending from the edge of the valve toward the
center are known as striae, or when thicker, as costae.
There may also be a longitudinal line called a raphe or
true raphe extending from one end of the cell to the
other but broken in the middle. If there is merely a clear
space with no striae crossing it rather than a longitudinal
line, the space is known as a false raphe or pseudoraphe.
Motile diatoms generally have a true raphe which is ap-
parently associated with their ability to swim or crawl.
Partial wall-like partitions are called septa and extend
lengthwise or crosswise into the protoplast. They appear
as coarser lines than the striae. On plate III Navicula shows
striae composed of punctae while Pinnularia has costae.
Both diatoms have a true raphe. In Diatoma and Synedra
on plate VIII a pseudoraphe is present. The former also
has transverse septa. Longitudinal septa are seen in the
girdle view of Tabellaria on plate VIM.
There are two major groups of diatoms, those circular
in valve view, with radiating striae, and those elongate in
valve view, with striae that tend to be transverse. The
former are known as centric diatoms, and the latter as the
pennate diatoms. On plate VIII Cydotella and Me/os/ra
-------
Identification
11
are centric in form while Nav/cu/a and Cymbella are of
the pennate type.
SPECIALIZED PARTS OF MULTICELLULAR ALGAE
The shape of the end of a filament is an important diag-
nostic characteristic. The end cells may be essentially the
same as other cells of the filament, or there may either
be a gradual or an abrupt decrease in width (attenuation)
to a point or even to a long spine or hair. On plate II,
Cladaphora and Lyngbya have terminal cells essentially
like others in the filaments while Stigeoclonium shows
gradual and Bulbochaete, abrupt attenuation. Some of
the filaments of blue-green algae have terminal cells
which are swollen (capitate) or covered with a thick, cap-
like or conical membrane (calyptra). These are present in
Osdllatoria on plate III and Phormidium on plate II.
Some multicellular blue-green algae also have occasional
special cells associated with the normal ones. One type,
the heterocyst, generally is swollen, has a clear, color-
less protoplast, and a thick wall with a knob-like thicken-
ing on the inside at the place or places where the cell is
connected to the adjacent cell or cells. Heterocysts are
shown in Anabaena and Aphanizomenon on plate VII.
Another specialized cell, the resting spore (akinete), is
swollen, has a dense, granular protoplast and a thick wall.
It is illustrated in /Anabaena on plate VII and Cylindro-
spermum and Nodularia on plate I.
A number of other specialized cells may be encoun-
tered in some of the algae, but these are too varied or too
infrequently found to be dealt with here in detail. Many
are reproductive cells (figs. 24-27). In some forms the
sexual reproductive cells must be present before identi-
fication of particular species can be made. These struc-
tures are well described in other references (1,2).
A peculiar type of branching of filaments found in cer-
tain blue-green algae requires explanation. It is called
false branching and is formed when a thread of cells splits
crosswise. One or both segments break through the sur-
rounding sheath at this point and a portion moves out to
the side of the original thread, thus giving the appearance
of branching. False branching is evident in To/ypothr/x
on plate II, while normal or true branching is shown in
Audouinella and Chaetorphora on plate II, and a blue-
green alga in Nostochopsis (fig. 28).
MEASUREMENTS
In some instances it is necessary to know the diameter
or the length and width of the algal body (thallus) or of
the individual cells before species belonging to the same
genus can be distinguished. The unit of measurement is
the micron, designated by the Creek letter ^. It is one
one-thousandth of a millimeter or approximately one
twenty-five thousandth of an inch. A linear scale on a
glass disc (ocular micrometer) which can be placed on the
interior shelf (diaphragm) of a microscope eye piece
(ocular) can be calibrated in microns with the aid of a
stage micrometer. The ocular micrometer can then be
used to obtain measurements of algae. A Whipple microm-
eter, used in plankton counting, can also be calibrated
in microns and thus serves in a similar manner.
TYPICAL DESCRIPTIONS OF ALGAE
A few examples of descriptions of algae adequate for
their identification are given below as an indication of
the information which would need to be obtained by
microscopic observation before attempting to determine
the genus and species name of the specimen.
Example No. 1: See Chlorella on plate VIII. Unicellular
or in loose irregular colonies; cell spherical; no outer
matrix; no projections or markings on the wall; protoplast
with one cup-shaped, green plastid, filling most of the
cell; one prominent pyrenoid in side or base of plastid;
no great variation in size of cells; diameter of cells 3-5
microns.
Example No. 2: See Phormidium on plate II. Short cy-
lindrical cells in simple filaments which are aggregated to
form a mat, with formless gelatinous matrix between
them; ends of filaments rather abruptly attenuate, bent,
capitate, and with a conical calyptra; protoplasts homo-
geneous, blue-green throughout, no plastids; no hetero-
cysts or akinetes.
Example No. 3: See Fragilaria on plate I. Numerous
cells united side by side into a ribbon; contact of adjacent
cells is continuous from one end of cell to the other; cells
with fine transverse striations in the wall but absent in a
wide band across the center; pseudoraphe present, septa
absent; valve view narrowly elliptical but with sides paral-
lel much of the way; end capitate; girdle view rectangular;
protoplast with two brown linear plastids, one on each
side; cell length, 25-100 microns.
Example No. 4: See Chrysococcus on plate III. Unicel-
lular; protoplast with two brown lateral plastids and an-
terior red eye spot; protoplast surrounded by a brown
spherical lorica with internal swelling at posterior end and
an opening surrounded by a thickened ring at anterior end
through which extends one flagellum that is about twice
as long as the lorica; cell very small, diameter of lorica 6
microns.
USE OF KEY FOR IDENTIFICATION OF ALGAE
In order to use the key, first observe the specimen and
determine its essential characteristics. Referring to the
key, lines 1a and 1b at the beginning are then com-
pared to one another and with the essential characteristics
of the specimen. At the end of the line which agrees with
the specimen is a number. Turn to the place in the key
where this same number is listed on the left hand side of
the page and is divided into lines a and b. Repeat the
above process and continue until a name for the alga
rather than an additional number is given at the end of
the line. Thus, in determining the name of Example No.
1 above, lines from the key are selected until line 334b is
reached, giving the species name for the alga. The appro-
priate lines are as follows: 1b, 2b, 3b, 262b, 263b, 268b,
269b, 276b, 278b, 297b, 298b, 299b, 307b, 308b, 311b,
315b, 317b, 318b, 325b, 326b, 328b, 329b, 330b, 331 b,
332b, 333b, 334b (Chlorella pyrenoidosa).
-------
12
ALCAE AND WATER POLLUTION
Figure 19.—Microcoleus paludosus, showing a single thread and a
group of threads surrounded by a sheath, under high and low
magnification.
Figure 25.—Enlarged terminal reproductive cells on filaments of
Audouinella violacea.
Figure 20.—Scenedesmus
quadricauda, showing
spine-like extensions on the
terminal cells.
Figure 26.—Terminal cells
specialized for sexual
reproduction in Vaucheria
arechavaletae.
Figure 21.—Lateral flagella in
Merotrich/a cap/fata.
Figure 22.—Anterior flagella
on cells of Pleodorina
illinoisensis.
Figure 27.—Thick-walled zygospores formed during sexual reproduction
in Zygnema normani.
Figure 23.—
Posterior and
lateral views of
anterior flagella
on Con/urn
soc/a/e.
Figure 24.—Two spore-
producing cells on filaments
of Trentepohlia aurea.
Figure 28.—True branching in the blue-green alga, Nostochopsis
lobatus.
-------
Identification
13
When a name has been reached in the key, reference
can then be made to illustrations and descriptions of that
particular genus or species in this and other manuals to
determine whether the specimen seen under the micro-
scope is correctly identified. Three manuals on algae in
water supplies have been published abroad, one in Dan-
ish (20), one in Japanese (21), and one in German (22).
TABLE 1.
COMPARISON OF THE FOUR MAJOR CROUPS OF ALGAE
IN WATER SUPPLIES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
REFERENCES
Suggested classification of algae and protozoa in sanitary science.
C. M. Palmer and W. M. Ingram. Sewage and Indust. Wastes
27:1183-1188. 1955.
The fresh-water algae of the United States. Ed. 2, C. M. Smith.
McGraw-Hill, N.Y., 719 p. 1950.
A treatise on the British freshwater algae. New and revised ed.
G. S. West and F. E. Fritsch. Univ. Press, Cambridge, England,
534 p. 1927.
Revision of the coccoid Myxophyceae. F. Drouet and W. A. Daily.
Butler Univ. Bot. Stud. 12:1-218. 1956.
The Characeae of Indiana. Fay K. Daily. Butler Univ. Bot. Stud.
11:5-49. 1953.
Nomenclatural changes in two genera of diatoms. Ruth Patrick.
Notulae Naturae, Acad. Natural Sci. Philadelphia, No. 28, 11 p.
1939.
Synopsis of North American Diatomaceae. Part II, Naviculatae,
Surirellatae. C. S. Boyer. Proc. Acad. Natural Sci. Philadelphia
79:229-583. 1927.
The genus Euglena. Mary Gojdics. Univ. Wis. Press, Madison,
Wise., 268 p. 1953.
The algae of Illinois. L H. Tiffany and M. E. Britton. Univ. Chicago
Press, Chicago, III., 407 p. 1952.
A preliminary study of the algae of northwestern Minnesota. F.
Drouet. Proc. Minnesota Acad. Sci. 22:116-138. 1956.
Algae of the western Great Lakes area. G. W. Prescott. Cranbrook
Inst. Sci., Bloomfield Hills, Mich., Bull. 31, 946 p. 1951.
Bacillariophyta (Diatomeae). F. Hustedt. Heft 10 in A. Pascher,
Die Susswasser-Flora Mitteleuropas. Gustav Fisher, Jena, Germany,
466 p. 1930.
The marine and fresh-water plankton. C. C. Davis. Mich. State
Univ. Press, East Lansing, Mich., 562 p. 1955.
Revision of the classification of the Oscillatoriaeceae. F. Drouet.
Monograph 15, Acad. Natural Sci. Philadelphia, 370 p. 1968.
Revision of the Nostocaceae with cylindrical trichomes. F. Drouet.
Hafner Press, Riverside, N.J., 256 p. 1973.
Algae of importance in water supplies. Plans for a manual with keys
and color plates. C. M. Palmer and H. J. Walter. News Bull., Phy-
cological Soc. Amer. 7 (No. 21):6-7. 1954.
Algae of importance in water supplies. C. M. Palmer and C. M.
Tarzwell. Public Wks. Mag. 86 (No. 6):107-120. With 6 color plates.
1955.
Algae of Marion County, Indiana. A description of thirty-two
forms. C. M. Palmer. Butler Univ. Bot. Stud. 2:1-21. 1931.
Additional records for algae, including some of the less common
forms. C. M. Palmer. Butler Univ. Bot. Stud. 5:224-234. 1942.
Dansk Planteplankton. G. Nygaard. Gyldendalske Boghandel Nor-
disk Forlag, Copenhagen, Denmark, 52 p. 1945.
The easy classification of important microorganisms in Japanese
water supplies. S. Kawakita. Jour. Japanese Waterwks. and Sew-
erage Assn., Nos. 251, 253, 257, 258, 263, 265. 1955-56. (In
Japanese.)
Das Phytoplankton des Susswassers. G. Huber-Pestalozzi. Band 16,
Teil 1-4. In Die Binnengewasser by A. Thienemann. E. Schweizer-
bart'sche Verlagsbuchhandlung, Stuttgart, Germany. 1938-55.
Algae groups
Characteristics
Color
Location of
pigment
Starch
Slimy
coating
Cell wall
Nucleus
Flagellum
Eye spot
Blue-green
algae
Blue-green
to brown
Throughout
cell
Absent
Present
Inseperable
from slimy
coating
Absent
Absent
Absent
Green algae
Green to
yellow-green
In plastids
Present
Absent
in most
Semirigid
smooth or
with spines
Present
Absent
Absent
Diatoms
Brown to light
green
In plastids
Absent
Absent
in most
Very rigid,
with regu-
lar marking
Present
Absent
Absent
Pigmented
flagellates
Green or
brown
In plastids
Present or
absent
Present or
absent
Thin, thick
or absent
Present
Present
Present
TABLE 2. ALGAE IN WATER SUPPLIES: A LIST OF THE MORE
IMPORTANT SPECIES
Key to Columns:
1. Alga name.
2. Croup: D, diatom; G, green; BG, blue-green; YG, yellow-green;
B, brown; R, red; Fl, flagellate; De, desmids.
3. Significance: A, attached; C, clean; E, eutrophication; F, filter;
I, indicator; PE, pollution, estuarine; PF, pollution, fresh; PI
plankton of lakes; SP, sewage pond; St, stream; T, taste and odor.
4. Plate number or figure number.
Achnanthes: D 59
lanceolata
microcephala II
minutissima
Achnanthidium breviceps var. intermedia D
Acrochaetium thuretii R PE
Acrochaetium virgatulum PE
Actinastrum: G E,PI,SP,St 33
gracillimum PI
hantzschii PF,PI
Agardhiella tenera R PE V
Agmenellum: CB E,SP,St
quadriduplicatum C,PF III,IV,9
Amphidinium fusiforme Fl PE V
Amphiprora alata D
Amphora: D
acutissima PE
ovalis C
Anabaena: BG E,SP,St,T 30
circinalis T
constricta PF IV,13
flos-aquae F,Pl VIII
planktonica T VII
Anabaenopsis BG SP
Anacystis BG E,l,Sp,St 29
cyanea I,T,PI Vll,8
dimidiata F VIII
montana A,PF IV
thermalis PI
Ankistrodesmus: G E,l,SP,St
falcatus PF,PI,SP Vl,35
var. acicularis C III
Anomoeoneis exilis D
Aphanizomenon flos-aquae BG E,SP,St,T VII
Apicoccus G SP
-------
14
ALGAE AND WATER POLLUTION
1
Arthrospira jenneri
Asterionella:
formosa
gracillima
japonica
Audouinella violacea
Bacillaria paradoxa
Batrachospermum:
moniliforme
vagum
Biddulphia laevis
Botryococcus braunii
Bulbochaete:
insignis
mirabilis
Caloneis
Calothrix:
braunii
parietina
Carteria multifilis
Ceramium
Ceratium hirundunnella
Chaetoceros decidiens
Chaetophora
Chaetomorpha area
Chaetopeltis megalocystis
Chaetophora:
attenuata
elegans
Chara:
globularis
vulgaris
Characium
Chlamydomonas:
globosa
pertusa
reinhardi
Chlorella:
ellipsoidea
pyrenoidosa
vulgaris
Chlorococcum humicola
Chlorogonium:
elongatum
euchlorum
Chodatella quadriseta
Chromulina:
rosanoffii
vagans
Chroomonas:
caudata
nordstetii
setoniensis
Chrysamoeba
Chrysidiastrum
Chrysococcus:
major
oval is
refescens
Chrysosphaerella longispina
Cladophora:
aegagropila
crispata
f racta
glomerata
insigms
profunda var. nordstedtiana
Closteridium
Closteriopsis brevicula
Closterium:
acerosum
aciculare
actum
minoliferum
Coccochloris stagnina
2
.... BC
.... D
.... R
.... D
.... R
.... D
.... G
.... G
.... D
.... BG
.... Fl
.... R
.... Fl
.... D
.... G
.... G
.... G
.... G
.... G
.... G
.... Fl
.... G
.... G
.... Fl
.... G
.... Fl
.... Fl
.... YG
.... YG
YG
.... Fl
C
G
G
De
BG
3
E,PF,SP
E
E,F
T
PE
A
St
A
C
PI
A
C
St
E,SP
A
C
I,PF
E
E,F,PI,T
PE
ST
PE
C
A
A
A
T
SP
l,PE,SP,St,T
T
SP
PF
l,E,SP,St
PI
F,PF
PF
PF,SP,St
SP
PF
PF
SP,St
SP,St
C
SP
PE,SP
SP
C
C
SP
E
St
C
C
C
T
A,E,SP,St
F
A
PI
A,C
T
A
SP
SP
E,l,SP,St
PF
PI
SP
F
C
4
IV
37
VIII
VII
V
ll,25
II
I
II
44
lll,48
IV
VII
V
V
II
II
60
VI
VI
VIII
IV
IV
IV,69
VI
III
VI
VI
III
II
III
VI
62
VI
VIII
III
i
Cocconeis:
pediculus
placentula
Codium fragile
Coelastrum microporum
Compsopogon coeruleus
Coscinodiscus:
denarius
rothii
Cosmarium:
botrytis
portianum
Crucigenia quadrata
Cryptoglena pigra
Cryptomonas:
cylindrica
erosa
Cyanomonas
Cyclotella:
atomus
bodanica
comta
glomerata
kutzingiana
meneghiniana
ocellata
pneudostelligera
stelligera
striata
Cylindrospermum:
musicola
stagnate
Cymatopleura solea
Cymbella:
cesati
prostrata
pusilla
tumida
turgida
ventricosa
Denticula wipplingeri
Dermocarpa
Desmidium grevillii
Diacanthos belenophorus
Diatoma:
anceps
elongatum
vulgare
Dichotomosiphon tuberosus
Dictyosphaerium:
ehrenbergianum
pulchellum
Dinobryon:
divergens
sertularia
sociale
stipitatum
Dimorphococcus lunatus
Diploneis smithii
Dispora
Draparnaldia:
glomerata
plumosa
Dunaliella
Elakatothrix gelatinosa
Enteromorpha intestinalis
Entophysalis lemaniae
Epithemia:
sorex
turgida
Euastrum oblongum
Eudorina elegans
Euglena:
acus
agilis
2
D
G
G
R
D
De
G
Fl
Fl
Fl
D
BG
D
D
D
BG
De
G
D
G
G
Fl
G
D
G
G
Fl
G
G
BG
D
De
Fl
Fl
3
l,St
A
C,PF
PE
E,PF,PI,St
A
PE
PI
PI
E,SP
SP
T
Pl,SP,St
PF
SP,T
SP
PF,T
SP
E,l,SP,St
PI
C
PI,T
PI
PI
F,PF
PI
PI
PI
PI
T
PI
PI,SP
SP,St
C
A
PE
PI
PI
F
PE
SP
PI,SP
SP
E
PI
St
F,PF,PI,St
A,F
SP,St
SP,T
F,PI
SPJ
PI,T
F
PI
C
A
St
SP
St
A
C
PE,SP
SP
A,SP,PE
C,l
SP
PI
A
C,PI
Pl,PF,SP
E,l,St,SP
PF
PF
4
III
V
1
11,18
VI
60
VI
37
III
VIM
I
It
VIII
I
VI
VIII
VI
60
VII
VIM
II
VI
45,V
III
I
I
58,60
-------
Identification
15
1
deses
ehrenbergii
gracilis
oxyuris
polymorpha
sangumea
spirogyra
viridis
Eunotia:
lunaris
pectinalis
Eutreptia:
lanowii
viridis
Fragilaria:
brevistriata
capucina
construens
crotonensis
leptostauron
pinnata
Frustulia vulgaris
Clenodinium palustre
Cloeocystis:
g'gas
planktonica
Cloeotrichia:
echinulata
natans
Colenkinia radiata
Gomphoneis
Gomphonema:
geminatum
olivaceum
parvulum
Gomphosphaeria:
aponina
lacustris
Gonium pectorale
Gynodinium
Gyrosigma:
attenuatum
kutzingii
Haematococcus
Hantzschia amphioxys
Hemidinium
Heterocapsa
Hildenbrandia rivularis
Hyalotheca mucosa
Hydrodictyon reticulatum
Hydrurus
Johannesbaptistia
Katodinium
Kirchneriella:
lunaris
subsolitaria
Lemanea annulata
Lepocinclis:
ovum
texta
Lyngbya:
aestuarii
digueti
lagerheimii
ocracea
putealis
versicolor
Mallomonas caudata
Massartia vorticella
Melosira:
ambigua
binderana
crenulata
distans var. alpigena
granulata
2
D
Fl
D
D
Fl
G
BG
D
D
BG
Fl
Fl
D
Fl
D
Fl
Fl
R
De
G
VG
BG
Fl
G
R
Fl
BG
Fl
Fl
D
3
PF
C
PI,PF
PI
PF
T
C
PF
PI
PI
PI
PE
I
PE
E,SP
PI
PI
T
E,PI,St,F
PI
PI
PI,SP
E,SP,St,T
E,SP
A
T
F
PI
PI,SP,St
PI
l,SP,St
A
A,St
I,PE,PF
E,SP
PI
PJ,A
PI,SP
PE,SP,St
E
C,PI
PI
SP
PF,SP
SP
PE
c,st
PI
A,E,T,F
C
SP
PE
SP
PI
I
c,st
l,SP,St
PF
PF
E,SP
A
PF
A
A
A
PI
C,PI,SP,T
SP
E,l
PI,St
PI
PI
PI
F,Pl,PF,St
4
I
IV
V
37
I
VIII
36
VI
II
IV
VII
23,60
II
III
Vll,2
17
III
IV
63
IV
II
VII
VI
37,56
VIII
1
granulata var. angustissima
islandica
italica
sulcata
varians
Meridion circulare
Micractinium pusillum
Micrasterias truncata
Microcoleus subtorulosus
Microspora:
amoena
wittrockii
Mougeotia:
genuflexa
scalaris
sphaerocarpa
Nannochloris atomus
Navicula:
accomoda
canalis
confervacea
contenta
cryptocephala
exigua var. capitata
graciloides
hartii
hungarica
incomposita
lanceolata
mutica
notha
radiosa
sydowii
tripunctata
viridula
Nitella:
flexis
gracilis
Nitzschia:
acicularis
amphibea
closterium
denticula
dissipata
fonticula
holsatica
hungarica
linearis
palea
parvula
sigma
sigmoidea
tryblionella
Nodularia spumigena
Nostoc:
carneum
pruniforme
Ochromonas
Oedogonium :
boscii
grande
idioandrosporum
suecicum
Olithodiscus
Oocystis:
borgei
lacustris
Ophiocytium capitatum
Oscillatoria:
agardhii
amphibia
chalybea
chlorina
curviceps
2 3
PI
PI
E,Pl
PE
F,PF
.... D C
.... G E,I,PF,PI,
St,SP
.... De C
.... BG C,PE
. . . . G SP
A
A
.... C A,E
PI
PI
F
.... G PE,SP
.... D E,l,PE,SP,St
I
PI
PI
PI
PF
C
T
PE
PI
PI
F
PI
PI
PI
PE
PI
PF
.... G
A
T
.... D E,l,SP,St
PF
PI
PE
PI
PI
PI
PI
PI
A,C
A,I,PF,F
PI
PI
PF,PI
PI
. . . . BG PI
.... BG
PI
A
. . . . Fl SP
.... G A,I,SP
A
A
PI
A
Fl PE
G E,SP,St
PI
PI
G PI
BG E,l,SP,St
PI
A,F
A,F,PF
PF
T
4
V
III
I
III
111,19
II
I
V
VIII
VII
V
IV
1,64
46
II
32,12
I
31
VIII
IV
-------
16
ALGAE AND WATER POLLUTION
1
formosa
lauterbornii
limosa
ornata
princeps
pseudogeminata
putrida
rubescens
splendida
tenuis
Ourococcus bicaudatus
Palmella mucosa
Palmellococcus
Pandorina morum
Pediastrum:
boryanum
duplex
tetras
Pedinopera
Pelvetia fastigiata
Peridinium:
cinctum
triquetum
trochoideum
wisconsinense
Phacotus lenticularis
Phacus:
longicauda
pleuronectes
pyrum
Phormidium:
autumnale
inundatum
retzii
subfuscum
uncinatum
Phytoconis botryoides
Pinnularia:
nobilis
subcapitata
Pithophora oedogonia
Planktosphaeria
Plectonema tomasiniana
Pleodorina
Pleurogaster
Pleurosigma:
delicatulum
salinarum
Polyedriopsis spinulosa
Polysiphonia
Porphyra atropurpurea
Prasiola:
nevadense
stipitata
Prorocentrum
Fteromonas angulosa
Pyrobotrys:
gracilis
stellata
Raphidiopsis
Rhizoclonium hieroglyphicum
Rhizosolenia:
eriensis
gracilis
Rhodoglossum affine
Rhodomonas lacustris
Rhoicosphenia curvata
Rhopalodia:
gibba
musculum
Rivularia:
dura
haematites
Sacheria ,
2
.... G
.... G
.... C
.... Fl
.... F
.... Fl
.... B
.... Fl
.... Fl
.... Fl
.... BG
.... G
.... D
.... G
.... G
.... BG
.... Fl
.... YG
.... D
.... G
.... R
.... R
.... G
Fl
.... Fl
.... Fl
.... BG
.... G
D
R
Fl
D
D
BG
R
3
PF
PF
PF
F
A,F,PF
F
PF
F,I
F,PF
A,PF
SP
A,F,SP
SP
E,I,PI,SP,T
E,SP,St
PF,PI
PI
T
SP
PE
T
1
PE
F
c,st
l,SP,St
C
PF,PI
PF
A,F,I,SP,ST
PF
A,C
A, PI
A
A,PF
A,E
SP
C
C
A
SP
PI
SP
SP
PI
PI
PE
SP
PE
PE
A
A
PE
PE
SP
SP
PF
PF
SP
A,C,St
PE
PI
PI
PE
C,SP
A
PI
PE
E
F
T
St
4
IV
50
Vlll,52
IV
VIII
51
VI
VIII
Vll,57
1,6
68
V
55
VII
V
III
1
IV
IV
11,53
11,10
III
41
VI
22
VI
V
V
V
VI
IV
111
37
V
III
Vltl
1
Scenedesmus:
abundans
bijuga
dimorphus
obliquus
quadricauda
Schizomeris leibleinii
Schizothrix calcicola
Schroederia setigera
Scytonema tlypothricoides
Scytosiphon lomentaria
Selenastrum:
capricornutum
gracile
Sirogonium
Skeletonema costatum
Sphaerellopsis
Sphaerocystis schroeteri
Spirogyra:
communis
fluviatilis
majuscula
porticalis
varians
Spirulina:
major
nordstedtii
subtilissima
Spondylomorum quaternarium
Staurastrum:
paradoxum
polymorphum
punctulatum
Stauroneis phoenicenteron
Stephanodiscus:
astraea
astraea var. minutula
binderanus
dubius
hantzschii
niagarae
niagarae var. magnifica
tenuis
Stephanoptera gracilis
Stichococcus:
bacillaris
marinus
Stigeoclonium:
lubricum
stagnatile
tenue
Stigonema minutum
Surirella:
angustata
brightwellii
ovata
splendida
striatula
Symploca muscorum
Synedra:
acus
var. angustissima
var. radians
capitata
hartii
nana
pulchella
tabulata
ulna
vaucheriae
Synura uvella
Tabellaria:
fenestrata
flocculosa
Tetradesmus
2
.... G
.... G
.... BG
.... G
.... BG
.... B
.... G
.... G
.... D
.... Fl
.... G
.... G
.... BG
.... Fl
.... De
.... D
.... D
.... Fl
.... G
.... G
.... BG
.... D
.... BG
.... D
.... Fl
.... D
.... G
3
E,l,SP,St
T
PI
P,SP
PF
PF,Pl
A
SP
PI,SP
PI
PE
I,SP
I
PI
A
PE
SP
E,PI,SP
A,E,SP
PF
PI
T
F
PI
E,SP
A,PE
PI
SP
PF
E,SP,St
T
PI
C
PI,SP
E
E
PI
F
PI
F,PF,PI,St
T
PI
PI
PE
SP
PF
PE
A,l,SP,St
A
PI
I,PF
A
E,SP,St
PI
PI
PF
C
PI
T
E,l,SP,St,T
F,PF
C
F
PI
PE
PI
F
PE,PI
PF,T
PI
PI,PF,T
E,F,St,T
F,T
F
SP
4
34
VI
67
1
41
VI
VI
V
V
I
3,4
IV
VIII
V
VI
VII
III
I
I
V
V
47
II
IV
42
III
13
37,55
VIII
VII
VII
37
VII
VIII
-------
Identification
17
Tetraedron: G SP
limneticum PI
muticum PF IV
Tetraspora gelatinosa G A,St 11,43
Tetrastrum G SP
Thorea ramosissima R A
Tolypothrix tenus BG A II
Trachelomonas crebea Fl F,SP,St Vlll,66
Tribonema: YG E
bombycinum F VIII
minus PI
Trichodesmium erythraeum BG PE V
Ulothrix: G E,SP,St
aequalis C 111
tenerrima PI
variabilis F
zonata A,C,PF 11,49
Ulva lactuca G PE V
Uroglenopsis americana Fl SP,T Vll,60
Vacuolaria novo-munda Fl SP VI
Vaucheria: G A,F,St 26
geminata A,C 38
sessilis A 11,39
terrestris PI
Volvox aureus Fl E,PI,T VII
Zoochlorella G SP
Zygnema: G A,SP 27
insigne F
pectinatum PI
sterile PI I
TABLE 3. RECENT CHANGES IN NAMES OF ALGAE
Old name
New name
Old name
New name
Aphanocapsa
Aphanothece
Chamaesiphon
Chamaesiphon incrustans
Chantransia
Anacystis
Coccochloris
Entophysalis
Entophysalis lemaniae
Audouinella
Chara fragilis
Chlamydobotrys
Chroococcus
Chroococcus limneticus
Chroococcus turgidis
Clathrocystis
Coelosphaerium
Coelosphaerium kuetzingianum
Coelosphaerium naegelianum
Encyonema
Encyonema paradoxum
Euglena pisciformis
Cloecapsa
Gloecapsa conglomerata
Gloeothece
Cloeothece linearis
Comphosphaeria naegeliana
Holopedium
Lagerheimia
Merismopedia
Merismopedia glauca
Merismopedia tenuissima
Microcystis
Microcystis aeruginosa
Odontidium
Oedogonium crassiusculum var.
idioandrosporum
Polycystis
Polycystis aeruginosa
Protococcus
Protococcus virdis
Sphaerella
Spirulina jenneri
Synechococcus
Synedra delicatissima
Chara globularis
Pyrobotrys
Anacystis
Anacystis thermalis
Anacystis dimidiata
Anacystis
Gomphosphaeria
Gomphosphaeria lacustris
Gomphosphaeria wichurae
Cymbella
Cymbella prostrata
Euglena agilis
Anacystis
Anacystis montana
Coccochloris
Coccochloris peniocystis
Gomphosphaeria wichurae
Microcrosis
Chodatella
Agmenellum
Agmenellum quadriduplicatum
Agmenellum quadriduplicatum
Anacystis
Anacystis cyanea
Diatoma
Oedogonium idioandrosporum
Anacystis
Anacystis cyanea
Phytoconis
Phytoconis botryoides
Haematococcus
Arthrospira jenneri
Coccochloris
Synedra acus var. radians
-------
CHAPTER IV
ALGAE IN STREAMS
A stream affects its algal flora in a number of ways which
are different from lakes. The flow of water in a stream is
constantly subjecting any area to a passing mass of water
causing all ingredients to be resupplied to that area from
the water upstream. Turbulence in a stream is almost al-
ways sufficient to prevent the formation of stratification
such as we find in lakes. This is one of the most important
differences between a stream and a lake. Even when a
river is deep, there tends to be a condition of complete
circulation (1). The stream bottom affects the condition
of the water constantly and in many ways. It is releasing
or receiving materials from the water, including silt, min-
erals, alkalies, acids, nutrients, and living or dead organ-
isms or organic debris. The exchange of materials varies
with the geologic nature of the bottom, the depth and rate
of flow of the water, the temperature, and other factors. A
stream also contains a mixture of the waters from its trib-
utaries, which may often be quite different from one an-
other. Contours of the stream channel change from place
to place; shallow flowage and backwater alternate with
swift water and with deep pools. Current velocities vary.
Different geological formations may follow one another in
quick succession. Clean, hard bottoms may give way to
soft mud deposits and vice versa. Wastewaters from hu-
man habitations and industries bring about sudden and
often catastrophic changes. Stream levels rise and fall ac-
cording to the amount of rainfall (2). Thus, conditions in
a stream tend to be very unstable at any location, in this
way also making it different from a lake.
Streams are rarely entirely destitute of raw materials, as
may be the case in some lakes, and probably on the whole
are better supplied with nitrogenous compounds (3).
Streams undefiled by anything other than natural enrich-
ment will contain at most only a few ppm of CO2. This is
one of the reasons why they fail to develop large crops of
algal growths (2). There is little correlation between the
seasonal flux in chemical conditions and the seasonal con-
dition of plankton production.
Stream temperature affects plankton profoundly. Below
45°F the plankton content of the Illinois River falls to about
9 percent of that present at higher temperatures. Light is
as important in streams as it is in lakes, but light in streams
may more often be reduced due to greater turbidity. Tur-
bidities of more than 30 ppm are high enough to cut off
sunshine almost completely except for a shallow layer very
close to the surface (2). Although some plankton occur
even in very muddy streams, turbidity usually seems to be
the major limiting factor in algal growth (4). Wind action
appears to be of little significance in streams. Area and
depth of a stream show little relation to plankton produc-
tion (2). Speed of the current and the nature of the bot-
toms are the factors which most affect the plants and
animals of a stream. But for most organisms, small, local
variations, such as the difference in the current at the
edge and in the middle of the stream, are more important
than the general condition (5).
Attached algae in fast currents take full advantage of
the water in their reproduction. Due to the mixing caused
by the current, these algae are able to disperse their re-
productive units into a high percentage of rock fissures,
cracks, scratches, and roughened areas to permit subse-
quent growth from the colonizing cells to cover almost all
of the available surfaces. Comphonema olivaceum and
D/atoma vulgare are examples of diatoms that can quickly
spread to additional rock surfaces, especially during the
cold water period from late November to early April (6).
The complete stream has three horizontal areas:
1. The upper or mountain course, with swift current,
especially after a rain. Stones are rolled along the bottom.
Its valley is V-shaped, with unstable banks. However,
some streams may arise instead from springs, lakes, or
from drainage of low-lying land.
2. The middle course is located over the foothills. It
has lost some of its velocity but is still rapid enough to
carry sand, silt, and mud in suspension and to roll pebbles.
Its main work is transportation. Its valley has a broad,
open section, stable sides, and less erosion than in the
first area.
3. The lower course meanders lazily over a plain. It
has lost much of its velocity and much of its power of
transportation. It lays down part of its load as beaches,
sand banks, and large flat plains of deposition, spreading
aluvium over a wide flood plain or delta (5).
The algae, especially of swift running streams, are more
distinctive than those of any other type of aquatic habitat
and include a larger percentage of genera and species
restricted to that particular habitat (7). In swift water the
characteristic algae are those with holdfast cells or similar
structures. The freshwater red algae Lemanea and Sachena
grow in rapid torrents and waterfalls. Batrachospermum
develops attached in cool, slightly alkaline, rapid waters
of small streams. The most common attached alga in
temperate zone streams is Cladophora, often extending
many feet with the current. In very shallow waters flow-
ing from springs, Vaucheria grows attached, forming large
mats. Tetraspora, Draparnaldia, and Chaetophora are com-
mon early spring forms in rapidly moving waters which
are well supplied with nitrogen and phosphorus com-
18
-------
Algae in Streams
19
pounds (3). In this rushing water of the rapids, the stones
are thickly overgrown with mosses and algae. Diatoms
which attach themselves to stones by means of gelatinous
masses or stalks include Achnanthes, Cocconeis, Cymbella,
and Comphonema (8). Stones in lakes, on the other hand,
exhibit much smaller growths (1). Other algae without
holdfast cells may be present on various substrata, in spite
of the current, due to copious secretion of mucus in which
the cells are imbedded. Attached and unattached des-
mids, diatoms, blue-green and green algae are often pres-
ent (3). Thus, in the swift current are found encrusting
algae such as Hildenbrandia, attached algae in which the
greater part projects into the current, and algal forms held
in place by the mucus (7).
During the winter, ice is responsible for scouring at-
tached algae from rocks and other bottom materials. An-
chor ice may form in the beds of rapid streams. The sur-
face water may not freeze because of its motion, but freez-
ing may occur on the bottom where the current is re-
tarded. It congeals in semi-solid flocculent masses which,
when attached to the stones, often bring them up and
cause them to be carried away. Thus, the organisms in
the stream bed are deprived of their shelter and exposed
to new perils (9).
The algae of areas of slower current are for the most
part unattached forms behaving as planktonic algae. These
are, in general, distinct from those of ponds and lakes and
are often designated by the terms potamoplankton or
rheoplankton (3). Since the possibilities of a good seed
bed are more remote than in lakes and ponds, the streams
depend upon their tributaries, backwaters, and ox-bows
for the source of most of their plankton. The plankton
that has become entirely adapted to river conditions is
much less rich in species than is the truly limnetic plank-
ton. The multiplication of the algal constituents, whatever
the source, may take place as they are carried downstream.
In general the less rapid the stream the greater the number
of plankton. Slow-moving areas in streams may often be
covered with blooms in summer, in many instances, uni-
algal growths of Chlamydomonas, Euglena, diatoms, or
blue-green algae (3). Unattached, filamentous algae may
form mats or blankets.
The current is slower at the bottom, around stones, and
along the sides of the stream. Many algae increase in
these areas of slow current, and some of them move into
the area of faster current (9). In lakes and ponds the algae
for the most part are ones not found in the benthos. In
streams there is a greater variety of microscopic organisms
in the littoral environment than in the channel proper.
The areas adjacent to the shores do not have any uni-
formity of plankton. Even here the ever-changing cross-
section of a stream does not permit the development of
as characteristic a littoral flora and fauna as is found along
the shores of lakes and reservoirs (2).
The stream plankton is thus seeded with a great range
and variety of organisms. It is not characterized by any
species peculiar to it, nor by any precise assemblages of
eulimnetic organisms. It is subject to extreme fluctuations
in quantity and constitution. The plankton production ap-
pears to exhibit a series of recurrent pulses which vary
from 3 to 5 weeks in duration (2).
Normally, most of the growth of algae in the stream is
planktonic. The planktonic organisms are usually dom-
inated by rotifers and diatoms. There is a marked ten-
dency of green algae and blue-green algae to appear in the
warm months. When streams are enriched, certain types
of algae tend to occur in great abundance. These in-
clude Stigeodonium, Cladophora, Ulothrix, Rhizodonium,
Osdllatoria, Phormidium, Comphonema, Nitzschia, Navi-
cula, and Surirella, all of which may be found in unen-
riched streams but far less abundantly. We do not know
why these particular genera are encouraged while others
are not. Cladophora growths appear to be stimulated by
the addition of phosphate to the water (4).
In the United States, the Southeast, the Northeast, the
Southwest, and the upper and lower Mississippi River each
have their characteristic diatom floras. Many individual
rivers have characteristic plankton. Diatoms found in large
numbers in all major drainage basins of the United States
are Diatoma vulgare, Fragilaria crotonensis, Melosira am-
bigua, Melosira granulata, and Stephanodiscus hantzschii.
Astereonella formosa and Diatoma elongatum become
abundant during cold water seasons. Other common dia-
toms of streams would include Achnanthes, Ca/one/s,
Cocconeis, Cyclotella, Cymbella, Diploneis, Comphonema,
Navicula, Nizschia, Surirella, Synedra, and Tabellaria. The
common blue-green algae, green algae, and pigmented
flagellates of streams would include the forms listed in
table 4 (10). Six of these algae are shown in figures 29-34.
The total number of species for any river varied from
about 70 to 140 in a study made of nine streams in the
eastern United States. The mean for all of these rivers was
84, for the soft water ones, 89, and the hard water ones,
78. Approximately 56 percent of the species were found
in only one river and 73 percent occurred in one or two
rivers. Less than 1 percent of the species occurred in all
the rivers studied (11).
The impression concerning the abundance of algae in
streams has changed in recent years. Formerly, the unat-
tached algae were considered to be so few that often they
were recorded in numbers per liter or cubic meter rather
than per ml. In such data, when converted to numbers
per ml, the algae are generally recorded as fewer than 100.
In 1957 the National Water Quality Network program was
inaugurated by the Public Health Service. Sampling sta-
tions on 16 rivers were chosen where water samples were
obtained at regular intervals for examination. The number
of sampling stations was soon increased to include other
rivers, and the program was continued for several years
(12).
Over a period of 2 years the average count was 3,625
algae per ml. April, September, and October had the high-
est counts. Some individual counts exceeded 20,000. The
five rivers with the highest average counts for the first year
were the Mississippi, Arkansas, Merrimack, Missouri, and
Columbia while the five with the lowest were the Red,
-------
20
ALGAE AND WATER POLLUTION
Figure 29.—Anacystis (Microcystis).
Figure 32.—Oocystis.
Figure 30.—Anabaena.
Figure 33.—Actinastrum.
Figure 31.—Oscillatoria (two sizes).
Figure 34.—Scenedesmus (reproducing).
-------
Algae in Streams
21
Detroit, Colorado, Savannah, and Tennessee Rivers (12).
Records compiled for the Public Health Service have been
published covering a period from October 1, 1957, to Sep-
tember 30, 1963 (13). In addition, an account of the prin-
cipal diatoms of the major waterways of the United States
has been published (14) and one on plankton population
dynamics (10).
Concern for the quality of river waters increases as the
many uses for these waters are intensified. It is necessary
to know the algal population of streams quantitatively
and qualitatively, if we are to be concerned with assessing
their value or their significance as stream purifiers, pollu-
tion indicators, or as producers of excessive growths, their
role in water treatment problems, and their function as
the primary food producers for fish. It can be important
to know the algal population of a river before any major
change is made in the use of the stream. Also, we need
to know the algal population of rivers throughout the
year and not merely for the warmer months. Determina-
tion of the effect of particular factors on the biota of rivers
will require detailed studies that should be planned for
that particular purpose (12).
REFERENCES
1. The communities of running water. F. Ruttner. In Fundamentals of
Limnology by F. Ruttner. University of Toronto Press, p. 198-210.
1953.
2. Rheology. Chapter XI in The Microscopy of Drinking Water, 4th
ed., by C. C. Whipple, C. M. Fair, and M. C. Whipple. J. Wiley &
Sons, N.Y., p. 282-312. 1948.
3. Algae of streams and rivers. Chapter V in Algae, the Crass of Many
Waters, by L. H. Tiffany. Charles C. Thomas, Springfield, III., p.
57-64. 1938.
4. The enrichment of streams. In Eutrophication: Causes, Consequen-.
ces, Correctives by H. B. N. Hynes. Proc. Symposium, National
Acad. Sci., Washington, D.C., p. 188-196. 1967.
5. Rivers. Chapter 5 in Life in Lakes and Rivers by T. T. Macan and
E. B. Worthington. Collins, London, p. 62-78. 1951.
6. The influence of water currents on the life functions of algae by
J. Blum. Ann. New York Acad. Sci. 108:353-358. 1963.
7. The algae of different types of habitat. In the Fresh-Water Algae of
the United States, 2nd ed., by G. M. Smith. McGraw-Hill Book
Co., N.Y., p. 17-26. 1950.
8. Water habitats. In The Diatoms of the United States by R. Patrick
and C. W. Reimer. Academy of Natural Sciences of Philadelphia.
Monograph No. 13. p. 39-44. 1966.
9. Streams. In The Life of Inland Waters by J. G. Needham and J. T.
Lloyd. Amer. Viewpoint Society, New York, p. 77-88. 1928.
10. Plankton population dynamics. L. G. Williams. U.S. Public Health
Publication No. 663. National Water Quality Network-Supplement
2, 90 p. 1962.
11. A study of the number and kinds of species found in rivers in East-
ern United States. R. Patrick. Proc. Acad. Natural Sciences of
Philadelphia 113:215-258. 1961.
12. Algae in rivers of the United States. C. M. Palmer. In Algae &
Metropolitan Wastes. Trans. 1960 Seminar. R. A. Taft San. Eng.
Ctr., Cincinnati, Ohio. Tech. Rept. W61-3:34-38. 1961.
13. National Water Quality Network, Annual Compilation of Data.
Public Health Service Publication No. 663, Editions: 1958, plus
Supplement; 1959, 1960, plus Supplement 2, 1961, 1962, 1963
(Water Pollution Surveillance System).
14. Principal diatoms of major waterways of the United States. L. G.
Williams and C. Scott. Limnology and Oceanography 7:365-379.
1962.
TABLE 4. COMMON ALGAE, EXCEPT DIATOMS, OF STREAMS
Blue-green algae
Agmenellum (Merismopedia)
Anabaena
Anacystis (Microcystis)
Aphanizomenon
Oscillatoria
Phormidium
Green algae
Actinastrum
Ankistrodesmus
Chlorella
Chlorococcum
Chodatella
Cladophora
Closterium
Coelastrum
Crucigenia
Dictyosphaerium
Golenkinia
Micractinium
Oocystis
Pediastrum
Scenedesmus
Staurastrum
Pigmented
flagellates
Chlamydomonas
Chromulina
Chrysococcus
Glenodinium
Gymnodinium
Lepocinclis
Phacotus
Phacus
Trachelomonas
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CHAPTER V
PLANKTON ALGAE IN LAKES AND RESERVOIRS
The water requirements of growing cities and industry
place increasing demands on surface water supplies. Al-
ready the majority of the larger communities are forced
to rely primarily on surface rather than groundwater. More
and more attention must therefore be given to both
pollution control and treatment of the water particularly
as supplies from less desirable sources have to be tapped
(1).
Reservoirs, lakes, and ponds are all normally capable of
supporting large, mixed groups of aquatic plants and ani-
mals. Algae of many kinds are included in this population.
In lakes and reservoirs the common forms would be those
found especially at or near the surface of the water where
light is present in sufficient intensity to permit the algae
to carry on their essential process of photosynthesis. The
planktonic algae are capable of growing and multiplying
while dispersed in the water and unattached to solid ob-
jects (2). Many other algae may be carried away from
the shore line and from shallow ponds to become mixed
with the true planktonic forms or to collect as mats of
growth on the surface. Some species of algae are able to
develop in abundance at depths of 10, 20, or more ft be-
low the surface.
Studies indicate that there are many very minute algae
and related organisms present in the water and that these
may often exceed in volume the larger microscopic forms.
These very minute forms are called nannoplankton, and
the smallest forms are generally missed in the routine
plankton analysis of water, in which only a low magnifi-
cation with the compound microscope is used (3). The
possible importance of these very small forms has not yet
been given much consideration.
The larger, unattached algae constitute the bulk of the
plankton counts made at many water treatment plants. As
long as the total count remains low and no taste-and-odor
algae or filter-clogging forms are present in conspicuous
numbers, the waterworks engineer assumes that he is un-
likely to have serious difficulties with the algae. A reason-
able number of various kinds of common plankton or-
ganisms indicates a balanced biological condition in his
raw water supply, implying that it will respond to water
works treatment with the minimum of trouble. If one
group, such as the blue-greens or the diatoms, or one
particular species, such as Anacystis cyanea (formerly
called Microcystis aeruginosa) or Dinobryon d/vergens, be-
gins to predominate, then he becomes alert for possible
trouble and can treat for the control of these algae before
undesirable conditions become serious. When blue-green
algae become predominant, it frequently indicates either
that the water has been enriched with organic matter or
that previously there has been a superabundance of dia-
toms. An understanding of relationships of this sort helps
in instituting measures to prevent troublesome growths
from developing (4).
In waters poor in nutrients, the factors limiting the num-
ber of algae may be the amounts of food materials avail-
able, particularly nitrates, phosphates, and, for diatoms,
silicates. Some localities are proposing to restrict algal
growths in the raw water supply by precipitating the phos-
phates as ferric phosphate. In one of the western cities a
problem developed when 20 percent of a groundwater
containing approximately 5 to 10 mg/l nitrogen as nitrate
was mixed with a relatively infertile surface supply, causing
heavy growths of the green algae, Golenkinia, Palmella,
and Scenedesmus. In England the addition of ground-
water to a reservoir caused a copious growth of the yel-
low-green alga, Tribonema. The growths of algae in some
localities have been so rank as to necessitate withdrawing
the reservoir from service. Many bodies of water are suf-
ficiently rich in the essential nutrients that these nutrients
do not become limiting factors in determining the abund-
ance of algae. Other factors such as turbidity, water tem-
perature, and parasitism may be the critical ones. Al-
though it is assumed that the chemical and physical
environment largely determines the amount of algal pro-
duction, the exact relationships remain in many respects
obscure.
BLOOMS
A number of the surface water algae have the ability to
accumulate at times in such numbers as to form loose,
visible aggregations called blooms which may cover very
large areas of lakes and reservoirs or even streams. Blue-
green algae may form these water blooms particularly
during periods of warm, calm weather, when the algae
which were previously distributed through the water rise
to the surface. Other blooms may be associated with a
rapid reproduction of a particular alga. Some water blooms
have resulted in fish kills by interfering with reaeration,
by excluding light necessary for photosynthesis in the
lower areas and thereby preventing release of oxygen in-
to the water, or by depleting the oxygen through decay or
respiration within the bloom. Some water blooms release
substances extremely toxic to fish, domestic animals, and
birds, and extensive kills have resulted in several areas (5).
A considerable number of species of algae are capable
of producing blooms. Some of the genera most frequently
involved are the blue-green algae, Anacystis (Microcystis),
22
-------
Plankton Algae
23
Anabaena, Aphanizomenon, and Osc///ator/a; the green
algae, Hydrodictyon, Chlorella, and Ankistrodesmus (fig.
35); the diatoms, Synedra and Cydotella; and the flagel-
lates, Synura, Euglena, and Chlamydomonas. Blooms of
blue-green algae are particularly obnoxious. Blooms of
flagellates and green algae are often encouraged by the
addition of fertilizer in farm hatchery ponds in order to in-
crease fish production (6).
Related to the blooms are the mats or blankets
of filamentous green algae such as Sp/rogyra, Zygnema,
Oedogonium, and Cladophora which at times may cover
large areas of a reservoir or lake (7). Certain blue-green
algae such as Gloeotrichia natans (fig. 36) may also form
extensive floating masses. These growths cause an un-
sightly appearance in a community's water supply and
serve as breeding places for gnats and midge flies. They
may clog intake screens, cause tastes and odors, and in-
terfere with the functioning of multiple-purpose reservoirs
by collecting as debris on the shores and interfering with
fishing and bathing. Many of the mat-forming algae are
resistant to effective treatment with copper sulfate. Fre-
quent inspections of raw water supplies for detection of
the visible growths, together with routine microscopic
analysis of water samples are necessary if the various kinds
of algae are to be effectively controlled.
The list of the more common surface water algae is
given in table 5. It is more extensive than for the other
groups and includes a total of 68 species. Twenty-two
plankton and other surface water algae are illustrated in
color on plate I. Many of the species on the other lists in
this manual could also be considered as prominent mem-
bers of the flora of surface waters. Additional species
would also need to be included to make the list fairly rep-
resentative for any particular locality. Since the total num-
ber of known species of algae is many thousands, it is ob-
viously not possible to include here all of even the com-
mon forms. Transeau (8) lists, for example, 275 species of
the genus Sp/rogyra, Hustedt (9) describes more than 125
species belonging to the genus Navicula, and Cojdics (10)
recognizes 155 species of Euglena.
It is emphasized that not all of the algae in the list of
surface water forms are planktonic. The list includes algae
which may originally be benthic (attached and bottom-
dwelling) forms but are frequently swept away into the
open water.
The open water algae have several mechanisms which
aid in keeping them dispersed in the water and retard
any tendency toward settling out. The pigmented flagel-
lates, represented on plate I by Euglena, Phacus, Conium,
and Eudornia, are swimming forms with whip-like flagella
which apparently aid in the forward movement of the
cells through the water. Spines or the spine-like shapes
of entire cells help to keep certain nonswimming green
algae such as /Vct/nastrum, Micractinium, and Scenedes-
mus suspended in the water. The large flat surfaces ex-
posed to the water do the same thing for the diatoms,
Fragilaria and Tabellaria, and the green alga, Pediastrum.
A number of planktonic blue-green algae have internal gas
vacuoles which help to keep the cells afloat.
Varieties are found among the surface water algae.
Spherical or subspherical colonies of cells are found in
Coelastrum, Oocystis, Gomphosphaeria, and Sphaerocystis.
Filamentous forms include Nodularia, Mougeot/a, Zyg-
nema, Cylindrospermum, Me/os/ra, and Desmidium. The
diatoms Stauroneia and Navicula are boat-shaped and
capable of moving through the water. The odd-colored
Botryococcus with its green cells embedded in a brownish
mucilaginous sheath is often irregular in form and surface.
From their specialization in shape and internal struc-
ture, many of the algae can be recognized readily under
the microscope (fig. 37). This makes possible, in the rou-
tine microscopic analysis of water samples, a record of the
presence and abundance of many of the significant genera
or species. Several helpful books have been published
giving lists, keys, descriptions, and illustrations of the al-
gal flora of particular states or regions. Examples of these
are the algae of Illinois (11), algae of Tennessee (12), algae
of the western Great Lakes area (13), and the algae of the
United States (14). Available information of this character
will facilitate the accurate recording of the algae found in
lakes and reservoirs which are being used as the water
supply for an ever-increasing number of cities, towns, and
industrial establishments.
Each year a seasonal cycle is evident in the plankton
population of lakes and reservoirs. Diatoms generally in-
crease in number in late winter, often with two or three
additional pulses ocurring during the spring months. In
early summer the green algae are likely to be abundant,
followed in the late summer and early autumn by an in-
creased growth of blue-greens. Then there will follow a
late autumn maximum of diatoms. Throughout most of
the winter the diatoms and certain other algae remain in
the water but with little or no increase in numbers until
conditions in the late winter stimulate the organisms to
begin the cycle all over again. Various brown and green
flagellates and the yellow-green alga Tribonema occa-
sionally appear in the cycle as abundant growth for brief
periods, the time of year depending in part upon the par-
ticular species involved.
When records of the phytoplankton present in a reser-
voir or lake are kept for a long period of time, they often
reveal that certain genera and species are predominant
year after year. In one metropolitan district (15) the res-
ervoirs contained enormous numbers of Tabellaria and
Ceratium with an abundance also of Asterionella, Fragi-
laria, Synedra, Cydotella, Dinobryon, and Pandorina. Over
a period of approximately 40 years, however, there was a
gradual change in the predominant algae. Tabellaria
dropped out completely and new forms appeared, chiefly
Stephanodiscus astraea and Stephanodiscus hantzchii, to-
gether with several filamentous blue-green algae.
Diatoms found in large numbers in the Great Lakes and
also in all major rivers of the United States are Diatoma
-------
24
ALGAE AND WATER POLLUTION
Figure 35.—/Anfe/strodesmus falcatus.
vulgare, Fragilaria crotonensis, Melosira ambigua, Melo-
sira granulata, and Stephanod/scus hantzsch//. Diatoms
characteristic of the Great Lakes but absent or extremely
rare in rivers of the United States are Cyclotella comta,
Cyclotella kutzingiana, Melosira binderana, Melosira islan-
d/ca, and Rh/zoso/en/a er/ense (16).
Although many environmental factors are relatively con-
stant for any body of water and tend to keep the phyto-
plankton population stable, other factors will change suf-
ficiently to influence the growth and relative abundance
of the various genera and species comprising the flora.
Figure 36.—G/oeotricfi/a natans.
Figure 37. —Plankton diatoms, showing distinctive shapes of cells and
colonies. The relative sizes of the various organisms are also evident
in this composite photomicrograph which was furnished by J. R, Baylis,
Engineering of Water Purification, Department of Water and Sewers,
Bureau of Water, Chicago, III.
REFERENCES
1. Ecology of significant organisms in surface water supplies. C. M.
Tarzwell and C. M. Palmer. Jour. Amer. Water Wks. Assn. 43:568-
578. 1951.
2. Some relationships of phytoplankton to limnology and aquatic bi-
ology. G. W. Prescott. In Problems of Lake Biology by F. R. Moul-
ton. Amer. Assn. for Advancement of Sci., Science Press, Lancaster,
Pa., p. 65-78. 1939.
3. A new counting slide for nannoplankton. C. M. Palmer and T. E.
Maloney. Amer. Soc. Limnol. and Oceanog., Special Publ. No. 21,
6 p. March 1954.
4. The importance of algae to waterworks engineers. J.W.C. Lund.
Jour. Inst. Water Engrs. 8:497-504. 1954.
5. Toxic fresh-water algae. W. M. Ingram and G. W. Prescott. Amer.
Midland Naturalist 52:75-87. 1954.
6. Manganese for increased production of water-bloom algae in
ponds. C.Henderson. Progressive Fish-Culturist 11:157-159. 1949.
7. The population of the blanket-algae of fresh-water pools. Emilie L.
Platt. Amer. Naturalist 49:752-762, 1915.
8. The Zygnemataceae (fresh-water conjugate algae) with keys for the
identification of genera and species. E. N. Transeau. Ohio State
Univ. Press, Columbus, Ohio, 327 p. 1951.
9. Bacillariophyta (Diatomeae). F. Hustedt. Heft 10 in Die Siisswasser-
Flora Mitteleuropas, by A. Pascher. Gustav Fisher, Jena, Germany,
466 p. 1930.
10. The genus Euglena. Mary Gojdics. Univ. Wisconsin Press, Madison,
Wis., 268 p. 1953.
11. The algae of Illinois. L. H. Tiffany and M. E. Britton. Univ. Chicago
Press, Chicago, III., 407 p. 1952.
12. Handbook of algae with special reference to Tennessee and the
southeastern United States. H. S. Forest. Univ. Tennessee Press,
Knoxville, Tenn., 467 p. 1954.
13. Algae of the western Great Lakes area, exclusive of desmids and
diatoms. G. W. Prescott. Cranbrook Inst. Sci., Bloomfield Hills,
Mich., Bull. No. 31, 946 p. 1951.
14. The fresh-water algae of the United States. Ed. 2. G. M. Smith.
McGraw-Hill, N.Y., 719 p. 1950.
15. The reservoirs of the Metropolitan Water Board and their influence
upon the character of the stored water. E. W. Taylor. Proc. Inter-
national Assn. Theoretical and Appl. Limnol. 12:48-65. 1955.
16. Plankton population dynamics. L. G. Williams. U.S. Public Health
Service Publication No. 663 — Supplement 2, 90 p. 1963.
TABLE 5. PLANKTON AND OTHER SURFACE WATER ALGAE
Group and algae
Plate or figure
Blue-Green Algae (Myxophyceae):
Anabaena flos-aquae
Anacystis cyanea
Anancystis thermalis
Cylindrospermum stagnale
Gloetrichia natans
Gomphosphaeria aponina
VIII
VII
Fig. 36
-------
Plankton Algae
25
Group and algae
Plate or figure
Group and algae
Plate or figure
Gomphosphaeria lacustris,
collinsii type
Gomphosphaeria wichurae
Lyngbya versicolor
Nodularia spumigena
Nostoc carneum
Oscillatoria agardhii
Phormidium retzii
Plectonema tomasiniana
Scytonema tolypothricoides
Spirulina nordstedtii
Filamentous Green Algae (of Chlorophyceae
and Chrysophyceae):
Cladophora fracta
Desmidium gravellei
Hyalotheca mucosa
Mougeotia genuflexa
Mougeotia scalaris
Oedogonium iodiandrosporum
Spirogyra fulviatilis
Spirogyra varians
Stigeocolonium stagnatile
Tribonema minus
Ulothrix tenerrima
Vaucheria terrestris
Zygnema pectinatum
Zygnema sterile
Nonfilamentous, Non-Motile Green
Algae (of Chlorophyceae):
Actinastrum gracillimum
Actinastrum hantzschii
Ankistrodesmus falcatus
Botryococcus braunii
Chlorella ellipsoidea
Closterium aciculare
Coelastrum microporum
Cosmarium botrytis
Crucigenia quadrata
Dictyosphaerium pulchellum
Fig. 34, VI
I
Dimorphococcus lunatus
Euastrum oblongum
Golenkinia radiata
Kirchneriella lunaris
Micractinium pusillum
Oocystis borgei
Oocystis lacustris
Ophiocytium capitatum
Pediastrum boryanum
Pediastrum duplex
Scenedesmus bijuga
Scenedesmus dimorphus
Scenedesmus quadricauda
Schroederia setigera
Selenastrum gracile
Sphaerocystis schroeteri
Staurastrum polymorphum
Tetraedrom limneticum
Diatoms (Baciltariophyceae):
Asterionella formosa
Cyclotella bodanica
Cyclotella kutzingiana
Cyclotella meneghiniana
Cymbella turgida
Diatoma vulgare
Eunotia lunaris
Fragilaria construens
Fragilaria crotonensis
Fragilaria pinnata
Melosira ambigua
Melosira binderana
Melosira granulata
Melosira islandica
Nitzschia acicularis
Rhizosolenia eriense
Synedra nana
Synedra ulna
Tabellaria fenestrata
Tabellaria flocculosa
VI
I
Fig. 68
VI
I
VIII
III
VIII
VIII
VIII
VIII
VII
VII
VIM
-------
CHAPTER VI
ATTACHED ALGAE
Many of the algae which grow attached to some sub-
strate are large and conspicuous, often covering a con-
siderable area and extending several inches or even a few
feet into the water. Those of importance in water supplies
may grow not only in the stream, lake, and reservoir, but
in the treatment plant itself. These algae are commonly
found attached to such objects as the wet concrete walls
of settling basins, the screens at the ends of the intake
pipes, and the wood, brick, stone riprap, or even soil sur-
faces of reservoir walls and bottoms. Many are abundant
in streams where they may be attached to submerged
twigs or rock and other materials forming the stream bed.
They are present in irrigation canals on the sides and bot-
tom and on the gates and screens. They form dense
growths in recreational lakes and in fish raising ponds,
causing serious problems.
In small amounts these algae are not a cause for alarm,
but when abundant they may become a decided nuisance.
They may clog screens to which they are attached and re-
duce the flow in canals by the amount of space they oc-
cupy and the increased friction of their surfaces. In mul-
tiple-purpose lakes and reservoirs, they often interfere
with swimming and fishing or develop such rank growths
in the shallow margins that they are the cause of constant
complaints from nearby residents. In addition, they may
break away from their attachments to form unsightly sur-
face mats, clog screens and filters, or produce offensive
odors in the air and water. Other smaller algal forms may
produce a continuous slimy and slippery layer on concrete
or other surfaces, which in swimming pools is undesirable
or even dangerous.
In Louisiana and other states just north of the Gulf of
Mexico, Pithophora often becomes the predominant
growth in fish ponds during the summer. It interferes with
high fish production by reducing the growth of phyto-
plankton required directly or indirectly as fish food. The
Pithophora also interferes with the harvesting of fish by
forming a heavy growth on the pond. The growth can
also promote overpopulation of bluegills by interfering
with bass predation (1).
The attached algae considered here number 42 species,
listed under their respective groups in table 6; 22 are il-
lustrated in color on plate II. Included are diatoms, blue-
green, green, and fresh-water red algae, but no flagellates.
Many of these algae grow in the form of unbranched or
branched filaments or tubes and are fastened at one end
to the substrate by means of a special anchoring device.
Vaucheria is a branched, tubular form with several com-
mon species (figs. 38, 39). Typical branching filamentous
green algae are Cladophora, Pithophora (fig. 40), Chaeto-
phora, Stigeoclonium, Draparnaldia, Bulbochaete, Chara,
and Nitella. The species Cladophora glomerata is a very
common attached alga in rapidly flowing water and is con-
sidered the most abundant filamentous alga in streams
throughout the world (2). Nonbranching filamentous
green algae include Oedogonium, Microspora, and Ulo-
thrix and the more complex Schizomeris (fig. 41). The
genera, Audouinella (formerly called Chantransia), Batrach-
ospermum, and Compsopogon are fresh-water red algae,
the last one being common in the southern states. Some
filamentous blue-green algae such as Phormidium, Lyng-
bya, To/ypothrix, and St/gonema (fig. 42) form dense mats,
one side of which is exposed and the other side attached
to the substrate.
Some diatoms, such as Achnanthes, Gomphonema, and
Cymbe//a are attached to surfaces by gelatinous stalks or
tubes. In Australia, Gomphonema developed as an ex-
tensive growth and formed a slippery, felt-like mat cov-
ering the cement walls of an aqueduct for several miles
(3). The species of Cymbella which grows inside a hollow
tube, as illustrated on plate II, has sometimes been placed
in a separate genus, Encyonema (4).
A white marble surface serving as the floor of an ob-
servation well in one water treatment plant became over-
grown with a continuous brown layer of /Achnanthes. The
observation well was located on a conduit carrying water
from sand filters to the clear well. The marble surface
was brushed clean but the color returned within 2 weeks.
After a second cleaning, electric lights that had been left
on continuously at the bottom of the observation well
were turned off, except for brief times when needed for
display. The brown color did not return because the dia-
toms were not capable of developing in darkness.
The green alga, Phytoconis (formerly called Protococcus)
is common as a thin green layer on the surface of moist
wood and bark above the water line, but it is seldom
found submerged. Another green alga, Tetraspora (fig.
43), is composed of minute, rounded cells in a soft, fragile,
mucilaginous, common tube which is attached at one end
to the substrate. It is one of the first algae to develop in
abundance in the cold water of streams and pools after
the ice melts in early spring. One of the most common
blue-green algae attached to stones is Calothrix (fig. 44).
In reservoirs and lakes having rocky rather than sandy
shores, Cladophora and other large filamentous algae of-
ten develop during the summer as extensive, massive
26
-------
Attached Algae
27
Figure 41.—Schizo-
mer/s leiblelnii.
Figure 38.-
gem/nata.
-Vauchena
Figure 42.—Stigonema
hormoides.
Figure 39.—Vauchena
sessiV/s.
Figure 43.—Tetraspora. Portion of colony showing cells grouped
in fours. Pseudocilia are barely visible on a few of the cells.
Figure 40.—Pithophora
oedogonia.
Figure 44.—Calothrix.
-------
28
ALGAE AND WATER POLLUTION
growths. When this material becomes detached and is
thrown up on the shore, it may require immediate re-
moval to prevent the development of septic odors (5).
In Lake Erie Cladophora has caused concern for many
years, with indications that its growth is expanding and
increasing in amount. One species, Cladophora g/omerata
is found growing on rock bottoms and sides down to al-
most 7 ft in depth. When the first crop matures in July
the filaments become free floating as a result of matura-
tion and of wave action. They are then frequently thrown
up on shore by suitable winds and currents. Its mass in-
terferes with the area as a bathing beach, and if not dis-
posed of, the alga disintegrates and produces a strong
odor of decomposition. A second crop may develop and
mature in the fall but is generally less extensive and too
late in the year to interfere with the use of bathing beaches
(6).
One species, Cladophora profunda var. nordstedtiana
has been found at 150 ft or more below the surface of
Lake Ontario. Increasingly it has become a problem for
fishermen using nets, since the nets become entangled
with the filaments of the alga.
Nuisance growths of Cladophora often occur in streams
or along the shoreline of lakes in the vicinity of sewer
outfalls. Large concentrations of wastes and certain me-
tallic ions can be toxic to Cladophora, and it may be re-
placed by Stigeoclonium, Phormidium, and other algae
that are more tolerant to these materials (7). The eutroph-
ication of Lake Erie and Lake Ontario is certainly directly
associated with the increased growth of Cladophora in
these lakes.
Drastic measures often have to be taken to control the
attached algae, especially if the growths are neglected un-
til large quantities threaten to cause trouble. One city
adapted a floor-cleaning machine, fitted with a cylindrical
wire brush, for use in scraping the agal growth from the
concrete floor of a 13-mil-gal reservoir. The machine
proved to be much more effective than hand scrapers in
removing the attached portions of the algae from the more
than 100,000 sq ft of concrete. The detached algae were
then flushed from the reservoir floor by streams of water
from a fire hose (7). The use of chemicals to kill attached
algae when they are present in quantity may not solve the
problem, because dead algae as well as living ones can
clog filters and screens, release slimes into water, and
cause tastes and odors.
In areas in the western part of the country where there
are extensive systems of canals for irrigation farming, mas-
sive growths of attached algae, together with certain aqua-
tic flowering plants, constitute a serious problem. Be-
cause of their bulk, they impede the flow of water through
the ditches and clog the control gates and the distribution
lines. Their large volume decreases the capacity of the
irrigation ditch, causing the water to overflow. In Cali-
fornia one canal overflowed while carrying only 25 per-
cent of its rated capacity due to a heavy growth of Clado-
phora. Near San Francisco the most troublesome alga in
open canals has been Cladophora. It produces long fila-
ments and mats on the sides and bottom (8). Cladophor
and Rhizoclonium are by far the most important algae en
countered. The peak of their development is generally i
the spring after which they often become inconspicuou
during the summer with new growth beginning in th
autumn. The green alga Enteromorpha (fig. 45), com
monly thought of as a brackish water form, may becom
abundant during the summer, and the fresh-water red al
ga, Compsopogon, may flourish during September.
The red alga Thorea forms long skeins of unbranchei
filaments, some as long as 20 ft, and is most abundant ii
October. The green alga Dichotomosiphon is anothe
filamentous form especially evident in the spring and fal
while Oedogonium (fig. 46), Spirogyra, and Oscillator!,
princeps form abundant growths in the summer (9, 10]
The algae which occur in sufficient quantities to affect thi
operation of the canals and ditches are listed in table 7
One common method of control has been the mechanica
removal of the algae by means of chains or scrapers tha
are pulled along the canals by tractors. Four irrigatioi
districts in Arizona spend a total of approximately $250,00(
annually to control this growth.
Attached algae are present and apparently significan
in the trickling filters of sewage treatment plants. The>
form a large part of the population of microorganism
growing in a layer around the stones of the filter. Th<
exposed surface of the layer is predominantly fungal, th<
intermediate portion is predominantly algal, and the basa
portion against the stone is a fungal, algal, and bacteria
mixture. The layer may reach a thickness of 1 to 2 mm
The attached alga most frequently encountered is Stigeo
clonium (fig. 47). In addition to its branching filament
it also develops as a basal, attached, irregular, tight mat o
cells which strongly resembles a colony of the nonfilamen-
tous green alga Chlorococcum. The branching filament;
of St/geoc/onium rise from this basal mat. Species of at-
tached algae from the trickling filters of one treatmem
plant (6) were reported as St/geoc/on/um nanum, Ulothrb
tenuissima, Phormidium uncinatum, Amphithrix janthina,
and Charac/um sp. Other algae commonly mixed with the
attached forms were Scenedesmus bijuga, Oocystis parva,
Chlorella vulgaris, Chlamydomonas, Nitzschia palea, and
Anacystis montana.
Consideration is being given to the use of attached al-
gae in tertiary treatment of sewage effluents. In addition,
the algal growth might be harvested and prepared for use
as fertilizer, mulch, or cattle feed. The attached forms
would not present the difficulty of harvesting that is en-
countered with plankton organisms.
In some areas adjacent to the sea, cattle have become
adjusted to feeding on the brown alga known as kelp. A
few reports indicate that cows and horses have eaten
fresh-water attached Cladophora or other bottom algae.
Even squirrels have been observed nibbling tender growths
of Cladophora from the stones along the shores of lakes
(11).
Thus, it is evident that the attached algae may produce
undesirable conditions or be put to good use depending
-------
/Attached Algae
29
upon the particular locations and conditions in which they
develop.
Figure 45.—Enteromorpha.
Figure 46.—Oedogonium.
REFERENCES
1. Control of a branched alga, Pithophora, in farm fishponds. J. M.
Lawrence. Progressive Fish Culturist 16:83-86. 1954.
2. The ecology of river algae. J.L.Blum. Bot. Rev. 22:291-341. 1956.
3. The effects of algae in water supplies. D. H. Matheson. Interna-
tional Water Supply Assn., General Rept. to 2d Congress. Paris,
France, 82 p. 1952.
4. Fresh-water biology. H. B. Ward and C. C. Whipple. J. Wiley and
Sons, N.Y., 1110 p. 1945.
5. Algal nuisances in surface waters. N. J. Howard and A. E. Berry.
Canadian Jour. Public Health 24:377-384. 1933.
6. Cladophora investigations, 1959. A report of observations on the
nature and control of excessive growth of C/adophora sp. in Lake
Ontario. Ontario Water Resources Commission, 30 p. 1959.
7. Environmental needs of nuisance organisms. C. M. Palmer. Proc.
4th Ann. Water Quality Res. Symp., N.Y. State Dept. Health, Albany,
N.Y., p. 8-35. 1967.
8. Weed growths in reservoirs and open canals. C. E. Arnold. Jour.
Amer. Water Wks. Assn. 27:1684-1693. 1935.
9. The study of the algae of irrigation waters. Janet D. Wien. Arizona
State College, Tempe, Arizona. 37 p. (Mimeographed). Mar. 31,
1958.
10. Continuous sampling of trickling filter populations. II. Populations.
W. B. Cooke and A. Hirsch. Sewage and Indust. Wastes 30:138-156.
1958.
11. Some economic aspects of the algae. L. S. Tiffany. School Sci. and
Math. 28:583-593. 1928.
TABLE 6. ATTACHED ALGAE
Group and algae
Plate or figure
Figure 47.—Stigeoclonium (immature).
Blue-Green Algae (Myxophyceae):
Calothrix braunii
Lyngbya lagerheimii
Lyngbya ocracea
Nostoc pruniforme
Oscillatoria tenuis
Phormidium retzii
Phormidium uncinatum
Stigonema minutum
Tolypothrix tenuis
Green Algae (Nonmotile Chlorophyceae,
Charophyceae):
Bulbochaete insignis
Chaetophora attenuata
Chaetophora elegans
Chara globularis
Cladophora crispata
Cladophora glomerata
Draparnaldia glomerata
Gloeocystis gigas
Microspora amoena
Nitella flexilis
Oedogonium boscii
Oedogonium grande
Oedogonium suecicum
Palmella mucosa
Phytoconis botryoides
Pithophora oedogonia
Rhizoclonium hieroglyphicum
Schizomeris leibleinii
Stigeoclonium lubricum
Tetraspora gelatinosa
Ulothrix zonata
Vaucheria geminata
Vaucheria sessilis
30
II
II
II
II
I!
40
III
41
38
II
-------
30
ALGAE AND WATER POLLUTION
Group and algae
Plate or figure
TABLE 7. ALGAE AFFECTING OPERATION OF CANALS
Red Algae (Rhodophyceae):
Audouinella violacea
Batrachospermum moniliforme
Compsopogon coeruleus
Diatoms (Bacillariophyceae):
Achnanthes microcephala
Cocconeis pediculus
Cymbella prostrata
Epithemia turgida
Gomphonema geminatum
Gomphonema olivaceum
Rhoicosphenia curvata
II
II
Chara
Cladophora glomerata
Compsopogon coeruleus
Dichotomosiphon tuberosus
Enteromorpha intestinalis
Hydrodictyon reticulatum
Lyngbya aestuarii
Lyngbya putealis
Microspora wittrockii
Mougeotia
Oedogonium
Oscillatoria amphibia
Oscillatoria chalybea
Oscillatoria princeps
Oscillatoria tenuis
Phormidium inundatum
Phormidium subfuscum
Phormidium uncinatum
Prasiola nevadense
Rhizoclonium hieroglyphicum
Sirogonium
Spirogyra
Spirulina major
Stigeoclonium lubricum
Thorea ramosissima
Vaucheria
Zygnema
-------
CHAPTER VII
ALGAE AND EUTROPHICATION
Eutrophication refers to the continuous enrichment of
waters by the addition of substances that provide for the
increasing growth of aquatic life. Commonly it is limited
to non-flowing bodies of water such as lakes and reservoirs
and not to rivers and smaller streams. The word pollution
could be substituted for eutrophication, although the em-
phasis of the word pollution is upon the addition of sub-
stances to water which directly and indirectly interfere
with the use of the water. The word pollution is com-
monly used in connection with flowing water and also
with lakes and reservoirs, at least when the substances
added do not stimulate increased growth of aquatic or-
ganisms. Thus a lake could be polluted with acids and
sulfates and debris from mining operations and could be
eutrophied with organic wastes from household sewage.
With a river the word pollution would more often be used
for both conditions (1).
Natural eutrophication tends to occur regularly but very
slowly, often over a period of hundreds of years. Human
activity is generally responsible for rapid eutrophication
as household wastes, agricultural land drainage, and or-
ganic industrial wastes or their decomposition products
reach the lakes and reservoirs.
Algae are invariably involved as representing part or
most of the increased growth stimulated by eutrophica-
tion. The two substances considered most significant in
this growth are nitrogenous compounds and phosphates.
These, together with carbon dioxide, are generally the
materials whose availability determines the quantity and
quality of algal growth. A relatively pure body of water
has a very limited amount of the essential nutrients. If all
three of these are increased, many kinds of algae may be
able to grow in large numbers. If one is increased much
more than the others, only a selected few types of algae
may be able to thrive. Many other elements and condi-
tions are also required for increased growth of algae, but
these are less often the critical factors determining the
amount and quality of algal growth in a body of water
with an established flora.
When gross eutrophication is reached, large, visible ag-
gregations of floating algae bloom extensively, particu-
larly blue-green forms which develop during the late sum-
mer. Anacystis (Microcystis), and Anabaena are the most
common algae to bloom but others such as Aphanizo-
menon, Comphosphaeria, Rivularia, and Oscillatoria may
also produce blooms. Less often Spirulina or Arthrospira
may be responsible. The blooms may cause unusually
severe problems of tastes and odors, filter and screen
clogging, and slime accumulation in pipes; some may be
toxic, and all may cause fish kills when large numbers of
the algae die at about the same time. In decomposition
they utilize oxygen in the water, thus depriving the fish
below of this essential element. Blooms also interfere in
recreational lakes, with fishing, bathing, boating, and often
reduce the beauty of the lake.
As eutrophication proceeds, the algae which tend to be-
come prominent, in addition to the bloom-formers listed
above, may be planktonic, floating, periphytic, or they
may be larger forms attached to rocks and soil. Included
would be Cladophora, Gloeocystis, Mougeotia, Oedogon-
ium, Spirogyra (2), and the diatoms which are character-
istic of and reach their best development in eutrophic
waters (3). The significance of large growths of Clado-
phora in the eutrophied Lakes Erie and Ontario is referred
to in the chapter on Attached Algae.
The quantity of phytoplankton that can develop in a
eutrofied lake can be very large. For Lake Sebastecook,
Maine, the net weight per surface area was calculated to
be 530 Ib/acre in February, 630 in May, 1,000 to 2,260 in
August, and 570 in November. Phytoplankton counts
ranged from 600/ml in February to 212,000/ml during a
bloom in August. The amount of the algal mass varied
from 15 to 560 ppm. In Lake Michigan, phytoplankton
populations in the Chicago - Calumet area were dense. In
1962, counts up to 1,298 algae/ml were recorded, while
in 1963, counts increased to a high of 2,143 (4).
In specific terms, a eutrophic lake has been character-
ized as one that is generally shallow and possesses an ex-
tensive littoral zone with plant growth. It is rich in basic
nutrients with the average annual concentrations of the
inorganic forms of nitrogen and phosphorus being some-
what greater than 0.300 mg/l and 0.015 mg/l, respec-
tively. The alkalinity ranges from 50 to 100 mg/l and the
water is moderately hard. Eutrophic lakes typically support
large quantities of phytoplankton composed of compar-
atively few species; pulses and blooms are common and
frequent during the growing season. In general the rate
of gross primary production in eutrophic lakes ranges from
0.5 to 5.0 gm dry organic material/sq m/day during the
most favorable growing season while the primary produc-
tion of organic carbon is on the order of 480 metric tons/
sq km/year (5).
Thus, Oneida Lake, New York, was considered in 1956
to meet the qualifications for a eutrophic lake from five
different considerations as follows:
31
-------
32
ALGAE AND WATER POLLUTION
1. It is relatively shallow with a mean depth of 25
ft and possesses extensive shoal areas with plant growth,
amounting to 23 percent of the lake's surface area.
2. The average concentration of nitrate nitrogen was
0.256 mg/l and of total phosphorus 0.190 mg/l. Am-
monia nitrogen and organic nitrogen were additional
sources of nitrogen. Alkalinity and hardness averaged 86
and 150 mg/l as CaCO,, respectively.
3. The algal population for the summer months in
1956 was predominantly blue-green and green algae,
whereas in 1927, it was predominantly a diatom popula-
tion. The algal growth was moderate on the average, but
there were frequent heavy blooms or pulses.
4. The rate of gross production was estimated to be
about 2.6 gm of organic material/sq m/day.
5. The degree of productivity was estimated to be
about 350 metric tons of organic carbon/sq km/year (5).
Oneida Lake produced blooms even before European
settlement. In the eighteenth century, Indians called it
"stinking green" (6). The most important contributors to
eutrophication of the lake are now a barge canal and four
creeks. They contribute substantially to the enrichment
of the lake. Wastes from lakeside dwellings are also im-
portant in effecting the condition of local shore-lying
areas. In 1961, 35 genera of algae were recorded as pre-
dominant in the lake. Included were 8 blue-greens, 3
flagellates, 13 greens (non-filamentous), 1 golden-brown,
4 filamentous greens and yellow-greens, and 6 diatoms.
These are listed in Table 8 (5).
The Great Lakes are a large expanse of water, covering
nearly 95,000 sq mi. Lake Superior is the second largest
lake in the world and even the smallest, Lake Ontario,
ranks fourteenth. Lakes Erie and Ontario and the southern
part of Lake Michigan have already become eutrophic,
and because of the increasing activities of the human pop-
ulation around all of the lakes, there has been a gradual
increase in dissolved solids, including nitrogen and phos-
phorus, in all but Lake Superior. Over a 60-year period,
Lakes Ontario and Erie had increases in dissolved solids of
more than 30 percent, Lake Michigan 20 percent, and Lake
Huron 10 percent.
Blooms of algae are frequent on Lakes Erie and Ontario
and the bloom rhythm is getting faster and faster on parts
of Lake Michigan (7).
Records of phytoplankton from a 12-month study in
1950-1951 from a total of 245 samples taken near the
mouths of 10 rivers flowing into Lake Erie showed four
classes and 30 genera of algae. The diatoms were the most
common and green algae were second in abundance.
Table 9 lists the genera of algae identified (8).
Reports of samples collected about 20 years before,
1928-1930, indicate a total at that time of 80 genera of
phytoplankton in Lake Erie, including 12 blue-greens, 20
diatoms, 13 flagellates, and 35 greens and related forms
(9,10). This drop from 80 genera to 30 genera in 20 years
could be evidence of a rapid eutrophication of the lake
during that period.
Prevention of further damage to the lake waters as well
as improvement in the water quality can be attempted
primarily by restricting the introduction of nutrients that
result from human activities (1). Gradual flushing of the
lakes by addition of rain water together with water flow
should eventually reduce the amounts of nutrients present.
Indications are now that the western end of Lake Erie is
already beginning to improve. "The advent of trout and
salmon in Lake Erie and the Detroit River, one of the most
polluted links in the Great Lakes chain, is viewed by some
observers as one of the many intriguing, sometimes dra-
matic signs that efforts to clean up the lakes are starting
to take effect" (11).
REFERENCES
1. Eutrophication, Introduction, Summary, and Recommendation. C.
A. Rohlich. In Eutrophication: Causes, Consequences, Correctives.
Proc. Symposium, 1967. National Acad. Sci., Washington, D.C., 661
p. 1969.
2. Some effects of sewage effluent upon phyco-periphyton in Lake
Murray, Oklahoma. H. E. Schlichting, Jr. and R. A. Cearheart. Proc.
Okla. Acad. Sci. 46:19-24. 1966.
3. The diatoms of Linsley Pond. R. Patrick. Proc. Acad. Natural Sci.
Philadelphia 95:53-110. 1943.
4. The practice of water pollution biology. K. M. MacKenthun. U.S.
Dept. Interior, Fed. Water Pollution Control Admin., Div. of Tech-
nical Support, 281 p. 1969.
5. Chemical and microbiological aspects of Oneida Lake, New York.
R. C. Mt. Pleasant, M. C. Rand, and N. L. Nemerow. New York
State Dept. of Health, Research Rept. No. 8. 1961.
6. Eutrophication in North America. W. T. Edmondson. In Eutrophi-
cation: Causes, Consequences, Correctives. Proc. Symposium, 1967.
National Acad. Sci., Washington, D.C., p. 124-149. 1969.
7. Superior-Michigan-Huron-Erie-Ontario. Is it too late? C. Young.
National Geographic 144 (2):147-185. 1973.
8. Survey of the phytoplankton at the mouths of ten Ohio streams
entering Lake Erie. C. R. Sullivan, Jr. In Lake Erie Pollution Survey,
Final Report. Ohio Dept. Natural Resources, Div. of Water, p. 152-
156. 1953.
9. The phytoplankton of western Lake Erie. L. H. Tiffany. In Limno-
logical Survey of Western Lake Erie by S. Wright. U.S. Dept. of
Interior, Fish and Wildlife Service, Special Scientific Rept. - Fisheries
No. 139, p. 139-200. 1955.
10. A survey of the microplankton of Lake Erie. R. R. Burkholder. In
Limnological Survey of Eastern and Central Lake Erie, 1928-1929.
U.S. Dept. Interior, Fish and Wildlife Service. Special Scientific
Rept. - Fisheries No. 334, Washington, D.C., p. 123-144. 1960.
11. Great Lakes pollution fight is gaining. W. K. Stevens. The New
York Times for May 23, 1974. p. 1 and 42.
-------
Eutrophication
33
TABLE 8. PREDOMINANT ALGAE IN ONEIDA LAKE, 196t
TABLE 9. PHYTOPLANKTON IN LAKE ERIE, 1951 -1952
Blue-Green Algae
Agmenellum (Merismopedia)
Anabaena
Anacystis
(Chroococcus)
(Microcystis)
Calothrix
Coelosphaerium (Comphosphaeria)
Lyngbya
Oscillatoria
Rivularia
Diatoms
Asterionella
Fragilaria
Nitzschia
Stephanodiscus
Synedra
Tabellaria
Flagellates
Ceratium
Euglena
Volvox
Green (Non-Filamentous) Algae
Actinastrum
Ankistrodesmus
Chlorella
Closterium
Coelastrum
Hydrodictyon
Micrasterias
Oocystis
Pediastrum
Phytoconis (Protococcus)
Scenedesmus
Sphaerocystis
Staurastrum
Green and Yellow-Green
(Filamentous) Algae
Cladophora
Mougeotia
Tribonema
Ulothrix
Golden-Brown Algae
Chrysidiastrum
Blue-Green Algae
Agmenellum
(Merismopedia)
Anabaena
Anacystis
(Chroococcus)
(Microcystis)
Diatoms
Asterionella
Cyclotella
Diatoma (Odontidium)
Flagilaria
Gyrosigma
Melosira
Navicula
Nitzschia
Stephanodiscus
Surirella
Synedra
Tabellaria
Flagellates
Ceratium
Glenodinium
Pandorina
Green Algae
Closterium
Cosmarium
Gloeocystis
Hydrodictyon
Oocystis
Pediastrum
Scenedesmus
Spirogyra
Staurastrum
Ulothrix
-------
CHAPTER VIII
CLEAN WATER ALGAE
Clean water organisms are those found in water which is
free of sewage or other organic enrichment due to waste
discharge. The clean water may be that portion of streams
above sewage outlets or far enough downstream for the
sewage to have been reduced to relatively inoffensive
salts and other simple compounds. Most of these prod-
ucts of sewage decomposition are nutrients and will stim-
ulate organisms such as algae to grow much more pro-
fusely than they do in the stream above the sewage out-
let, where nutrients are limited in quantity. The kinds of
algae in the clean waters upstream and downstream tend,
however, to be similar.
Large numbers of algae are found in the section of the
stream often called the recovery zone, which contains
partially decomposed sewage. It is difficult to select par-
ticular algae as the best indicators of the downstream
clean water zone, since it is adjacent to the recovery zone
where purification is still in progress. As with the polluted
water forms, it is more satisfactory to emphasize the pres-
ence or absence of several of the clean water algae rather
than of any one species in defining the clean water zone.
Forty-six species have been selected as representative
of the clean water algae and are listed in table 10. Twenty-
two of these species are illustrated in color on plate III.
The group includes several diatoms, several brown-to-
reddish flagellates, certain greens and blue-greens, and a
few fresh-water red algae of the class Rhodophyceae. A
number of them, particularly the flagellates, are very mi-
nute and appear small even under the high power of a
compound microscope, but they frequently are better in-
dicators of clean water than many larger algae that may
be mixed with them. However, a few of the larger forms
are also useful in indicating the condition of the water
and are represented by certain species of Cladophora,
Rhizoclonium, Lemanea, and others.
Some of the clean water algae are planktonic, while
others are attached to rocks or other material at the bot-
tom or sides of the stream like Calothrix parietina (fig. 48).
The blue-green algae Entophysalis lemaniae (formerly
called Chamaesiphon incrustans) and the diatom Cocco-
ne/s p/acentu/a are epiphytic, i.e., they grow attached to
the surface of other plants in the water. Several of the
genera having clean water species include also other spe-
cies whose reaction to sewage pollution is different from
the clean water forms. Both the pollution and clean
water groups are represented by contrasting species of
Navicula, Nitzschia, Phormidium, Agmenellum, Surirella,
U/othnx, and Euglena. In these same genera, as well as
in Pinnularia, Cydotella, and Cladophora, there are also
species considered to be indifferent to sewage. Identifi-
cation as to species is, therefore, essential for any accurate
differentiation of pollution zones through the use of algae
as indicator organisms.
Clean water algae are listed by some writers as typical
of the oligosaprobic zone, which is defined as the zone of
cleaner water where mineralization has been completed.
The water is often saturated or supersaturated with oxy-
gen. It is clear and transparent, and the bottom is usually
relatively free of sediment. Organic material containing
nitrogen or phosphorus is small in amount. The water
generally is cold and often deep. It is low in calcium,
magnesium, iron, sulfates, and half-bound carbonates. The
alkalinity should be less than 40 ppm and the pH below
7.4 (1). The water body has no shoals and little beach.
Algae and higher green plants predominate, while molds
and bacteria are present in only small numbers. Protozoa,
rotifers, Crustacea, small fish, and game fish are all present
in moderate numbers. Almost all of the algae are attached
forms and even these are few in number. The number of
species present generally ranges from 1 to 7. At high
elevations Hydrurus may be the only alga present. Spring
water may contain minerals but commonly is very low in
nitrates and phosphates (1). However, from the stand-
point of sanitation this zone of water is not likely to be
clean or pure, since it undoubtedly is not free of bacteria
and viruses of intestinal origin. The oligosaprobic zone
does not have a fixed location or length, since the distance
required for stream purification varies according to tem-
perature, the pollution load, the rate of flow, and other
factors. The limited flora and fauna of springs and pure
mountain streams are placed in a separate group known
as katarobic (2). More extensive lists of organisms con-
sidered characteristic of the various pollution zones have
been published recently by Butcher (3), Kolkwitz (4),
Lackey (5), Liebmann (6), Patrick (7), and others.
Butcher (3) claimed that a community composed of the
diatom Coccone/s and the blue-green alga Entophysalis
(listed as Chamaes/phon) is present in the portion of the
stream which has returned to normal following purification
of a polluted condition. Kolkwitz (4) lists as oligosaprobic
61 diatoms, 42 green algae, 41 pigmented flagellates, 23
blue-green algae, and 5 red algae. Lackey (5) found 77
species of planktonic algae in the clean water portion of
a small stream, 40 of which were absent in the polluted
area a short distance downstream. Liebmann (6) em-
phasized particularly the following algae as characteristic
34
-------
Clean Water
35
•~o
Figure 48.—Calothrix parietina is attached to logs and stones in running
water.
6. Handbuch der Frischwasser-, und Abwasserbiologie. H. Liebmann.
R. Oldenbourg, Miinchen, Germany, 539 p. 1951.
7. Factors effecting the distribution of diatoms. Ruth Patrick. Bot.
Rev. 14:473-524. 1948.
8. Biological studies, Ohio River pollution survey. I. Biological zones
in a polluted stream. F. G. Brinley. Sewage Wks. Jour. 14:147-
159. 1942.
9. Two groups of flagellated algae serving as indicators of clean
water. J. B. Lackey. Jour. Amer. Water Wks. Assn. 33:1099-1110.
1941.
10. A proposed biological measure of stream conditions. Ruth Patrick.
Proc. 5th Indust. Waste Conf., Purdue Univ. Eng. Bull. 34:379-399.
1950.
11. The microscopical examination of potable water. G. W. Rafter. Van
Nostrand Co., N.Y. 1900.
of the oligosaprobic zone: The flagellate Chromulina ro-
sanoffi in slow-flowing water, and the flagellate Mallo-
monas caudata, the green algae Ulothrix zonata and M/cro-
spora amoena, and the red algae Lemanea annulata and
Batrachospermum vagum in rapidly flowing water. Patrick
(7) listed Amphora ovalis and Cyrosigma attenuatum as
examples of diatoms that seemed to be adversely affected
by high organic content of water. Brinley (8) reported that
the presence of the flagellate algae Chrysococcus and
Cryptomonas in large numbers indicated that the decom-
position of organic matter in the stream had been com-
pleted.
Some workers have emphasized the relationship of
whole groups of algae to pollution in studies involving
stream purification. Lackey (9) reported that two classes
of algae, the olive green flagellates, or Cryptop/iyceae,
and the yellow-green flagellates, or Chrysophyceae, ap-
peared to be indicators of clean, unpolluted water. They
tend to be present in moderate to great abundance in
clean water and reacted adversely to pollution. In an-
other study (5) he observed that all of the Chrysop/iyceae
and most of the Cryptop/iyceae, Vo/voca/es, and Bacil-
larieae (diatoms) which were present in clean water were
killed in the zone of pollution. Patrick (10) stated that a
healthy portion of a stream contained mostly diatoms and
green algae. Rafter (11) and other earlier workers as-
sumed that the absence of large amounts of blue-green
algae was an indication of clean water.
It is apparent that the lists of clean water algae reported
by various workers include a wide variety of forms be-
longing to various groups. Some are planktonic while
others are epiphytic or attached to rocks and other ma-
terial on the bottom of the stream.
REFERENCES
1. The algae: a review. G. W. Prescott. Houghton, Mifflin Co., 436
p. 1968.
2. The microscopy of drinking water. Ed. 4. G. C. Whipple, G. M.
Fair, and M. C. Whipple. J. Wiley and Sons, N.Y., 586 p. With
19 color plates. 1948.
3. Pollution and repurification as indicated by the algae. R. W. But-
cher. Fourth International Congress for Microbiology, held 1947.
Rept. of Proc. 1949.
4. Oekologie der Saprobien. Uber die Bezeihungen der Wasser-
organismen zur Umwelt. R. Kolkwitz. Schriftenreihe des Vereins
fur Wasser-, Boden-, und Lufthygiene. No. 4, 64 p. 1950.
5. Stream enrichment and microbiota. J. B. Lackey. Public Health
Repts. 71:708-718. 1956.
TABLE 10. CLEAN WATER ALGAE
Group and algae
Plate or figure
Blue-Green Algae (Myxophyceae):
Agmenellum quadriduplicatun
glauca type
Calothrix parietina
Coccochloris stagnina
Entophysalis lemaniae
Microcoleus subtorulosus
Phormidium inundatum
Green Algae (Nonmotile Chlorophyceae):
Ankistrodesmus falcatus,
var. acicularis
Bulbochaete mirabilis
Chaetopeltis megalocystis
Cladophora glomerata
Draparnaldia plumosa
Euastrum oblongum
Micrasterias truncata
Rhizoclonium hieroglyphicum
Staurastrum punctulatum
Ulothrix aequalis
Vaucheria geminata
Red Algae (Rhodophyceae):
Batrachospermum vagum
Hildenbrania rivularis
Lemanea annulata
Diatoms (Bacillariophyceae):
Amphora ovalis
Cocconeis placentula
Cyclotella bodanica
Cymbella cesati
Meridion circulare
Navicula exigua var. capitata
Navicula gracilis
Nitzschia Tinearis
Pinnularia nobilis
Pinnularia subcapitata
Surirella splendida
Synedra acus var. angustissima
Flagellates (Chrysophyceae, Cryptophyceae,
Euglenophyceae, and Volvocales
of Chlorophyceae):
Chromulina rosanoffi
Chroomonas nordstetti
Chroomonas setoniensis
Chrysococcus major
Chrysococcus ovalis
Chrysococcus refescens
Dinobryon stipitatum
Euglena ehrenberqii
Euglena spirogyra
Mallomonas caudata
Phacotus lenticularis
Phacus longicauda
Rhodomonas lacustris
III
III
III
III
III
III
III
III
III
III
Fig. 39
III
III
III
III
III
III
III
III
VII
III
III
-------
CHAPTER IX
ALGAE AND POLLUTION-FRESH WATER
Water containing one or more of various types of im-
purities may be said to be polluted. The term pollution,
however, is usually restricted to situations in which the
condition is considered potentially harmful to human
health or capable of interfering seriously with the use of
the water or its immediate environment. Most of the in-
formation available on algae in relation to polluted water
is limited to water containing treated or untreated do-
mestic sewage and closely related organic wastes. The
following account, therefore, will deal primarily with this
type of water pollution.
The algae are affected by pollution in a number of
ways. They may be discouraged from growing as a result
of being deprived of sunlight; the substances may be toxic
or may ecologically modify the physical or chemical en-
vironment sufficiently to retard or prevent growth; they
may suddenly have competition with additional organ-
isms; certain algae may be stimulated to increased growth
and multiplication; a change may also occur in the in-
dividual types or the groups of organisms that predom-
inate (1); some algae may form blooms; the total algal
population may be increased or decreased; oxygen pro-
duction and utilization of nutrient substances by algae
may be greatly modified; and the color, odor, and taste
of the water may be changed by the algae.
Household sewage contains many kinds of organic ma-
terial together with products formed from their partial,
preliminary decomposition. In addition, the phosphates
from detergents and small amounts of other wastes will be
present (2). The relative effect on algae of each constitu-
ent in the complex mixture has not been determined.
Studies have shown that the sodium triphosphate ingre-
dient of a synthetic detergent stimulates the growth of the
unicellular green alga, Chlorella (3).
In one river polluted with sewage, it was calculated that
the phytoplankton contributed an average of 38 percent
of the particulate organic matter from May to November
(4).
After domestic sewage or effluent has polluted a body
of water such as a stream, the algae present react in a
manner that is of considerable importance. During the
process of natural purification, the algae oxygenate the
water and also utilize byproducts of the purification proc-
ess. The kinds and numbers of algae and other organ-
isms in the sewage-polluted portion of a stream are dif-
ferent from those present in the unpolluted portion above
the sewer outlet. As the sewage goes through stages of
decomposition in the stream, the numbers and kinds of
microorganisms continue to change until eventually the
aquatic flora and fauna in the newly purified water be-
come somewhat similar to those found above the point
of pollution. The algae represent a conspicuous and sig-
nificant group in this continuously changing population in
a stream. The variation in the algal population at different
points or under different conditions of organic pollution
constitutes one of the indices that can be applied to any
desired location in the stream to determine the presence
or absence of domestic sewage or other putrescible wastes
or to measure the degree of recovery from pollution with
these wastes.
After examining the reports of 165 authors, the writer
has compiled a list of more than 850 names of algae com-
monly found in water containing a high concentration of
organic wastes (1). Fifty of the more important species
are listed in table 11, and 23 appear on plate IV.
Many genera of algae include certain species that tol-
erate organic enrichment and others that do not. This is
particularly true of Chlamydomonas, Euglena, Navicula,
Oscillatoria, Phormidium, and Synedra. In a few instances,
it may also be true of strains or varieties of a species. For
example, Fjerdingstad (5) claims that there are two sep-
arate strains of the species Ulothrix zonata (fig. 49), the
pollution type and the pure water type.
Included in the group of pollution algae are some forms
of unusual interest. Researchers say that Euglena viridis,
Nitzschia palea, Oscillatoria limosa (fig. 50), and Oscilla-
toria tenuis (fig. 51) are more likely to be present than
any other species when organic pollution exists (1). Next
in order are Arthrospira jenneri, Stigeoclonium tenue, Eu-
glena gracilis, and Chlorella vu/gar/s. Anabaena constr/cta,
Chlorella vulgaris, and Euglena viridis are also found on
sludge or in retention basins of sewage treatment plants.
Chlorella grows readily in artificial culture media and is
being used in a number of laboratories to determine the
feasibility of producing algae on a large scale for food,
animal feed, and other products. Two additional blue-
green algae that tolerate organic enrichment are Osc///a-
toria princeps (fig. 52) and Phormidium uncinatum (fig.
53).
The blue-green algae and the flagellates are the algal
groups most frequently encountered in the portion of a
stream containing organic wastes. Not all representatives
of the blue-green algae are actually blue-green; for ex-
ample, the three species of Oscillatoria illustrated on plate
IV tend to be decidedly yellow-green, although they be-
long to the above group. The flagellate green alga, Chlam-
ydomonas, is one of the very common organisms in water.
Since this genus has a large number of species and other
36
-------
Fresh Water
37
Figure 49,—Ulothrix zonata, vegetative filament and stages in spore
production. Its two strains react differently to pollution.
Figure 50.—Oscillatoria limosa.
Figure 51.—Oscillatoria tenuis.
Figure 52.—Oscillatoria princeps.
Figure 53.—Phormidium uncinatum.
algae have chlamydomonad stages, workers generally have
not identified the particular species of Chlamydomonas
they have encountered in polluted water. It is probable
that there are a number of species other than the Chlam-
ydomonas reinhardi shown on plate IV which could be
listed as algae indicative of organic pollution.
Many of the non-swimming green algae with rounded
cells are difficult to identify correctly and often have been
mistakenly labeled Profococcus (name now changed to
Phytoconis), a type which is common on moist surfaces of
tree trunks and which is attached and not normally plank-
tonic. The two genera of green algae with rounded cells
that are included here as pollution algae are Chlorella and
Chlorococcum, both of which are illustrated on plate IV.
Some common industrial wastes are organic in nature
but generally differ from household sewage in that they
are composed primarily of one or more groups of organic
compounds, or at least much less of a mixture than is
household sewage. Examples would be the whey from
dairy product processing plants, the blood and other ani-
mal products from slaughter and meat packing plants, the
saw dust from saw mills, the discarded materials from
canning factories, the beet particles from the sugar beet
industry, mash from distilleries, and the lime, pulp screen-
ings, filter slurry, lignans, and other carbohydrates from
pulp and paper factories. Practically all of these pollut-
ants tend to stimulate the growth of particular kinds of
yeasts, bacteria, molds, and protozoa but are likely to be
harmful to the algae. The algae in sewage ponds receiv-
ing a large amount of any of the above wastes are not
likely to function efficiently. High turbidity produced by
some of them will reduce light penetration in the stream
or lake and thus prevent algal activity (6-8).
Other industrial wastes are composed of inorganic
chemicals. Included are those from steel mills, mining
operations, and chemical manufacturing plants. Steel in-
dustry wastes contain strong acid in- unneutralized steel-
pickling liquor, oil, grease, phenols, dissolved and sus-
pended iron salts, and oxides (9).
In lakes the wastes are often in areas where the cur-
rents are sluggish, so that the wastes do not disperse or
float away. Mining operations generate such wastes as
sulfides of various metals, acid, mine slimes from pul-
verized ore, and silt (including those from strip-mining
and stream-dredging activities). Chemical plants may re-
lease many different chemicals, some of which are fre-
quently toxic to aquatic life. Slimes, silt, and sludges pro-
duce turbidity and, when they settle, cover up and destroy
bottom-dwelling organisms. Inorganic chemical wastes
invariably have deleterious effects on aquatic organisms
(10-12).
Oil refineries release surface films of oil, tars, and oily
soda-lime water, sludge, ammonia, and phenols, which
may sink to the bottom and destroy aquatic organisms.
Oil wells may release, in addition to oil, salt brine capable
of making life impossible for most fresh-water organisms
(6, 10). Artificial gas plants and railroad yards also dis-
charge oily wastes.
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38
ALGAE AND WATER POLLUTION
Pulp and paper mills, agricultural land users, textile
plants, and leather processing plants generate wastes that
contain both organic and inorganic ingredients. All of
these wastes tend to produce high turbidity, frequently
dark discoloration, often acids or alkalies, complex or-
ganic materials, and often mineral salts, some of which
are algal nutrients. However, the high turbidity, the dark
color of the water, and the strong acids or alkalies are
generally sufficient to destroy the algal growth in spite of
the additional nutrients.
Insecticides, herbicides, and fungicides applied to or
sprayed over agricultural areas can enter a body of water
or impinge on river bank forests and marsh areas. They
may not always destroy the algae but may concentrate on
or in them and thus affect other organisms higher up the
food chain (10).
Excess irrigation water that drains back into streams
brings much silt with it, builds up the mineral content, and
frequently adds nitrogen, phosphorus, and other algal nu-
trients. Its most obvious influences are accelerated hard-
ness and alkalinity in addition to the turbidity. Silt ac-
cumulations suppress benthic algae, and turbidity reduces
the phytoplankton concentration (6).
Power plants and atomic energy plants generally use
large quantities of stream water for cooling purposes. The
warm waters from such plants should not be discharged
in such a manner as to create a temperature block across
the stream (13). A high water temperature tends to favor
the proliferation of blue-green algae, a medium temper-
ature encourages green algae, and a low temperature is
beneficial to diatoms. Certain species of blue-green algae,
primarily Oscillatoria, are the most heat-tolerant organ-
isms. Green filamentous algae tend to grow more rapidly
in areas of heated water during spring and early summer
(13).
Algae are able to accumulate the radioactive materials
which later could affect other organisms that use algae
directly or indirectly as food (14). One investigator found
that the concentration of radio-phosphorus in phytoplank-
ton had reached 200,000 times that in the surrounding
water and the concentration in Spirogyra was 850,000
times that in the water (15).
Important physical and chemical characteristics of water
which pollutants tend to change are turbidity, temperature,
color, radioactivity, organic compounds, BOD, acidity,
alkalinity, DO, minerals, oil, sludge, herbicides, and pesti-
cides.
Particularly in the case of sewage pollution (and to
some extent with regard to industrial organic wastes), al-
gae and bacteria (and to a lesser extent, other organisms)
are capable of bringing about the self-purification of
water, especially in streams. Some kinds of algae are tol-
erant to sewage, that is, they are able to survive in its
presence and may even be capable of growing and mul-
tiplying. For the most part, these algae utilize the nitrogen
and phosphorus salts that are present, and in growing
vigorously they carry on photosynthesis and release oxy-
gen into the water as a byproduct. Sewage-polluted water
is low in DO, since bacteria have already used what oxy-
gen was present in initiating the decomposition of organic
wastes.
The oxygen added by the algae permits the bacteria to
continue decomposing the sewage. The waste products
produced include ammonia, nitrates, and phosphates,
which immediately serve as additional nutrients for the
algae. Thus the algae stimulate the bacteria and the bac-
teria stimulate the algae. Both types of organisms in-
crease rapidly in numbers, and the breakdown of the
sewage is therefore enhanced. Unsightly, partially insol-
uble, turbid, gray, unstable, odoriferous material is
changed into simpler, soluble, odorless, stable, clear,
colorless, inorganic compounds.
During this process, the stream can conveniently be di-
vided into several zones. The zone of degradation, also
known as the polysaprobic zone, is the area just below
the source of the pollutant. Most of the sewage there has
not yet decomposed, non-tolerant algae and other organ-
isms are being destroyed, and the DO is at or near zero.
The next area is the zone of active decomposition, also
designated the alpha-mesosaprobic zone, where bacteria
and sewage-tolerant algae begin to flourish and the sew-
age is in the process of active decomposition. The third
area is the zone of recovery or the beta-mesosaprobic
zone, where the water becomes clear and offensive odors
are absent. Algae are abundant while bacteria are de-
creased in numbers. Sewage is in the final stages of de-
composition. The final area is known as the zone of
cleaner water, also called the oligosaprobic zone, because
the stream has been purified of sewage. Algae intolerant
of sewage return, and sewage-tolerant algae decrease in
numbers.
Various writers draw lines in slightly different places be-
tween the above zones. The description above represents
the general distinctions among them (16).
Published records indicate that algae are most likely to
be present in each zone (16). The general tendency is for
diatoms to be common in the cleaner water, for blue-
green algae and pigmented flagellates to be predominant
in the zone of degredation and the first part of the zone
of active decomposition, and for the green algae to pre-
vail in the remainder of the zone of active decomposition.
Streams and lakes which have been polluted with or-
ganic compounds gradually become richer in algal nu-
trients, especially nitrates and phosphates, which are in-
corporated into the cells of algae during the self-purifica-
tion process. As algae die the nutrients are released into
the water after the algal protoplasm decomposes. This
often stimulates the rapid development of nuisance algae
that may form blooms or surface mats, cause taste and
odor problems, and clog filters and screens in water treat-
ment plants. It may also interfere with fishing, boating,
swimming, and fish culture. In some cases the nuisance
algae are toxic to both man and animals. They also make
the body of water unsightly (17).
It is essential, therefore, to emphasize the great need
for reducing the pollution load in streams and lakes by
-------
Fresh Water
39
developing sewage treatment plants and processes for
treating wastes. Tertiary sewage treatment is now being
tried in which phosphates are removed before the efflu-
ent flows into the water. This would rob the algae of one
of the essential nutrients required for growth (18).
Through concerted efforts the Willamette River in Ore-
gon and the Connecticut River in New England have been
changed from two of the most polluted streams in the
nation to water courses that are approximately records of
cleanliness. They serve to demonstrate that streams can
be cleaned up and freed of pollution.
It is obvious that there are numerous relationships be-
tween various types of water pollution and algae. These
have been considered separately but various combinations
of these are often encountered, making it difficult to de-
termine what the combined effect will be.
REFERENCES
1. A composite rating of algae tolerating organic pollution. C. M.
Palmer. Jour. Phycology 5:78-82. 1969.
2. Microbiology of water and sewage. P. L. Cainey and T. H. Lord.
Prentice-Hall, Inc., N.Y., 430 p. 1952.
3. Detergent phosphorus effect on algae. T. E. Maloney. Jour. Water
Po!. Contr. Fed. 38:38-45. 1966.
4. Phytoplankton, seston and dissolved organic carbon in the Little
Miami River at Cincinnati, Ohio. C. I. Weber and D. R. Moore.
Limnolog. and Oceanog. 12:311-318. 1967.
5. The microflora of the River Molleaa with special reference to the
relation of the benthal algae to pollution. E. Fjerdingstad. Folia
Limnologica Scandinavica, No. 5, 123 p. 1950.
6. Some aspects of water pollution in the Missouri basin. J. R. Neel.
In Biological Problems in Water Pollution. C. M. Tarzwell (ed.),
U.S. Dept. Health, Education and Welfare, Pub. Hlth. Serv., Robt.
A. Taft San. Engr. Center, Cincinnati, Ohio, p. 209-214. 1957.
7. Certain limnological features of a polluted irrigation stream. J. K.
Neel. Trans. Amer. Microscop. Soc. 72:119-135. 1953.
8. The chemistry and biology of milk waste disposal. T. F. Wisnieuski.
Jour, of Milk and Food Tech. 11:293-300. 1948.
9. Report on water pollution study of Mahoning River Basin, Water
Pollution Control Unit. Sanitary Engineering Division, Ohio Depart-
ment of Health, 91 p. 1954.
10. The effect of pollution upon wildlife. O. L. Mechean. In Biological
Problems in Water Pollution. C. M. Tarzwell (ed.), U.S. Dept. Hlth.,
Educ., Welf., Pub. Hlth. Serv., Robt. A. Taft San. Engr. Center, Cin-
cinnati, Ohio, p. 240-245. 1957.
11. Effects of turbidity and silt on aquatic life. J. N. Wilson. In Bio-
logical Problems in Water Pollution. C. M. Tarzwell (ed.), U.S. Dept.
Hlth., Educ., and Welf., Publ. Hlth. Serv., Robert A. Taft San. Engr.
Center, Cincinnati, Ohio, p. 235-239. 1957.
12. Aquatic life in waters polluted by acid mine waste. J. B. Lackey.
Pub. Hlth. Repts. 54:740-746. 1939.
13. Effects of cooling water from steam-electric power plants on stream
biota. F. J. Trembley. In Biological Problems in Water Pollution.
C. M. Tarzwell (ed.), U.S. Dept. Health, Education, and Welfare,
Pub. Hlth. Serv., RATSEC, Cincinnati, Ohio, Third Seminar 1962.
Pub. Hlth. Serv. Publ. No. 999-WP-25. p. 334-345. 1965.
14. Pollution problems created by power reactors and other uses of
atomic energy. C. P. Straub. In Biological Problems in Water Pol-
lution. C. M. Tarzwell (ed.), U.S. Dept. Health, Education, and Wel-
fare, Pub. Hlth. Serv., Robt. A. Taft San. Engr. Center, Cincinnati,
Ohio, 2nd Seminar. W60-3. p. 33-39. 1960.
15. The practice of water pollution biology. K. M. MacKenthun. U.S.
Dept. of Interior, Fed. Water Pol. Contr. Admin., Div. of Tech.
Support. 281 p. 1969.
16. Self-purification of streams (Chapter 12) and ecological classifica-
tion of microscopic organisms (Chapter 32). In the Microscopy of
Drinking Water. G. C. Whipple, G. M. Fair, and M. C. Whipple.
4th ed. J. Wiley and Sons. p. 313-336 and p. 540-557. 1948.
17. The problem of nuisance growths due to organic enrichment. H.
Heukelekian. In Biological Problems in Water Pollution. C. M.
Tarzwell (ed.), U.S. Dept. of Health, Education, and Welfare, Publ.
Hlth. Serv., Robert A. Taft San. Engr. Center, Cincinnati, Ohio, 2nd
Seminar. W60-3. p. 250-251. 1960.
18. Phosphate extraction process. O. E. Albertson and R. J. Sherwood.
Jour. Water Pol. Contr. Fed. 41:1467-1490. 1969.
TABLE 11. POLLUTION ALGAE—ALGAE COMMON IN
ORGANICALLY ENRICHED AREAS
Group and algae
Plate or figure
Blue-Green Algae (Myxophyceae):
Agmenellum quadriduplicatum,
tenuissima type
Anabaena constricta
Arthrospira jenneri
Oscillatoria chalybea
Oscillatoria chlorina
Oscillatoria formosa
Oscillatoria lauterbornii
Oscillatoria limosa
Oscillatoria princeps
Oscillatoria putrida
Oscillatoria splendida
Oscillatoria tenuis
Phormidium autumnale
Phormidium uncinatum
Green Algae (nonmotile Chlorophyceae):
Actinastrum hantzchii
Ankistrodesmus falcatus
Chlorella pyrenoidosa
Chlorella vulgaris
Closterium acerosum
Coelastrum microporum
Micractinium pusillum
Pediastrum boryanum
Scenedesmus obliquus
Scenedesmus quadricauda
Stigeoclonium tenue
Diatoms (Bacilariophyceae):
Cocconeis placentula
Cyclotella meneghiniana
Diatoma vulgare
Gomphonema parvulum
Hantzschia amphioxys
Melosira granulata
Melosira varians
Navicula cryptocephala
Navicula viridula
Nitzschia acicularis
Nitzschia palea
Nitzschia sigmoidea
Stephanodiscus hantzschii
Surirella ovata
Synedra acus
Synedra ulna
Flagellates (Euglenophyceae,
Volvocales of Chlorophyceae, others):
Chlamydomonas reinhardi
Chlorogonium elongatum
Chlorogonium euchlorum
Cryptomonas erosa
Eudorina elegans
Euglena acus
Euglena agilis
Euglena deses
Euglena gracilis
Euglena oxyuris
Euglena polymorpha
Euglena viridis
Lepocinclis ovum
Lepocinclis texta
Pandorina morum
Phacus pleuronectes
Phacus pyrum
Spondylomorum quaternarium
Synura uvella
IV
IV
IV
Vlll
IV
IV
29
Vlll
IV
Vlll
30
IV
35
Vlll
IV
I
67
IV
Vlll
Vlll
IV
Vlll
IV
I
Vlll
VII
IV
IV
I
IV
IV
VII
I
IV
VII
-------
CHAPTER X
ALGAE AND POLLUTION-ESTUARINE
An estuary is the area where a river or stream meets the
tide of the ocean. As the waters of the two generally do
not mix quickly but remain temporarily as separate layers,
the estuary may extend up the river channel for a con-
siderable distance and also out into the ocean. Because
of this resistance to sudden mixing, the nature of the
environment, and the differences between the two waters,
there tends to be a great variation in the conditions pres-
ent at different locations in the estuary and at the same
location at different times. The more important factors
would include wave action, tides (causing periodic immer-
sion), temperature differences between river and ocean
waters and between seasons, the physical nature of the
substratum, salinity, the nitrate and phosphate content of
the waters, and the degree of turbulence and wind that
exists (1). Many estuaries are shallow, and this factor
stimulates the rapid cycling of nutrients between organic
and inorganic phases. Thus, the principal feature of an
estuary is the exceeding variability of its environment (2).
The algae of estuaries are of three major types, sea
weeds, phytoplankton, and benthic forms including peri-
phyton. The sea weeds may be attached to rocks along
the shore or may be on the bottom covered by consid-
erable depth of water. Often they become detached and
can be collected using a boat with the aid of a net.
Since the organisms inhabiting the estuary are subjected
to a constantly changing environment, they are naturally
tolerant to and able to withstand a rugged environment.
Pelvetia is an example of a brown sea weed that can re-
main alive while uncovered by the water for long periods
of time. Ceramium, Polysiphonia, and Porphyra are com-
mon red sea weeds (3).
Of the phytoplankton, diatoms rank first in abundance
and photosynthetic activity. Dinoflagellates are generally
considered second to diatoms as primary producers, par-
ticularly in warmer waters. The nannoplanktonic phyto-
flagellates also appear to be very common and abundant,
but they are difficult to study, and many workers have,
therefore, overlooked them. Examples of common genera
are the diatoms, Chaefoceros, Cosdnodiscus, Navicula,
and Rhizosolinea. Common dinoflagellates include Cym-
nodinium, Katodinium, and Heterocapsa. Other common
flagellates are Olithodiscus, Chlamydomonas, and Chroo-
monas (2). Examples of benthic forms are such blue-green
algae as Microcoleus and the red flagellate Dunaliella (1).
Even when unpolluted, marine waters are extremely
hard as compared to most inland waters. The total dis-
solved solids content is measured in terms of parts per
thousand rather than parts per million. Water in the ocean
ranges from 33 to 35 parts per thousand of total salinity.
Almost all estuaries are polluted because they receive
the accumulated pollution of streams and lakes and con-
tain the wastes dumped directly into them, including in-
dustrial, household, and oil materials. Wastes that are
present or dumped into the open ocean are often carried
back into estuaries.
While formerly neglected, more and more concern is
being expressed about estuarine pollution since the areas
involved are of increasing significance. Approximately
one third of the population of the United States lives near
estuaries, and seven of the world's 10 largest cities are on
estuaries (4). Estuaries are habitats of both fin and shell-
fish and support huge commercial and sport fisheries.
Estuaries provide bathing, sailing, and power boating and
are also of great aesthetic value. Finally, industries draw
large quantities of brackish water from them for cooling
and processing purposes. All of these activities depend
in some degree upon the quality of the water available
(5). "To see the effect of pollution at its worst, one must
as a rule go to the estuaries and tidal waters .... There
is a feeling that once polluted water has left a river it goes
away to sea and there gradually oxidizes where it does no
one any harm .... [However] the next tide brings much
of the pollution in again and the part that gets out seems
to travel along the coast with succeeding tides coming
backwards and forwards as the ocean currents carry it,
until it finally oxidizes away." (6)
Since estuarine algae can withstand moderately large
changes in the natural environment, the effects of pol-
lutants must dominate the natural effects in order to be
detected. Color plate V contains illustrations of 24 pollu-
tion-tolerant estuarine algae selected from a much larger
number of species that have been reported. Represented
in the group are brown, red and green sea weeds, diatoms,
blue-green algae, dinoflagellates, various other pigmented
flagellates, and one attached prostrate form.
In summer, diatoms often appear to be able to utilize
the nutrient salts in highly polluted water. It is interesting
that dinoflagellates play such an important part in the
plankton of polluted water, whereas in fresh water they
are practically absent in polluted areas. Green flagellates,
such as Eutreptia and Chlamydomonas, thrive in highly
polluted water but are very scarce in unpolluted estuaries
(7).
Discharges into Boston Harbor caused very high con-
centrations of ammonia nitrogen (N) and soluble phos-
40
-------
Estuarine
41
phorus (P) that often exceeded 100 and 40 micrograms
per liter respectively in all reaches of the harbor. Dense
populations of phytoplankton, averaging more than 1,000/
ml, were present in about 66 percent of this harbor. Other
estuarine waters having phytoplankton populations denser
than 1,000/ml are considered to be over-enriched.
Sewage pollution also stimulates dense growths of at-
tached sea weeds which give off noxious odors, cause un-
sightly growths at marine facilities, and increase the costs
of maintaining buoys and piers. In some cases, decom-
posing masses of Ulva (sea lettuce) have emitted enough
hydrogen sulfide to discolor paint on nearby buildings (8).
The discharge of pollutant-laden water from duck farms
into Long Island Bay has allowed large numbers of the
green alga Codium to develop as a bottom-attached form.
This plant seriously interferes with the development of
shellfish.
Pollutants which reach an estuary may be oxidized with
the aid of oxygen produced by the algae during photo-
synthesis, may settle to the bottom, or may be carried
out to sea. In shallow estuaries, the benthic algae may aid
in further decomposition of the sludge deposits.
The prevention or reduction of estuarine pollution is
dependent primarily upon stopping or modifying the
dumping of pollutants into estuaries and the bodies of
water that flow into them.
REFERENCES
1. Ecology of marine algae. J. Feldman. Chapt. 16 in Manual of Phy-
cology by G. M. Smith (ed.), Chronica Botanica Co., Wallham,
Mass., p. 313-334. 1951.
2. Studies in brackish water phytoplankton. P. H. Campbell. Sea Grant
Publication UNC-SC-73-07, Univ. N. Carolina, 409 p. 1973.
3. Algal vegetation types along the shores of inner bays and lagoons
of Curacao, and of the lagoon lac (Bonaire), Netherlands Antilles.
C. van den Hock, F. Colijn, A. M. Cortal-Breeman and J. B. W. Wan-
ders. Verhandelingen der Komnklijke Nederlandse Akademie van
Wetenschappen, afd. Natuurkunde. Tweede Reeks, Deel 61. No.
2:1-72. 1972.
4. Hydrographic factors involved in the dispersion of pollutants intro-
duced into tidal estuaries. D. H. J. Hull. Proc. 34th Ann. Conf., Mary-
land-Delaware Water and Sewage Assn., p. 37-52. 1961.
5. Algal and organic waste assimilation in tidal estuaries. D. H. J. Hull.
Proc. 34th Ann. Conf., Maryland-Delaware Water and Sewage Assn.,
p. 37-52. 1961.
6. The danger of estuary pollution. Chapt. 1 in River Pollution. H. D.
Turing. E. Arnold & Co., London, p. 9-35. 1952.
7. A phytoplankton survey of the polluted waters of Inner Oslo Fjord.
T. Braarud. Hvalraadets Skrifter, Scientific Results of Marine Bio-
logical Research. No. 28:1-142. 1945.
8. The practice of water pollution biology. K. M. MacKenthun. Fed.
Water Pol. Contr. Admin., Div. of Tech. Support. 281 p. 1969.
-------
CHAPTER XI
ALGAE AS INDICATORS OF WATER QUALITY
Changes in water quality exert a selective action on the
flora and fauna which constitute the living population of
water, and the effects produced in them can be used to
establish biological indices of water quality. Changes in
water quality may affect the amount of oxygen and nu-
trients present or cause the water to become toxic to
some types of organisms. The change may result from
the amount of inert solids present in the water. In study-
ing and observing any particular body of water, the
aquatic biologist applies certain types of measurements,
such as a biological index, to obtain information about
the conditions that are present (1).
In the past, chemical, physical, and bacteriological cri-
teria were considered to be easier to evaluate and apply
than biological indices, which were thought to be rel-
atively underdeveloped (2). Chemical and physical meas-
urements, however, tend to measure only the cause of
change in water quality, while biological tests deal pri-
marily with effects of the change. Simple, rapid, and re-
liable methods for assessing the degree of purity or con-
tamination of water have now been developed to such
an extent that certain of them will soon merit considera-
tion as standardizable procedures, applicable over a wide
range of waters.
There are in general two types of biological tests:
1. All organisms present in a water sample are iden-
tified and their relative frequency is established. These
tests are direct or ecological ones and can deal with all
kinds of organisms present, or they may be limited to a
few groups, one group, or one or a few types of individ-
uals.
2. Indirect or physiological methods are used to
estimate the living activity of the organisms. They may be
limited to a particular species or test organism, which is
cultured in the laboratory and inoculated into a sample of
water to be tested. Certain selected reactions serve as in-
dices of water quality (3).
The classic direct or ecological test is the saprobity
system of Kolkwitz and Marsson (4), which has been
revised by several other workers, including Liebmann (5).
Originally the indicator species found in a sample were
merely listed and the list was used to define the particular
zones of pollution. Indicator species had previously been
designated as belonging to four water quality zones:
oligosaprobic (clean), beta-mesasaprobic (sub-pollutional),
alpha-mesasaprobic (pollutional), and polysaprobic (sep-
tic). Some modifications of the procedure have been de-
veloped, especially those involving the relative frequency
of each species. Statistical calculations were also intro-
duced, allowing the results to be expressed on graphs.
One procedure that is considered convenient has been
adopted as a preliminary standard procedure in East Ger-
many. Each species is assigned a number from 1 to 4 in
a sample of water from a particular location. The number
is based on its position in the saprobity system and its
frequency (3). The oligosaprobic zone organism is s = 1
and so on through the 4 zones. Frequency (h) is divided
into three: rare = 1, common = 3, and abundant = 5.
The saprobity index (S) can be calculated for each samp-
s-h
ling area by the following formula: S = — . The sapro-
h
bity index for each degree of pollution is as follows:
Saprobity index
1.0 - 1.5
1.5 - 2.5
2.5 - 3.5
3.5 - 4.0
Degree of pollution
Very slight
Moderate
Heavy
Very heavy
Various other modifications have been made such as
subdividing the water quality zones (6,7), comparing the
number of chlorophyll-bearing organisms (producers) with
the number of non-chlorophyll-bearing organisms (con-
sumers). In one of these a biological index of pollution
(BIP) is calculated by the formula
BIP =
B
-x100
A + B
where A represents the producers (algae) and B repre-
sents the consumers (protozoa). Individual non-filamen-
tous bacteria and other organisms are not used. The fol-
lowing BIP numbers are examples fitting into the various
water quality zones: 0.6 = zone of clean water, 12.0 =
zone of moderate decomposition, 30.9 = zone of active
decomposition, and 55.1 = septic zone (8).
In 1969, a procedure was described for using the 20
genera or species most emphasized by workers as being
tolerant of high organic pollution to determine the algal
pollution index of a sample of water. Five of these genera,
Synedra, Nitzschia, Melosira, Pandohna, and Euglena, are
illustrated in figures 54-57. For each of the 20 algae, a
pollution index factor was assigned (see table 12). In
making a microscopic analysis of a sample, all of the 20
algae that are observed are recorded (providing 5 or more
individuals, per slide, of a particular kind are present).
The index factors of the algae present are then totaled. A
42
-------
Indicators of Water Quality
43
score (pollution index) of 20 or more is taken as evidence
that high organic pollution exists, while a score of 15 to
19 represents probability. Lower figures indicate that the
organic pollution of the sample is not high, that the
sample is not representative, or that some substance or
factor interfering with algal growth is present (9).
In some cases particular groups of algae have been used
to indicate the quality or type of water. Lakes have been
characterized in terms of their dominant phytoplankton
groups. Many desmid species are most frequent in oli-
gotrophic waters, while a few are most frequent in eu-
trophic bodies of water. Many blue-green algae occur in
nutrient-poor waters, while others are tolerant of high or-
ganic pollution (10).
A diatometer has been developed and used to non-
selectively and continually sample a diatom flora. The dia-
tometer holds microscope slides that are immersed in the
surface water and are removed after predetermined pe-
riods of time. The diatoms collected are first processed,
then fixed on clean slides, and identified and counted
under the microscope. A graph is made in which the
ordinate equals the number of species on an arithmetic
scale and the abscissa represents the numbers of speci-
mens whose intervals are on a logarithmic scale. A trun-
cated normal curve is constructed which best fits the data.
When the diatom flora has been adversely affected by
slight pollution, the length of the curve is extended. Fur-
thur pollution causes a reduction in the height of the
mode. By means of this procedure it is possible to spot
the badly polluted areas in a body of water (11).
Diatom associations have also been selected as indi-
cators of the presence of certain industrial wastes and of
sewage. Particularly emphasized have been species and
varieties of Gomphonema (12,13).
Through species numbers of diatoms, the ecosystem
approach to water quality assessment has been used. At
eutrophic stations, a few species generally compose a
large portion of the diatom population and their density
level is usually high. "Clean" stations, on the other hand,
have more species that compose a small portion of the
total diatom population and the overall density level is
low. For example, over a 27-month period, the average
number of species of diatoms present in random counts
of 250 to 300 organisms at Buffalo, where the water was
of very poor quality, was only 12. In contrast, during the
same period, the average for Sault Ste. Marie, which has
high quality water, was 41 (14).
Navicula accomoda is claimed to be an indicator of sew-
age pollution, a position not occupied by any other spe-
cies of diatom. Other species may be present but are not
limited to the alpha-mesosaprobic zone as this form seems
to be (15).
The red-colored blue-green alga, Osdllatoria rubescens,
develops suddenly in large numbers, discolors the water,
and is considered, especially in Europe, as the first acute
indication that a lake is undergoing a distinctly unfavor-
able development. Later symptoms include turbidity, dis-
agreeable odor, and disappearance of the higher grade fish
(16).
Five algae were selected as reflecting the amount of
pollution in rivers in England. Stigeodonium tenua is
present at the downstream margin of the foulest part of a
river, Nitzschia palea and Gomphonema parvulum always
appear to be dominant in the mild pollution zone, and
Coccone/'s and Chamaesiphon are almost always found in
unpolluted streams or in the repurified zone (17).
In estuarine waters, a certain few algae are claimed to
be indicators of pollution. When the population is large,
Peridinium triquetum may be used as a reliable indicator
that the water is highly contaminated. There is hardly any
other species which is so characteristic of polluted waters
as is Eutreptia lanowli. It is considered remarkable that
dinoflagellates play such an important part in the plankton
of estuarine polluted waters. In fresh water the dinoflag-
ellates are practically absent in the polysaprobic and
mesosaprobic regions (18).
Indirect or physiological tests are being used with
increasing frequency to study the potential fertility of wa-
ter. In 1927, a procedure was described in which a species
of Carter/a was used as a test organism in sea water to
determine the phosphorus and nitrogen content. From
the results it could be determined what combination of
salts was the limiting nutrient factor for the growth of
phytoplankton in the area tested.
For fresh water, the unicellular green alga Selenastrum
capricornutum has several superior qualities as a labora-
tory organism: (1) it is easy to identify; (2) form variations
with changing growth conditions are small; (3) it is soli-
tary; (4) it is an obligate autotroph; and (5) it has a mini-
mum of growth requirements. It has been used in Nor-
way and the test procedure is as follows:
1. Water samples are autoclaved and inoculated from
a culture of Selenastrum.
2. The flask is shaken slowly at 30°C and illuminated
by flourescent lights.
3. The extent of growth of the alga is determined
by measuring the red flourescence due to chlorophyll. The
results, which are compared with those obtained using a
standard solution, indicate the amount of fertilizing sub-
stances present in the water (19).
A culture test was developed in Vermont in 1956 to de-
termine the nutrients available for plant growth in natural
waters using a pure culture of the green alga Kirchneriella
subsolitaria (fig. 58) as the indicator organism. Six samples
of the natural water are inoculated with Kirchneriella. One
sample serves as a control and sodium carbonate, calcium
carbonate, diacid potassium phosphate, magnesium sul-
fate, or all four are added to the remainder. Cell counts
are made daily and population densities are estimated by
statistical techniques (20).
Due to rapidly increasing concern for the problems
generated by eutrophication and pollution, it is essential
that acceptable standardized algal growth tests be de-
veloped to measure these conditions. A Joint Industry/
U.S. Government Task Force on Eutrophication determined
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44
ALGAE AND WATER POLLUTION
Figure 54.—Synedra and Nitzschia.
Figure 55.—Melosira (indicator alga).
Figure 57.—Euglena (indicator alga).
Figure 58.—Kirchneriella subsolitaria, the alga used in the Vermont test.
Figure 56.—Pandorina (indicator alga).
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Indicators of Water Quality
45
in 1969 that there should be provisionally three funda-
mental test algal assay procedures: a bottle test, a con-
tinuous-flow-chemostat test, and an in situ test. After
about two years of research, it was decided that the bottle
test was reliable and ready for routine use. Further re-
search is needed on the other two tests before they be-
come ready for universal use.
Three standard test organisms are recommended for the
bottle test, Selenastrum capricornutum, Anabaena flos-
aquae, and Anacystis cyanea (Microcystis aeruginosa).
A sample of unknown strength from some water source
can be assayed in comparison to media of known strength.
Further evaluation is needed to refine the technique.
Bottle algal assays consist of three steps:
1. Selection and measurement of appropriate para-
meters during the assay, for example, biomass indicators
such as total cell carbon, maximum specific growth rate,
and maximum standing crop. Determination of the algal
growth may be accomplished by several methods such as
dry weight, direct microscopic counting, use of an elec-
tronic particle counter, absorbance with a spectrophotom-
eter or colorimeter at a wave length of 600-750 m/x
(millimicrons), chlorophyll content by direct fluorometric
determination or total cell carbon.
2. Presentation and statistical evaluation of the meas-
urements made during the assay.
3. Interpretation of the results with respect to the
specific problem being investigated.
It is intended that the test be used to: (1) identify algal
growth-limiting nutrients; (2) determine biologically the
availability of algal growth-limiting nutrients; and (3) quan-
tify the biological response to changes in concentration
of algal growth-limiting nutrients. These measurements
are made by adding a selected test alga to the test water
and determining algal growth at appropriate intervals (21).
The methods using algae as indicators of water quality
vary, therefore, from identifying the algal flora of the
sample of water, detecting one or a few forms or groups,
to culturing a selected test alga in the water being stud-
ied. Books giving precise descriptions of techniques in
which algae are used to measure the quality of surface
waters and effluents are Biological Field and Laboratory
Methods (22), Handbook of Phycological Methods (23),
and Standard Methods for the Examination of Water and
Wastewater (24). Progress toward the selection in stand-
ardization of one or more of these methods is being made
in Europe and the United States.
REFERENCES
1. The biological indices of stream quality. W. M. VanHorn. Proc.
Fifth Indus. Waste Conf., Purdue Univ. 1949. Purdue Univ. Eng.
Bull. 34:215-222. 1950.
2. California water quality criteria. State of California. 1952.
3. A review of central European methods for the biological estima-
tion of water pollution levels. H. Bick. Bull. World Health Organ-
ization 29:401-413. 1963.
4. Oekologie der Saprobien. Uber die Bezeihungen der Wasserorgan-
ismen zur Umwelt. R. Kolkwitz. Schriftenreihe des Vereins fur
Wasser-, Boden-, und Lufthygiene Berlin-Dahlem/Gegrundet im
Jahre 1902. Herausgegeben im Auftrage des Vereins fur Wasser-,
Boden-, und Lufthygiene von Prof. Dr. E. Tiegs, Nr. 4. 64 p. 1950.
5. Handbuch der Frischwasser und Abwasserbiologie. Band 1. H.
Liebmann. R. Oldenbourg, Munchen, Germany, 539 p. 1951.
6. Water quality system. V. Sladecek. Verh. Internal. Verein. Limnol.
16:809-816. 1966.
7. Pollution of streams estimated by benthal phytomicro-organisms.
I. A saprobic system based on communities of organisms and
ecological factors. E. Fjerdingstad. Int. Revue Ges. Hydrobiol.
49:63-131. 1964.
8. A preliminary report on the biological index of water pollution.
I. Horasawa. Zool. Mag. (Tokyo) 54:37-38. 1942.
9. A composite rating of algae tolerating organic pollution. C. M.
Palmer. Jour. Phycol. 5:78-82. 1969.
10. Planktonic algae as indicators of lake types, with special reference
to the Desmidiaceae. A. J. Brook. Limnol. and Oceanog. 10:403-
411. 1965.
11. Diatoms as an indication of river change. R. Patrick. Proc. 9th
Indus. Waste Conf. 1954, Purdue Univ. Eng. Bull. 39:325-330. 1955.
12. Diatomaceas no trato digestive do Australorbis glabratus (Say,
1818). H. M. Filko and D. M. M. Momoli. Botanica (Brazil), No.
9:1-7. 1963.
13. Diversity in some South African diatom associations and its rela-
tion to water quality. R. E. M. Archibald. Water Research 6:1229-
1238. 1972.
14. Possible relationships between plankton-diatom species numbers
and water-quality estimates. L. G. Williams. Ecology 45:809-823.
1964.
15. Notes on the ecology of the diatom Navicula accomoda Hustedt.
E. G. Jorgensen. Saertryk af Botanisk Tidsskrift 49(1):189-191. 1952.
16. The Alpine lakes, a heritage in danger. O. Jaag. World Health
Organization News Letter 8 (5):3. 1955.
17. Pollution and re-purification as indicated by the algae. R. W. But-
cher. Fourth Internal. Congress for Microbiology, 1947. Rept. of
Proc. p. 149-150. 1949.
18. A phytoplankton survey of the polluted waters of Inner Oslo Fjord.
T. Braarud. Hvalraadets Skrifter, Scientific Results of Marine Bio-
logical Research. No. 28:1-142. 1945.
19. Algal problems related to the eutrophication of European water
supplies, and a bio-assay method to assess fertilizing influences
of pollution on inland waters. O. M. Skulberg. Chapt. 13 in Algae
and Man. D. F. Jackson (ed). Plenum Press, N.Y. p. 262-299. 1964.
20. A biological test for determining the potential productivity of
water. M. Potash. Ecology 37:631-639. 1956.
21. Algal assay procedure: bottle test. A. F. Bartsch (ed). National
Eutrophication Research Program. Environmental Protection
Agency. 82 p. 1971.
22. Biological field and laboratory methods fpr measuring the quality
of surface waters and effluents. C. I. Weber. National Environmen-
tal Research Center. Office of Research and Development. U.S.
Environmental Protection Agency, Cincinnati, Ohio. EPA Rept. No.
670/4-73-001. 187 p. 1973.
23. Handbook of phycological methods, culture methods & growth
measurements. J. R. Stein (ed). Cambridge Univ. Press, London,
England. 448 p. 1973.
24. Bio-assay methods for aquatic organisms. Part 800 In Standard
Methods for the Examination of Water and Wastewater. Ed. 14.
Amer. Pub. Hlth. Assn., Washington, D.C. p. 685-869. 1975.
TABLE 12. ALGAL GENUS POLLUTION INDEX
Genus
Anacystis
Ankistrodesmus
Chlamydomonas
Chlorella
Closterium
Cyclotella
Euglena
Gomphonema
Lepocinclis
Melosira
Pollution
index
1
2
4
3
1
1
5
1
1
1
Genus
Micractinium
Navicula
Nitzschia
Oscillatoria
Pandorina
Phacus
Phormidium
Scenedesmus
Stigeoclonium
Synedra
Pollution
index
1
3
3
5
1
2
1
4
2
2
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CHAPTER XII
ALGAE IN SEWAGE STABILIZATION PONDS
There are several processes that have been developed
for the treatment of municipal sewage. The three most
commonly used methods are trickling filters, activated
sludge systems, and lagoon systems. In total there are
approximately 16,000 treatment plants in the United States.
Of these, 4,000 are municipal wastewater lagoon systems,
and more than 90 percent are used for communities of
less than 10,000 population. With the exception of com-
pletely anaerobic lagoons used for pretreatment of certain
industrial wastes, lagoons depend on algae to aid in the
transformation of the sewage to a stable secondary efflu-
ent that can be released into the receiving water. The
biological processes occurring in facultative lagoon sys-
tems are described in the following pages. Some lagoon
systems are aerated through submerged tubing using air
supplied by compressors installed in blower houses near
the lagoon, or by mechanical aerators, but the biological
processes remain similar to those of the facultative lagoon
systems. The aerated lagoon systems are used where high
concentrations of organic wastes may be anticipated or
where extremely cold temperatures and ice cover over
the lagoon system may restrict the activities of the algae
during the winter period.
In the waste oxidation-stabilization method, liquid sew-
age is released into a man-made or natural pond before
or after receiving preliminary treatment and is held there
to permit desired microbiological transformation to take
place. Algae, bacteria, and other microorganisms com-
bine to change the waste into stabilized forms which are
unobjectionable when discharged. The process can be so
regulated that no offensive conditions occur during treat-
ment (1).
Although bacteria are the most significant saprobic or-
ganisms, molds and yeasts may also be present. Molds are
particularly abundant when the pH is low and in pond
sludges and scums. Fungal colonies in a pond can reach
a maximum of about 1 million colonies/gm dry weight
of sludge and liquid (2).
If proper environmental factors such as light, tempera-
ture, and the absence of toxic materials (such as chromate)
exist, 150 mg/l of BOD can be lowered to approximately
20 mg/l if sewage is kept in an oxidation-stabilization
pond for about 15 days. Detention periods of 20 to 30
days are, however, generally recommended, and the ini-
tial BOD loading is commonly less than 150 mg/l (3).
This procedure has been accepted in many areas as a
satisfactory method for disposing of household sewage and
some types of industrial wastes. In a few states, for ex-
ample, up to one-half or more of the communities are
treating their wastes in this manner. Brazil is constructing
additional oxidation-stabilization ponds for use in large
cities as well as smaller towns. Warm climates stimulate
rapid changes in the sewage and also permit deeper ponds
and more concentrated loadings than are possible in the
United States. In North America, the proper loading of
sewage ponds has generally been considered to be from
25 to 50 Ib BOD/acre-feet/day, and in Australia, about
70 Ib (4,5). In the southern United States, loadings of
100 to 250 Ib/acre/day have sometimes been used suc-
cessfully. In Brazil, however, loadings up to about 700 Ib
are being used, sometimes with the aid of agitators or
aerators, and often a deep primary pond. Intense sunlight
may be a factor that permits this also. In the northern
states where ice develops on the ponds in winter, the
loading must be low enough to prevent problems of
anaeoobic decomposition and odor production in the
spring, when the ice melts and before the algae have
developed in sufficient amount to stimulate aerobic activi-
ty. Odor problems can often be handled satisfactorily by
adding sodium nitrate at the rate of 1 Ib/lb of BOD (6).
The transformations in a stabilization pond correspond
closely to the natural purification that occurs in a stream
receiving organic wastes. Aerobic and anaerobic saprobic
bacteria are available to act on the organic debris in the
water and to break down the material into simpler com-
pounds. In the presence of sufficient quantities of sew-
age, any dissolved oxygen in the water may be consumed
very quickly. This generally limits the activities of the
aerobic bacteria, and the aerobic process, therefore, comes
to a standstill. In many cases, however, it is desirable to
encourage the aerobic process and to limit the anaerobic,
since the former can be faster and the amount of inter-
mediate malodorous products is less than in the latter
process.
When an anaerobic process is used as a part of the
treatment in heavily loaded ponds, the relative areas of
aerobic and anaerobic units should probably have a ratio
of about 15 to 1 (7).
Products of the anaerobic process include sulfides, ni-
trogen gas, volatile acids, and methane, while products of
the aerobic process include water, nitrates, phosphates,
sulfates, and carbon dioxide. The latter products are more
readily utilized by algae and other pigmented plants than
are the former, and they are mostly odorless and generally
soluble in water.
46
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Sewage Stabilization Ponds
47
The sewage stabilization pond contains an algal popula-
tion which is continually active and subject to substantial
changes in number and constituent members. It thus
tends to be very different from the algal populations pres-
ent in stagnant pools, eutrophic ponds or lakes, and lab-
oratory cultures. As soon as the population in the sewage
pond changes in the direction of the type population of
these other habitats, it is evidence that oxidation and
stabilization in the pond are not functioning properly.
In a stabilization pond where there is a continuous re-
placement of sewage, the algae present must be capable
of existing under the condition imposed by such an en-
vironment. In addition, they must be metabolically very
active, absorbing carbon dioxide, nitrates, phosphates, and
other nutrients from the pond and releasing an abundance
of oxygen. This high activity is possible only in young al-
gal cells. There must be continual, rapid reproduction of
new algal cells into which the protoplasmic contents of
the parent cells are completely incorporated into the
cells of the new generation. Otherwise the increased al-
gal catabolism, together with decomposition of old cells
that die, will more than counteract the desirable changes
brought about by the young algal cells in the pond. A
static algal bloom on the surface of the pond or a slowly
developing mass of attached algae on the sides or bottom
is seldom found in a sewage pond where the algal popu-
lation is functioning at its best.
In this report, all genera of algae recorded from the
samples are classified as representatives of four groups
which are often used in the field of sanitary biology. These
are blue-green algae, diatoms, flagellate algae, and green
algae. Typical examples of genera representative of the
four groups found in stabilization ponds are blue-green
algae: Anacystis (Microcystis), Osdllatoria, Schizothrix;
diatoms: Cyclotella, Gomphonema, Nitzschia; flagellate
algae: Chlamydomonas, Euglena, Cryptomonas; green al-
gae: Ankistrodesmus, Chlorella, Scenedesmus (table 13).
Algae present in the sewage pond, because of their
photosynthetic activity, release oxygen into the water and
the oxygen is then available to increase the aerobic de-
composition of the organic wastes by bacteria.
The rate of oxygen production by algae in daylight may
be up to 20 times the rate of oxygen uptake by algae in
respiration at night. Thus, even though the DO may go
down to zero in sewage ponds at night, due to bacterial
and algal metabolism, the DO of the pond may reach up
to about 25 mg/l in the daylight because of algal photo-
synthesis.
Oxygen production in algal photosynthesis decreases
with depth, e.g., it is often five times greater near the sur-
face than at a depth of 2.5 ft. Thus, from this standpoint,
the use of shallow ponds of about 2.5 ft would be the
most efficient, since below that depth the amount of oxy-
gen used in algal respiration is at least as much as the oxy-
gen released by photosynthesis. Other factors such as
temperature, water movement, and problems of weed
control indicate that a pond 3 to 4 ft in depth would be
desirable (8,9).
When illuminated, algae excrete no other gas than oxy-
gen. Normally, only a minimal amount of soluble organic
material is excreted and, therefore, in a living state, they
do not increase the amount of organic matter in a pond
(10). However, some forms of Chlamydomonas and Scen-
edesmus are known to excrete organic material. In some
cases the former genus has excreted up to 40 percent of
the oxidizable soluble material formed in algal photosyn-
thesis (11).
Although many kinds of algae are sensitive to large
amounts of organic wastes in their environment, others
are tolerant and may be stimulated in their growth and
reproduction by the presence of the wastes. These latter
forms are often called pollution-tolerant algae or merely
pollution algae.
Algae function in another significant way in a pond. The
simpler compounds that result when aerobic bacteria de-
compose organic wastes include nitrates, ammonia, phos-
phates, and lesser amounts of other compounds, all of
which are the nutrients algae require for growth. The
pond water does not accumulate any large quantity of
these nutrients, since they are quickly absorbed and as-
similated by the algae. In this way, the chemical units
that comprised the organic wastes are eventually incor-
porated into the algae as relatively stabilized organic com-
ponents of living algal cells.
Ordinarily domestic sewage does not provide a balanced
diet, since both carbon and nitrogen are deficient in re-
lation to the amount of phosphorus normally present.
Theoretically, therefore, it would increase algal growth if
additional inorganic carbon (such as carbon dioxide) and
nitrogen (such as ammonia nitrogen or sodium nitrate)
were available to supplement the sewage in the pond.
Algae appear to offer the most easily exploited bio-
logical system for extracting phosphorus from domestic
sewage. Tests indicate that algae can bring about phos-
phorus reductions of 0.8 to 2.0 mg/l. Laboratory and pilot
plant studies indicate that in the presence of adequate
amounts of light, soluble phosphate reductions equivalent
to 90 percent or more can be achieved with contact times
as brief as 6 to 12 hr (12). Another method of removing
both phosphorus and nitrogen would be to increase the
pH and thus precipitate the nutrients (13). Reports indi-
cate that biological processes can effect a phosphorus re-
duction ranging from 83 to 92 percent (14). Much more
research effort would be needed to optimize this type of
removal process.
Considering the two functions of the algae, sewage
ponds may be called oxidation ponds if the release of oxy-
gen by algae is emphasized, or stabilization ponds if the
assimilation of nutrients into stable living algal cells is
stressed.
When the algae in the ponds die, their organic con-
tents are subject to decomposition by saprobic bacteria.
The death and decomposition at one time of large num-
bers of algae would again bring about nuisance conditions
approximating those caused by the original sewage wastes
placed in the pond. It is desirable, therefore, to prevent
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48
ALCAE AND WATER. POLLUTION
this by stimulating the algae to continue growing or by
arranging for the algae to leave the pond continuously in
moderate numbers.
The use of a sewage oxidation-stabilization pond per-
mits control of a number of factors that affect the effi-
ciency of treatment. The working capacity of the pond
should be large enough to permit the optimum detention
period for the concentration of wastewater that can be
treated in the particular climatic zone. A shallow depth,
often about 4 ft, is used so that sunlight may reach even
the lower layers of water and thus allow algal photosyn-
thesis to take place throughout the pond. The movement
of water through the pond is controlled by regulating the
rate and volume of flow of the effluent. It must also be
determined whether to use the pond for primary, secon-
dary, or tertiary treatment of the sewage. Some states
have statutes that regulate the use of such ponds and al-
low only one type of treatment.
A study of many sewage ponds in widely scattered parts
of the United States and other American countries indi-
cates that of a total of 125 genera recorded, any one of
approximately 15 may be a frequent and dominant form.
Only two of these are diatoms and only two are blue-
green algae. Five are pigmented flagellates; the remainder
are nonmotile, nonfilamentous green algae.
A study of algae from sewage ponds was conducted
throughout 18 states, the Panama Canal Zone, and the
West Indies; all major areas of the United States were in-
cluded. It covered 74 ponds, involved 929 sampling dates,
and lasted for more than six years (15). The number of
algal genera recorded per sample ranged from 1 to 33.
Approximately one-third of the ponds had a maximum of
13 to 33 types per sample. Of the 125 recorded, roughly
50 percent were green algae, 25 percent were pigmented
flagellates, 15 percent were blue-green algae, and 10 per-
cent were diatoms. An example is Achnanthes (fig. 59).
A number of the algae are well represented in ponds
throughout the country. Among the most abundant are
(in decreasing order of abundance): Chlorella, Ankistro-
desmus, Scenedesmus, Euglena, Chlamydomonas, Oscilla-
toria, Micractinium, Colenkinia, Anacystis, and Oocystis
(table 14). Ch/amydomonas has been the only genus
abundant throughout the country, and Chlorella has been
abundant in all but the southeastern states. Numerous
flagellates and green algae appear to be limited in abun-
dance geographically. Some algae unusual for sewage
ponds have been recorded as follows: Aphanizomenon
(ND), Dinobryon (Md), Enteromorpha (ND), Fragilaria
(Md), Gloeocystis (NH), Con/urn (Col), Lyngbya (ND),
Microspora (Md), Oedogonium (Ind), Pediastrum (Col),
Pyrobotrys (Oh), Spirogyra (ND), and Zygnema (Md).
At Lancaster, California, samples were obtained on 294
days during a period of over 6 years; 25 algae were very
abundant in one or more instances. Scenedesmus was the
most consistently abundant every year and every month.
Closteridium was absent during the first year but reached
a very high abundance in the last year, while Chodatella
was present in large numbers during the first two years
but almost disappeared during the last two years. Euglena
also gradually became less abundant from the first to the
last year.
Each pond tends to have a distinctive group of genera
that generally is present week after week and distinguishes
that pond from all others. Any change in the flora is likely
to be gradual (16).
In some ponds in Africa, Chlorella was reported as be-
ing predominant in the first stage of treatment, but in the
second stage its numbers fell off and Spirulina began to
proliferate. In the third stage Chlorella had almost disap-
peared, and Spirulina predominated. Many other less
prominent algae were present in all three stages (17).
At one pond in California, Chlamydomonas and related
forms were dominant when the pH ranged from 7.0 to 7.7;
Euglena was usually dominant where the pH ranged from
7.7 to 8.9; and Chlorella, Scenedesmus, and other related
genera were abundant when the mid-day pH ranged from
8.4 to 9.8. A pH change caused a shift in the relative abun-
dance of the various genera in the pond (18).
An examination of pond effluent for algae may give
useful information. If it contains principally Chlorella,
this indicates that the pond is working at or over its ca-
pacity. If it contains a mixed algal flora, and Chlorella is
prominent only farther back in the pond, this suggests
that the pond could handle a heavier load (11).
A number of the sewage pond algae are illustrated on
plate IV and 23 more are shown on plate VI. The latter
includes the green alga Diacanthos, which has possibly not
been recorded previously in the United States. Vacuo/ar/a
has been considered rare for this country, and Schizothrix,
Figure 59.—Achnanthes, a sewage pond diatom.
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Sewage Stabilization Ponds
49
as it is now called, has in the past been confused with
certain species of Oscillatoria and other filamentous blue-
green algae (19).
Table 15 indicates in a very general way the various
conditions of sewage oxidation-stabilization ponds and
the relationship of the ponds to number and types of al-
gae, the pH, DO, BOD, and nitrogen reduction. Since
these all vary in actual ponds, the table can be considered
only as a guide (20).
Practically all of the common sewage algae tend to be
planktonic, that is, they remain dispersed in the water and
are unattached to other objects. Most of them do not
tend to collect on the surface as a mat or bloom, although
Anacystis (Microcystis), Chlamydomonas, and others oc-
casionally do.
Problems caused by many blue-green algae in the sum-
mer generally can be handled if 2,3-dichloronaphtho-
quinone is applied at the rate of 1 ppm at the pond in-
fluent and around the water edges. Also the algal mats
may be broken up by the use of an outboard motor (6).
As planktonic forms all of the sewage algae are well
equipped in form and distribution to absorb sunlight, nu-
trient salts, and carbon dioxide and to release oxygen
throughout the length and depth of the pond. Algae,
when they concentrate as mats or blooms on the surface,
are undesirable because they release most of their oxygen
into the air. Algal communities remain about the same
at various depths in the aerobic zone which indicates ef-
fective vertical mixing in the pond (21).
A few of the sewage pond algae, particularly certain
strains of Chlamydomonas, Pyrobotrys (Chlamydobotrys),
Chlorogonium, Euglena, and Chlorella, have the unusual
ability to utilize acetate in their photoassimilation. These
algae produce little or no oxygen and are therefore inef-
ficient in stimulating aerobic bacteria to act on sewage
(22). There is no indication at present that these strains
are a significant part of the flora of most sewage ponds.
Several of the algae are unable to develop in the pres-
ence of large amounts of certain organic wastes such as
those from milk processing plants, food canneries, beet
sugar factories, and slaughter houses. In southern Califor-
nia, the whey content of dairy wastes reaching sewage
ponds through the sewer system caused them to perform
poorly, as indicated by the low concentrations of dissolved
oxygen and desirable algae as well as the presence of dis-
solved sulfides and hydrogen sulfide odors (23). In Aus-
tralia, it was found possible to treat food cannery wastes
in large anaerobic lagoons after mixing them with sewage
plant effluent and digested sludge or digester supernatant.
The wastewater was then passed through an aerobic pond
or oxidation ditch. Vigorous algal growth was observed
to persist at all times in all the lagoons, both anaerobic
and aerobic (24).
In northwestern United States and Pennsylvania, wastes
from sugar beet factories have sometimes caused algae to
disappear from sewage ponds and to be replaced by sul-
fur bacteria, which turned the water pinkish-red. In cen-
tral California, the wastes from a slaughter house caused
the water of a sewage pond to become almost free of al-
gae and a blood-red color to form on the surface due to
the presence of sulfur bacteria.
The algal population in sewage ponds may also be
radically reduced in quantity by small aquatic animals,
particularly Daphnia, which can develop in large numbers
and consume the algae. This has been observed in ponds
in southern California. In one case the Daphnia were
purple and were so numerous as to color the surface of
the water. The life cycle of these aquatic animals is rel-
atively short, and they generally disappear in 2 to 4 weeks.
Sometimes it is desired that the final pond containing
stabilized sewage be a clarified polishing pond relatively
free of algae. This has been accomplished by introducing
the floating green plant Lemna which shades the water
below. The shaded water causes algae to die out and to
decompose rapidly with the aid of bacteria. This results
in encouragement of Crustacea especially Daphnia which
feed on the saprobic bacteria. Daphnia cultures may have
to be introduced to quicken the process. The Lemna —
bacterium — Daphnia procedure clarifies the stabilized
sewage pond, frees it of algae and total bacteria, and
leaves microscopically clear water. The Daphnia are first-
class food for fish and can be so utilized either in a final
pond or in the stream that receives the effluent (25).
It may be concluded that the application of biological
principles should make it possible to improve the effi-
ciency of waste treatment oxidation-stabilization ponds.
REFERENCES
1. Nutrient assimilation by algae in waste stabilization ponds. C. M.
Palmer. Proc. Ind. Acad. Sci. for 1966, 76:204-209. 1967.
2. Waste stabilization pond study, Lebanon, Ohio. W. B. Horning II,
R. Forges, H. F. Clarke, and Wm. B. Cooke. Pub. Hlth. Serv. Publ.
No. 999-WP-16:1 -48. 1964.
3. An evaluation of stabilization pond literature. C. P. Fitzgerald and
G. A. Rohlich. Sew. and Indus. Wastes 30:1213-1224. 1958.
4. Algae in waste treatment. W. J. Oswald, H. B. Gotaas, C. G. Gol-
ueke, and W. R. Kellen. Sew. and Indus. Wastes 29:437-457. 1957.
5. Depth and loading rates of oxidation ponds. D. A. Mills. Water
and Sew. Wks. 108:343-346. 1961.
6. Waste stabilization lagoons in Missouri. J. K. Smith. Proc. Sym-
posium on Waste Stabilization Lagoons. Kansas City, Mo., Aug.
1960. U.S. Pub, Hlth. Serv. 157-161. 1960.
7. Performance of large sewage lagoons at Melbourne, Australia. C.
D. Parker, H. L. Jones, and N. C. Green. Sew. and Indus. Wastes
31:133-152. 1959.
8. Stabilization pond studies in Wisconsin. K. M. MacKenthun and
C. D. McNabb. Jour. Water Pol. Contr. Fed. 33:1234-1251. 1961.
9. Studies of sewage lagoons. J. Myers. Pub. Wks. 79(12):25-27. Dec.
1948.
10. Chromatographic assay of extracellular products of algal metabo-
lism. R. C. Merz, R. G. Zehnpfennig, and J. R. Klima. Jour. Water
Pol. Contr. Fed. 34:103-115. 1962.
11. General features of algal growth in sewage oxidation ponds. M.
B. Allen. Cal. State Water Pollution Control Board. Publ. No. 13.
p. 1-47.1955.
12. Removal of sewage nutrients by algae. R. H. Bogan. Pub. Hlth.
Repts. 76:301-308. 1961.
13. Nutrient removal from sewage effluents by algal activity. J. Hemens
and G. J. Stanoler. Advances in Water Pollution Research. Fourth
Internal. Conf. on Water Pol. Res., Prague. Pergamon Press, p. 701-
711. 1969.
14. Experimental lagooning of raw sewage at Fayette, Missouri. J. K.
Neel, J. H. McDermott, and C. A. Monday, Jr. jour. Water Pol.
Contr. Fed. 33:603-641. 1961.
-------
50
ALGAE AND WATER POLLUTION
15. Algae in American sewage stabilization ponds. C. M. Palmer. Rev.
Microbiol. (Sao Paulo, Brazil) 5(4):75-80. 1974 (Released Aug.
1975).
16. Algal records for three Indiana sewage stabilization ponds. C. M.
Palmer. Proc. Indiana Acad. Sci. for 1968, 78:139-145. 1969.
17. Some observations on the action of algae on sewage in ponds. H.
T. Clausen. Jour, and Proc. Institute of Sew. Purif. Part. 3:345-348.
1959.
18. A systematic study of the algae of sewage oxidation ponds. P. C.
Silva and C. F. Papenfuss. Cal. State Water Pol. Control Bd. Publ.
No. 7:1-35. 1953.
19. Ecophenes of Sch/zothrix ca/c/co/a (Osci//aton'acea). F. Drouet.
Proc. Acad. Nat. Sci. Phila. 115:261-281. 1963.
20. Guide to operators of raw sewage stabilization ponds. In National
Institute for Water Res. Council for Scientific and Indus. Res. Rept.
of Director for 1962. CSIR Special Rept. No. WAT. 27: Pretoria,
South Africa. 76 p. June 1963.
21. Algal community structure in artificial ponds subjected to con-
tinuous organic enrichment. M. S. Ewing. Thesis, Oklahoma St.
Univ., Grad. Col. 41 p. July 1966.
22. Rapid growth of sewage lagoon Chlamydomonas with acetate. R.
W. Eppley and F. M. Maciasa. Physiologia Plantarum 15:72-79.
1962.
23. Effect of whey wastes on stabilization ponds. T. E. Maloney, H. F.
Ludwig, J. A. Harmon, and L. McClintock. Jour. Water Pol. Contr.
Fed. 32:1283-1299. 1960.
24. Food cannery waste treatment by lagoons and ditches at Sheppar-
ton, Victoria, Australia. C. D. Parker. Proc. 91st Indus. Waste Conf.
May 1966. Pt. 1. Eng. Bull. Purdue Union 50 (No. 1), Eng. Exten-
sion Ser. No. 121:284-301. 1966.
25. Two experiments in the biological clarification of stabilization-
pond effluents. S. Ehrlich. Hydrobiologia 27:70-80. 1966.
TABLE 13. ALGAL GENERA IN AMERICAN SEWAGE PONDS
TABLE 14. ALGAE MOST ABUNDANT AND WIDESPREAD
IN SEWAGE PONDS
Achnanthes
Actinastrum
Agmenellum
Anabaena
Anabaenopsis
Anacystis
Ankistrodesmus
Aphanizomenon
Apiococcus
Arthrospira
Calothrix
Carteria
Characium
Chlamydomonas
Chlorella
Chlorococcum
Chlorogonium
Chodatella
Chromulina
Chroomonas
Chrysamoeba
Cladophora
Closteridium
Closteriopsis
Closterium
Coccomonas
Coelastrum
Cosmarium
Crucigenia
Cryptomonas
Cyanomonas
Cyclotella
Cymatopleura
Cymbella
Dermocarpa
Desmidium
Diacanthos
Dictyosphaerium
Dinobryon
Dispora
Dunaliella
Elakatothrix
Enteromorpha
Epithemia
Eudorina
Euglena
Fragilaria
Frustulia
Glenodinium
Cloeocystis
Colenkinia
Gomphonema
Gomphosphaeria
Gonium
Gymnodinium
Haematococcus
Hantzschia
Hemidinium
Johannesbaptistia
Kirchneriella
Lepocinclis
Lyngbya
Mallomonas
Massartia
Micractinium
Microspora
Nannochloris
Navicula
Nitzschia
Ochromonas
Oedogonium
Oocystis
Oscillatoria
Ourococcus
Palmella
Palmellococcus
Pandorina
Pediastrum
Pedinopera
Phacus
Phormidium
Pinnularia
Planktosphaeria
Pleodorina
Pleurogaster
Polyedriopsis
Pteromonas
Pyrobotrys
Raphidiopsis
Rhodomonas
Scenedesmus
Schizothrix
Schroederia
Selenastrum
Sphaerellopsis
Sphaerocystis
Spirogyra
Spirulina
Staurastrum
Stauroneis
Stichococcus
Stigeoclonium
Surirella
Synedra
Tetradesmus
Tetraedron
Tetrastrum
Trachelomonas
Ulothrix
Uroglenopsis
Vacuolaria
Zoochlorella
Zygnema
Rank
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Genus
Chlorella
Ankistrodesmus
Scenedesmus
Euglena
Chlamydomonas
Oscillatoria
Micractinium
Golenkinia
Anacystis
Oocystis
Chodatella
Nitzschia
Nannochloris
Planktosphaeria
Pandorina
Pteromonas
Closteridium
Cryptomonas
Chlorococcum
Schizothrix
Cyclotella
Phacus
Schroederia
Trachelomonas
Actinastrum
Score*
51
49
49
48
47
46
39
37
34
34
33
32
31
29
29
28
28
28
28
28
27
27
25
25
25
•Note: Score was determined by adding together the highest sampling date abundance
figure, the number of states for the genus, and the number of states where
abundance figure was 5 or above. Genera with similar scores were ranked
according to the first item.
-------
Sewage Stabilization Ponds
51
TABLE 15. VARIOUS CONDITIONS OF SEWAGE OXIDATION-STABILIZATION PONDS
(Adapted with many modifications from CSIR Special Report (19))
•D
C
8.
£•
i
™
Q.
•o
c
o
Q.
£
cr
0)
V)
.£3
3
v>
C
re
re
c
8
01
Observations
Green to depth of 2'.
No smell from pond or
effluent sample.
Green to depth of 6".
Blackfish tint below 6".
Sulfide odor slight.
Grey, black or clear black.
Sulfide odor strong.
Surface smooth and oily.
Green color.
Surface easily rippled.
Light Green.
Surface easily rippled.
Greenish or brownish tint.
Clear.
Black.
Clear.
Pond
conditions
Aerobic
Aerobic
above
Anaerobic
below
Anaerobic
Aerobic
Aerobic
Aerobic
Anaerobic or
not functioning
Dominant
algae
Algae abundant:
Scenedesmus,
etc.
Algae common
Chlamydomonas
Algae scarce:
Chlamydomonas,
Euglena
Algae abundant:
Ankistrodesmus,
Scenedesmus,
Golenkinia,
etc.
Algae common:
Scenedesmus,
Nitzschia,
Chlorella,
etc.
Algae moderate:
Cryptomonas,
Chlamydomonas,
etc.
Algae scarce:
Chlamydomonas,
Euglena,
Oscillatoria
Mid-afternoon BODs mg/l
pH DO at at
(mg/1) inlet outlet
8.5 10+ 50 25
7.5 4 75 45
7.0 0 80 70
10± 30± 45± 15
9 20 45± 20
8 6± 15± 10
7± 0 100± 70
Total
nitrogen
reduction
Good
Poor
Poor
Good
Good
Poor
Poor
-------
CHAPTER XIII
TASTE AND ODOR ALGAE
One of the requirements in the production of potable
water for communities is that the product be free of ob-
noxious tastes and odors. If such problems exist, they are
generally attributable to the algae present in the raw
water supply. In a comprehensive study made of algae in
the central Missouri River, the time when taste and odor
difficulties occurred was recorded at treatment plants of
cities and towns that used the river as their source of
water (1). It was found that practically all of the taste and
odor occurrences coincided with the presence of algal
blooms and that the few exceptions noted came during
declines of dense algal growths. It is evident that, for the
central Missouri River area as well as for many other parts
of the country, algae are involved either directly or in-
directly in causing taste and odor problems in water sup-
plies.
A nationwide survey conducted in 1957 indicated that
water works officials considered algae to be the most fre-
quent causes of tastes and odors in water supplies, and
decaying vegetation to be second in importance (2). The
decay or decomposition is brought about by the activity
of fungi and bacteria, including the actinomycetes. A con-
siderable proportion of all decaying vegetation is often
composed of dead algal cells. The odors that are produced
as a result of the activities of fungi and bacteria may be
either from the intermediate products formed during the
decomposition or from special substances that are synthe-
sized within the cells of the microorganisms. The latter
appears to be true in the case of actinomycetes.
A few algae are known to produce specific distinctive
tastes and odors, while a larger number of others are
associated with tastes and odors that vary in type accord-
ing to local conditions. Certain diatoms, blue-green algae,
and pigmented flagellates are the principal offenders, but
green algae, including desmids, may also be involved.
Forty species representative of the more important taste
and odor algae are listed alphabetically under their re-
spective groups in table 16 and eighteen are illustrated on
plate VII. Other genera and species must also be con-
sidered as potential offenders, and many of these are in-
cluded in table 17, which lists the odor, taste, and tongue
effects of more than 50 genera of algae. Most of the re-
ports dealing with specific instances in which algae were
regarded as having been the cause of taste and odor prob-
lems did not give the species name of the particular forms
involved. In the following discussion, therefore, refer-
ence is made to the genera rather than the species of al-
gae.
TYPICAL ODORS FROM ALGAE
Some algae produce an aromatic odor resembling that
given off by a particular flower or vegetable, e.g., geran-
ium, nasturtium, violet, muskmelon, and cucumber. In
some cases it is described as an attractive, spicy odor, but
in others it may be very objectionable, for example, a
skunk or garlic odor. Some pigmented flagellates and
diatoms produce the aromatic odors when these organisms
are present in small numbers in the water.
A fishy odor is often produced by the same algae that
are responsible for the aromatic odors, but the organisms
generally are present in much larger numbers. More spe-
cific terms that have been used to describe the fishy odors
are clam-shell, cod-liver oil, sea weed, Irish moss, rock-
weed, and salt marsh. The differences between these are
probably insignificant in water supply studies.
A grassy odor is the most common one produced by
green algae and generally is apparent only when the or-
ganisms are present in large numbers. Certain blue-green
algae and occasionally diatoms and pigmented flagellates
are said to cause this odor.
The fourth type of odor is one described as being musty
or earthy. The latter is commonly associated with actino-
mycetes (3,4) and with a few algae; it can vary from mild
to decidedly pungent. The earthy odor of soil is also
probably caused by the presence of actinomycetes. The
musty odor frequently given off by water is associated
with the presence of certain blue-green algae and a few
other forms, especially the diatom Synedra. It has also
been described as being potato bin and moldy. Some
waters have been reported as having weedy, swampy,
marshy, peaty, straw-like, and woody odors, and these are
possibly modifications or combinations of the grassy and
musty odors.
A septic odor has been associated frequently with the
presence of large accumulations of blue-green algae and
occasionally of the green algae, Hydrodictyon and C/acfo-
phora. Other names applied to this type of odor are pig-
pen, foul, objectionable, vile, fermentation, and putrefac-
tive (5). As these terms suggest, it is produced when
masses of algae decompose, especially when a lack of
sufficient oxygen permits the formation of odoriferous in-
termediate products from the algal proteins.
Chlorophenolic, iodoform, or medicinal odors may be
produced by the action of chlorine on the products of
certain algae, but somewhat similar odors may be present
in water at other times because of industrial wastes.
52
-------
Taste and Odor
53
MEASUREMENT OF ODORS
The threshold odor test is commonly employed to
measure odors in water. The threshold odors caused by
algae tend in some areas to be comparatively low (1 to
14), but in other areas they frequently go up to 30 or 40
and occasionally exceed 90. Algal odors are generally ob-
jectionable, however, even when the threshold odor num-
ber is low. For satisfactory treatment, the threshold odor
usually has to be reduced to 5 or less. However, each
water supply and often each odor outbreak must be
judged independently in determining the threshold num-
ber below which the water is considered palatable.
In some plants the treatment is instituted as soon as
any algae that can cause taste and odor problems in-
crease to a predetermined number of areal standard units
per ml. The number varies according to the particular
kind of alga involved: for Asterionella and Synedra it may
be 3,000; Tabellaria, 2,500; Aphanizomenon, 1,000; Ana-
baena, 600; Dinobryon, 500; Cryptomonas, Synura, and
Uroglenopsis, 200; and Chlamydomonas, 10 (7,8).
Tastes produced by algae are seldom separated from
and are often confused with odor. Sweet and bitter are
the adjectives generally recorded, and it is quite possible
that a sour taste may be present whenever the odor is
acid or is of the putrefactive, septic, or pigpen type. A
salty taste apparently has never been associated with the
fishy, clam-shell, salt marsh, rockweed, Irish moss, or sea-
weed-like odors.
The tongue can also detect a sensation that might be
listed as "feel" or "touch." Included here would be a
slick or oily feel as well as a metallic, dry, or an astringent
sensation. Odor, taste, and feel, as associated with each
algal genus are given in table 17. The word "flavor" could
be used as an inclusive term embracing taste, odor, and
touch or feel (9).
PRINCIPAL ODOR-PRODUCING ALGAE
Synura is one of the more potent algae in giving water
an odor which is often described as resembling that of a
ripe cucumber or muskmelon. A comparatively few col-
onies per milliliter may be sufficient to cause a very per-
ceptible odor. This organism also produces a bitter taste
in water and leaves a persistent dry metallic sensation on
the tongue. When present in large numbers, this flagel-
late as well as others may develop a fishy odor. In Mas-
sachusetts, for example, Dinobryon, Uroglenopsis (fig. 60),
and the armored flagellate Peridinium produced a strong
fishy odor in a large reservoir holding over 600 million
gal water. These forms developed in February under a
16-inch layer of ice (10). There is some evidence that
Uroglenopsis is stimulated to rapid growth following an
abundant growth of other algae. Among other flagellate
algae which produce tastes and odors are Eug/ena, Gon-
ium, Chlamydomonas, and Cryptomonas (fig. 60).
In California one of the worst offenders was the armored
flagellate Ceratiums which produces a fishy to pronounced
septic odor. The organism is capable of very rapid mul-
tiplication during any season (11).
Dinobryon develops in the southern end of Lake Mich-
igan almost every June and July in numbers sufficient to
impart a pronounced fishy odor to the water. As many
as 700 areal standard units/ml of this alga have been re-
ported, and it has represented at times up to 47 percent
of the total algal count. Even though its odor is readily
adsorbed by activated carbon, it is estimated that one
treatment plant required over $70,000 worth of the car-
bon to control the odor for a period of 2 months (12).
Dinobryon and other taste and odor algae may develop
as pulses which follow one another in a lake or reservoir
(fig. 61).
Asterionella is considered one of the worst offenders
among the diatoms because its geranium-like odor changes
to a fishy smell when the alga is present in large numbers.
Tabellaria produces a similar effect, while Synedra has an
earthy to musty odor, and Stephanodiscus imparts a vege-
table to oily taste but has very little odor.
Certain blue-green algae develop very foul, pigpen
odors in water. Three of these algae, illustrated on plate
VII are Anabaena, Anacystis (formerly known as Micro-
cystis, Polycystis, and Clathrocystis), and Aphanizomenon.
All of these are capable of collecting in large masses suffi-
cient to form water blooms. The foul odor undoubtedly
develops from products of decomposition as the algae be-
gin to die off in large numbers. These blue-green algae,
together with others such as Gomphosphaer/a (which now
includes Coelosphaerium), Cylindrospermum, and Rivu-
laria have a natural odor which is commonly described
as grassy. This often changes to the odor of nasturtium
stems, probably as a result of oxidation.
On several occasions in July, /Anabaena in Chicago's
raw water gave an unpleasant, persistent odor even when
present in very small numbers, and large doses of acti-
vated carbon were required to remove the odor (13).
There were 48 genera detected in the raw lake water
supply of Celina, Ohio, in one year. Almost 50 percent of
them were taste and odor producing types. The worst of-
fenders were Anacystis (Microcystis), Scenedesmus, Syn-
edra, Gomphosphaer/a, Coelospherium, Dictyosphaerium,
and Tabellaria. The threshold odor number of the raw
water reached as high as 24. The installation of an intake
structure designed to allow water to be drawn from var-
ious levels in the lake, facilities for use of algicides and
other chemicals, and the addition of a presedimentation
basin were recommended for future control of taste and
odor algae (14).
Green algae are less often associated with tastes and
odors in water. In fact, their growth may help to keep in
check the blue-green algae and the diatoms. However,
Hydrodictyon (water net), the desmid Staurastrum, and the
large massive stone-worts Nitella and Chara may offend
rather than help in this biological competition between
types. Distyosphaerium is regarded as one of the worst
offenders among the green algae. It gives off a fishy as
-------
54
ALGAE AND WATER POLLUTION
DINOBRYON
CRYPTOMONAS
UROGLENOPSIS
Figure 60.—Some flagellate algae producing tastes and odors.
1600
400
100
1600
400
100
800
200
800
200
LEGEND:
SYNEDRA
DINOBRYON
CYCLOTELLA
(D
(2)
(3)
APR.I MAY I JUNE I JULY I AUG. I SEPT. I OCT. I NOV. I DEC. I JAN
MONTH
Figure 61.—Pulses, over a four year period, of three
taste and odor algae in a water supply reservoir.
FEB.
-------
Taste and Odor
55
well as a grassy to nasturtium odor (15). Some of the
swimming green algae which are listed with the flagel-
lates, including Vo/vox, Pandorina, and Chlamydomonas,
are able to produce fishy odors.
Research was conducted at the Robert A. Taft Sanitary
Engineering Center on taste and odor algae. Suspected
forms were obtained in pure growth cultures (16), and
chemical analyses were made of their products and of
various organic materials on water which had odor (17,18).
Additional research was directed toward the finding of
algicides which were sufficiently selective to destroy cer-
tain taste and odor algae without simultaneously being
wasted on non-offending types (19). The relationship of
actinomycetes to earthy odors in water was also studied
(20-22).
The following statement by Laughlin (23) is an expres-
sion of the emphasis which the control of taste and odor
problems must be given in modern programs for water
treatment: "It is one of the basic duties and responsibili-
ties of the water purification plant operator to furnish his
public with palatable water 24 hours a day. The presence
of any objectionable odor may cause the consumer to go
to a more palatable but unsafe water supply. Therefore,
the importance of producing a palatable water supply
cannot be overemphasized."
REFERENCES
1. Central Missouri River water quality investigation for 1955. U.S.
Dept. Health, Education and Welfare, Public Health Service, Water
Supply and Water Pollution Control Section, Region 6, Kansas City,
Mo., 50 p. (Mimeographed). 1956.
2. Control of odor and taste in water supplies. E. A. Sigworth. Jour.
Amer. Water Wks. Assn. 49:1507-1521. 1957.
3. The role of actinomycetes in producing earthy tastes and smells in
potable water. B. A. Adams. Dept. of Public Wks., Roads and
Transport Congress. Paper No. 4. London, England. 1933.
4. Actinomycetes may cause tastes and odors in water supplies. J. K.
Silvey and A. W. Roach. Public Wks. Mag. 87:103-106, 210, 212.
1956.
5. The microscopy of drinking water. Ed. 4. G. C. Whipple, C. M.
Fair, and M. C. Whipple. J. Wiley and Sons, N.Y., 586 p. With 19
color plates. 1948.
6. Standard methods for the examination of water, sewage and in-
dustrial wastes. Ed. 10. Amer. Public Health Assn., N.Y., 522 p.
1955.
7. Tastes and odor control. C. E. Symons. Water and Sewage Wks.
1903:307-310,348-355. 1956.
8. The effects of algae on water quality. D. F. Jackson. Proc. 1st
Amer. Water Qual. Res. Symp., N.Y. State Dept. Health and N.Y.
Water Pol. Assn., Albany, N.Y., p. 2-23. 1964.
9. The relation of taste and odor to flavor. C. W. Aman. Taste and
Odor Control Jour. 21 (No. 10):1-4. 1955.
10. Treating algae under the ice at Westfield, Mass. E. A. Snow and A.
lantosca. Jour. New England Water Wks. Assn. 66:47-54. 1952.
11. Microscopic organisms in reservoirs. C. A. Cofoid. Jour. Amer.
Water Wks. Assn. 10:183-191. 1923.
12. Fishy odor in water caused by Dinobryon. ]. R. Baylis. Pure
Water, Chicago, III., South District Filtration Plant, 3:128-150. 1951.
13. Operation of the South District filtration plant. A. F. Mrva. Pure
Water, Chicago Bur. of Waters 17:51-71. 1965.
14. Taste and odor removal at Celina. C. Bauer. Jour. Amer. Water
Wks. Assn. 58:113-118. 1966.
15. Review of microorganisms in water supplies. S. O. Swartz. Jour.
New England Water Wks. Assn. 69:217-227. 1955.
16. The use of algal cultures in experiments concerned with water
supply problems. C. M. Palmer and T. E. Maloney. Butler Univ.
Bot. Stud. 11:87-90. 1953.
17. Drinking water taste and odor correlation with organic chemical
content. F. M. Middleton, G. Wallace, and A. A. Rosen. Indust.
Eng. Chem. 48:268-274. 1956.
18. Identification of odor producing substances elaborated by algae.
T. E. Maloney. Public Works Mag. 89:99-100. 1958.
19. Evaluation of new algicides for water supply purposes. C. M. Pal-
mer. Jour. Amer. Water Wks. Assn. 48:1133-1137. 1956.
20. Identification of odors produced by actinomycetes. A. H. Romano.
Public Works Mag. 89:100-101. 1958.
21. A method for the isolation and enumeration of actinomycetes re-
lated to water supplies. R. S. Safferman and M. E. Morris. Robt. A.
Taft San. Eng. Center, Tech. Rept. W62-10. 15 p. 1962.
22. Studies on actinomycetes and their odors. A. H. Romano and R. S.
Safferman. Jour. Amer. Water Wks. Assn. 55:169-176. 1963.
23. Palatable level with the threshold odor test. H. F. Laughlin. Taste
and Odor Control Jour. 20 (No. 8):1-4. 1954.
TABLE 16. TASTE AND ODOR ALGAE,
REPRESENTATIVE SPECIES
Group and algae
Flagellates (Chrysophyceae, Euglenophyceae, etc.):
Ceratium hirundinella
Chlamydomonas globosa
Chrysosphaerella longispina
Cryptomonas erosa
Dinobryon divergens
Euglena sanguinea
Glenodinium palustre
Mallomonas caudata
Pandorina morum
Peridinium cinctum
Synura uvella
Uroglenopsis americana
Volvox aureus
Plate
VII
VII
VII
VII
Blue-Green Algae (Myxophyceae):
Anabaena circinalis
Anabaena planctonica
Anacystis cyanea
Aphanizomenon flos-aquae
Cylindrospermum musicola
Gomphosphaeria lacustris, kuetzingianum type
Oscillatoria curviceps
Rivularia haematites
Symploca muscorum
Green Algae (nonmotile Chlorophyceae, etc.)
Chara vulgaris
Chladophora insignis
Cosmarium partianum
Dictyosphaerium ehrenbergianum
Gloeocystis planctonica
Hydrodictyon reticulatum
Nitella gracilis
Pediastrum tetras
Scenedesmus abundans
Spirogyra majuscula
Staurastrum paradoxum
Diatoms (Bacillariuphyceae):
Asterionella gracillima
Cyclotella comta
Diatoma vulgare
Fragilaria construens
Stephanodiscus niagarae
Synedra ulna
Tabellaria fenestrata
VII
VII
VII
VII
VIII
VII
VII
VII
VII
VII
VII
VII
VII
VII
VII
-------
56
ALGAE AND WATER. POLLUTION
TABLE 17. ODORS, TASTES, AND TONGUE SENSATIONS ASSOCIATED WITH ALGAE IN WATER
Algal genus
Algal group
Odor when algae
Moderate
Abundant
Taste
Tongue
sensation
Actinastrum
Anabaena ..
Anabaenopsis .,
Anacystis
Aphanizomenon
Asterionella
Ceratium
Chara
Chlamydomonas .
Chlorella
Chrysosphaerella
Cladophora
(Clathrocystis)
Closterium
(Coelosphaerium)
Cosmarium
Cryptomonas
Cyclotella
Cylindrospermum
Diatoma
Dictyosphaerium .
Dinobryon
Eudorina
Euglena
Fragilaria
Glenodinium
(Cloeocapsa)
Gloeocystis
Gloeotrichia
Gomphosphaeria .
Gonium
Hydrodictyon
Mallomonas
Melosira
Meridion
(Microcystis)
Nitella
Nostoc
Oscillatoria
Pandorina
Pediastrum
Peridinium
Pleurosigma ....
Rivularia
Scenedesmus
Spirogyra
Staurastrum
Stephanodiscus .
Symploca
Synedra
Synura
Green
Blue-green Grassy, nasturtium,
musty.
Blue-green
Blue-green Grassy
Blue-green Grassy, nasturtium,
musty.
Diatom Geranium, spicy
Flagellate Fishy
Green Skunk, garlic
Flagellate Musty, grassy
Green
Flagellate
G reen
See Anacystis.
Green
See Gomphosphaeria.
Green
Flagellate Violet
Diatom Geranium
Blue-green Grassy
Diatom
Green Grassy, nasturtium ....
Flagellate Violet
Flagellate
Flagellate
Diatom Geranium
Flagellate
See Anacystis.
Green
Blue-green
Blue-green Grassy
Flagellate
Green
Flagellate Violet
Diatom Geranium
Diatom
See Anacystis.
Green Grassy
Blue-green Musty
Blue-green Grassy
Flagellate
Green
Flagellate Cucumber
Diatom
Blue-green Grassy
Green
Green
Green
Diatom Geranium
Blue-green
Diatom Grassy
Flagellate Cucumber, muskmelon,
spicy.
Grassy, Musty
Septic
Grassy
Septic Sweet
Septic Sweet
Fishy
Septic Bitter
Spoiled, garlic
Fishy, septic Sweet
Musty
Fishy
Septic
Dry.
Slick.
Grassy
Grassy
Violet Sweet
Fishy
Septic
Aromatic
Fishy
Fishy
Fishy
Fishy Sweet
Musty
Fishy
Slick.
Slick.
Septic
Grassy
Grassy Sweet
Fishy
Septic
Fishy
Musty
Spicy
Slick.
Grassy, septic Bitter
Septic
Musty, spicy
Fishy
Grassy
Fishy
Fishy
Musty
Grassy
Grassy
Grassy
Fishy
Musty
Musty
Fishy Bitter
Tabellaria ...
Tribonema ..
(Uroglena) ..
Uroglenopsis
Ulothrix
Volvox
Diatom Geranium Fishy .
Green Fishy .
See Uroglenopsis.
Flagellate Cucumber Fishy .
Green Grassy
Flagellate Fishy Fishy .
Slick.
Slick.
Dry,
metallic,
slick.
Slick.
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CHAPTER XIV
FILTER AND SCREEN CLOGGING ALGAE
As water passes through a sand filter in a treatment
plant, the spaces between the grains of sand become
filled with colloidal and solid particles which had been
dispersed in the water. If the raw water comes from a sur-
face supply such as a reservoir, lake, or stream, the algae
which are invariably present will be well represented in
the material collected by the sand filter and are frequently
the primary causes for the clogging of the filter.
In most places the algae and other particulate materials
are sufficiently numerous throughout most of the year to
require that the water be treated by coagulation and sedi-
mentation previous to filtration through sand. Without
this preliminary treatment, the filter would clog so rapidly
that it would be uneconomical to use, except when rel-
atively clear water is available. Certain plants in California
and in Canada have been using a rapid sand filter without
prior coagulation, at least during portions of the year (1).
Efficient coagulation and sedimentation can remove up
to 90 or 95 percent of the algae from the water, but those
algae remaining may still cause a gradual or even rapid
loss of head in the sand filter. The clogged filter must then
be taken out of service and cleaned or backwashed. Nor-
mal filter runs are from 30 to 100 hr before cleaning is
required, but the presence of algae can reduce the time to
less than 10 hr (2). In extreme cases the clogging may
recur so frequently that the amount of water required to
backwash the filter is greater than the volume of filtered
water which reaches the distribution system. Thus the
presence of algae can slow up the process of water treat-
ment and add materially to its cost.
CLOGGING PROCESSES
Both the slow and rapid sand filters may become
clogged with algae, but in the former the algae and other
aquatic microorganisms may play a useful part in the
treatment process. They form a loose, slimy layer over the
surface of the sand and act as a filter. The algae in this
layer release oxygen during photosynthesis, and the oxy-
gen in turn is utilized by aerobic saprophytic bacteria,
fungi, and protozoa which establish themselves in and on
the filter. This permits the decomposition or stabilization
of the organic material that was present in the raw water.
On the other hand, diatoms, which have rigid walls, may
do more harm than good because they speed up the clog-
ging of the filter, but it is possible to use slow sand filters
when diatoms have put rapid filters out of commission
(3). The water that has passed through a slow sand filter
is relatively free of bacteria, algae, other organisms, and
organic matter.
It is not yet fully understood why certain algae are more
effective than others in reducing the movement of water
through the filters, but an ability to develop in large num-
bers is certainly essential. A rigid wall such as that found
in the diatoms, the copious mucilaginous material around
the cells, as in the case of Palmella, and the tendency to
form flakes or a network of strands, as in Fragilaria and
Tribonema, are other factors.
Diatoms are present during all seasons of the year and
are by far the most important group of organisms which
clog filters. The most serious offenders are Asterionella,
Fragilaria, Tabellaria, and Synedra. Other diatoms that
may occasionally cause this trouble include Navicula, Cy-
dotella, Diatoma, and Cymbella, all of which are illustrated
on plate VIII. The rigid cell wall of diatoms is composed
principally of silica and is not subject to decomposition.
Therefore, even though the diatoms may die off rapidly
on the surface of the filter, their silica walls remain and
plug the pores in the sand.
In England a relatively pure growth of Fragilaria de-
veloped in a reservoir to the extent that it was necessary
to remove huge quantities of this diatom at the water
treatment plant. Counts of another filter clogging diatom,
Asterionella, indicated that the organism had reached a
density as high as 20,000/ml (4).
In Chicago, when the water to be filtered contained
approximately 700 microorganisms/ml, principally Tabel-
laria and Fragilaria, the filter runs lasted only 4.5 hr. Three
days later, when the count was down to approximately
100/ml, the filter run increased to 41 hr (5).
Tabellaria is the organism causing most short filter runs.
It is likely to be present in considerable numbers all year
long except during January and February. Tabellaria,
which is a free-floating diatom, is most abundant in water
having little turbidity, and when coagulated with alumi-
num sulfate, the coagulated material does not settle rap-
idly. The cells are generally united in zigzag chains by
gelatinous cushions at the corners. The zigzag arrange-
ment and the gelatinous cushions, which can be stretched,
make the length of the chain flexible, and this helps to
prevent it from breaking on the filter surface. These
chains, therefore, may be more effective than long fila-
mentous algae in producing a clogging membrane on the
top of the filter. At Chicago there have been a dozen or
more periods of short filter runs within 1 year, and some
of the periods lasted for two or three weeks (6). In Wash-
57
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58
ALGAE AND WATER POLLUTION
ington, D.C., filter runs were reduced from an average of
50 hr to less than 1 hr due to the sudden influx of the
diatom Synedra, which reached a concentration in the
raw water of 4,800 cells/ml (7).
The filter clogging blue-green algae are represented on
plate VIII by Anacystis (Chroococcus type), R/vufaria, Ana-
baena, and three species of Osc/7/ator/a. Anafaaena is
known to have caused filter trouble in Illinois and Minn-
esota while Oscillatoria has been one of the offenders in
Switzerland. Dinobryon and Trachelomonas are pigmented
flagellates, the former being common in the Great Lakes
and in the soft waters of the eastern United States. A
treatment plant in England experienced phenomenally
high counts of Ceratium hirundinella during the summer.
The counts reached almost 750,000 cells/ml and created
major coagulation and filtration problems. At one time
nearly 40 percent of the treated water was required to
backwash the filters (8). Chlorella, Palmella, Spirogyra, and
the desmid, Closterium, are green algae, while Tribonema
is a yellow-green filament. Chlorella is the alga which
has given trouble by clogging filters made of glass wool.
In addition, it grows on the inner surfaces of glass bottles
in water coolers and in water lines constructed of plastic
tubing, when these have been exposed to light. In the
tropics and the warm temperate zone, the filamentous
green algae often clog sand filters.
Forty-five of the more important filter clogging algae
are listed alphabetically under their major groups in table
18. Twenty-two are illustrated in color on plate VIII, and
a few of the remaining forms are to be found on the
other plates, as indicated in the table.
Most of the microscopic organisms present in water
that is sand filtered generally will be caught in the top
0.5 in. of the sand, particularly when the organisms are
abundant in the water. A few of the organisms will pene-
trate deeper into the filter bed, while others disintegrate
quickly as they come in contact with the sand. The longer
the filter run, the greater the percentage of organisms
that will penetrate below the top 0.5 in.
In Chicago a study was made of the numbers of certain
diatoms that were caught on the surface of rapid sand fil-
ters. The samples were collected immediately before the
filters were backwashed. During 1 year of this study, Ta-
bellaria ranged in numbers from 496,000 to 936,000 sq in.
of filter surface in April, and from 1,824,000 to 8,016,000
in November. In contrast, the range for Melosira was from
784,000 to 2,624,000 in April, and only 16,000 to 416,000
in November (9).
At the water intake cribs of Chicago's water system, a
tubular branching green alga, Dichotomosiphon tuberosus,
was caught on 33 of the fish-collecting screens in suffi-
cient amount to clog them. Compressed air hoses were
used to separate the algal growth from the screens. The
alga resembles Vaucheria but has constrictions at the
base of each tubular branch. It normally develops in deep
water and was evidently brought into the water system
after breaking away from its original location. It has
caused this problem in Chicago at least three times in a
period of 8 years (10).
The relationships of algae to sand filters involve also the
problem caused by the passage of certain algae through
both rapid and slow filters and into the treated water. A
number of the same algae that can clog filters have at
other times been able to penetrate them. Algae that have
passed through rapid filters include Synedra and Oscilla-
toria and through slow filters, Chlamydomonas, Euglena,
Navicula, Nitzschia, Phacus, and Trachelomonas (11). The
ease with which the algae penetrate depends upon sev-
eral factors, the principal ones being the rate of flow, the
grade of sand used, and the type of organism. Very mi-
nute algae and flagellates penetrate with greater facility
than other types. When the penetration is slow, it may be
a few hours before the algae reach the underdrains. Fre-
quent backwashing, even when the filter is not clogged,
tends to remove the algae and reduce the number that
reach the filtered water.
REFERENCES
1. The effects of algae in water supplies. D. H. Matheson. Inter-
national Water Supply Assn., General Rept. to 2d Congress, Paris,
France, 82 p. 1952.
2. Algae control at Danbury, Connecticut. E. A. Tarlton. jour. New
England Water Wks. Assn. 63:165-174. 1949.
3. Interesting experiences with microorganisms in the Washington
water supply. G. E. Harrington. Proc. 9th Ann. Conf. Md.-Del.
Water and Sewerage Assn., p. 74-99. 1935.
4. Freshwater biology and water supply in Britain. W. H. Pearsall,
A. C. Gardiner, and F. Greenshields. Freshwater Biolog. Assn. of
the British Empire. Publ. No. 11, 90 p. 1946.
5. Effect of microorganisms on lengths of filter runs. J. R. Baylis.
Water Wks. Eng. 108:127-128, 158. 1955.
6. Microorganisms and short filter runs. J. R. Baylis. Pure Water,
Dept. of Water and Sewers, Chicago, III. 10:184-196. 1958.
7. The significance of microorganisms in plant design. C. J. Lauter.
Proc. 11th Ann. Conf. Md.-Del. Water and Sewerage Assn., p. 67-
74. 1937.
8. Treatment difficulties due to a massive crop of Ceratium hirun-
dinella. K. B. Clarke. Jour. Inst. Water Eng. (Brit.) 15:233-238. 1961.
9. Microorganisms that have caused trouble in the Chicago water
system. J. R. Baylis. Pure Water, Dept. of Water and Sewers, Chi-
cago, III. 9:47-74. 1957.
10. Screen clogging by a rare species of algae. W. W. DeBard and
J. R. Baylis. Water & Sew. Wks. 93:223-224. 1946.
11. The biological examination of water. A. T. Hobbs. Chapt. 18, p.
716-758 in Manual of British Water Supply Practice. Ed. 2. H.
Heffer and Sons, Ltd., Cambridge, England. 1954.
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Filter and Screen Clogging 59
TABLE 18. FILTER AND SCREEN CLOGGING ALGAE
Group and algae Plate
Blue-Green Algae (Myxophyceae):
Anabaena flow-aquae VIII
Anacystis dimidiata
(Chroococcus turgidus) VIII
Cloeotrichia echinulata
Oscillatoria amphibia
Oscillatoria chalybea VIII
Oscillatoria ornata
Oscillatoria princeps VIII
Oscillatoria pseudogeminata
Oscillatoria rubescens
Oscillatoria splendida VIII
Phormidium IV
Rivularia dura VIII
Green and Yellow-Green Algae
(nonmotile Chlorophyceae, etc.)
Chlorella pyrenoidosa VIII
Cladophora aegagropila
Closterium moniliferum VIII
Dichotomosiphon tuberosus
Dictyosphaerium pulchellum
Hydrodictyon reticulatum VII
Mougeotia sphaerocarpa
Palmella mucosa VIII
Spirogyra porticalis VIM
Tribonema bombycinum VIII
Ulothrix variabilis VIII
Zygnema insigne
Diatoms (Bacillariophyceae):
Asterionella formosa VIII
Cyclotella meneghiniana VIII
Cymbella ventricosa VIII
Diatoma vulgare VIII
Fragilaria crotonensis VIII
Melosira granulata VIII
Melosira varians
Navicula graciloides VIII
Navicula lanceolata
Nitzschia palea IV
Stephanodiscus binderanus
Stephanodiscus hantzschii I
Synedra acus VIII
Synedra acus var. radians
(S. delicatissima)
Synedra pulchella
Tabellaria fenestrata VII
Tabellaria flocculosa VIII
Pigmented Flagellates
(Chrysophyceae, etc.):
Ceratium hirundinella VII
Dinobryon sertularia VIII
Perindinium wisconsinense
Trachelomonas crebea VIM
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CHAPTER XV
ADDITIONAL PROBLEMS CAUSED BY ALGAE
The widespead distribution of algae in water supplies,
together with their unique combination of characteristics,
allows them to exert effects in many places and in many
ways. In addition to those activities discussed in the pre-
ceding chapters, the algae have been implicated in pro-
ducing slime in industrial water supplies, causing colora-
tion of water, inducing corrosion of concrete and of
metals, reducing the potability of treated water by their
presence in distribution systems, interfering with the
chemical treatment of water, and causing illness in man
and animals (1).
SLIME
Slime formation can be caused or aided by various kinds
of algae, bacteria, and other organisms (2). Slime-pro-
ducing algae are important in open reservoirs and in un-
covered holding basins of recirculating systems. They can
become a serious problem especially in the water supplies
for pulp mills and food industries by causing slime spots
or masses in the products. Coatings of slime may also
develop on condenser tubes in industrial cooling systems
and have the effect of reducing the rate of heat transfer
to the water (3). Slime accumulation in the unlighted por-
tions of distribution systems may be due to bacteria, to
the tardy settling out of the coagulant, or to other agents,
but not to algae.
Algal slime commonly is derived from the mucilaginous
capsule or sheath which envelops the cells. The blue-
green algae as a group are notorious slime producers.
Their technical name, Myxophyceae, contains the prefix
"myxo" which means slime or mucus. Several diatoms as
well as green and red algae and a few flagellates also pro-
duce slimy sheaths or capsules. A few of the slime-forming
algae are given in table 19.
COLORATION
Algal coloration of finished water is most frequent in
communities that have uncovered storage reservoirs, or
where the treatment of the raw water supply is not effi-
cient in reducing the numbers of phytoplankton present.
Almost any small alga capable of rapid multiplication could
be involved. Complaints come from patrons when the
water from the faucet is colored, or when a colored mar-
ginal ring forms at the surface of the water in the tumbler
or bathtub. Colors ranging from yellow-green through
green, blue-green, red, and brown to black could all be
due to algae. In table 19 are listed some of the algae that
have been implicated. However, colors in water may also
be caused by substances other than algae.
CORROSION
Corrosion of concrete and of metals in pipes and boilers
is a continual problem. Algae sometimes contribute to
corrosion either directly in localized places where they
may be growing or through their modification of the water
by physical or chemical changes. Green and blue-green
algae, along with lichens and mosses growing on the sur-
face of submerged concrete, have caused the concrete to
become pitted and friable (4).
Typical algae are unlikely to be the direct cause of cor-
rosion of iron or steel pipes in a distribution system be-
cause most are incapable of active growth in the absence
of light. However, algae have been reported to cause
corrosion in metal tanks or basins open to sunlight. Oscil-
latoria growing in abundance in water in an open steel
tank has caused serious pitting of the metal. The pits were
bright and clean because the iron was apparently going
into solution and not producing any covering compound
such as an oxide or sulfide. The algal growth permitted
the pitting to take place by releasing oxygen which com-
bined with the protecting film of oxide over the steel.
When the steel tank was covered to prevent entrance of
light, the algae disappeared and the corrosion stopped
(5).
Indirectly, algae may affect the rate of corrosion in a
number of ways. Increases in organic deposits in the
pipe, increases in the dissolved oxygen in the water
through photosynthesis in the raw water supply, and chan-
ges in the pH, CO2 content, and calcium carbonate content
of the water can all be brought about by algae. These
changes can, in turn, have a more direct relationship to
corrosion and may be significant particularly on the out-
side surfaces of pipe buried in the ground.
ALGAE IN TREATED WATERS
The persistence of algae in the water of distribution
systems tends to become more pronounced as additional
surface water supplies are tapped but less evident as ef-
fective measures for reducing the plankton in the water
are practiced. As most algae cannot grow and multiply
without light, the only algae which would be encountered
in the pipes of the distribution system would be first,
those not removed in the treatment process; second, the
few algae unusual in their ability to grow in the dark; and
third, those that develop in an uncovered reservoir con-
taining treated water. The algae capable of growth in the
dark include some species of Scenedesmus, Euglena, Ana-
cystis, Coe/astrum, and Ch/orococcum.
60
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Additional Problems
61
Since the treated water in most distribution systems has
a free chlorine residual, the algae most likely to remain
intact in the pipelines would be the chlorine-resistant
forms. These algae might be capable of carrying into the
distribution system living bacteria, presumably even path-
ogenic forms, which are protected from the lethal effect of
the chlorine by being embedded in the gelatinous cov-
ering surrounding the algal cells (6). Algae reported to be
resistant to chlorine in distribution systems include Elaka-
tothrix gelatinosa, Comphosphaeria aponina, Closterium
(fig. 62), Cosmarium, and Chlorella. In one water supply
receiving a normal chlorine treatment but no coagulation
or filtration, counts of up to 2,200 algae/ml were recorded
for the tap water. In counting, no distinction was made
between living and dead organisms. Some of the most
abundant genera were Asterionella, Cydotella, Dinobryon,
and Synedra (7).
Figure 62.—Closterium
lunula, a desmid.
Reservoirs in the distribution system can be provided
with covers to keep out the sunlight and thus prevent the
growth of algae. Groundwaters stored in open reservoirs
are often more susceptible to prolific algal growths than
are treated surface waters, possibly because their lower
turbidity permits greater light penetration. The ground-
waters can contain in solution a supply of nitrates, phos-
phates, iron, silica, and carbonic acid in quantities suffi-
cient to support the phytoplankton and especially the dia-
toms. The groundwater is easily seeded with algae and
other organisms which may be carried to the reservoir by
the wind or on the bodies of aquatic birds. The algae can
impart their characteristic odors to the stored water and
these can be carried into the remainder of the distribution
system (8).
Algae that persist in distribution systems can increase
the organic content of the water sufficiently to deplete the
residual chlorine in the water. In addition, this organic
content may feed bacteria, blood worms, nematodes,
copepods, freshwater sponges, bryozoa, and other unde-
sirable organisms. Organisms that grow attached to the
inner surface of the pipes are commonly known as pipe
moss.
ROLE OF ALGAE IN WATER TREATMENT PROBLEMS
Interference by algae with the chemical treatment of
water can be due to the changes they cause in pH, alka-
linity, total hardness, and DO of the raw water, or to their
increasing of the organic content carried by the water. It
may be necessary, for example, to vary the dosage of
chlorine in direct proportion to the quantity of algae pres-
ent in order to obtain a constant amount of residual chlo-
rine in the water.
In the clarification of water it is necessary to treat water
with a coagulant aid in addition to the coagulant if the
raw water has a low plankton population and low tur-
bidity due to silt or other particles. The aid may be finely
divided clay, bentonite, fuller's earth, activated carbon,
or similar materials composed of finely divided insoluble
particles. The addition of a small amount of the aid will
furnish particles which act as centers for the formation of
the floe. Asterionella and Synedra have been reported as
inhibiting proper floe formation (9). While it is possible
that particular kinds of algae might give more difficulty
than others during coagulation and sedimentation, the
total volume of all the algae is apparently more important.
Sedimentation alone would permit dead algae to settle
out gradually along with clay and other inorganic particles
present. The living planktonic algae would tend to remain
distributed throughout the water in the absence of a coag-
ulant.
Many industrial establishments require a water with
narrow ranges of variation in physical and chemical char-
acteristics. In one Connecticut city the felting and dyeing
processes were a part of the major industries, and they
required a water free of color, turbidity, iron and alumi-
num, and with low, constant pH and hardness (10). The
city water treatment plant is charged with the responsi-
bility of supplying water satisfactory for the city's indus-
tries. The raw water supply comes from reservoirs which
support populations of algae that change in concentration
from day to day. As this change occurs, small daily ad-
justments in chemical feed, equipment, and operational
methods are made in the water treatment plant in order
to maintain the predetermined optimum conditions such
as turbidity of not more than 2.0 at the filters, minimum
filter runs of 23 hr, maximum pH of 6.7 in the treated
water, minimum rates of flow of 70,000 gal/ft head loss/
filter, and minimum floe size in the last flocculator of 2.0
mm.
Normally a large floe particle is obtained quickly and
without agitation. Agitators are used, however, when cer-
tain free floating algae, particularly Comphosphaeria and
Anabaena, are abundant. The agitation causes smaller floe
particles to be formed which in this situation gives a set-
tled water with lower turbidity and color than would be
obtained with large floe particles.
Daily blooming of algae in the reservoirs frequently in-
duces the formation of a weak floe during coagulation in
the treatment plant and allows appreciable amounts of
undesired substances to remain in the water and to pass
through the sand filters into the finished water. The
blooming of the algae may cause the pH of the raw water
to rise from 7.0 to 10.0 in a few hours. It is the high pH
which causes a poor floe to be formed when alum is
added. Formerly the importance of algae in causing this
change was not recognized, and treatment plant operators
were continually puzzled by the sudden inexplicable shift
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62
ALGAE AND WATER POLLUTION
to a settled water of poor quality. During the high peak
of the pH cycle the normal amount of alum which they
had added to the water was insufficient to lower the pH
to the point where good floe formation would occur.
In some cases, the pH of the finished water is adjusted
to be within a desired range for industry by the addition
of acid or alkali. The water for a certain steel mill requires
approximately 800 Ib of 60 percent H2SO4 per day to
keep the pH of the water down to 8 as it is drawn from
a 320-acre lake. The algae in this lake are responsible for
increases in the pH of the water, and regular phytoplank-
ton counts are made as an aid in estimating the amount
of change in pH which will occur.
In another state a reservoir of 350 acres had a total
hardness normally of 120 ppm. In early June of one year
this suddenly dropped to 90 ppm. The DO increased from
8.3 to 13.0 ppm; the pH, from 8.6 to 8.9; the carbonate
alkalinity, from 20 to 30 ppm; and the turbidity, from 9
to 18 ppm. At the same time the blue-green alga Ana-
baena which was then the dominant form increased from
750 to 4,730 areal standard units/ml. Favorable condi-
tions were created for the precipitation of calcium car-
bonate and thus a softening of the water. According to the
report, the many cells of Anabaena had utilized sufficient
"half-bound" carbon dioxide in their metabolism to in-
crease the pH, which in turn made possible the precipita-
tion of the calcium carbonate (11). Other algae have been
observed to bring about a similar change. These are listed
in table 19. British experience has shown that vigorous
algal growth of many kinds can reduce water hardness by
as much as one-third (12).
TOXICITY OF ALGAE
Illness in man and animals has been attributed to both
marine and freshwater algae. A toxic agent produced by
the marine armored flagellate Conyaulax (13) can cause
serious illness in man following eating of clams that have
fed on particular species of this genus. The poison has
been described as a toxin 10 times as potent for mice as
strychnine. Conyaulax and Gymnodinium and other dino-
flagellates may accumulate in very large numbers in ocean
water near the shore and produce a condition known as
red tide or yellow-green peril. These flagellate blooms
have been reported for a number of localities throughout
the world, including the coasts of California, Florida, and
Texas, as well as Peru, Japan, Australia, India, Africa, and
Europe. Shellfish poisoning due to Gonyau/ax has also
been reported for Quebec, Nova Scotia, New Brunswick,
and Vancouver Island in Canada, and for California,
Alaska, Oregon, Maine, Mexico, British Isles, Norway,
France, Belgium, and New Zealand (14,15).
Many kinds of fish and other marine animals are often
killed during the time of the red tide but perhaps as the
result of factors other than the toxin since according to
some workers the poison has little or no effect on fish.
When the decaying fish are washed up on the beaches, the
stench and the need for quick disposal constitute a seri-
ous problem for the communities affected. Gymnodinium
veneficum, a species related to red tide algae, has been
found to kill fish in a short time and is lethal also to shell-
fish, arthropods, and echinoderms (16).
Several other marine algae have been implicated as
causing reef fishes to be poisonous in some areas. Large
numbers of poisonous fishes are known to be herbivorous,
and considerable evidence exists to indicate that these
fish are poisonous as food only after they have fed on
certain kinds of algae (17). In a large majority of the poi-
sonous fishes that were examined, the blue-green alga
Lyngbya (fig. 63) was detected in the alimentary tract.
Lyngbya majuscula and Lyngbya aestuar// were the com-
mon species in the area and in the fish samples. It is
interesting to find a report published in 1904 that "num-
bers of horses have frequently been killed by feeding on
Lyngbya majuscula which occurs in abundance on the
coral beaches in the Gulf of Manor" along the coast of
India (18). Other marine algae have been found toxic to
mice, but their possible toxicity to man has not been de-
termined (19). An algal flagellate Prymnesium parvum,
reported for Europe and common in brackish water ponds
in Israel, produces an extracellular toxin which has resulted
in mass mortality among fishes and in Israel is considered
the most serious natural obstacle to fish breeding (20).
Figure 63.—Lyngbya majuscula, showing empty sheath extending
between threads of cells.
Toxic freshwater algae affecting man have been reported
in the United States and elsewhere. Contact types of der-
matitis and symptoms of hay fever have been reported to
be caused by blue-green algae. Anabaena was implicated
in the former reaction (21) while Anacystis (Microcystis)
-------
Additional Problems
63
and Lyngbya contorta were listed for the latter (22). In a
few cases the green alga Chlorella has been found associ-
ated with fungi in mycotic lesions in man, but its signifi-
cance has not been determined (23). Unexplained out-
breaks of gastroenteritis involving thousands of people
and possibly related to the water supplies have been re-
ported in areas where extensive algal blooms were pres-
ent (24). However, direct relationship between the algal
blooms and the intestinal disorders in humans has not
been clearly demonstrated (25). It has been suggested as
a possibility that the disintegration of large amounts of
blue-green algae on the sand filters of water treatment
plants and the passage of toxic products into the distribu-
tion mains may be the cause of the gastro-intestinal dis-
turbances (26).
There are many records of acute and often fatal poison-
ing of livestock where the animals had been drinking from
ponds containing dense algal blooms (27). Animals affected
have included horses, cattle, hogs, sheep, dogs, rabbits,
and poultry. In all cases the algae implicated as the toxic
agents are blue-greens, Anacystis (Microcystis) being the
genus most often involved. The first alga reported as toxic
was Nodularia spumigena (fig. 64). The several genera and
species which are reported as toxic are listed in table 19.
Areas which have reported poisoning of animals, presum-
ably due to algal blooms, include Colorado, Idaho, Illinois,
Iowa, Michigan, Minnesota, Montana, North Dakota, Wis-
consin, and Alberta, Manitoba, Ontario, Saskatchewan,
Bermuda, Argentina, Finland, U.S.S.R., Australia, New Zea-
land, South Africa, and Morocco (28). The outbreaks have
occurred only during the summer months when algae are
abundant. The symptoms associated with poisoning by
the blue-green algae are generally prostration and convul-
sions followed by death (29).
Figure 64.—Nodularia spumi-
gena, the first blue-green alga
reported as toxrc.
In Saskatchewan particularly, there is evidence that the
toxic blue-green algae can affect humans as well as ani-
mals, causing severe headache, high fever, nausea, vomit-
ing, painful gastrointestinal upsets (including diarrhea),
pains in muscles and joints of limbs, and exhaustion.
Health authorities have warned persons against swimming
in water containing a bloom of blue-green algae (30).
There are two reports of fresh-water dinoflagellates
causing fish kills. One was in Lake Austin, Texas, and the
other was in a small lake in Louisiana. In both cases the
dinoflagellate Gymnodinium or Clenodinum was present
in high numbers. Fish that were killed included a large
number of gizzard shad which obtain food primarily by
straining algae from the water. Toxicity appears to be
related to the high concentration of the algal cells, a water
temperature of 70° to 75°F, high pH, and length of expo-
sure to sunlight (31,32).
Fish kills in fresh-water lakes and reservoirs have often
been blamed, with considerable justification, on the algae.
When there is a heavy algal growth, a reduction in the
amount of sunlight due to weather conditions will reduce
the photosynthetic activity of the algae. With insufficient
by-product oxygen being produced the algae are forced
to use in respiration the oxygen stored in the water. If this
condition should exist for any length of time, the water
would lose most of its oxygen, causing the algae and the
fish to die of oxygen starvation.
On the other hand, normal amounts of sunshine on a
very thick mat of algae can bring about a fish kill. If the
mat becomes thick enough to prevent the passage of
light to planktonic algae below the surface, the latter will
then use up more oxygen than is produced and oxygen
depletion takes place, affecting the fish.
A balance tends to exist between the amount of algae,
the sunlight, and the total oxygen requirements of the fish
and other aquatic organisms. A rise in water temperature
might easily be the factor which stimulates an excessive
growth of algae and thereby sets off the chain of events
leading to oxygen starvation and a fish kill (33).
PARASITIC ALGAE
Algae are known to be living on or in the tissues of some
aquatic vertebrates and in the bodies of many lower ani-
mals. They have been found in Stentor, Paramedum, Hy-
dra, water sponges and mussels, snails, and turbellaria. In
many cases the alga involved is Chlorella or Zoochlorella,
but others found are Carter/a, Phytoconis (Protococcus),
Aphrydium, Coccomyxa, Scenedesmus, Chlamydomonas,
and Trockisda. The relationship between the alga and its
host appears to vary from symbiosis to parasitism (34).
A few aquatic algae are known to infest the gills of fish,
causing a disease which interferes with respiration and is
often fatal (35). The dinoflagellate Oodinium ocellatum
parasitizes small fresh-water fishes. Other species of this
genus occur in the marine tunicates, annelid worms, and
other aquatic invertebrates (36).
In connection with fish, unicellular algae are often pres-
ent on the scales of mullet, and one species was improp-
erly distinguished from another by the presence of dark
spots on the scales. These dark spots were later found to
be the presence of algae and the species was declared in-
valid. A kissing gourami at the Bronx Zoo had a greenish
spot along the right dorso-lateral area, just below the dor-
sal fin. It was underneath the epidermis and was com-
posed of unicellular algae. Algal growths were also found
within the nasal capsule and between the eyes. Some of
the algae were filamentous and identified as St/geoc/o-
nium. The fish was anemic which may have been related
to toxic substances from the algae (37).
-------
64
ALGAE AND WATER POLLUTION
In a large fish farm in Florida, swordtails and kissing
gourami were found to have many algal cells in the epi-
thelium of the skin and gills. The algae appeared to be
Mucophilus cyprini. It is 15 to 20 microns in diameter and
has 8 to 12 chloroplasts. The affected fish were emaciated
and the mortality rate was high (38).
Other algae reported to be parasitic on fish in North
America are Oodinium limneticum, a dinoflagellate, and
Cladophora. In Japan algae have been found growing on
the teeth and surrounding tissues of fish (39). In the skin
of the carp, a green alga, Chlorochytrium, has been re-
ported (34).
Additional algae are parasitic on higher plants. One
species, Cephaleuros virescens, is the causal agent of red
rust of tea, one of the most serious diseases for the tea-
plant. It affects both leaf and stem. This same species of
alga also is parasitic on coffee. Cephaleuros is a branch-
ing filament. Branched rhizoids extend from the filament
and ramify in all directions in the host tissues. At least
some of the algal cells contain chloroplasts and produce
orange-to-green areas in the host (34).
Some non-filamentous colonial algae are parasitic on
plants. Chlorochytrium which resembles Chlorococcum
is parasitic on duck weed (Lemna). It enters through a
stoma or between two epidermal cells and develops as a
large ellipsoidal, sometimes lobed cell between the cells
of the host. This can also attack other aquatic plants such
as Elodea, Ceratophyllum, and certain mosses. A red uni-
cellular alga, Rodochytrium inhabits the leaves of ragweed.
A branching tubular alga, Phyllosiphon lives in the leaf
tissues of plants of the arum family. The leaves become
discolored with yellowish blotches because of orange
gobules of oil that accumulate due to the irration of the
parasite. The area of the leaves around the algae even-
tually lose their chlorophyll (40).
Some algae are parasitic on other algae. This is par-
ticularly true of certain marine red algae.
RADIOACTIVITY IN ALGAE
Algae take up and concentrate many dissolved minerals,
both stable and radioactive, even from great dilutions in
the water. Some bodies of water contain naturally radio-
active materials, others become radioactive through con-
tamination. The abundant alga in a naturally radioactive
spring in Japan was Ca/othr/x par/et/na (41). The spring
contained 18 kinds of algae, 12 of them being diatoms.
Radioactivity may be relatively harmless to algae, but
if the algae are used as food by higher organisms, then
directly or indirectly the radioactive materials can be in-
corporated into fish. The simpler aquatic organisms may
also reach crop soils through irrigation or flooding and
animals may ingest the organisms when drinking from
streams and ponds. From all three of these sources hu-
mans may receive the potentially harmful radioactive
materials.
Experiments with Euglena indicate that some of the
radionuclides are bound by that alga with a chemical
mechanism. This bound condition enables the nuclides to
pass along a food chain through Daphnia into bluegills.
Bluegills, getting cesium from the Eug/ena-Daphn/a food
chain, retained about 72 percent of the element (42).
The algae may take up radioactive substances in three
ways: by engulfment, by absorption through cell mem-
branes exposed to the surrounding water, and by adsorp-
tion onto exposed surface areas. Algae do not distinguish
between stable and radioactive materials. Also, because
of the three methods of collecting materials they may con-
centrate not only materials utilized in metabolism but use-
less substances as well. For example, cells of Carter/a can
adsorb yttrium and can absorb strontium neither of which
is used in cell activities but both of which can be radio-
active (43).
The sorption of cesium-137 by algae is of particular
interest because it is one of the fission products in power
reactor wastes and atomic weapon fallout, and because it
has an estimated half-life off 26.6 years. Table 20 shows
the uptake of cesium-137 by various species of algae (44).
Algae were found to remove phosphorus from water,
concentrating the tracer materials 300,000 times. Maxi-
mum accumulations of radio-phosphorus by the algae
were reached in 18 days. Spirogyra concentrated radio-
phosphorus by a factor 850,000 times that of water. Algae
in settling ponds concentrated the radionuclides in their
structure but the release of the nuclides can be retarded
in waters of low pH. This could form a zone of high ac-
tivity of undesirable magnitude at the mud-water interface
(45).
The concentration of radionuclides by algae can be
very high, as shown in table 21. The uptake of trace ele-
ments by organisms is not a phenomenon which is peculiar
to the radioactive forms of the elements. The radioisotope
acts only as a tracer that demonstrates the difference be-
tween the abundance of the element in the water and in
the organism. From measured amounts of radionuclides in
the effluent from Hanford, Washington, reactors and in
types of organisms living on the Columbia River immedi-
ately below the reactors, maximum concentration factors
have been calculated for the more abundant isotopes.
These are listed in table 21 (46).
The concentration factors for several isotopes are quite
low in fish in comparison to those In algae and insect
larvae. Thus, food chains can serve, in some cases, to
reduce the concentration of radionuclides in large animals.
Organisms tend to eliminate non-essential elements mak-
ing a selection against such nuclides along the food chain.
Also, short-lived isotopes will decay to lower levels as they
pass through the chain.
Differences in the concentration factors for various iso-
topes among algae, insect larvae, and fish lead to different
levels of radioactivity in these groups of organisms. This
is indicated in table 22 (47). The short-lived isotopes con-
-------
Additional Problems
65
tribute significantly to the large quantity of radioactive
materials in lower organisms, but in the fish about 95 per-
cent of the activity originates from P32.
It is obvious that radionuclides which enter fresh water
streams and lakes may enter the food chain especially by
means of the algae and thus appear in fish and other forms
eaten by humans. The radioactive contamination levels in
the organisms are affected by a number of physical, chem-
ical, and biological factors. Fresh water communities vary
so greatly from one another that monitoring of the con-
centrations of the radionuclides must be carried out at
each locality.
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3. Experiences in chlorinating condenser circulating water. V. M.
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Agric. and Bur. Reclamation, U.S. Dept. Interior, 8 p. Jan. 1954.
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Wks. Assn. 39:322-324. 1947.
6. Quality and quantity of plankton in the south end of Lake Michi-
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1944.
7. Plankton removal tests and potable water supply at Naval Station,
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and Welfare, Public Health Service, Robt. A. Taft San. Eng. Center,
Cincinnati, Ohio, 60 p. (Mimeographed). Jan. 1955.
8. Covers for reservoirs for filtered waters and ground waters. Amer.
Water Wks. Assn., p. 243-245 in Water Wks. Practice. Williams and
Wilkins, Baltimore, Md. 1925.
9. Algae and other natural sources of tastes and odors in water sup-
plies. G. J. Turre. Chapt. 2 in Taste and Odor Control in Water
Purification. West Va. Pulp and Paper Co. N.Y. Bull. 1955.
10. Algae control at Danbury, Connecticut. E. A. Tarlton. Jour. New
England Water Wks. Assn. 63:165-174. 1949.
11. Investigation of an unusual natural water softening. D. W. Graham.
Jour. Amer. Water Wks. Assn. 34:589-594. 1942.
12. Freshwater biological research and water supply. W. H. Pearsall.
Jour. Inst. Water Engrs. 5:482-484. 1951.
13. The Florida Gulf Coast red tide. J. B. Lackey and J. A. Hynes.
Florida Eng. and Indust. Exp. Sta. Bull., Series No. 70, 23 p. Feb.
1955.
14. Mussel poisoning—a summary. H. Sommer and K. F. Meyer. In
Manual for Control of Communicable Diseases in California. Cali-
fornia State Dept. Public Health. 1948.
15. Public health significance of paralytic shellfish poison: a review of
literature and unpublished research. E. F. McFarren, M. L. Schafer,
J. E. Campbell, K. H. Lewis, E. T. Jensen, and E. J. Schantz. Proc.
National Shellfisheries Assn. 47:114-141.1956.
16. Two new species of Gymnod/nium isolated from the Plymouth
area. D. Ballantine. Jour. Marine Biol. Assn. United Kingdom
35:467-474. 1956.
17. Marine algae from Palmyra Island with special reference to the
feeding habits and toxicity of reef fishes. E. Y. Dawson, A. A.
Aleem, and B. W. Halstead. Allan Hancock Foundation Publ. Univ.
Southern California. Occasional paper No. 17. 39 p. Feb. 1955.
18. Treatise on the British freshwater algae. Revised Ed. (p. 451). G. S.
West and F. E. Fritsch. Cambridge Univ. Press, Cambridge, England,
534 p. 1927.
19. Observations on toxic marine algae. R. C. Habekost, I. M. Fraser,
and B. W. Halstead. Jour. Washington State Acad. Sci. 45:101-103.
1955.
20. Conditions which determine the efficiency of ammonium sulfate
in the control of Prymnesium parvum in fish breeding ponds. M.
Shilo and M. Shilo. Appl. Microbiol. 1:330-333. 1953.
21. Cutaneous sensitization to blue-green algae. S. G. Cohen and
C. B. Reif. Jour. Allergy 24:452-457. 1953.
22. Symptoms of hay fever caused by algae. II. Microcystis, another
form of algae producing allergenic reactions. H. A. Heise. Ann.
Allergy 9: 100-101. 1951.
23. The role of algae and plankton in medicine. M. Schwimmer and
D. Schwimmer. Grune and Stratton, N.Y., 85 p. 1955.
24. Epidemic of intestinal disorders in Charleston, West Virginia, oc-
curring simultaneously with unprecedented water supply condi-
tions. E. S. Tisdale. Amer. Jour. Public Health 21:198-200. 1931.
25. Unusually mild recurring epidemic simulating food infection. R. R.
Spencer. Public Health Repts. 45:2867-2877. 1930.
26. Discussion of article by W. D. Monie on algae control. T. C. Nel-
son. Jour. Amer. Water Wks. Assn. 33:716-720. 1941.
27. Toxic fresh-water algae. W. M. Ingram and G. W. Prescott. Amer.
Midland Naturalist 52:75-87. 1954.
28. Algal poisoning in Ontario. A. G. Stewart, D. A. Barnum, and J. A.
Henderson. Canadian Jour. Comparative Med. 14:197-202. 1950.
29. Toxic algae. P. R. Gorham. In Algae and Man, D. F. Jackson (ed.).
Plenum Press, N.Y., p. 307-336. 1964.
30. Toxic waterbloom in Saskatchewan, 1959. H. O. Dillenbery and
M. K. Dehnel. Canadian Med. Assn. Jour. 83:1151-1154. 1960.
31. Red tide of Lake Austin. K. C. Jurgens. Texas Game and Fish 11
(11): 8, 24. 1953.
32. Observation on the factors involved with fish mortality as the
result of dinoflagellate bloom in a freshwater lake. R. J. Muncy.
Proc. 17th Ann. Conf. Southeastern Assn. Game & Fish Comm.
p. 218. 1963.
33. The algal environment in relation to fish. A. S. Kennedy. Jour.
New England Water Wks. Assn. 62:196-201. 1948.
34. The structure and reproduction of the algae. F. E. Fritsch. Cam-
bridge Univ. Press. Vol. 1: 791 p. Vol. 2: 939 p. 1935, 1945.
35. The use of copper sulfate as a cure for fish diseases caused by
parasitic dinoflagellates of the genus Oodinium. R. P. Dempster.
Zoologica 40:133-138. 1955.
36. How to know the Protozoa. F. L. Jahn. Wm. C. Brown Co., Du-
buque, Iowa, 234 p. 1949.
37. Histozoic algal growth in fish. R. F. Nigrelli, J. J. A. McLauchlin
arid S. Jakowska. Copeia. No. 4:331-333. 1958.
38. Algal parasite in fish. L Glenn, H. Bishop, and C. E. Dunbar. Prog.
Fish Culturist 22:120. 1960.
39. An alga growing on the teeth and the surrounding tissues of fish.
S. Isokawa. Zool. Mag. (Japan) 65:319-321. 1956.
40. The algae: a review. G. W. Prescott. Houghton Mifflin Co., 436 p.
1968.
41. The thermal algae in certain strong radioactive springs in Japan.
M. Mifune, H. Hirose, and K. Tsumura. Hot Springs Science,
Ansen Kagaku 10 (3): 60-64.
42. Direct and food-chain uptake of cesium-137 and strontium-85 in
bluegill fingerlings. L. G. Williams and Q. Pickering. Ecology
42:205-206. 1961.
43. Uptake of cesium-137 by cells and detritus of Euglena and Cn/o-
rella. L. G. Williams. Limnol. and Oceanog. 5:301-311. 1960.
44. Concentration of cesium-137 by algae. L. G. Williams and H. D.
Swanson. Science 127:187-188. 1958.
45. Radioactive wastes. Chapt. 8 in The Practice of Water Pollution
Biology. K. M. MacKenthun. U.S. Dept. Interior, Fed. Water Pol.
Contr. Admin., Div. of Tech. Support. U.S. Printing Office. 1969.
46. Radioactive materials in aquatic and terrestrial organisms exposed
to reactor effluent water. J. J. Davis, R. W. Perkins, R. F. Palmer,
W. C. Hanson, and J. F. Cline. Second Internal. Conf. on Peaceful
Uses of Atomic Energy. Paper No. 393. 1958.
-------
66
ALGAE AND WATER POLLUTION
47. Bioaccumulation of radioisotopes through aquatic food chains.
J. J. Davis and R. F. Foster. Ecology 39:530-539. 1958.
TABLE 19. ADDITIONAL PROBLEMS CAUSED
BY ALGAE IN WATER SUPPLIES
Problem and algae
Algal group
Problem and algae
Algal group
Slime-producing Algae:
Anacystis (Aphanocapsa, Gloeocapsa)
Batrachospermum
Chaetophora
Cymbella
Euglena sanguinea var. furcata
Euglena velata
Gloeotrichia
Gomphonema
Oscillatoria
Palmella
Phormidium
Spirogyra
Tetraspora
Algae Causing Coloration of Water:
Color of water:
Anacystis
Ceratium
Chlamydomonas
Chlorella
Cosmarium
Euglena orientalis
Euglena rubra
Euglena sanguinea
Oscillatoria prolifica
Oscillatoria rubescens
Algae Causing Corrosion of Concrete:
Anacystis (Chroococcus)
Chaetophora
Diatoma
Euglena
Phormidium
Phytoconis (Protococcus)
Algae Causing Corrosion of Steel:
Oscillatoria
Algae Persistent in Distribution Systems:
Anacystis
Asterionella
Chlorella
Chlorococcum
Closterium
Coelastrum
Cosmarium
Cyclotella
Dinobryon
Elakatothrix gelantinosa
Epithemia
Euglena
Gomphosphaeria aponina
Scenedesmus
Synedra
Algae Interfering With Coagulation:
Anabaena
Asterionella
Euglena
Gomphosphaeria
Synedra
Algae Causing Natural Softening of Water:
Anabaena
Aphanizomenon
Cosmarium
Scenedesmus
Synedra
Toxic Marine Algae:
Caulerpa serrulata
Cochlodinium catenatum
Blue-green
Rusty brown
Green
Green
Green
Red
Red
Red
Purple
Red
Blue-green
Red
Green
Diatom
Flagellate
Flagellate
Blue-green
Diatom
Blue-green
Green
Blue-green
Green
Green
Blue-green
Flagellate
Flagellate
Green
Green
Flagellate
Flagellate
Flagellate
Blue-green
Blue-green
Blue-green
Green
Diatom
Flagellate
Blue-green
Green
Blue-green
Blue-green
Diatom
Green
Green
Green
Green
Green
Diatom
Flagellate
Green
Diatom
Flagellate
Blue-green
Green
Diatom
Blue-green
Diatom
Flagellate
Blue-green
Diatom
Blue-green
Blue-green
Green
Green
Diatom
Green
Dinoflagellate
Egregia laevigata Brown
Exuviaella ballicum Dinoflagellate
Gelidium cartilagineum var.robustum Red
Gonyaulax catenella Dinoflagellate
Gonyaulax polyedra Dinoflagellate
Gonyaulax tamarensis Dinoflagellate
Gymnodinium brevis Dinoflagellate
Gymnodinium splendens Dinoflagellate
Gymnodinium mitimoto Dinoflagellate
Gymnodinium veneficum Dinoflagellate
Hesperophycus harveyanus Brown
Hornellia marina Flagellate
Lyngbya aestuarii Blue-green
Lyngbya majuscula Blue-green
Macrocystis pyrifera Brown
Pelvetia fastigiata Brown
Prymnesium parvum Flagellate
Pyrodinium phoneus Dinoflagellate
Trichodesmium erythraeum Blue-green
Toxic Fresh Water Algae:
Anabaena Blue-green
Anabaena circinalis Blue-green
Anabaena flos-aquae Blue-green
Anabaena lemmermanni Blue-green
Anacystis (Microcystis) Blue-green
Anacystis cyanea (Microcystis aeruginosa) Blue-green
Anacystis cyanea (Microcystis flos-aquae) Blue-green
Anacystis cyanea (Microcystis toxica) Blue-green
Aphanizomenon flos-aquae Blue-green
Gloeotrichia echinulata Blue-green
Gloeotrichia pisum Blue-green
Gomphosphaeria lacustris
(Coelosphaerium kuetzingianum) Blue-green
Lyngbya contorta Blue-green
Nodularia spumigena Blue-green
Rivularia fluitans Blue-green
Parasitic Aquatic Algae:
Oodinium limneticum Dinoflagellate
Oodinium ocellatum Dinoflagellate
TABLE 20. UPTAKE OF CESIUM-137 BY ALGAE
Algae
Rhizoclonium hieroglyphicum
Oedogonium vulgare
Euglena intermedia
Oocystis elliptica
Spirogyra ellipsospora
Spirogyra communis
Chlorella pyrenoidosa
Gonium pectorale
Chlamydonomas sp.
Days after
dosing
5
3
14
10
2
5
11
2
5
Cesium-137
concentration
factor
1,530
790
706
670
341
220
154
138
52
-------
Additional Problems
67
TABLE 21. MAXIMUM CONCENTRATION FACTORS FOR ISOTOPES
IN COLUMBIA RIVER ORGANISMS
TABLE 22. RELATIVE CONCENTRATION OF RADIOACTIVE
MATERIALS IN VARIOUS TYPES OF ORGANISMS
Isotope
p32
Zn65
Cs"7
Sr»°
Na"
As78
Sc46
Cr«
Cu«*
Algae
1,000,000
100,000
5,000
10,000
100
10,000
100,000
1,000
10,000
Insect
larvae
100,000
10,000
1,000
100
100
1,000
1,000
1,000
1,000
Fish
100,000
10,000
10,000
1,000
1,000
100
10
10
10
Item
Plan L~trtn
rldJtKlOn
Sessile algae
Caddis larvae
May fly nymphs
Shiners
Crayfish
Water
0
X
X
X
X
X
X
X
X
X
X
V
A
X
X
X
25 50
Y V Y Y Y Y Y
A A A A A A A
X X X X X
X X X X
75 100
V Y Y Y Y
A A A A A
-------
CHAPTER XVI
ADDITIONAL USES FOR ALGAE FOUND IN WATER SUPPLIES
Reference has already been made to the utilization of
algae as indicators of domestic pollution and of natural
purification in streams. They are also considered useful
as indicators of the sources of a particular water supply,
the pollution of groundwater supplies by surface water,
the pH and temperature ranges of a stream or lake, the
toxicity of industrial wastes, and the relative abundance
in water of chemicals such as sodium chloride, iron, and
calcium phosphate.
INDUSTRIAL USES
Algae constitute the raw material used to manufacture
sodium alginate, agar, iodine, diatomaceous earth, and
various food products. The food products known under
various names such as amanori, kombu, kan-ten, carra-
geen, dulse, and limu are an important part of the diet in
Hawaii, Japan, China, the Philippines, Ireland, and several
other areas. These products are derived principally from
marine algae and are used especially as seasonings and
in soups. The alga most widely used is Porphyra. Most of
the supply is from plants cultivated in estuaries in Japan,
where the sea water is about 20 ft deep. It grows on im-
planted objects such as rocks or bundles of bamboo.
There are about 70 species of edible marine algae.
Almost all of these are used in Hawaii while about 20 are
used in Japan, 8 in the Philippines, and 5 in Canada.
Several products made from marine algae have indus-
trial uses. Celidium and related red algae are used in the
production of agar, while the giant brown kelp, Macro-
cystis, is a source of the widely used alginate. The brown
seaweeds, especially Laminaria and AscophyHum, have
been utilized as fertilizer and as a feed supplement for
livestock in Great Britain and Ireland (1).
The utilization of fresh water algae in large amounts
awaits the development of practical methods for their
mass culture and harvesting (2). Their potential value as
producers of concentrated protein, carbohydrates, and fat
is very great, for there is no waste in the form of fibrous
or woody portions that are always present in land plants.
Investigations have been conducted to develop practical
methods for using sewage in the production of the algae
that would be suitable for animal feeds, fertilizers, and
other products (3). Algae may serve in the near future as
commercial sources for vitamins, hormones, and antibiotics
(4). It has been estimated that about 5 million tons of algal
nutrients are wasted each year in the United States alone
by present methods of sewage disposal (5). If algae are
grown in a closed system for treatment of sewage, there
need be no waste of the nutrients (6). Many technical
problems must be solved before this type of system can
be widely utilized.
It is estimated that algae synthesize 90 percent of the
world's organic carbon, and they are more efficient utiliz-
ers of solar energy than are higher plants. Thus it seems
probable that the algae will some day be used commer-
cially to produce a large amount of the proteins, fats, and
carbohydrates required by man. Many areas of the world
now have food shortages which mass culturing of fresh
water algae could solve, even in dry regions, since much
of the water used could be recycled. Fresh water algae are
already being cultured and used in Japan. Almost all of
the present production of dried Chlorella and related algae
in Japan is sold to industries producing a fermented milk
product. Chlorella was found to accelerate the rate of
fermentation of milk.
The culture of unicellular algae is amenable to treatment
as an industrial process that can operate continuously un-
der strictly controlled conditions. Ch/ore//a, Scenec/esmus,
Ankistrodesmus, and some other algae are easily grown in
culture and can tolerate a wide range of environmental
factors. Their growth is very rapid and the yield per acre
per year is many times greater than for higher plants. It is
estimated, for instance, that in the case of Chlorella 14,000
Ib of protein/acre/year could be produced; the figures for
grass and beans would be 600 and 370 respectively. Chlo-
rella is very rich in protein as well as various vitamins and
minerals. It contains all of the ammo acids known to be
essential for the nutrition of man and animals. Under nor-
mal conditions the organic content of Chlorella is approxi-
mately (by dry weight) 50 percent proteins, 20 percent car-
bohydrates, 20 percent lipids, and 10 percent ash. There is
no waste in the form of fibers or other inedible parts, with
the exception of the cellulose in the cell walls. The ele-
ments essential for human nutrition are found in algae in
sufficient amounts except for calcium and sodium.
In Japan the yield of freshwater algae at the Microalgae
Research Institute near Tokyo is about 13 metric tons per
acre per year (dry weight). Assuming that one-half of the
per capita requirements of 65 gm of protein/day was to
be obtained from algae, the total area required for algae
culture would be less than 1,000,000 acres to feed the
present world population.
Harvesting of the algae is one of the biggest problems.
Centrifugation is much in use but is presently too expen-
sive. Enlargement of culture facilities and installing of
automatic devices should reduce labor costs which at pres-
68
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Additional Uses
69
ent amount to about 40 percent of the cost of production
(7).
The product has an appearance, flavor, and taste similar
to powdered green tea and to certain powdered seaweeds.
However, the intense green of the powder gives foods a
dark green to black color requiring that it be decolorized.
The bleached powder is milder in odor and taste as well
as in color.
ALGAE AS FOOD FOR FISH
Algae represent indirectly the primary food of the fish.
The smaller algae are devoured by most of the plank-
tonic crustaceans and by rotifers. Many very young fish
feed on the zooplankton. These fish include trout, perch,
and minnows. Other fish feed upon the smaller fish which
fed on plankton. Algae, being the first link in the food
chain, determine in a direct or indirect manner the kind
and the amount of food available for fish. Recently a
number of fish have been investigated which are herbivor-
ous. Milk-fish in the brackish ponds of Thailand, Indonesia,
and the Philippines feed mostly on filamentous blue-green
algae and diatoms. In Australian estuaries, garfish, mullets,
black bream, and cobblers frequently have very little in
their guts but filamentous green algae, such as Cladophora,
Chaetomorpha, and Enteromorpha, and diatoms, especially
Melosira and Cosc/nod/scus.
A number of species of Chinese carp have been intro-
duced into commercial pond farms in eastern Europe.
There, herbivorous fish eat natural food consisting of algae
or higher aquatic plants. Some prefer filamentous algae
while others use microscopic planktonic algae, filtered
from the water by the gill apparatus. Attempts are being
made to develop an artificial pelleted food for the carp,
and algae are always one of the components. In the future
this kind of food will probably be the basis for food in the
European carp farms.
A European teleost possesses a mouth opening with
sharp edges situated on the ventral side of the head, and
this makes it possible for the fish to scrape epiphytic algae
from stones. Its food consists mainly of diatoms. No other
European species living in cold streams matches this one
as a consumer of algae.
One species of trout feeds nearly exclusively on algae
by scraping them from the surface of stones on the river
bottom. Other species of trout are carnivorous (8).
All of the examples given above are of fish which
shorten the food chain between primary production and
animal protein, between algae and fish. In many other
cases algae present only the first link in the food chain that
eventually reaches fish production. In each step from algae
to crustacean to small fish to large fish it appears to re-
quire about 7 to 10 Ib of the first step to produce 1 Ib
of the second. Thus at 10 Ib per step, it would require
1,000 Ib of algae to produce 1 Ib of large fish. Fish ponds
in the southern states are commonly fertilized with nutri-
ents to stimulate higher production of algae in order to
eventually produce more large fish.
ALGAE AS WATER SOURCE INDICATORS
It is often possible to identify the probable source of a
sample of surface water through a determination of the
number and kinds of algae and related organisms present.
This is possible because the number and kinds of micro-
organisms which develop are related to the hydrographic
features of bodies of water. The chief types of lakes, for
instance, are: (a) the hard water lake with an outlet; (b)
hard water landlocked lake; (c) soft water lake with an
outlet; (d) soft water landlocked lake; (e) acid bog lake;
and (f) alkaline bog lake.
The hard water lake with an outlet tends to have an
algal flora that is predominantly the blue-green-diatom
type. Typical components of a hard water landlocked lake
include an equal abundance of greens and blue-greens
plus some of the euglenoids and yellow-greens (Chryso-
phyta). In the soft water lake with an outlet, the algal
flora is predominantly composed of green algae and the
total number is low. The soft water landlocked lake has a
scant algal flora and the filamentous forms are practically
nonexistent. This type of lake may produce blooms of
blue-green algae, but the number of species involved is
still small. A great variety of desmids will be present in an
acid bog lake, and certain species of blue-greens can be
expected. Plankton forms are not abundant but filamen-
tous ones are well developed and common. The alkaline
bog lake has an algal flora which is poor both in numbers
and kinds. Hard water organisms, such as Chara, Spirogyra
crassa, and Spirogyra dedmena, are often abundant (9).
A knowledge of the typical algal floras of various lakes
which represent the sources of a water supply will help,
therefore, in determining the breeding grounds of the
particular algae that interfere with the treatment or use
of the water.
ALGAE IN WASTE TREATMENT SYSTEMS
Reference was made in chapter XII to the use of algae
for production of oxygen in sewage stabilization ponds.
Research carried out in California has indicated that the
determination of the number and kinds of the more abun-
dant algae in these ponds can be used as a reliable index
of the progress achieved in the oxidation of the sewage
(10). If the effluent contains principally Chlorella, the pond
is assumed to be working at or over its capacity; if it con-
tains a mixed flora, the pond can handle a heavier load.
Chlamydomonas is one of the common forms in the mixed
flora which develops when most of the organic matter is
gone and mineral nutrients have been precipitated be-
cause of a high pH. Chlamydomonas in turn appears to
excrete an organic compound which again makes the
minerals available for" algal growth.
Examination of the pond effluent for its algal flora may,
therefore, be a useful tool for operators of sewage plants
having sewage stabilization ponds. The microscopic ex-
amination would require only a few minutes, and no ex-
tensive training is required to recognize the few types of
important algae. It has not yet been determined whether
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70
ALCAE AND WATER POLLUTION
the procedure is applicable for use in all parts of the
country.
Algae may also be put to use in the treatment of in-
dustrial wastes. By selecting and adapting particular strains
of algae, yeasts, and bacteria, it may be possible to bring
about, biologically, changes in industrial wastes which
otherwise might be toxic or in other ways unsuitable for
release into streams, lakes, or marine waters. The use of
algae would be particularly advantageous when the release
of oxygen into the waste is one of the required factors
(6). The process has already been developed for treatment
of oil wastes from refineries. The aerobic lagoon design
also often includes additional features such as presedimen-
tation, recirculation, and supplemental aeration. A few
thousand stabilization ponds for treatment of industrial
wastes are in use in the United States and most of them are
working satisfactorily. They are being employed by the
canning, chicken processing, dairy, laundry, meat packing,
oil refining, pulp and paper, organic chemical, and other
industries. Data are not yet available for comprehensive
evaluation of loading factors and design criteria (11). Forms
which are tolerant of various industrial wastes might be
utilized in their treatment. These are listed in table 23.
Included are Scenedesmus bijugatus (fig. 65) in salt brines,
Closterium acerosum in chromium, Chlorella variegata in
iron, Navicula minima in hydrogen sulfide, Diatoma vul-
gare in oil, and Chlorogonium euchlorum in distillery
wastes.
Figure 65.—Scenedesmus bijugatus.
ALGAE AS MARINE POLLUTION INDICATORS
Pollution of estuaries and of coastal marine waters is
rapidly becoming a problem at bathing beaches and where
the ocean frontage is used for residences, for industry, and
for recreation. Pollution is also influencing the marine fish-
ing and shellfish industries.
As with fresh water forms, severe pollution in salt water
first tends to reduce the marine algae population to a few
of the more resistant species, but the decomposition prod-
ucts in turn stimulate a vigorous subsequent growth of
algae. In marine polluted areas in northern Europe, the
sewage pollution is reported to prevent the growth of
the brown rock weed, Fucus, while algae that are stimu-
lated include Blindingia minima, Enteromorpha, Ulva lac-
tuca, Porphyra leucosticta, Erythrotrichia carnea, Acro-
chaetium virgatulum, Acrochaetium thuretii, and Calothrix
confervicola. In addition to these large seaweed algae,
microscopic planktonic algae thrive in the polluted areas,
causing a decrease in the transparency of the water (12).
The sea lettuce, Ulva latissima, was stimulated to active
growth by sewage in England (13). Industrial pollution in
an estuary, involving principally iron sulfate, stimulated
the growth of the pollution alga Chlorella variegata and
caused the sensitive diatoms Chaetoceros and Skeleto-
nema to settle out (14).
Marine and brackish water diatoms are being studied
to determine their usefulness as indicators of pollution
with either domestic sewage or industrial wastes. One
apparatus for obtaining the diatoms from the water is a
slide rack with floats known as a diatometer (15). Its use
is being studied in both fresh and salt waters.
TEMPERATURE, pH, AND TOXICITY
Several physical characteristics of water are influenced
by its utilization for industrial purposes. The largest single
industrial use is cooling. In general the various classes as
well as individual species of algae have minimum, opti-
mum, and maximum temperatures for growth (16-18). The
optimum temperature for diatoms is 18°-30°C, for green
algae, 30°-35°C, and for blue-green algae, 35°-40°C, ac-
cording to Cairns (19). He reports that the diatom Com-
phonema parvulum grew best at 22°C, and still showed
considerable growth at 34°C, while another diatom Nitz-
schia /mean's, which grew best at 22°C, showed little or no
growth at 30°C. Temperature changes are considered more
important than any other environmental factor in influenc-
ing diatom growth (20). A few blue-green algae are capa-
ble of growth at temperatures much higher than 40°C.
The optimum temperature for Osdllatoria filiformis is
85.2°C. Diatoms have been present in moderately hot
water (40°C), but green algae are conspicuously absent in
hot springs. The types of algae found in a particular stream
may be a good indication of the range of temperature that
the water has experienced (21-24).
Change in pH of water due to industrial wastes or to
natural causes will also greatly modify the algal popula-
tion. Mine wastes tend to lower the pH drastically and
reduce the algal flora to a few acid-tolerant forms such as
Euglena mutabilis, Ochromonas, Chromulina ovalis, Lepo-
cinclis ovum, Cryptomonas erosa, and Ulothrix zonata (25).
Additional acid-tolerant algae are included in table 23.
The majority of algae grow best in water at or near the
neutral point of pH, but a considerable number, particu-
larly among the blue-green algae, develop readily or may
even grow best in water with a high pH. In cultures the
optimum for Anacystis (Microcystis) and for Coccochloris
(Cloeothece) has been found to be pH 10, with little or no
growth below pH 8 (26).
Other physical factors such as light and turbulence also
play their part in determining the particular algal flora
that will develop or remain in the water. In bioassays to
determine the toxicity of pollutants in water, certain kinds
of fish and the crustacean Daphnia are being used. Algae
also are being considered for the test. Some may become
useful as indicators of toxicity, especially in waters where
the wastes reduce the DO below that in which animals
can survive. Comparatively little information is available
on the tolerance limits of particular species of algae for
the various toxic pollutants.
Me/os/ra varians may be the only dominant diatom in
streams polluted with oil (16). Iron, which is a pollutant
-------
Additional Uses
71
from steel mills, may be toxic to most algae but the flagel-
lates Chromulina and Trachelomonas hispida (fig. 66) may
remain active. Certain diatoms are also found in iron-rich
water, including many species of Eunotia and some large
forms of Pinnularia (27). However, other diatoms as well
as several blue-green algae and a few others appear to be
tolerant to oil (28). Algae require a small amount of iron
for the production of their chlorophyll and most algae
grow best when the iron content of the water is between
0.2 and 2.0 mg/l. Distinct toxicity is frequently noted
when it exceeds 5.0 mg (29).
Copper is well known to be toxic to many algae, but
some species are reported to be resistant to limited con-
centrations of this metal; these include Cymbella ventri-
cosa, Calothrix braunii, and Scenedesmus obliquus (fig.
67). Others are listed in tables 23 and 24.
Phenol at a concentration of 1.9 mg/l appears to have
no toxic effect on diatoms (30). Chromium, bromine, and
many dyes from textile operations are very toxic to algae.
Spondylomorum, Pediastrum (fig. 68), and Pandorina are
capable of developing in the presence of paper mill wastes
toxic to most algae (31). Distillery wastes may limit the
algae growth to a few forms such as Chlamydobotrys,
Chlorogonium (fig. 69), and Chlorobrachis (32). Hydrogen
sulfide at a concentration of 3.9 mg/l is toxic to most dia-
toms. Four resistant species are Achnanthes affinis, Cym-
bella ventr/cosa, Hantzschia amphioxys, and Nitzschia pa-
lea (30). Pollution of water in oil fields and in salt works
with salt brine composed largely of sodium chloride may
destroy most of the normal flora. Blooms of marine or
estuarine forms such as the green flagellate Dunaliella
may develop. Many diatoms and other algae are tolerant
to various concentrations of salt in water. Certain species
of the following algae are reported to be remarkably re-
sistant to the presence of chromium (33): Stigeoclonium,
Tetraspora, Closterium, Nitzschia, Navicula, and Euglena.
Carefully controlled bioassay experiments with known
wastes and cultures of algae, followed by additional obser-
vations in polluted streams, should help in obtaining more
accurate information on the toxicity to algae of some
important industrial wastes.
Figure 66.—Trachelomonas hispida.
Figure 67.—Scenedesmus obliquus.
Figure 68.—Pediastrum duplex.
Figure 69.—Chlorogonium euchlorum.
REFERENCES
1. Protein quality of some freshwater algae. H. E. Schlichting, Jr.
Econ. Bot. 25:317-319. 1971.
2. Some problems in large-scale culture of algae. H. W. Milner. Sci.
Monthly 80:15-20. 1955.
3. Can sewage be converted into human food? L. G. Williams. Fur-
man Univ. Faculty Stud. 2 (No. 2):16-24. 1955.
4. Algal culture from laboratory to pilot plant. J. S. Burlew. Carnegie
Inst. Washington Publ. 600. 357 p. 1953.
5. Photosynthetic reclamation of organic wastes. H. B. Cotaas, W. J.
Oswald, and H. F. Ludwig. Sci. Monthly 79:368-379. 1954.
6. Specialized biological treatment opens new possibilities in treat-
ment of industrial wastes. W. B. Hart. Indust. and Eng. Chem.
48:93A-95A. Mar. 1956.
7. Mass culture of algae for food and other organic compounds. R.
W. Krauss. Amer. Jour. Bot. 49:425-435. 1962.
8. Algae and fish relationships. S. Zarnecki. Chapt. 23, in Algae, Man
and the Environment, D. F. Jackson (ed.). Syracuse Univ. Press, p.
459-478. 1968.
9. Lake types and algae distribution. C. W. Prescott. p. 13-33 in his
Algae of the Western Great Lakes Area Exclusive of Desmids and
Diatoms. Cranbrook Inst. Sci., Bloomfield Hills, Michigan, Bull. No.
31, 946 p. 1951.
10. General features of algal growth in sewage oxidation ponds. M. B.
Allen. California State Water Pollution Control Board. Publ. No.
13. 1955.
11. Waste stabilization ponds, use, function, and biota. R. Porges and
K. M. MacKenthun. U.S. Dept. Health, Educ., and Welfare. Taft
San. Eng. Center, Cincinnati, Ohio. (Mimeographed), 40 p. 1963.
12. The algal vegetation of Oslo Fjord. O. Sundene Skr. Norsk. Vid-
ensk. Akad., Norway. No. 2, 244 p. 1953.
13. Treatment and disposal of industrial waste waters. B. A. South-
gate. British Govt. Dept. Sci. and Indust. Res., London, England.
1948.
14. The effect of copperas pollution on plankton. C. C. Davis. No. 2
in his Studies of the Effects of Industrial Pollution in the Lower
Patapsco River Area. Chesapeake Biolog. Lab. Publ. No. 72. June
1948.
15. A new method for determining the pattern of the diatom flora.
Ruth Patrick, M. H. Hohn, and J. H. Wallace. Notulae Naturae,
Acad. Natural Sci. Philadelphia. No. 259, 12 p. July 1954.
16. Okologische Untersuchungen uber des Phytoplankton des Klop-
einersees in Karnten. C. W. Czernin-Chaudinitz. Arch. f. Hydro-
biol. 51:54-97. 1955.
17. The biology of the algae. F. E. Round. Edw. Arnold, Ltd., London,
Eng., 269 p. 1965.
18. Manual of phycology. G. M. Smith (ed.). Cronica Botanica Co.,
Mass., 375 p. 1951.
19. Effects of increased temperatures on aquatic organisms. J. Cairns,
Jr. Indust. Wastes 1:150-152. 1956.
20, Factors effecting the distribution of diatoms. Ruth Patrick. Bot.
Rev. 14:473-524. 1948.
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72
ALGAE AND WATER POLLUTION
21. Studies of snow algae and fungi from the Front Range of Colo-
rado. J. R. Stein and C. C. Amundsen. Canadian Jour. Bot.
45:2033-2045. 1967.
22. Algae of some thermal and mineral waters of Colorado. M. H.
Jones. Univ. Col. Stud. 24:117-119. 1937.
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1971.
24. The algae: a review. G. W. Prescott. Houghton Mifflin Co. 436 p.
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25. Aquatic life in waters polluted by acid mine waste. J. B. Lackey.
Public Health Repts. 54:740-746. 1939.
26. The mineral nutrition of Coccochloris peniocystis. G. C. Gerloff,
C. P. Fitzgerald, and F. Skoog. Amer. Jour. Bot. 37:835-840. 1950.
27. Biological studies of polluted areas in the Genesee River system.
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System. N.Y. State Dept. Conservation, Suppl. to 16th Ann. Rept.
for 1926. 1927.
28. The biological effects of oil pollution in a river. R. N. McCauley.
Limnol. and Oceanog. 11:475-486. 1966.
29. Limnology. Revised ed. P. S. Welch. McGraw-Hill, N.Y. 538 p.
1952.
30. Die Algenflora der Mulde. Ein Beitrag zur Biologie Saprober
Fliisse. H. Schroeder. Pflanzenforschung 21:1-88. 1939.
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32. The effects of distillery wastes and waters on the microscopic
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J. L. Blum. Hydrobiologia 9:361-408. 1957.
TABLE 23. OTHER USES FOR ALGAE IN WATER SUPPLIES
Problem and algae
Atgal group
Problem and algae
Algal group
Algae as water source indicators:
From hard water lake with an outlet:
Blue-green algae
Diatoms
Green flagellates:
Pandorina
Volvox
From hard water lake with no outlet:
Green algae
Blue-green algae
Euglenoids:
Euglena
Phacus
Trachelomonas
Chrysophyta:
Synura uvella
Tribonema
From soft water lake with an outlet:
Desmids
Diatoms
From soft water lake with no outlet:
Green algae
From acid bog lake:
Desmids
Anacystis thermalis f. major
(Chroococcus prescottji)
Batrachospermum
Hapalosiphon pumilus
Microspora
Oedogonium
Scytonema ocellatum
From alkaline bog lake:
Chara
Spirogyra crassa
Spirogyra decemina
Algae as indicators of temperature
range of waters:
Snow and ice algae:
Blue-green
Diatom
Flagellate
Flagellate
Green
Blue-green
Flagellate
Flagellate
Flagellate
Flagellate
Yellow-green
Green
Diatom
Green
Green
Blue-green
Red
Blue-green
Green
Green
Blue-green
Green
Green
Green
Ankistrodesmus
Carteria nivale
Chlamydomonas nivalis
Chlamydomonas sanguinea
Chlamydomonas yellowstonensis
Chlorella
Chodatella brevispina
Chodatella granulosa
Haematococcus pluvialis
Hormidium
Koliella nivalis
Raphidonema
Scotiella cryptophila
Scotiella nivalis
Scotiella polyptera
Stichococcus
Tetraedron valdezi
Trochiscia americana
Very low temperature algae (5°-15°C):
Achnanthes lanceolata
Batrachospermum
Chlamydomonas
Cosmarium pseudobroomei
Cryptomonas erosa
Dactylococcopsis raphidioides
Denticula tenuis
Dinobryon cylindricum
Fragilaria construens
Mallomonas alpina
Rhodomonas lacustris
Synedra acus
Low temperature algae (15°-30°C):
Anacystis cyanea (Microcystis
aeruginosa)
Dactylococcopsis smithii
Lyngbya limnetica
Microspora tumidula
Nitzschia filiformis
Nitzschia linearis
Oedogonium tapeinosporum
Spirogyra
Tribonema bonbycinum
Hot temperature algae (40°-85°C):
Coccochloris (Synechococcus)
Lyngbya contorta var. calida
Mastigocladus laminosus
Onkonema compactum
Onkonema thermale
Oscillatoria filiformis
Phormidium bijahensis
Phormidium cebennense f. thermale
Phormidium geysericola
Phormidium laminosum
Phormidium tenue
Phormidium treleasii
Plectonema notatum var. africanum
Pleurocapsa fluviatilis
Scytonema coactile var. thermale
Synechococcus elongatus f. thermalis
Synechocystis aquatilis
Algae as indicators of high acidity:
Actinella
Anomoeoneis serians
Chlamydomonas
Chromulina ovalis
Cladophora
Closteriopsis
Cryptomonas erosa
Desmidium
Diatoma vulgare
Dinobryon
Euglena adhaerens
Green
Flagellate
Flagellate
Flagellate
Flagellate
Green
Green
Green
Flagellate
Green
Green
Green
Green
Green
Green
Green
Green
Green
Diatom
Red
Flagellate
Desmid
Flagellate
Green
Diatom
Flagellate
Diatom
Flagellate
Flagellate
Diatom
Blue-green
Green
Blue-green
Green
Diatom
Diatom
Green
Green
Yellow-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Blue-green
Diatom
Diatom
Flagellate
Flagellate
Green
Green
Flagellate
Desmid
Diatom
Flagellate
Flagellate
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Additional Uses
73
Problem and algae
Algal group
Problem and algae
Algal group
Euglena hiemalis Flagellate
Euglena mutabilis Flagellate
Euglena stellata Flagellate
Euglena tatrica Flagellate
Euglena viridis Flagellate
Eunotia exigua Diatom
Eunotia lunaris Diatom
Eunotia pectinalis var. minor Diatom
Eunotia robusta Diatom
Eunotia tautonensis Diatom
Eunotia tenella Diatom
Eunotia trinacria Diatom
Frustulia megaliesmontana Diatom
Frustulia rhomboides var. saxonica Diatom
Lepocinclis ovum Flagellate
Mougeotia Green
Navicula bryophila Diatom
Navicula minima var. atomoides Diatom
Navicula roteana Diatom
Navicula subatomoides Diatom
Navicula subtilissima Diatom
Navicula viridis Diatom
Ochromonas Flagellate
Penium cucurbitinum Desmid
Phaeothamnion Yellow-green
Pinnularia acoricola Diatom
Pinnulana subcapitata var. hilseana Diatom
Pinnularia viridis var. sudetica Diatom
Stauroneis anceps Diatom
Tabellaria flocculosa Diatom
Ulothrix zonata Green
Vanheurckia rhomboides
var. crassenervia Diatom
Xanthidium antilopaeum Desmid
Algae indicating progress of change in sewage
oxidation ponds:
Chlamydomonas Flagellate
Chlorella Green
Scenedesmus Green
Algae as indicators of marine and
estuarine pollution:
Acrochaetium thuretii Red
Acrochaetium virgatulum Red
Actinastrum hantzschii Diatom
Calothrix confervicola Blue-green
Chlorella variegata Green
Enteromorpha intestinalis Green
Enteromorpha prolifera Green
Erythrotrichia carnea Red
Porphyra leucosticta Red
Spirulina subsalsa Blue-green
Ulva lactuca Green
Ulva latissima Green
Algae indicating industrial wastes:
Distillery wastes:
Chlamydobotrys Flagellate
Chlorobrachis gracillima Flagellate
Chlorogonium euchlorum Flagellate
Oil:
Amphora ovalis Diatom
Ankistrodesmus Green
Asterionella Diatom
Chlamydomonas Flagellate
Closterium Desmid
Cyclotella Diatom
Diatoma vulgare Diatom
Euglena Flagellate
Fragilaria Diatom
Gomphonema herculaneum Diatom
Gonium Flagellate
Lyngbya Blue-green
Melosira varians Diatom
Meridion Diatom
Navicula radiosa Diatom
Oscillatoria
Scenedesmus
Surirella molleriana
Synedra acus
Synedra ulna
Tabellaria
Trachelomonas
Hydrogen sulfide:
Achnanthes affinis
Calonels amphisbaena
Camphlodiscus
Cyclotella memeghiniana
Cymbella ventricosa
Hantzschia amphioxys
Navicula minima
Neidium bisulcatum
Nitzschia ignorata
Nitzschia palea
Nitzschia tryblionella var. debilis
Surirella ovata var. salina
Iron:
Anomoeoneis serians var. brachysira
Chlorella variegata
Chromulina
Eunotia
Gomphonema acuminatum
Pinnularia microstauron
Pinnularia subcapitata var. hilseana
Stauroneis phoenicenteron
Stenopterobia intermedia
Surirella delicatissima
Surirella linearis
Trachelomonas hispida
Chromium:
Closterium acerosum
Euglena acus
Euglena oxyuris
Euglena sociabilis
Euglena stellata
Euglena viridis
Navicula atomus
Navicula cuspidata
Nitzschia linearis
Nitzschia palea
Stigeoclonium tenue
Tetraspora
Salt brine (principally NaCI):
Achnanthidium brevipes var. intermedia
Actinastrum hantzschii
Amphiprora paludosa
Amphora coffeiformis
Amphora ovalis
Anacystis
Calothrix
Chaetoceros elmorei
Chaetomorpha
Chlamydomonas ehrenbergii
Coccochloris elabens
(Aphanothece halophytica)
Cyclotella meneghiniana
Cymbella lacustris
Cymbella ventricosa
Diatoma elongatum
Diploneis eliptica
Dunaliella salina
Enteromorpha intestinalis
Enteromorpha prolifera
Entophysalis deusta
(Aphanocapsa littoralis)
Euglena
Eunotia
Frustulia rhomboides var. saxonica
Gomphonema
Gyrosigma attenuatum
Blue-green
Green
Diatom
Diatom
Diatom
Diatom
Flagellate
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Green
Flagellate
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Flagellate
Desmid
Flagellate
Flagellate
Flagellate
Flagellate
Flagellate
Diatom
Diatom
Diatom
Diatom
Green
Green
Diatom
Green
Diatom
Diatom
Diatom
Blue-green
Blue-green
Diatom
Green
Flagellate
Blue-green
Diatom
Diatom
Diatom
Diatom
Diatom
Flagellate
Green
Green
Flagellate
Flagellate
Diatom
Diatom
Diatom
Diatom
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74
ALGAE AND WATER POLLUTION
Problem and algae
Algal group
Problem and algae
Algal group
Hantzschia elongata
Lyngbya aestuarii
Melosira arenaria
Meridion circulare
Microcoleus chthonoplastes
Navicula anglica
Navicula cincta var. heufleri
Navicula cryptocephala
Navicula gregaria
Navicula longirostris
Navivula minuscula
Navicula pygmaea
Navicula salinarum
Navicula subtilissima
Nitzschia apiculata
Nitzschia epithemoides
Nitzschia frustulum
Nitzschia palea
Oscillatoria
Pediastrum simplex
Pinnularia
Phormidium tenue
Scenedesmus bijugatus
Scoleopleura peisonis
Spirulina subsalsa
Stephanoptera gracilis
Synedra acus
Synedra affinis
Synedra pulchella
Trachelomonas
Trichodesmium
Ulothrix
Copper:
Achnanthes affinis
Asterionella formosa
Calothrix braunii
Chlorococcum botryoides
Cymbella naviculiformis
Cymbella ventricosa
Navicula viridula
Neidium bisulcatum
Diatom
Blue-Green
Diatom
Diatom
Blue-green
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Blue-green
Green
Diatom
Blue-green
Green
Diatom
Blue-green
Flagellate
Diatom
Diatom
Diatom
Flagellate
Blue-green
Green
Diatom
Diatom
Blue-green
Green
Diatom
Diatom
Diatom
Diatom
Nitzschia palea
Scenedesmus obliquus
Stigeoclomum tenue
Symploca erecta
Paper mill wastes:
Amphora ovalis
Caloneis amphisbaena
Cocconeis diminuta
Cocconeis pediculus
Cymatopleura solea
Cymbella ventricosa
Diatoma vulgare
Gomphonema herculaneum
Navicula cryptocephala
Navicula radiosa
Oscillatoria
Pandorina
Pediastrum
Scenedesmus
Spondylomorum
Surirella ovata
Surirella ovata var. salina
Synedra pulchella
Synedra ulna
Ulothrix
Phenolic wastes:
Achnanthes affinis
Ceratoneis arcus
Cocconeis placentula
Cyclotella kutzingiana
Cymatopleura solea
Cymbella naviculiformis
Diatoma vulgare
Fragilaria virescens
Gomphonema parvulum
Navicula cryptocephala
Neidium bisulcatum
Nitzschia palea
Pinnularia borealis
Surirella ovata
Synedra ulna
Diatom
Green
Green
Blue-green
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Blue-green
Flagellate
Green
Green
Flagellate
Diatom
Diatom
Diatom
Diatom
Green
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
Diatom
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CHAPTER XVII
PROCEDURES FOR ENUMERATION OF ALGAE IN WATER
It is necessary to know the purpose for which any
algological investigation is to be made before a particular
analytic procedure is selected. In some instances there
may be need to designate only certain groups or genera
or species of algae. This might be the case when analyz-
ing samples from oxidation ponds to determine the prog-
ress of sewage change or when analyzing stream samples
to determine whether indicator algae or certain taste and
odor producing algae are present. In other situations a
knowledge of the number as well as the general groups
of algae may be required. This might be needed to deter-
mine the most effective time for treating a reservoir with
an algicide. The total area or volume, particularly of the
diatoms, would be useful data for determining the rela-
tionship of plankton to the length of filter runs.
At many treatment plants using surface water supplies,
adequate procedures include periodic inspections of the
raw water supply, the treatment plant, and the distribution
system for attached growths and for floating mats and
blooms. This should be followed by laboratory examina-
tions and recording of the dominant organisms present
in these visible growths of algae. In addition plankton
analyses of water samples from these same areas should
be made at regular intervals. Information of this sort,
especially when taken over a period of time and when
supplemented by adequate physicochemical data, is very
valuable in determining the type and application time of
measures necessary for the prevention and control of prob-
lems brought about by algae.
No method has yet been widely accepted as being
accurate for determining and reporting the number or
volume of attached algae or of those in floating mats.
Observations can be recorded as notes or indicated on
an outline map to designate the location and the extent
of the areas of algal growths. Changes in location and
amount can then be followed by comparing the notes or
map records for different dates. Identification of the algae
can be accomplished with the aid of a microscope and a
key such as is included in the appendix.
In the recording of plankton algae (1) the common
procedure begins with the collection of a water sample
from a designated location and depth. If the sample is
not to be taken immediately to the laboratory for analysis,
it is preserved by the addition of formaldehyde. Refrigera-
tion is often satisfactory for one- or two-day preservation.
The plankton in the sample are then concentrated by
means of a centrifuge or a Sedgwick-Rafter sand filter.
The writer has found a simple procedure to be the addi-
tion of a polyacrylamide gel to a small portion of the
sample to absorb some of the water and leave the algae
concentrated in the remainder of the sample. Using the
concentrate, 1 ml is placed in a Sedgwick-Rafter counting
cell and enumeration of the organisms is made with the
aid of a compound microscope fitted with a Whipple
ocular micrometer. The magnification commonly used is
100X, which is obtained by means of a 10X ocular and a
10X objective. With microscopes suitable for this type of
analysis, the field of view, as delimited by the ocular mi-
crometer, can be adjusted to cover 0.001 ml of the con-
centrate. The plankton organisms appearing in 10 fields
are counted and, from their total, the number of organ-
isms per milliliter, liter, or gallon of the unconcentrated
water sample can be calculated (2). Instead of separate
fields, one or more strips may be counted crosswise or
lengthwise of the plankton cell, the total area determined,
and the numbers per mm extrapolated from this.
Quantitative records for each genus or species may be
reported separately as well as the totals for the major
groups of algae. The enumeration may be in number of
cells, number of clumps (isolated cells plus colonies),
areal standard units, or cubic standard units. Several varia-
tions of the clump count method are in use. No single
method of enumeration has been selected as a standard
procedure to be followed by water treatment laboratories.
However, the clump count procedure is probably the
simplest method and also the basic one, since the others
are often derived from it by extrapolation.
The low magnification of 100X commonly used in count-
ing plankton, together with the loss of significant numbers
of algae during preservation and concentration of the
samples, results in plankton values lower than those actu-
ally present. It has been estimated that many waters con-
tain a larger volume of minute nannoplankton than of the
larger forms readily visible under low magnification. In
one experiment the use of a nannoplankton counting slide
(fig. 70) gave an average clump count of 3,055 algae/ml,
while the count with the Sedgwick-Rafter slide was only
1,165 (3). When samples from four different water sources
were used, the count obtained using the nannoplankton
slide was significantly higher in each case than that derived
by the Sedgwick-Rafter slide because the latter's lower
magnification missed many small algae.
A number of pigmented flagellates and diatoms are so
small that the very high magnification of an oil immersion
objective lens is required for their identification and enu-
meration. Even the nannoplankton slide cannot be used
with the oil immersion lens because of its very short focal
length. However, if a drop of known volume of the con-
75
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76
ALGAE AND WATER POLLUTION
centrate is placed on a standard microscope slide and
covered with a No. 1 cover glass so that the drop spreads
out to occupy the area beneath it, the organisms can be
counted for a known portion of this area using the oil
immersion lens, and an extrapolation may then be made
to indicate the number per milliliter (4).
Special care may have to be taken to obtain accurate
records of some of the algal flagellates that are taste and
odor producers or that may be indicators of clean water.
When preserved in formalin, they may be changed to such
an extent that they are difficult to identify (4). They be-
come distorted in form or altered in color, and the flagella
are lost. This is true particularly of Cryptomonas, Chroo-
monas, Rhodomonas, Chromulina, Synura, Uroglenopsis,
Eudorina, Mallomonas, and Merotrichia. Even Euglena may
be so distorted as to prevent its identification as to species.
Unpreserved samples may be required, therefore, when
accurate records of these sensitive algae are needed.
If there is special reason for enumerating all kinds and
sizes of plankton in a water supply, the usual procedures
may have to be modified. For the larger forms (meso-
plankton), a 100-1 water sample is passed through a silk
bolting cloth net, size 25, which has 200 meshes to the
linear inch and apertures 30-40 microns wide. The orga-
nisms caught by the net are then washed into 5 percent
formalin with a final volume of 100 ml. This would give
a concentration of 1,000 to 1, which might be too high and
need dilution for easier counting. Enumeration may be
accomplished using a 1-ml sample in a Sedgwick-Rafter
slide having a magnification of 25X. The count should be
limited to organisms 30 microns or more in width or di-
ameter, principally the ciliates, Crustacea, and other animal
forms rather than algae. Extrapolation depends on the
actual sample concentration used.
The smaller forms of plankton can be obtained in num-
bers sufficient for counting by using the Foerst centrifuge
for concentrating the sample. At a speed in excess of
15,000 rpm, the 500 ml are centrifuged at a flow that per-
mits completion in 3 minutes. The concentrate can then
be washed into a bottle and the volume brought up to
20 ml. This gives a concentration of 25-1, which may have
to be reduced if the algae are found to be too numerous
per field under the microscope.
Enumeration of the organisms in the concentrate is first
made using the common procedure, employing a Sedg-
wick-Rafter slide under a magnification of 100X. A concen-
tration providing from 10 to 100 organisms per micro-
scopic field tends to reduce the counting error, providing
the range in width or diameter of the organisms is 5 to 30
microns (microplankton). The forms that are 1 to 5 microns
in width or diameter (nannoplankton) can be enumerated
with much greater precision by using a counting slide
which permits a magnification of 430X. Some specialized
work may require a magnification of approximately 1,OOOX.
The combined results of the three procedures are then
summarized as follows: net (meso-) plankton, no. per 100
ml; microplankton, no. per ml; and nannoplankton, no.
per ml. A typical form for use in recording the results of
the analysis for plankton algae is shown in figure 71.
The interpretation of plankton records has seldom been
based on a predetermined set of criteria, but there are
a number of aids Which at least have a limited or localized
use. For example, a water source for which the environ-
mental factors are not too variable from year to year
Figure 70.—Nannoplankton counting slide.
ALGAL PLANKTON RECORD
Locality Station No Collected 19__ Hr__
Type of analysis (Meso-, Micro-, Nanno-)
Organisms
(Diatoms)
(Greens)
(Blue-Greens)
(Pigrnented flagellates)
Total algae
Unpigmented forms
Total organisms
Pseudoplankton
Grand total
Number per field
—
Total
No. per
Information by Collector:
Collected by
Depth
Volume of sample
Preservative (kind and amt.) _
Weather
Visible algal growths
Water temp pH
Turbidity
Raw water odor
Threshold No. Raw
Finished
Length of filter run
Information by Examiner:
1. Analyzed by
2. Date ---
3. Method of concentration —
4. Amt. of water concentrated.
5. Amt. of concentrate —
6. Concentration
7. Type of counting cell
8. Magnification used
Area of microscopic field—
Factor for No. per ml.
9.
10.
11. Interpretation of results.
12. Treatment recommended--.
Figure 71.—Typical form of algal plankton record.
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Procedures for Enumeration
77
would tend to produce similar amounts of algal growth
each year. Experience indicates that this constitutes a use-
ful working basis. Pearsall et al. (5) make the following
statement: "We should expect, on this basis, that each
year we might get algal growth that would tend to consist
of a similar number of cell divisions in succession, to show
a similar rate of growth and to yield a similar maximum
number. It is clear that the possibility of forecasting de-
pends largely upon this being approximately correct, as
it appears to be." Thus, the plankton records of the pre-
vious years may give good clues as to particular times
during each season when large numbers or particular types
of interference organisms are likely to appear.
Pearsall et al. emphasize in addition that the form and
structure of particular plankton are indicative of whether
their numbers will increase or decrease. They state that
"populations of algae that are not growing or that are
approaching their numerical maximum tend to show cer-
tain changes in appearance. When these changes can
easily be recognized, they afford useful indications of the
end of a period of algal growth. This is often extremely
useful when the question arises of whether or not to apply
treatment."
In some areas the plankton count of the raw water has
been correlated with the threshold odor test, and in one
state the plankton count of the raw water has been sug-
gested as a means of predicting the probable plankton
count of the finished water following coagulation and
rapid sand filtration (6).
The number of organisms and the number of areal stan-
dard units of organisms have been used to determine the
amount of trouble to be expected and the time when
treatment should begin. Thus, Whipple (7) stated that
"when organisms were less than 500 per cc they would
cause no trouble; between 500 to 1,000 per cc little
trouble; between 1,000 and 2,000 noticeable trouble;
between 2,000 and 3,000 decided trouble; and above
3,000 trouble would be serious."
At one treatment plant where lake water was being used,
the length of the filter run was found to be reduced rap-
idly when areal standard units of algae increased from 50
to about 300. When the areal standard units of algae
totaled 50 the probable run was 70 hr; with 100 areal
units, the filter run dropped to 35 hr; with 200 units, 18
hr; with 400 units, 11 hr; and with 1,000 units, 6 hr.
A diatometer has been described for sampling the dia-
tom population of streams (8). By enumerating and identi-
fying up to 8,000 or more diatom specimens obtained from
the diatometer, it is possible through statistical analysis to
determine the frequency distribution and to construct a
truncated normal curve for the sample. The height and
position of the mode, shape of the curve, number of
frequency intervals, number of observed species, number
of species in the theoretical universe, and number of speci-
mens required for construction of the curve are reported
to be important in evaluating the data for indications of
water pollution. Thus, when the water is relatively free
of pollution, the number of species in the mode is high
(generally between 20 and 28), the mode is located be-
tween the second and fourth intervals, the curve covers
only 10 or 11 intervals, the number of observed species
is generally between 120 and 180, the theoretical universe
contains from 150 to 210 species, and the number of speci-
mens required for the count is low (approximately 8,000).
In stream segments affected by pollution the number
of species in the mode, the number of observed species,
and the number in the theoretical universe will all be
reduced in varying amounts corresponding to the degree
of pollution.
In stream segments slightly enriched by nontoxic or-
ganic materials, the height of the mode remains about
the same as that for the clean water station but the curve
extends to the right as a "tail." If pollution increases or
toxic materials are also present, the height of the mode
will decrease, the tail will usually extend still farther, the
curve may cover as many as 14 to 16 intervals, and up to
40,000 specimens must be counted before the mode is
evident. Because diatoms can be obtained in large num-
bers in surface waters, this type of statistical analysis can
be made. This and other procedures for detection of pol-
lution are described in the chapter on Algae as Indicators
of Water Quality.
In summary, it is evident that of the many procedures
that can be used for listing and counting algae, it is neces-
sary to select those that will produce the amount and kind
of information needed for satisfactory treatment and use
of each particular water supply. In addition to Standard
Methods (1), other major references are Biological Field
and Laboratory Methods (9) and Handbook of Phycological
Methods (10).
REFERENCES
1. Biological examination of water. Part 1000 in Standard Methods
for the Examination of Water and Wastewater. Ed. 14. Amer.
Public Health Assn., Washington, D.C. 1975.
2. Simplified procedures for collecting, examining and recording
plankton in water. W. M. Ingram and C. M. Palmer. Jour. Amer.
Water Wks. Assn. 44:617-624. 1952.
3. A new counting slide for nannoplankton. C. M. Palmer and T. E.
Maloney. Amer. Soc. Limnol. and Oceanog., Special Publ. No. 21,
6 p. 1954.
4. The manipulation and counting of river plankton and changes in
some organisms due to formalin preservation. J. B. Lackey. Public
Health Repts. 53:2080-2093. 1938.
5. Freshwater biology and water supply in Britain. W. H. Pearsall,
A. C. Gardiner, and F. Creenshields. Freshwater Biolog. Assn. of
the British Empire, Sci. Publ. No. 11, 90 p. 1946.
6. Numerical rating of water supplies. Section 14, Table 1416, in
Manual of Water Supply Sanitation. Minnesota Dept. Health, Min-
neapolis, Minn. 1941.
7. Records of examination. C. C. Whipple, C. M. Fair, and M. C.
Whipple. Chapt. 6 in The Microscopy of Drinking Water. Ed. 4.
J. Wiley and Sons, N.Y. 1948.
8. A new method for determining the pattern of the diatom flora.
Ruth Patrick, M. H. Hohn, and J. H. Wallace. Notulae Naturae,
Acad. Natural Sci. Philadelphia. No. 259. 12 p. July 1954.
9. Biological field and laboratory methods for measuring the quality
of surface waters and effluents. C. I. Weber. U.S. Environmental
Protection Agency, Cincinnati, Ohio. EPA Report No. 670/4-73-001.
187 p. 1973.
10. Handbook of phycological methods. J. R. Stein. Cambridge Univ.
Press. 448 p. 1973.
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CHAPTER XVIII
CONTROL OF ALGAE
It is better to anticipate and prevent problems caused
by algae than to delay until they become serious. Effective
control of algal growth requires adequate records as to
the numbers, kinds, and locations of algae in the water
supply.
Control of algae applies to the raw water supply, to
the treatment plant, and to the distribution system. The
use of algicides will be considered in more detail under
raw water applications, although similar procedures may
sometimes be applied in the other two control areas.
CONTROL IN RAW WATER SUPPLIES
The application of an algicide is frequently carried out
to prevent or destroy the excessive growths of algae which
occur as blooms, mats, or as marginal growths represent-
ing high concentrations of plankton. However, the algicide
may sometimes be applied to control relatively low con-
centrations of certain algae such as Synura and Uroglen-
opsis, which may cause trouble even in small numbers.
Copper sulfate is the only algicide in common use on
water supplies at present, although chlorine may serve as
an algicide as well as a bactericide or an oxidizing agent.
The blue stone or copper sulfate, toxic to many algae at
comparatively low concentrations, is ordinarily non-lethal
to fish at the strengths recommended and is relatively in-
expensive. However, in alkaline water it precipitates quickly
as copper carbonate and more slowly as copper hydrate,
and in such instances it is considered to be effective as
an algicide for only a short time following its application.
Bartsch (1) emphasizes that the dosage should be depen-
dent upon the alkalinity of the water and states that the
following rule has been used successfully in various mid-
western lakes: If the methyl orange alkalinity is less than
50 ppm the rate should be 5.4 Ib/acre. In the waters with
a high alkalinity the dosage is not dependent upon depth
since precipitation would make it ineffective below the
surface.
The various genera and species of algae are not all alike
in their reaction to copper sulfate, and this factor has
frequently been neglected in determining the concentra-
tion of the algicide to be applied. A number of the very
minute planktonic green algae are very resistant to the
toxic effects of blue stone. The stonewarts, Chara and
Nitella, are also considered to be resistant as are a few of
the green flagellates and some of the filamentous blue-
green algae. The diatoms as a group are relatively suscep-
tible, but they have often developed in large numbers
following the destruction of other algae through treatment
with copper sulfate.
Fortunately a considerable number of the taste and odor
and filter clogging algae are very susceptible to low con-
centrations of this algicide. All of the following interfer-
ence algae are normally considered to be very susceptible
to copper sulfate: Asterionella, Fragilaria, Spirogyra, Dino-
bryon, Synura, Anabaena, and Anacystis (Microcystis). A
more complete list of the genera of algae grouped accord-
ing to their reported susceptibility to the toxic effect of
copper sulfate is given in table 24.
The lowest concentration of copper sulfate which is
toxic for a particular alga also varies according to the
abundance of the alga, the temperature of the water, the
alkalinity of the water, the amount of organic material in
the water, and other factors. Thus, the listing of a specific
concentration of an algicide as the minimum effective dos-
age is not reliable unless these other factors have first been
taken into consideration. In table 24, therefore, the group-
ing of the algae is by very general ranges in the dosage
required for treatment. The information used in prepar-
ing table 24 was obtained from several sources, including
Hale (2), Cox (3), Prescott (4), Maloney and Palmer (5),
Pearsall et al. (6), Matheson (7), Taft (8), Smith (9), Snow
(10), Huff and House (11), and Moore and Kellerman (12).
A number of chemical compounds are algicidal. The
most promising of these include the inorganic salts (copper
sulfate, potassium permanganate), chlorine and its com-
pounds, and organic compounds such as rosin amines,
antibiotics, quinones, substituted hydrocarbons, quater-
nary ammonium compounds, amide derivatives, and phe-
nols (13). The chemicals, to be selected as satisfactory for
use in domestic water supplies, will have to be not only
economically feasible but also nontoxic to animal life and
to plants other than algae. Algicides should be used only
where careful plankton records are kept, which would
permit early localized treatment to prevent undesirable
species of algae from increasing in number. Algicides
which are selectively toxic to the algae which produce
tastes and odors, mats or blankets, blooms, slimes, and
other undesirable conditions, and clog filters would be
particularly valuable (figs. 72a and 72b).
A pretreatment basin may simplify the control of algae
and algal odors when the raw water has a high algal pro-
ductivity. The algicide is released continuously into the
water as it enters the basin. Cement baffles installed in
the basin and arranged alternately from the two sides
force the water to flow zig-zag through the basin before
reaching the outlets. For one supply in Wisconsin where
78
-------
Control
79
Figure 72a.—Experimental testing of a potential algicide: Applying the
algicide to a blanket of algae.
Figure 72b.—Experimental testing of a potential algicide: Result of the
test: Blanket of algae has disappeared.
this procedure has been in use, the algal population is
consistently and radically reduced. The threshold odor
number has also been reduced an average of 67 percent
(14).
Continuous treatment with copper sulfate of Croton
Lake Reservoir in New York was established in 1925. The
copper sulfate dosage over a period of almost 20 years
averaged 0.18 mg/l and the overall reduction of plankton
for this period was 65 percent (15).
A number of methods other than algicidal are in use
for the control of algae in raw water supplies. An increase
in turbidity due to silt will tend to reduce the phyto-
plankton population by limiting the penetration of light
that is essential for the growth of algae. Thus, in shallow
reservoirs fish which stir up the bottom mud and make
the water turbid will aid in controlling plankton popula-
tions. A turbidity of 100 ppm in rivers may be sufficient
to cause plankton algae to disappear but they quickly
reappear as the turbidity decreases (16).
Attached algae and water weeds can become a prob-
lem in the shallow margins of lakes and reservoirs. When
sodium arsenite cannot be employed, these forms are
often difficult to control (17). The common procedure is
to cut them or pull them out. One Connecticut utility
riprapped the shore of the reservoir in an attempt to
eliminate their growth.
Mechanical removal of algae may be the simplest way
to dispose of massive growths which become detached
and washed ashore or collect in localized areas of the
reservoir. This is of particular importance when the reser-
voir or lake is used for recreational purposes as well as
for domestic water supply. Reduction in the amount of
plankton algae in a lake has been attempted by passage
of the water through a rapid sand filter, the filtered water
being returned to the lake (18). The backwash containing
the algae collected by the filter can be used as a land
fertilizer or disposed of in a lagoon.
For new reservoirs, clearing the site of vegetation and
organic debris before filling will reduce the nutrients that
otherwise would be present to stimulate algal growths.
For all water supply reservoirs, provisions should be put
into effect as early as possible for keeping the inflow of
nutrients to a minimum. These would include measures
for reducing the runoff from agricultural land and the
selection of a supply as free as possible of upstream sew-
age effluents and other organic wastes.
When a reservoir receives its water from a stream there
is a period of time after which the stream plankton dies
out in the reservoir and before the reservoir plankton has
had time to develop. The ideal period of storage, as far
as water with a low plankton count is concerned, may
therefore be between 10 and 14 days rather than the
longer period of 28 to 30 days often recommended in the
past. It is not usually possible, of course, for the capacity
of the reservoir to be governed by this consideration (19).
The particular position and depth of the raw water sup-
ply intake in a reservoir or lake often predetermines the
quality of the water which will enter the treatment plant.
In order to ascertain the optimum position and depth for
the intake, a knowledge of the biological as well as the
chemical and physical characteristics of the water at vari-
ous locations is required. For one water supply in Europe,
3 years of investigating plankton and water temperature
indicated that a depth of 60 m was to be recommended
for the intake. This depth was below the area of greatest
density of plankton and below the autumn thermocline
and the strata of greatest decomposition and mineraliza-
tion of organic matter. No important improvement in
quality of water would have been obtained by placing
the intake at a greater depth (20).
RECREATIONAL WATERS AND FISH PONDS
Control of algae in recreational waters and fish ponds
depends upon the types and location of the algae. Plank-
tonic forms can be treated as in reservoirs with copper
sulfate or other algicides. Attached algae, especially fila-
mentous forms, are often hard to control. Pithophora is a
common and abundant branching filamentous form in the
-------
80
ALGAE AND WATER POLLUTION
warm waters of farm fish ponds in southern states. The
algicide rosin amine D acetate (RADA) has been found
effective in controlling Pithophora (21) and the attached
filamentous alga Ulothrix present in cooler waters in the
northern states (22). Cladophora, especially in the Great
Lakes, can be difficult or impossible to control. In areas
of limited water supply temporary control has been ef-
fected by the use of chlorophenyl dimethyl urea (23). In
irrigation waters many algicides cannot be used since they
are also toxic to crop plants. Cladophora is one of the
most abundant of the attached algae in the irrigation ca-
nals. A mechanical method of dragging a chain through
the canal has frequently been used to dislodge filamentous
algae and other water weeds (24).
CONTROL IN TREATMENT PLANTS
Control of algae in the water treatment plant involves
primarily the processes of coagulation, sedimentation, and
filtration. Well regulated coagulation with sedimentation
will often remove up to 90 percent of the algae, and in
some cases 95-96 percent removal has been reported. A
similar percentage of removal may occur in a rapid sand
filter that is run efficiently. Assuming 90 percent removal
by each of the two processes, 1,000 algae/ml in raw water
would be reduced to 100 by coagulation and to 10 by filtra-
tion. However, if the removal was only 70 percent in each
case, the treated water would still contain 90 algae/ml.
The percentage removal by coagulation tends to be low
when the number of algae in the raw water is low, but
the efficiency of the process can be improved through
the use of a coagulant aid such as activated silica.
Treatment with chlorine is often carried out in the plant
primarily to destroy pathogenic organisms, but the dos-
ages commonly used are sufficiently high to be toxic also
to many algae. However, dead as well as living organisms
can cause tastes and odors and clog filters. Coagulation
of motile algae such as Euglena may be improved by pre-
chlorination. When plain sedimentation is used, prechlori-
nation will kill many of the algae and facilitate their set-
tling out, since their motility is stopped and their buoyancy
due to oxygen production in photosynthesis is reduced.
A process known as micro-straining is being used in
some treatment plants, particularly in England. This in-
volves the passing of the water through a finely woven
fabric of stainless steel. The size of the openings of the
mesh determines the size of the plankton organisms re-
moved from the water. The micro-strainer is usually in
the form of a partially submerged drum. While it revolves,
that portion exposed to air is backwashed with jets of
water (25).
The use of absorbents such as activated charcoal may
be required to remove tastes and odors or other algal
products from water in the treatment plant as was de-
scribed in chapter XIII.
Growths sometimes develop to such an extent that the
treatment basin has to be emptied of water and the walls
then scraped free of algae. This may also be done for
swimming pools when the walls and steps would be
cleared of algae using a wire brush. Removing the slip-
pery surface growth makes the pool safer and improves
its appearance.
CONTROL IN DISTRIBUTION SYSTEMS
Control of algae in the distribution system is generally
limited to the use of algicides in open reservoirs contain-
ing treated water. A permanent control would involve
covering the reservoir to exclude light in order to prevent
the algae from developing. Where covering is considered
too costly, chlorine or copper sulfate is required at least
during the warmer months. When the former is used
certain chlorine-resistant algae sometimes tend to become
predominant. One of these is a minute desmid belonging
to the genus Cosmarium. Most of the algae in the distri-
bution system either develop in the exposed reservoirs or
are transient organisms remaining in the water after its
passage through the treatment plant. The majority of the
organisms capable of multiplying in the pipes of the dis-
tribution system are not algae but are heterotrophic forms
represented by various bacteria, fungi, protozoa, worms,
copepods, and other small aquatic animals.
SUMMARY OF CONTROL METHODS
Control of algae in water supplies may thus involve the
use of algicides; the mechanical cleaning of settling basins,
filters, intake channels, and reservoir margins; the modi-
fication of coagulation, filtration, chemical treatment, or
location of the raw water intake; and, finally, the modifica-
tion of the reservoir to reduce the opportunities for mas-
sive growths. Control of tastes, odors, and other algal
products involves additional procedures such as the use
of absorbents and the removal of organic deposits from
settling basins and distribution lines. Effective control of
algae is dependent upon adequate procedures for detect-
ing their presence and interpreting the significance of any
change in their numbers and kinds.
REFERENCES
1. Practical methods for control of algae and water weeds. A. F.
Bartsch. Public Health Repts. 69:749-757. 1954.
2. The use of copper sulphate in control of microscopic organisms.
F. E. Hale. Phelps Dodge Refining Corp., N.Y. 1950.
3. Water supply control. C. R. Cox. N.Y. State Dept. Health, Bur.
Environmental San., Bull. 22, 279 p. 1952.
4. Objectionable algae and their control in lakes and reservoirs. C.
W. Prescott. Louisiana Municipal Rev. 1, Nos. 2 and 3. 1938.
5. Toxicity of six chemical compounds to thirty cultures of algae.
T. E. Maloney and C. M. Palmer. Water and Sewage Wks. 103:509-
513. 1956.
6. Freshwater biology and water supply in Britain. W. H. Pearsall,
A. C. Gardiner, and F. Creenshields. Freshwater Biolog. Assn. of
the British Empire, Sci. Publ. No. 11, 90 p. 1946.
7. The effects of algae in water supplies. D. H. Matheson. Inter-
national Water Supply Assn., General Rept. to 2d Congress, Paris,
France. 82 p. 1952.
8. Water and algae—world problems. C. E. Taft. Educational Pub-
lishers, Inc., Chicago, III. 236 p. 1965.
9. Ecology of the plankton algae in the Palisades Interstate Park, in-
cluding the relation of control methods to fish culture. G. M.
Smith. Roosevelt Wildlife Bull. 2(2):93-195. 1924.
10. The most troublesome algae in New England waters. E. A. Snow,
Jr. Jour. New England Water Wks. Assn. 72:328-331. 1958.
11. Copper sulfate treatment of St. Paul, Minnesota water supply. N.
L Huff and G. D. House. Jour. Amer. Water Wks. Assn. 3:581-621.
1916.
-------
Control
81
12. A method of destroying or preventing the growth of algae and
certain pathogenic bacteria in water supplies. G. T. Moore and
K. F. Kellerman. U.S. Dept. Agr., Bur. Plant Indus. Bull. No. 64.
44 p. 1904.
13. Evaluation of new algicides for water supply purposes. C. M. Pal-
mer. Jour. Amer. Water Wks. Assn. 48:1133-1137. 1956.
14. Pre-treatment basin for algae removal. A. J. Marx. Taste and Odor
Control Jour. 17 (No. 6): 1-8. 1951.
15. Methods of controlling aquatic growths in reservoirs. B. C. Nesin
and R. L. Derby. Jour. Amer. Water Wks. Assn. 46:1141-1158. 1954.
16. Plankton ecology of the Licking River, Ky. J. B. Lackey. U.S. Public
Health Service, San. Eng. Div., Water and Sanitation Investig.,
Cincinnati, Ohio. 14 p. (Mimeographed.) 1942.
17. A study in the chemical control of aquatic vegetation. M. M. Bos-
chetti. Sanitalk 5 (No. 2):21-25. 1957.
18. Control of algae, a means of prolonging the life of lakes. H. C.
Leibee and R. L. Smith. Wastes Eng. 24:620-621. 1953.
19. The reservoirs of the Metropolitan Water Board and their influence
upon the character of the stored water. E. W. Taylor. Proc. Inter-
national Assn. Theoretical and Appl. Limnol. 12:48-65. 1955.
20. The limnological conditions for a large water-supply intake on the
Uberlinger Lake (Lake Constance). R. Muckle. Gas-u Wasserfach
97:213-222. 1956.
21. Control of a branched alga, Pithophora, in farm fish ponds. J. M.
Lawrence. Prog. Fish Culturists. 16(2):83-87. 1954.
22. Control of Ulothnx zonata in circular ponds. L. D. Johnson. Prog.
Fish Culturist 17 (3):126-128. 1955.
23. Control of algae with chlorophenyl dimethyl urea. T. E. Maloney.
Jour. Amer. Water Wks. Assn. 50:417-422. 1958.
24. A study of the algae of irrigation waters. J. D. Wien. Second
Ann. Progress Rept. 26 p. 1959. Arizona State Univ., Tempe, Ariz.
25. Micro-straining. P. L. Boucher. Jour. Institution Water Engrs.
9:561-595. 1955.
TABLE 24. RELATIVE TOXICITY OF COPPER SULFATE TO ALGAE
Group
Green
Diatoms
Flagellates
Very susceptible
Susceptible
Resistant
Very resistant
Blue-green
Anabaena, Anacystis,
Aphanizomenon, Gom-
phosphaeria, Rivularia
Cylindrospermum,
Oscillatoria, Plectonema
Lyngbya, Nostoc,
Phormidium
Calothrix,
Symploca
Hydrodictyon, Oedo-
gonium, Rhizoclonium,
Spirogyra, Ulothrix
Asterionella, Cyclotella,
Fragilaria, Melosira
Dinobryon, Synura,
Uroglenopsis, Volvox
Botryococcus, Cladophora,
Oscillatoria
Enteromorpha, Gloeo-
cystis, Microspora,
Phytoconis, Tribonema,
Zygnema
Gomphonema, Navicula,
Nitzschia, Stephano-
discus, Synedra,
Tabellaria
Ceratium, Cryptomonas,
Euglena, Glenodinium,
Mallomonas
Characium, Clorella,
Chlorococcum, Cocco-
myxa, Crucigenia,
Desmidium, Draparnaldia,
Golenkinia, Mesotaenium,
Oocystis, Palmella,
Pediastrum, Staurastrum,
Stigeoclonium, Tetra-
edron
Achnanthes, Cymbella,
Neidium
Chlamydomonas, Peri-
dinium, Haematococcus
Ankistrodesmus, Chara,
Coelastrum, Dictyo-
sphaerium, Elakatothrix,
Kirchneriella, Nitella,
Pithophora, Scenedesmus,
Tetrastrum
Eudorina, Pandorina
-------
PLANKTON ALGAE IN LAKES AND RESERVOIRS
FRAGILARIA
SCENEDESMUS
STAURONEIS
PEDIASTRUM
PLATE I
-------
PLATE I
PLANKTON ALGAE IN LAKES AND RESERVOIRS
Linear
Species Names Magnifications
Actinastrum gracillimum 1000
Botryococcus braunii 1000
Coelastrum microporum 500
Cylindrospermum stagnale 250
Desmidium grevillei 250
Euastrum oblongum 500
Eudorina elegans 250
Euglena gracilis 1000
Fragilariacapucina 1000
Gomphosphaeria aponina 1500
Gonium pectorale 500
Micractinium pusillum 1000
Mougeotia scalaris 250
Nodularia spumigena 500
Oocystis borgei 1000
Pediastrum boryanum 125
Phacus pleuronectes 500
Scenedesmus quadricauda 1000
Sphaerocystis schroeteri 500
Stauroneis phoenicenteron 500
Stephanodiscus hantzschii 1000
Zygnema sterile 250
-------
ATTACHED ALGAE
PHORMIDIUM
PLATE
-------
PLATE II
ATTACHED ALGAE
Linear
Species Names Magnifications
Achnanthes microcephala 1500
Audouinella violacea 250
Batrachospermum moniliforme 3
Bulbochaete insignis 125
Chaetophora elegans 250
Chara globularis 4
Cladophora crispata 125
Compsopogon coeruleus 125
Cymbella prostrata 250
Draparnaldia glomerata 125
Gomphonema geminatum 250
Lyngbya lagerheimii 1000
Microspora amoena 250
Oedogonium suecicum 500
Phormidium uncinatum 250
Phytoconis botryoides 1000
Stigeoclonium lubricum 250
Tetraspora gelatinosa 125
Tolypothrix tenuis 500
Ulothrix zonata 250
Vaucheria sessilis 125
-------
CLEAN WATER ALGAE
CLADOPHORA
COCCOCHLORIS
PLATE
-------
PLATE III
CLEAN WATER ALGAE
Linear
Species Names Magnifications
Agmenellum quadriduplicatum, glauca type 250
Ankistrodesmus falcatus var. acicularis 1000
Calothrix parietina 500
Chromulina rosanoffi 4000
Chrysococcus rufescens 4000
Cladophora glomerata 100
Coccochloris stagnina 1000
Cocconeis placentula 1000
Cyclotella bodanica 500
Entophysalis lemaniae 1500
Hildenbrandia rivularis 500
Lemanea annulata 1
Meridion circulare 1000
Micrasterias truncata 250
Microcoleus subtorulosus 500
Navicula gracilis 1000
Phacotus lenticularis 2000
Pinnularia nobilis 250
Rhizoclonium hieroglyphicum 250
Rhodomonas lacustris 3000
Staurastrum punctulatum 1000
Surirella splendida 500
Ulothrix aequalis 250
-------
FRESH WATER POLLUTION ALGAE
PHORMIDIUM
PLATE IV
-------
PLATE IV
FRESH WATER POLLUTION ALGAE
Linear
Species Names Magnifications
Agmenellum quadriduplicatum, tenuissima type 1000
Anabaena constricta 500
Anacystis montana 1000
Arthrospira jenneri 1000
Carteria multifilis 2000
Chlamydomonas reinhardi 1500
Chlorella vulgaris 2000
Chlorococcum humicola 1000
Chlorogonium euchlorum 1500
Euglena viridis 1000
Gomphonema parvulum 3000
Lepocinclis texta 500
Lyngbya digueti 1000
Nitzschia palea 2000
Oscillatoria chlorina (top) 1000
Oscillatoria putrida (middle) 1000
Oscillatoria lauterbornii (bottom) 1000
Phacus pyrum 1500
Phormidium autumnale 500
Pyrobotrys stellata 1500
Spirogyra communis ' 250
Stigeoclonium tenue 500
Tetraedron muticum 1500
-------
ESTUARINE POLLUTION ALGAE
ENTEROMORPHA
AGARDHIELLA
STICHOCOCCUS
PLATE V
-------
PLATE V
ESTUARINE POLLUTION ALGAE
Linear
Species Names Magnifications
Agardhiella tenera 2
Amphidinium fusiforme 1500
Asterionella japonica 500
Chaetoceros decipiens 750
Chaetomorpha aerea 125
Codium fragile 0.25
Enteromorpha intestinalis 0.25
Eutreptia viridis 750
Melosira sulcata 500
Nannochloris atomus 2500
Nitzschia closterium 500
Pelvetia fastigiata 0.25
Peridinium trochoideum 1000
Porphyra atropurpurea 0.25
Prasiola stipitata 10
Prorocentrum micans 750
Rhodoglossum affine 0.5
Scytosiphon lomentaria 0.25
Skeletonema costatum 500
Spirulina major 2500
Stephanoptera gracilis 2000
Stichococcus marinus 125
Trichodesmium erythraeum 2000
Ulva lactuca 0.5
-------
SEWAGE POND ALGAE
SCHROEDERIA
CHLAMYDOMONAS GOLENKINIA
PLATE VI
-------
PLATE VI
SEWAGE POND ALGAE
Linear
Species Names Magnifications
Ankistrodesmus falcatus 1000
Chlamydomonas pertusa 2000
Chodatella quadriseta 3000
Chromulina vagans 2000
Chroomonas caudata 2500
Closteriopsis brevicula 250
Closterium acutum 500
Cosmarium botrytis 500
Cryptomonas cylindrica 2000
Diacanthos belenophorus 750
Dictyosphaerium ehrenbergianum 1000
Elakatothrix gelatinosa 1000
Colenkinia radiata 500
Massartia vorticella 1500
Ourococcus bicaudatus 1500
Planktosphaeria gelatinosa 500
Polyedriopsis spinulosa 500
Pteromonas angulosa 1250
Scenedesmus dimorphus 1500
Schizothrix calcicola 2000
Schroederia setigera 250
Spirulina subtilissima 4000
Vacuolaria novo-munda 1250
-------
TASTE AND ODOR ALGAE
5»-»-. •,. «. „• • • v*v
\tf * :»*•,.- v.w
<&:£&&&
PLATE VII
-------
PLATE VII
TASTE AND ODOR ALGAE
Linear
Species Names Magnifications
Anabaena planctonica 250
Anacystis cyanea 250
Aphanizomenon flos-aquae 250
Asterionella gracillima 250
Ceratium hirundinella 250
Dinobryon divergens 250
Gomphosphaeria lacustris, kuetzingianum type 500
Hydrodictyon reticulatum 10
Mallomonas caudata 500
Nitella gracilis 1
Pandorina morum 500
Peridinium cinctum 500
Staurastrum paradoxum 500
Synedra ulna 250
Synura uvella 500
Tabellaria fenestrata 250
Uroglenopsis americana 125
Volvox aureus 125
-------
FILTER AND SCREEN CLOGGING ALGAE
ANACYSTIS
PLATE VIII
-------
PLATE VIII
FILTER AND SCREEN CLOGGING ALGAE
Linear
Species Names Magnifications
Anabaena flos-aquae 500
Anacystis dimidiata 1000
Asterionella formosa 1000
Chlorella pyrenoidosa 5000
Closterium moniliferum 250
Cyclotella meneghiniana 1500
Cymbella ventricosa 1500
Diatoma vulgare 1500
Dinobryon sertularia 1500
Fragilaria crotonensis 1000
Melosira granulata 1000
Navicula graciloides 1500
Oscillatoria princeps (top) 250
Oscillatoria chalybea (middle) 250
Oscillatoria splendida (bottom) 500
Palmella mucosa 1000
Rivularia dura 250
Spirogyra porticalis 125
Synedra acus 500
Tabellaria flocculosa 1500
Trachelomonas crebea 1500
Tribonema bombycinum 500
-------
APPENDIX
Key to Fresh Water Algae
Common in Water Supplies and in Polluted Waters
Beginning with "1a" and "1b," choose one of the two
contrasting statements and follow this procedure with the
"a" and "b" statements of the number given at the end of
the chosen statement. Continue until the name of the alga
is given instead of another key number. (Where recent
changes in names of algae have been made, the new name
is given followed by the old name in brackets.)
1a. Plastid (separate color body) absent; com-
plete protoplast pigmented; generally blue-
green; iodine starch test* negative
(blue-green algae) 4
1b. Plastid or plastids present; parts of proto-
plast free of some or all pigments; gener-
ally green, brown, red, etc., but not
blue-green; iodine starch test* positive or
negative 2
2a. Cell wall permanently rigid (never showing
evidence of collapse), and with regular pat-
tern of fine markings (striations, etc.); plas-
tids brown-to-green; iodine starch test*
negative; flagella absent; wall of two essen-
tially similar halves, one placed over the
other as a cover (diatoms)
2b. Cell wall is present, capable of sagging,
wrinkling, bulging, or rigidity, depending on
existing turgor pressure of cell protoplast;
regular pattern of fine markings on wall gen-
erally absent; plastids green, red, brown,
etc.; iodine starch test* positive or negative;
flagella present or absent; cell wall continu-
ous and generally not of two parts
3a. Cell or colony motile; flagella present (often
not readily visible); anterior and posterior
ends of cell different from one another in
contents and often in shape
(flagellate algae)
3b. Non-motile; true flagella absent; ends of
cells often not differentiated
(green algae and associated forms)
Blue-Green Algae
4a. Cells in filaments (or much elongated to
form a thread)
75
198
262
4b.
5a.
5b.
6a.
6b.
7a.
7b.
8a.
8b.
9a.
9b.
10a.
10b.
12a.
12b.
13a.
13b.
14a.
14b.
15a.
15b.
16a.
16b.
17a.
17b.
18a.
15
8
11
9
10
Cells not in (or as) filaments 61
Heterocysts present 6
Heterocysts absent 25
Heterocyst located at one end of filament. . 7
Heterocyst at various locations in filament. .
Filaments radially arranged in a gelatinous
bead
Filaments isolated or irregularly grouped. . .
Akinetes present (Gloeotrichia)
Akinetes absent (Rivularia)
Gelatinous colony a smooth bead
Gloeotrichia echinulata
Gelatinous colony irregular
Gloeotrichia natans
Cells near the narrow end as long as wide. .
Rivularia dura
Cells near the narrow end twice as long as
wide Rivularia haematites
Filament gradually narrowed to one end ....
(Calothrix)
Filament not gradually narrowed to one end
Cells adjacent to heterocyst wider than het-
erocyst Calothrix braunii
Cells adjacent to heterocyst narrower than
heterocyst Calothrix parietina
Heterocysts at both ends; filaments bent. . .
Anabaenopsis
Heterocysts at one end; filaments straight
(Cylindrospermum)
Heterocysts round
Cylindrospermum muscicola
Heterocysts elongate
Cylindrospermum stagnate
Filaments unbranched or with true branches
Filament with occasional false branches. . . .
12
13
14
16
24
•Add one drop Lugol's (iodine) solution, diluted 1:1 with distilled
water. In about 1 min, if positive, starch is stained blue.
True branching present; filament all or
partly multiseriate . . . .Stigonema minutum
Branching absent; filaments uniseriate 17
Cross-walls much closer together than width
of filament Nodularia spumigena
Cross-walls at least as far apart as width of
filament 18
Filaments normally in tight parallel clusters;
heterocysts and spores cylindric to long oval
Aphanizomenon flos-aquae
98
-------
Key
99
18b. Filaments not in tight parallel clusters; het-
erocysts and spores often round to oval.... 19
19a, Filaments in a common gelatinous mass . .
(Nostoc) 20
19b. Filaments not in a common gelatinous mass
(Anabaena) 21
20a. Heterocysts and vegetative cells rounded..
Nostoc pruniforme
20b. Heterocysts and vegetative cells oblong. ...
Nostoc carneum
21a. Cells elongate, depressed in the middle; het-
erocysts rare Anabaena constricta
21b. Cells rounded; heterocysts common 22
22a. Heterocysts with lateral extensions
Anabaena planctonica
22b. Heterocysts without lateral extensions 23
23a. Threads 4-8 microns wide
Anabaena flos-aquae
23b. Threads 8-14 microns wide
Anabaena circinalis
24a. False branches in pairs
Scytonema tolypothricoides
24b. False branches single. . . .Tolypothrix tenuis
25a. Filament or elongated cell attached at one
end and with one or more round cells
(spores) at the other end
Entophysalis lemaniae
25b. Filament generally not attached at one end;
no terminal spores present 26
26a. Filament with regular spiral form throughout 27
26b. Filament not spiral or with spiral limited to
a portion of filament 30
27a. Filament septate Arthrospira jenneri
27b. Filaments not septate (Spirulina) 28
28a. Thread 0.9 micron or less in diameter
Spirulina subtillissima
28b. Thread 1.2 microns or more in diameter.. . 29
29a. Thread 1.2-1.7 microns in diameter
Spirulina major
29b. Thread 2.0 microns in diameter
Spirulina nordstedtii
30a. Filament aggregates forming conical tufts. .
Symploca muscorum
30b. Filament aggregates not forming conical
tufts 31
31 a. Filament very narrow, only 0.5-2.0 microns
wide Schizothrix calcicola
31b. Filament 3.0-95.0 microns wide 32
32a. Filaments loosely aggregated or not in clus-
ters 33
32b. Filaments tightly aggregated and surrounded
by a common gelatinous secretion that may
be invisible 56
33a. Filament surrounded by a wall-like sheath
that frequently extends beyond the ends of
the filament of cells; filament generally
without movement 34
33b. Filament not surrounded by a wall-like
sheath; filament may show movement 41
34a. False branching present
Plectonema tomasiniana
34b. False branches absent 35
35a. Cells separated from one another by a space
Johannesbaptistia
35b. Cells in contact with adjacent cells
(Lyngbya) 36
36a. Threads in part forming spirals
Lyngbya lagerheimii
36b. Straight or bent but not in spirals 37
37a. Threads colored yellowish to brown 38
37b. Sheaths colorless 39
38a. Cells rounded Lyngbya ochracea
38b. Cells short discs Lyngbya aestuarii
39a. Cells constricted at the joints
Lyngbya putealis
39b. Cells not constricted at the joints 40
40a. Sheath very thick Lyngbya vers/co/or
40b. Sheath very thin Lyngbya digueti
41 a. All filaments short, with less than 20 cells;
one or both ends of filament sharp pointed
Raphidiopsis
41 b. Filaments long with more than 20 cells;
filaments commonly without sharp-pointed
ends (Oscillatoria) 42
42a. Cells very short, generally less than one-
third the thread diameter 43
42b. Cells generally one-half as long to longer
than thread diameter 46
43a. Cross walls constricted
Oscillatoria ornata
43b. Cross walls not constricted 44
44a. Ends of mature threads curved 45
44b. Ends of mature threads straight
Oscillatoria limosa
45a. Threads 10-14 microns thick
Oscillatoria curviceps
45b. Threads 16-60 microns thick
Oscillatoria princeps
46a. Threads appearing red to purplish
Oscillatoria rubescens
46b. Threads yellow-green to blue-green 47
47a. Threads blue-green 48
47b. Threads yellow-green 53
48a. Cells 1/2-2 times as long as thread diameter. 49
48b. Cells 2-3 times as long as thread diameter. 55
49a. Cell walls between cells thick and trans-
parent Oscillatoria pseudogeminata
49b. Cell walls thin, appearing as a dark line.... 50
50a. Ends of thread straight
Oscillatoria agardhii
50b. Ends of mature threads curved 51
51a. Prominent granules present especially at
both ends of each cell
Oscillatoria tenuis
-------
100
ALGAE AND WATER POLLUTION
51b. Cells without prominent granules 52
52a. Cross walls constricted
Osdllatoria chalybea
52b. Cross walls not constricted
Osdllatoria formosa
53a. Cells 4-7 times as long as thread diameter. .
Osdllatoria putrida
53b. Cells less than 4 times as long as the thread
diameter 54
54a. Prominent granules (pseudovacuoles) in cen-
ter of each cell . . .. Osci7/atoria /auterborn/i
54b. No prominent granules in center of cells . .
Osdllatoria chlorina
55a. End of thread long tapering
Osdllatoria splendida
55b. End of thread not tapering
Osdllatoria amphibia
56a. Filaments arranged in a tight, essentially par-
allel bundle Microcoleus subterulosus
56b. Filaments arranged in irregular fashion, often
forming a mat (Phormidium) 57
57a. Ends of some threads with a rounded swol-
len "cap" cell 58
57b. Ends of all threads without a "cap" cell. . . 60
58a. Cells quadrate Phormidium autumnale
58b. Cells much shorter than broad 59
59a. Ends of some threads with round cap and
abruptly bent Phormidium undnatum
59b. Ends of some threads with conical cap and
straight Phormidium subfuscum
60a. Threads 3-5 microns in width
Phormidium inundatum
60b. Threads 5-12 microns in width
Phormidium retzii
61a. Cells in a regular pattern of parallel rows,
forming a plate
(Agmenellum quadriduplicatum) 62
61 b. Cells not regularly arranged to form a plate 63
62a. Cell diameter 1.3-2.2 microns Agmen-
ellum quadriduplicatum, tenuissima type
62b. Cell diameter 3-5 microns
Agmenellum quadriduplicatum, glauca type
63a. Cells regularly arranged near surface of a
spherical gelatinous bead 64
63b. Gelatinous bead, if present, not spherical. . 68
64a. Cells ovate to heart-shaped; connected to
center of bead by colorless stalks
(Comphosphaeria) 65
64b. Cells round; without gelatinous stalks
(Comphosphaeria [Coelosphaerium type]) 65
65a. Cells with pseudovacuoles
Comphosphaeria w/churae
65b. Cells without pseudovacuoles 66
66a. Cells 2-4 microns diameter
(Comphosphaeria lacustris) 67
66b. Cells 4-15 microns diameter
Comphosphaeria aponina
67a. Cells spherical Com-
phosphaeria lacustris, kuetzingianum type
67b. Cells ovate
.... Comphosphaeria lacustris, collinsii type
68a. Cells attached Dermocarpa
68b. Cells unattached 69
69a. Cells cylindric-oval . . Coccochloris stagnina
69b. Cells spherical 70
70a. Two or more distinct layers of gelatinous
sheath around each cell or cell cluster
(Anacystis [Gloeocapsa]) 72
70b. Gelatinous sheath around cells not distinctly
layered 71
71a. Cells isolated or in colonies of 2-32 cells. .
(Anacystis [Chroococcus]) 72
71 b. Cells in colonies of many cells
(Anacystis [Microcystis]) 72
72a. Cell containing pseudovacuoles
Anacystis cyanea
72b. Cell not containing pseudovacuoles 73
73a. Cell 2-6 microns diameter; sheath often
colored Anacystis montana
73b. Cell 6-50 microns diameter; sheath colorless 74
74a. Cell 6-12 microns diameter; cells in colonies
are mostly spherical . . . .Anacystis thermalis
74b. Cell 12-50 microns diameter; cells in colo-
nies are often irregular. Anacystis dimidiata
Diatoms
75a. Transverse wall markings not in one or two
longitudinal rows; front (valve) view gener-
ally circular in outline; markings, if present,
radial in arrangement; cells may form a fila-
ment (centric diatoms) 76
75b. Front (valve) view elongate, not circular;
transverse wall markings in one or two longi-
tudinal rows; cells if grouped, not forming
a filament but a ribbon, star, etc
(pennate diatoms) 107
76a. Cells pillow shaped in girdle view with a
blunt process at each corner
Biddulphia laevis
76b. Cells without blunt processes 77
77a. Cells very long, cylindrical in girdle view,
with a long spine at each end
(Rh/zoso/en/a) 78
77b. Cells a disc or short cylinder in girdle view
with no long spine at each end of side.... 79
78a. Setae shorter than cell length
Rh/zoso/en/a eriensis
78b. Setae longer than cell length
Rh/zoso/en/a gradlis
79a. Cells in persistent filaments with valve faces
in contact; therefore, cells commonly seen
in side (girdle) view (Melosira) 80
79b. Cells isolated or in fragile filaments, often
seen in front (valve) view 88
-------
Key
101
80a. Distinct pores on valve mantle (shoulder). . 98b.
Melosira binderana
80b. No distinct pores on valve mantle (shoulder) 81 99a.
81 a. No visible ornamentation. .Melosira varians 99b.
81 b. Ornamentation visible 82 100a.
82a. Terminal cells with long spines 83
82b. Terminal cells without long spines 84 100b.
83a. Diameter 5-21 microns. .Melosira granulata 101a.
83b. Diameter 3-5 microns
Melosira granulata var. angustissima 101b.
84a. Sulcus (groove) angular at base 102a.
Melosira ambigua
84b. Sulcus (groove) not angular at base 85 102b.
85a. Semi-cells shorter than wide 103a.
Melosira distans var. a/p/gena
85b. Semi-cells about as long as wide 86 103b.
86a. With robust short spines. . .Melosira italica
86b. With fine teeth 87 104a.
87a. Sulcus distinctly acute-angled
Melosira crenulata 104b.
87b. Sulcus not distinctly acute-angled 105a.
Melosira islandica
88a. Radial markings (striations), in valve view, 105b.
extending from center to margin; short mar-
ginal spines sometimes present in valve view 89 106a.
88b. Area of prominent markings, in valve view,
limited to about outer half of circle; mar- 106b.
ginal spines generally absent . . . (Cydotella) 90
89a. Radiate hyaline areas on valve view 107a.
(Stephanodiscus) 99 107b.
89b. No radial hyaline areas on valve view
(Cosc/noc/iscus) 106 108a.
90a. Cells with marginal spines 108b.
Cydotella pseudostelligera
90b. Cells without marginal spines 91 109a.
91 a. Central area with 3-4 round, raised spots
Cydotella ocellata 109b.
91b. Central area without such ocelli 92 110a.
92a. Central area with star-shaped lines around
a central dot Cydotella stelligera 11 Ob.
92b. Central area otherwise 93 111a.
93a. Cells small; 4-10 microns diameter 94
93b. Cells larger; 10-80 microns diameter 95
94a. Cells in chains; single ocellus in central area 111b.
Cydotella atomus
94b. Cells all isolated; no ocellus in central area 112a.
Cydotella glomerata
95a. Central area clear. .Cydotella meneghiniana 112b.
95b. Central area with markings 96 113a.
96a. Circular shadow line passes through the 113b.
costae Cydotella striata 114a.
96b. No circular shadow line 97 114b.
97a. Central area with punctae or short lines. ... 115a.
Cydotella kutzingiana 115b.
97b. Central area with fine radial striae 98
98a. A puncta at inner end of several shortened 116a.
marginal costae Cydotella bodanica
No puncta at inner end of several marginal
costae Cydotella comta
Cell diameter 4-30 microns 100
Cell diameter 30-80 microns 104
Prominent rib-like structures over outer
third of cell Stephanodiscus dubius
No prominent rib-like structures 101
„ Spine at end of each striation
Stephanodiscus tenuis
Spines not as above 102
Spines alternating with striae
Stephanodiscus hantzschii
Spines not as above 103
Girdle view with two transverse bands. . ..
Stephanodiscus binderanus
Girdle view without transverse bands
Stephanodiscus astraea var. minutula
Outer punctae of striae 12 in 10 microns. ..
Stephanodiscus astraea
Outer punctae of striae 16 in 10 microns. . 105
Cell diameter 30-60 microns
Stephanodiscus niagarae
Cell diameter 72-80 microns
.... Stephanodiscus niagarae var. magnifica
Surface slightly undulate; markings poly-
gonal Cosdnodiscus rothii
Surface flat; markings angular with centra!
dots Cosdnodiscus denarius
Cell longitudinally symmetrical in valve view 108
Cell longitudinally unsymmetrical (two sides
unequal in shape), at least in valve view.. . 188
Raphe at or near the edge of the valve 109
Raphe or pseudoraphe median or sub-
median 124
Cells lying side by side in colonies
Bacillaria paradoxa
Cells isolated or in twos 110
Valve face transversely undulate
Cymatopleura solea
Valve face not transversely undulate 111
Marginal, keeled raphe areas lie opposite
one another on the two valves
Hantzschia amphioxys
Marginal, keeled raphe areas lie diagonal to
one another on the two valves. .(Nitzschia) 112
Valve long-pointed, spine-like
Nitzschia acicularis
Valve not long-pointed and spine-like .... 113
Valve axis sigmoid 114
Valve axis not sigmoid 116
Cell 20-40 microns long . .Nitzschia parvula
Cell more than 40 microns long 115
Cell 50-70 microns long .. .Nitzschia sigma
Cell 160-500 microns long
Nitzschia sigmoidea
Carinal dots extended far across the valve
Nitzschia denticula
-------
102
ALGAE AND WATER POLLUTION
116b. Carinal dots not extended far across the
valve 117
117a. Cells in star-shaped colonies
Nitzschia holsatica
117b. Cells not in star-shaped colonies 118
118a. Keel only slightly excentric
Nitzschia dissipata
118b. Keel distinctly excentric 119
119a. Cell distinctly pulled in at the middle
Nitzschia linearis
119b. Cell not distinctly pulled in at the middle. . 120
120a. Cell with longitudinal fold 121
120b. Cell without longitudinal fold 122
121a. Cell 6-9 microns broad. .Nitzschia hungarica
121b. Cell 16-35 microns broad
Nitzschia tryblionella
122a. Striae 15-17 in 10 microns
Nitzschia amphibia
122b. Striae more than 25 in 10 microns 123
123a. Striae 28-30 in 10 microns; cells elliptical-
lanceolate Nitzschia fonticula
123b. Striae 35-40 in 10 microns; cells linear-lan-
ceolate Nitzschia palea
124a. Cell transversely symmetrical in valve view 125
124b. Cell transversely unsymmetrical (two ends
unequal in shape or size), at least in valve
view 175
125a. Cell round-oval in valve view; not more
than twice as long as wide (Coccone/s) 126
125b. Cell elongate, more than twice as long as
wide 127
126a. Wall markings (striae) 18-20 in 10 microns
Coccone/s pediculus
I26b. Wall markings (striae) 23-25 in 10 microns
Coccone/s placentula
127a. Cell flat; girdle face wide, valve face narrow
(Tabellaria) 128
127b. Girdle and valve faces about equal in width 129
128a. Girdle face less than one-fourth as wide as
long Tabellaria fenestrata
128b. Girdle face more than one-half as wide as
long Tabellaria flocculosa
129a. Cell with several markings (septa) extending
without interruption across the valve face;
no marginal line of pores present (Diatoma) 130
129b. Cross-markings (striations or costae) on
valve surface, either interrupted by longi-
tudinal space (pseudoraphe), line (raphe), or
line of pores (carinal dots) 132
130a. Cells 2-4 microns wide.D/atoma elongatum
130b. Cells 4-13 microns wide 131
131a. Cells 4-8 microns wide . . . .Diatoma anceps
131b. Cells 10-13 microns wide. .Diatoma vulgare
132a. Cells attached side by side to form a ribbon
of several-to-many cells (Fragilaria) 133
132b. Cells isolated or in pairs 138
133a. Cells attached at middle portion only
Fragilaria crotonensis
133b. Cells attached along entire length 134
134a. Central area clear Fragilaria capudna
134b. Central area not clear; has striations 135
135a. Striae coarse 136
135b. Striae fine 137
136a. Valves much inflated at center
Fragilaria leptostauron
136b. Valves not inflated at center
Fragilaria pinnata
137a. Striae very short; cells 3-5 microns wide..
Fragilaria brevistriata
137b. Striae long; cells 5-12 microns wide
Fragilaria construens
138a. Cell narrow, linear, often narrowed to both
ends; true raphe absent (Synedra) 139
138b. Cell commonly "boat" shaped in valve
view; true raphe present 147
139a. Cell width 1-2 microns Synedra nana
139b. Cell width 2-10 microns 140
140a. Cell width 2-5 microns 141
140b. Cell width 5-10 microns 144
141a. Central clear area on one side of valve only
Synedra vaucheriae
141 b. No clear area on one side of center of valve
only 142
142a. Central clear area present; striae almost
continuous 143
142b. Central clear area absent; striae short
Synedra tabulata
143a. Cell length about 500 microns
Synedra acus var. angustissima
143b. Cell length 40-200 microns
Synedra acus var. radians
144a. Valves linear Synedra cap/fata
144b. Valves lanceolate to linear-lanceolate 145
145a. Valves narrow lanceolate; striae 12-14 in 10
microns Synedra acus
145b. Valves linear-lanceolate; striae not 12-14 in
10 microns 146
146a. Large clear refractive central area; ends
generally capitate Synedra pulchella
146b. Large clear non-refractive central area; ends
non-capitate Synedra ulna
147a. Cell longitudinally unsymmetrical in girdle
view; sometimes with attachment stalk . . .
(Achnanthes) 148
147b. Cell symmetrical in girdle as well as valve
view; generally not attached 150
148a. Valves constricted toward poles
Achnanthes microcephala
148b. Valves gradually tapering toward the poles
149
149a. Striations pronounced
Achnanthes lanceolata
149b. Striations fine . . . Achnanthes minutissima
-------
Key
103
150a.
150b.
151 a.
151 b.
152a.
152b.
153a.
153b.
154a.
154b.
155a.
155b.
156a.
156b.
157a.
157b.
158a.
158b.
159a.
159b.
160a.
160b.
161 a.
161b.
162a.
162b.
163a.
Area without striations extending as a trans-
verse belt around middle of cell
Stauroneis phoenicenteron
No continuous clear belt around middle of
cell 151
Cell with coarse transverse markings (costae),
which appear as solid lines even under high
magnification (Pinnularia) 152
Cell with fine transverse markings (striae),
which appear as lines of dots under high
magnification 153
Cell 5-6 microns broad
Pinnularia subcapitata
Cell 34-50 microns broad
Pinnularia nobilis
Girdle view hour-glass shaped; valves with
median longitudinal keel (extension)
Amphiprora alata
Girdle view not hour-glass shaped; valves
without median longitudinal keel 154
Longitudinal black spaces extending across
striations 155
No longitudinal black spaces extending
across striations 157
Longitudinal black spaces wavy
Anomoeone/s exilis
Longitudinal black spaces straight 156
Longitudinal black spaces near margin ....
Ca/one/s
Longitudinal black spaces near raphe: cen-
tral nodules with pair of extensions along
each side of raphe Diploneis smithii
Raphe and valve sigmoid 158
Raphe and valve not sigmoid 160
Valve striae forming transverse and longi-
tudinal rows (Gyrosigma) 159
Valve striae forming transverse and oblique
rows P/euros/gma delicatulum
Cell length 150-240 microns
Gyrosigma attenuatum
Cell length 80-120 microns
Gyrosigma kutzingii
Pair of longitudinal extensions of central
nodule along sides of raphe
Frustulia ovulgaris
Central nodule without longitudinal exten-
sions (Navicula) 161
Striae irregularly shortened in central area
Navicula mutica
Striae not irregularly shortened in central
area 162
Broad clear lanceolate area over much of
valve Navicula confervacea
No broad clear area over much of valve
Central area long, rectangular
Navicula accomoda
163b. Central area not long and rectangular
163
164
164a. Margin of valve undulate
Navilcula contenta
164b. Margin of valve not undulate 165
165a. Short septum at apices of valve
Navicula incomposita
165b. No short septum at apices of valve 166
166a. Central area large, irregularly rectangular . .
Navicula exigua var. cap/fata
166b. Central area not irregularly rectangular ... 167
167a. Central area strongly widened transversely 168
167b. Central area round, rhombic, lanceolate, or
small 169
168a. Valve length less than 25 microns
Navicula canalis
168b. Valve length more than 25 microns
Navicula graciloides
169a. Valve ends distinctly narrowed 170
169b. Valve ends truncate, rounded, or acute ... 172
170a. Valve broadly lanceolate; 5-7 microns ... 171
170b. Valve narrowly lanceolate; width 4-5 mi-
crons Navicula notha
171 a. Central area large, rounded; ends not capi-
tate Navicula viridula
171b. Central area medium sized, irregular; ends
capitate Navicula cryptocephala
172a. Terminal striae more strongly marked than
elsewhere Navicula hungarica
172b. Terminal striae not more strongly marked
than elsewhere 173
173a. Valves almost linear
Navicula tripunctata
173b. Valves lanceolate 174
174a. Central area large; valve lanceolate
Navicula lanceolata
174b. Central area small; valve linear-lanceolate
Navicula radiosa
175a. Cells attached together at one end only to
form radiating colony (Aster/one//aj 176
175b. Cells not forming a loose radiating colony 177
176a. Larger terminal swelling 11/2 to 2 times
wider than the other . . Asterione//a iormosa
176b. Larger terminal swelling less than 11/2 times
wider than the other
Asterionella gracillima
177a. Cells in fan-shaped colonies
Meridion circulare
177b. Cells isolated or in pairs 178
178a. Prominent wall markings in addition to
striations present just below lateral margins
on valve (Surirella) 179
178b. Wall markings along sides of valve limited
to striations 183
179a. Cell width 40-160 microns 180
179b. Cell width 8-30 microns 181
180a. Cell transversely symmetrical
Surirella striatula
180b. Cell transversely unsymmetrical
Surirella splendida
-------
104
ALGAE AND WATER POLLUTION
181a. Cell linear, symmetrical
Surirella angustata
181b. Cell wider at one end 182
182a. Longitudinal folds marginal
Surirella brightwellii
182b. Longitudinal folds extend to the center . . .
Surirella ovata
183a. Cell elongate; sides of valve almost parallel
except for terminal knobs .. . (Asterionella) 176
183b. Sides of valve converging toward one end 184
184a. Cells bent in girdle view
Rhoicosphenia curvata
184b. Cells straight in girdle view 185
185a. Longitudinal line crossing striae near both
sides of valve Comphoneis
185b. No longitudinal line crossing striae near
both sides of valve (Gomphonema) 186
186a. Narrow end enlarged in valve view
Gomphonema geminatum
186b. Narrow end not enlarged in valve view . .. 187
187a. Tip of broad end about as wide as tip of
narrow end in valve view
Gomphonema parvulum
187b, Tip of broad end much wider than tip of
narrow end in valve view
Gomphonema olivaceum
188a. Valve with transverse septa or costae 189
188b. Valve with no transverse septa or costae . . 191
189a. Central portion of raphe "V" shaped
(Epithemia) 190
189b. Central portion of raphe straight
Rhopalodia gibba
190a. Cells 8-15 microns wide; constricted below
the recurved capitate poles
Epithemia sorex
190b. Cells 15-18 microns wide; only slightly con-
stricted below the recurved somewhat capi-
tate poles Epithemia turgida
191a. Convex margin of valve undulate at least .
near the ends (Eunotia) 192
191b. Convex margin of valve not undulate 193
192a. Valve arcuate Eunotia lunaris
192b. Valve linear, only slightly curved
Eunotia pectinalis
193a. Raphe located almost through center of
valve (Cymbella) 194
193b. Raphe excentric; near concave edge of valve
Amphora ovalis
194a. Cell only slightly unsymmetrical
Cymbella cesati
194b. Cell distinctly unsymmetrical 195
195a. Central area with a puncta
Cymbella tumida
195b. Central area without puncta 196
196a. Striations distinctly cross-lined
Cymbella prostrata
196b. Striations not distinctly cross-lined 197
197a. Striae 7-9 in 10 microns; cells 30-100 mi-
crons long Cymbella turgida
197b. Striae 12-18 in 10 microns; cells 10-40 mi-
crons long Cymbella ventricosa
Flagellate Algae
198a. Cell in a loose, rigid, conical sac (lorica);
isolated or in a branching colony
(Dinobryon) 199
198b. Case or sac, if present, not conical; colony,
if present, not branching 202
199a. Branches diverging, often almost at a right
angle Dinobryon divergens
199b. Branches compact, often almost parallel .. 200
200a. Narrow end of lorica sharp pointed 201
200b. Narrow end of lorica blunt pointed
Dinobryon sertularia
201 a. Narrow end drawn out into a stalk
Dinobryon stipitatum
201 b. Narrow end diverging at the base
Dinobryon sociale
202a. Cells isolated or in pairs 203
202b. Cells in a colony of four or more cells . . . 252
203a. Prominent transverse groove encircles the
cell 209
203b. Cell without transverse groove 204
204a. Plastid golden-brown 205
204b. Plastid green, yellow-green, red, or blue-
green 215
205a. Anterior end of cell rounded; one flagellum
(Chromulina) 206
205b. Anterior end of cell oblique; two flagella . . 207
206a. Plastid in anterior half of cell; posterior por-
tion of cell attenuate
Chromulina rosanoffii
206b. Plastid almost full length of cell; Posterior
portion of cell wide, rounded
Chromulina vagans
207a. Flagella extending from gullet; flagella al-
most equal in length (Cryptomonas) 208
207b. No gullet; flagella very unequal in length ..
Ochromonas
208a. Cell narrowed to posterior end
Cryptomonas cylindrica
208b. Cell not narrowed to posterior end
Cryptomonas erosa
209a. Cell with prominent projections, rigid, one
forward and two or three on posterior end
Ceratium hirundinella
209b. Cell without several rigid, polar projections 210
21 Oa. Portions above and below transverse groove
about equal 211
21 Ob. Front portion distinctly larger than posterior
portion 214
211 a. Cells naked, with no cell wall Gymnodinium
211b. Cells with cell wall composed of several
plates 212
-------
Key
105
212a. Cell wall thin but composed of plates
Glenodinium palustre
212b. Cell wall thick with clearly evident plates
(Peridinium) 213
213a. Ends of cells pointed
Peridinium wisconsinense
213b. Ends of cell rounded . .Peridinium cinctum
214a. Transverse furrow extends about half way
around cell Hemidinium
214b. Transverse furrow extends all way around
cell Massart/a vorticella
215a. Cell with long bristles extending from sur-
face plates Mallomonas caudata
215b. Cells without bristles and surface plates .. 216
216a. Plastids blue-green Cyanomonas
216b. Plastids green, yellow-green, or red 217
217a. Cell naked, not covered by wall or lorica or
rigid membrane Dunaliella
217b. Cell covered by wall or loose rigid covering
or rigid membrane 218
218a. Space between protoplast and wall with
radial strands of protoplasm Haematococcus
218b. No radial strands of cytoplasm between
protoplast and wall or lorica 219
219a. Cell protoplast enclosed in loose rigid cov-
ering (lorica) 220
219b. Cell with membrane or wall but no loose
rigid covering 225
220a. Cell with four flagella Pedinopera
220b. Cell with one or two flagella 221
221a. Lorica flattened; cell with two flagella
Phacotus lenticularis
221 b. Lorica not flattened; cell with one flagellum 222
222a. Lorica often opaque, generally dark brown
to red; plastid green Trachelomonas crebea
222b. Lorica often transparent, colorless to light
brown; plastid light brown (Chrysococcus) 223
223a. Outer membrane (lorica) oval
Chrysococcus ovalis
223b. Outer membrane (lorica) rounded 224
224a, Lorica thickened around opening
Chrysococcus rubescens
224b. Lorica not thickened around opening ....
Chrysococcus major
225a. Plastids brown to red to olive- or blue-green 226
225b. Plastids grass green 229
226a. Plastid blue-green to blue .. (Chroomonas) 227
226b. Plastids brown to red to olive-green
Rhodomonas lacustris
227a. Cell not pointed at one end
Chroomonas setoniensis
227b. Cell pointed at posterior end 228
228a. Plastid one per cell . . . Chroomonas caudata
228b. Plastids two per cell Chroomonas nordstetii
229a. Cell with colorless, rectangular wing
Pteromonas angu/osa
229b. No wing extending from cell 230
230a. Cells with two chloroplasts, one on each
side Cryptoglena nigra
230b. Cells with more than two chloroplasts .... 231
231a. Cells flattened; margin rigid (Phacus) 232
231 b. Cell not flattened; margin rigid or flexible 233
232a. Posterior spine short, bent
Phacus pleuronectes
232b. Posterior spine long, straight
Phacus longicauda
233a. Pyrenoid present in the single plastid; no
paramylon; margin not flexible; two or
more flagella per cell 234
233b. Pyrenoid absent; paramylon present; several
plastids per cell; margin flexible or rigid;
one flagellum per cell 240
234a. Cells long fusiform (tapering at each end)
(Chlorogonium) 397
234b. Cells not fusiform, generally almost spher-
ical 235
235a. Plastids numerous Vacuo/ar/a novo-munda
235b. Plastids few, commonly one 236
236a. Two flagella per cell 237
236b. Four flagella per cell .... Carteria multifilis
237a. Cell with sheath of different shape from pro-
toplast Sphaerellopsis
237b. Cell not as above (Chlamydomonas) 238
238a. Distinct clear area across middle of cell ....
Chlamydomonas pertusa
238b. No distinct clear area across middle of cell 239
239a. Pyrenoid angular; eyspot in front third of
cell Chlamydomonas reinhardi
239b. Pyrenoid circular; eyespot in middle third of
cell Chlamydomonas globosa
240a. Cell flexible in form; paramylon a capsule or
disc; cell elongate (Euglena) 241
240b. Cell rigid in form; paramylon ring-shaped;
cell almost spherical 250
241 a. Green plastids hidden by a red pigment . ..
Euglena sanguinea
241 b. No red pigment except for the eyespot . . . 242
242a. Plastids at least one-fourth the length of the
cell 243
242b. Plastids discoid or at least shorter than one-
fourth the length of the cell 244
243a. Plastids two per cell Euglena agilis
243b. Plastids several per cell, often extending
radiately from the center . .Euglena viridis
244a. Posterior end extending as a colorless spine 245
244b. Posterior end rounded or at least with no
colorless spine 247
245a. Posterior end gradually narrowed to a spine
Euglena acus
245b. Posterior end with an abrupt spine 246
246a. Spiral markings very prominent and granular
Euglena spirogyra
246b. Spiral markings fairly prominent, not granu-
lar Euglena oxyuris
-------
106
ALGAE AND WATER POLLUTION
247a. Small; length 35-55 microns Euglena gracilis
247b. Medium to large; length 65 microns or more 248
248a. Medium in size; length 65-200 microns .... 249
248b. Large in size; length 250-290 microns
Euglena ehrenbergii
249a. Plastids with irregular edge; flagellum two
times as long as cell . . Euglena polymorpha
249b. Plastids with smooth edge; flagellum about
one-half as long as the cell . . .Euglena deses
250a. Cell almost spherical or with abrupt poste-
rior tip; paramylon ring-shaped
(Lepodnclis) 251
250b. Posterior end of cell gradually pointed; cell
margin with spiral ridges . . . .Phacus pyrum
251a. Posterior end with an abrupt, spine-like tip
Lepodnclis ovum
251 b. Posterior end rounded ...Lepodnclis texta
252a. Plastids brown 253
252b. Plastids green 254
253a. Cells in contact with one another
Synura uvella
253b. Cells separated from one another by a space
Uroglenopsis americana
254a. Colony flat; one cell thick Conium pectorale
254b. Colony rounded; more than one cell thick . 255
255a. A long straight rod extending from each cell
Chrysosphaerella longispina
255b. No long straight rod extending from each
cell 256
256a. Cells in contact with one another 257
256b. Cells separated from one another by a
space 260
257a. Cells radially arranged . . Pandorina morum
257b. Cells all facing one direction 258
258a. Cells each with two flagella . . (Pyrobotrys) 259
258b. Cells each with four flagella
Spondylomorum quaternarium
259a. Eyespot in the wider (anterior) end of the
cell Pyrobotrys stellata
259b. Eyespot in the narrower (posterior) end of
the cell Pyrobotrys gracilis
260a. Cells more than 400 per colony
Vo/vox aureus
260b. Cells less than 150 per colony 261
261 a. Cells of two distinct sizes in colony
Pleodorina
261 b. Cells all of one size in colony
Eudorina elegans
Green Algae and Associated Forms
262a. Cells joined together to form a net
Hydrodictyon reticulatum
262b. Cells not forming a net 263
263a. Cells attached side by side to form a plate
or ribbon one cell thick and one (or two)
cells wide; Number of cells commonly 2, 4,
or 8 (Scenedesmus,) 264
263b. Cells not attached side by side 268 279b.
264a.
264b.
265a.
265b.
266a.
266b.
267a.
267b.
268a.
268b.
269a.
269b.
270a.
270b.
271 a.
271 b.
272a.
272b.
273a.
273b.
274a.
274b.
275a.
275b.
276a.
276b.
277a.
277b.
278a.
278b.
279a.
Middle cells without spines but with
pointed ends 265
Middle cells with rounded ends 266
All cells in colony erect
Scenedesmus obliquus
Median cells erect, terminal cells lunate . . .
Scenedesmus dimorphus
Terminal cells with spines 267
Terminal cells without spines
Scenedesmus bi/uga
Terminal cells with two spines each
Scenedesmus quadricauda
Terminal cells with three or more spines
each Scenedesmus abundans
Cells isolated or in nonfilamentous or non-
tubular thalli 269
Cells in filaments or other tubular or thread-
like thalli 335
Cells isolated and narrowest at the center
due to incomplete fissure (desmids) 270
Cells isolated or in clusters but without cen-
tral fissure 276
Each half of cell with three spine-like or
pointed knobular extensions . .(Staurastrum) 271
Cell margin with no such extensions 273
Margin of cell with long spikes
Staurastrum paradoxum
Margin of cell without long spikes 272
Ends of lobes with short spines
Staurastrum polymorphum
Ends of lobes without spines
Staurastrum punctulatum
Semi-cells with no median incision or de-
pression (Cosmarium) 274
Semi-cells with a median incision or de-
pression 275
Median incision narrow linear
Cosmarium botrytis
Median incision wide, "U" shaped
Cosmarium portianum
Margin with rounded lobes
Euastrum oblongum
Margin with sharp-pointed teeth
Micrasterias truncata
Lunate or otherwise bent cells in a wide
gelatinous matrix (Kirchneriella) 277
Cells otherwise 278
Cells sharply pointed
Kirchneriella lunaris
Cells bluntly pointed
Kirchneriella subsolitaria
Cells elongate 279
Cells round to oval to angular 297
Cells quadrately arranged in fours
Tetradesmus
Cells not quadrately arranged 280
-------
Key
107
280a. Cells radiating from a central point
(Actinastrum) 281
280b. Cells isolated or in irregular clusters 282
281a. Cells cylindric . . . .Actinastrum gracillimum
281 b. Cells distinctly bulging
Actinastrum hantzschii
282a. One or both cell ends gradually narrowed
to an acute spine-like point
Ourococcus bicaudatus
282b. Cells either with true spines or without
spine-like points 283
283a. Cells with terminal spines 284
283b. Cells without terminal spines 285
284a. Cell ends blunt . . . Ophiocytium capitatum
284b. Cell ends tapering . . . .Schroederia setigera
285a. Cells with colorless attachment area at one
end Characium
285b. No attachment area at one end of cell. . . . 286
286a. Plastids two per cell; unpigmented area
across center of cell (Closterium) 287
286b. Cell with plastid that continues longitudi-
nally across the center of the cell 290
287a. Cell small; length up to 177 microns
Closterium acutum
287b. Cell larger; length more than 240 microns 288
288a. Cell long and narrow; width up to 5 mi-
crons Closterium aciculare
288b. Cell wide; minimum width 19 microns. . . . 289
289a. Inner margin of cell straight
Closterium acerosum
289b. Inner margin of cell tumid and curved . . .
Closterium moniliferum
290a. Two, four, or many cells surrounded by
homogenous envelope
Elakatothrix gelatinosa
290b. No gelatinous envelope 291
291 a. Cell five to ten times as long as broad .... 292
291 b. Cell two to four times as long as broad .. . 294
292a. Pyrenoid absent or one per cell
(Ankistrodesmus) 293
292b. Pyrenoids several per cell
Closteriopsis brevicula
293a. Cells bent Ankistrodesmus falcatus
293b. Cells straight
.... Ankistrodesmus falcatus var. acicularis
294a. Plastid pale yellow-green; reddish oil drop-
lets present Pleurogaster
294b. Plastid grass-green; storage food is starch 295
295a. Cells semi-circular; cell ends pointed but
with no terminal spines (Selenastrum) 296
295b. Cells arcuate but less than semi-circular;
cell ends pointed and each with a short
spine Closteridium lunula
Cells with rounded ends
Selenastrum capricornutum
Cells with pointed ends
Selenastrum gracile
Plastids green 298
297b. Plastids golden-brown; cells with pseudo-
podia 306
298a. Numerous gelatinous setae extending from
surface of colony Chaetopeltis megalocystis
298b. No gelatinous setae extending from surface
of colony 299
299a. Cells arranged in a flat regular colony .... 300
299b. Cells not in a tight, flat, regular colony ... 307
300a. Marginal cells with one or two or more
spines or spine-like extensions 301
300b. Marginal cells otherwise 304
301a. Colonies limited to four cells with true
spines Tetrastrum
301 b. Colonies generally of eight or more cells, if
limited to four cells, without true spines
(Pediastrum) 302
302a. Numerous spaces between cells
Pediastrum duplex
302b. Cells fitted tightly together 303
303a. Cell incisions deep and narrow
Pediastrum tetras
303b. Cell incisions deep and wide
Pediastrum boryanum
304a. All cells in contact with neighboring cells. . 305
304b. At least some cells lie free from one an-
other Dispora
305a. Quadrangular space in center of each group
of four cells Crucigenia quadrata
305b. No quadrangular space in center of each
group of four cells .... Prasiola nevadense
306a. Cells isolated Chrysamoeba
306b. Cells in colonies Chrysidiastrum
307a. Plastid distinctly central Apiococcus
307b. Plastid parietal 308
308a. Cells angular 309
308b. Cells round to oval 311
309a. Two or more spines at each angle
Polyedriopsis spinulosa
309b. Spines none or less than two at each angle
(Tetraedron) 310
31 Oa. Corners produced into processes
Tetraedron limneticum
31 Ob. Corners not produced into processes ....
Tetraedron muticum
311a. Cells with long sharp spines 312
311 b. Long sharp spines absent 315
312a. Cells round 313
312b. Cells oval 314
313a. Cells isolated Golenkinia radiata
313b. Cells in colonies ... Micractinium pusillum
314a. Each cell end with one spine
Diacanthos belenophoris
314b. Each cell end with more than one spine ...
Chodatella quadriseta
315a. Each cell with a sheath which is not con-
fluent with sheaths of adjacent cells
(Gloeocystis) 316
315b. Cells or sheaths otherwise 317
-------
108
ALGAE AND WATER POLLUTION
316a. Colonies angular . . .Gloeocystis planctonica
316b. Colonies rounded Gloeocystis g/'gas
317a. Each cell group with two shapes of cells . .
Dimorphococcus lunatus
317b. All cells of essentially the same shape . . . 318
318a. Colony of definite, regular form, round to
oval 319
318b. Colony, if present, not a definite oval or
sphere; or cells may be isolated 325
319a. Colony a tight sphere of cells 320
319b. Colony a loose sphere of cells enclosed by
a membrane 321
320a. Sphere solid, slightly irregular; no connect-
ing processes between cells
Planktosphaeria gelatinosa
320b. Sphere hollow, regular; short connecting
processes between cells
Coelastrum microporum
321a. Cells round 323
321b. Cells oval (Oocystis) 322
322a. Cells with polar nodules .Oocystis lacustris
322b. Cells without polar nodules Oocystis borgei
323a. Cells connected to center of colony by
• branching stalk (Dictyosphaerium) 324
323b. No stalk connecting the cells
Sphaerocystis schroeteri
324a. Cells rounded Dictyosphaerium pulchellum
324b. Cells straight, oval
Dictyosphaerium ehrenbergianum
325a. Oval cells enclosed in a somewhat spherical,
often orange-colored matrix
Botryococcus braunii
325b. Cells round, isolated or in colorless matrix 326
326a. Adjoining cells with straight, flat walls be-
tween their protoplasts 327
326b. Adjoining cells with rounded walls between
their protoplasts 328
327a. Cells embedded in a common gelatinous
matrix Palmella mucosa
327b. No matrix or sheath outside of cell walls
Phytoconis botryoides
328a. Cells loosely arranged in a large gelatinous
matrix Tetraspora gelatinosa
328b. Cells isolated or tightly grouped in a small
colony 329
329a. Cells located inside of protozoa
Zoochlorella
329b. Cells not inside of protozoa 330
330a. Cells with two or more plastids
Palmellococcus
330b. Each cell with a single plastid 331
331a. Plastid filling two-thirds or less of the cell.. 332
331 b. Plastid filling three-fourths or more of the
cell Chlorococcum humicola
332a. Cell diameter 2 microns or less; reproduc-
tion by cell division Nannochloris
332b. Cell diameter 2.5 microns or more; repro-
duction by internal spores (Chlorella) 333
333a. Cells rounded 334
333b. Cells ellipsoidal to ovoid
Chlorella ellipsoidea
334a. Cell 5-10 microns in diameter; pyrenoid
indistinct Chlorella vulgaris
334b. Cell 3-5 microns in diameter; pyrenoid
distinct Chlorella pyrenoidosa
335a. Cells attached end to end in an unbranched
filament 336
335b. Thallus branched or more than one cell
wide 362
336a. Plastids in form of one or more marginal,
spiral ribbons; spirals may be incomplete. . 337
336b. Plastids not in form of spiral ribbons 342
337a. Spiral turn of plastic incomplete Sirogonium
337b. Plastid forming one or more spiral turns . . .
(Spirogyra) 338
338a. One plastid per cell 339
338b. Two or more plastids per cell 341
339a. Threads 18-26 microns wide
Spirogyra communis
339b. Threads 28-50 microns wide 340
340a. Threads 28-40 microns wide
Spirogyra varians
340b. Threads 40-50 microns wide
Spirogyra porticalis
341a. Threads 30-45 microns wide; 3-4 plastids
per cell Spirogyra fluviatilis
341 b. Threads 50-80 microns wide; 5-8 plastids
per cell Spirogyra majuscula
342a. Filaments when breaking, separating
through middle of cells 343
342b. Filaments, when breaking, separating irregu-
larly or at ends of cells 346
343a. Starch test positive; cell margin straight; one
plastid, granular (Microspora)
343b. Starch test negative; cell margin slightly
bulging; several plastids (Tribonema)
344a. Cells 22-33 microns broad
Microspora amoena
344b. Cells 11-20 microns broad
Microspora wittrockii
345a. Plastids two to four per cell
Tribonema minus
345b. Plastids more than four per cell
Tribonema bombycinum
346a. Filaments short; generally 2-3 cells long . ..
Stichococcus bacillaris
346b. Filaments longer than 2-3 cells 347
347a. Marginal indentations between cells 348
347b. No marginal indentations between cells . . 349
348a. Cells much shorter than broad
Desmidium grevillii
348b. Cells almost as long as broad
Hyalotheca mucosa
349a. Plastids two per cell (Zygnema) 350
344
345
-------
Key
109
349b. Plastid one per cell (sometimes appearing
numerous) 352 365b.
350a. Cell dense green, each plastid reaching to 366a.
the wall Zygnema steri/e 366b.
350b. Cells light green; plastids not completely 367a.
filling the cell 351
351 a. Width of thread 26-32 microns; maximum 367b.
cell length 60 microns . .. Zygnema insigne 368a.
351 b. Width of thread 30-36 microns; maximum
cell length 120 microns
Zygnema pectinatum 368b.
352a. Some cells with walls having transverse
wrinkles near one end; plastid an irregular 369a.
net (Oedogonium) 353
352b. No apical wrinkles in wall; plastid not 369b.
porous 356
353a. Thread diameter less than 25 microns .... 354 370a.
353b. Thread diameter 25 microns or more .... 355
354a. Thread diameter 9-14 microns
Oedogonium suedcum 370b.
354b. Thread diameter 14-23 microns 371 a.
Oedogonium boscii
355a. Dwarf male plants attached to normal thread 371b.
when reproducing 372a.
Oedogonium idioandrosporum 372b.
355b. No dwarf male plants produced 373a.
Oedogonium grande
356a. Plastid a flat or twisted axial ribbon 373b.
(Mougeotia) 357 374a.
356b. Plastid an arcuate marginal band (U/othr/x) 359
357a. Threads with occasional "knee-joint" bends 374b.
Mougeotia genuf/exa
357b. Threads straight 358
358a. Threads 19-24 microns wide; pyrenoids 4-16 375a.
per cell Mougeotia sphaerocarpa 375b.
358b. Threads 20-34 microns wide; pyrenoids 4-10 376a.
per cell Mougeotia scalaris
359a. Threads 10 microns or less in diameter . . . 360 376b.
359b. Threads more than 10 microns in diameter 361
360a. Threads 5-6 microns in diameter 377a.
Ulothrix variabilis
360b. Threads 6-10 microns in diameter 377b.
Ulothrix tenerrima
361a. Threads 11-17 microns in diameter 378a.
Ulothrix aequalis
361 b. Threads 20-60 microns in diameter 378b.
Ulothrix zonata
362a. Thallus a tangled tubular mass of filaments 379a.
Thorea ramosissima
362b. Thallus otherwise 363 379(5.
363a. Thallus a gelatinous tube in which cells are
embedded Hydrurus 380a.
363b. Thallus otherwise 364 380b.
364a. Thallus a flat plate of cells
Hildenbrandia rivularis 331 a.
364b. Thallus otherwise 365
365a. Thallus a tubular layer of cells
Enteromorpha intestinalis
Thallus otherwise 366
Thallus a long tube without cross-walls . .. 367
Thallus otherwise 370
Tube with constrictions especially at base of
branches .... Dichotomosiphon tuberosus
Tube with no constrictions . . . . (Vaucheria) 368
Egg sac attached directly, without a stalk,
to the main vegetative tube
Vauchen'a sessilis
Egg sac attached to an abrupt, short, side
branch 369
One egg sac per branch
Vaucheria terrestris
Two or more egg sacs per branch
Vaucheria gem/nata
Thallus a leathery strand with regularly
spaced swellings and a continuous mem-
brane of cells 396
Thallus otherwise 371
Filament unbranched
Schizomeris leibleinii
Filament branched 372
Branches in whorls (clusters) 373
Branches single or in pairs 378
Thallus embedded in gelatinous matrix .. .
(Batrachospermum) 374
Thallus not embedded in gelatinous matrix 375
Nodal masses of branches touching one an-
other Batrachospermum vagum
Nodal masses of branches separated from
one another by a narrow space
Batrachospermum moniliforme
Main filament one cell thick (Nitella) 376
Main filament three cells thick (Chara) 377
Short branches on the main thread re-
branched once Nitella flexilis
Short branches on the main thread re-
branched two to four times Nitella gracilis
Short branches with 2 naked cells at the
tip Chara globularis
Short branches with 3-4 naked cells at the
tip Chara vu/gar/s
Most of filament surrounded by a layer of
cells Compsopogon coeru/eus
Filament not surrounded by a layer of cells
379
End cell of branches with a rounded or
blunt-pointed tip 380
End cell of branches with a sharp-pointed
tip 387
Plastid green; starch test positive 381
Plastids red; starch test negative
Audou/ne//a v/o/acea
Some cells dense, swollen, dark green
(spores); others light green, cylindric
Pithophora oedogonia
-------
110
ALGAE AND WATER POLLUTION
381 b. All cells essentially alike, being light to me-
dium green, cylindric (C/adophoraj 382
382a. Branches arising from below apices of cells
. . . Cladophora profunda var. nordstedtiana
382b. Branches arising from apices of cells 383
383a. Branches often appearing forked or in threes
Cladophora aegagropila
383b. Branches distinctly lateral 384
384a. Branches forming acute angles with main
thread, thus forming clusters
Cladophora glomerata
384b. Branches forming wide angles with the main
thread 385
385a. Threads crooked and bent
Cladophora fracta
385b. Threads straight 386
386a. Branches few, seldom rebranching
Cladophora insignis
386b. Branching numerous, often rebranching . . .
Cladophora crispata
387a. Filaments embedded in gelatinous matrix . 388
387b. Filaments not embedded in gelatinous . . .
matrix 391
388a. Cells of main filament much wider than
even the basal cells of the branches
(Draparnaldia) 389
388b. No abrupt change in width of cells from
main filament to branches . .(Chaetophora) 390
389a. Branches (from the main thread) with a cen-
tral main axis Draparnaldia plumosa
389b. Branches diverging and with no central
main axis Draparnaldia glomerata
393
394
390a. End cells long-pointed with colorless tips
Chaetophora attenuata
390b. End cells abruptly pointed, mostly without
long colorless tips . . . Chaetophora elegans
391 a. Branches very short, with no cross-walls
Rhizodonium hieroglyphicum
391 b. Branches long, with cross-walls 392
392a. Branches ending in an abrupt spine having
a bulbous base (Bulbochaete)
392b. Branches gradually reduced in width, end-
ing in a long pointed cell, with or without
color fSt/geoc/on/umJ
393a. Vegetative cells 20-48 microns long
Bulbochaete mirabilis
393b. Vegetative cells 48-88 microns long
Bulbochaete insignis
394a. Branches frequently in pairs 395
394b. Branches mostly single
Stigeoclonium stagnatile
395a. Cells in main thread 1-2 times as long as
wide Stigeoclonium lubricum
395b. Cells in main thread 2-3 times as long as
wide Stigeoclonium tenue
396a. Nodes covered by a ring of antheridial tis-
sue Lemanea annulata
396b. Nodes covered by wart-like outgrowths of
antheridial tissue Sacheria
397a. Pyrenoids two per cell
Chlorogonium elongatum
397b. Pyrenoids several per cell
Chlorogonium euchlorum
-------
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Glossary
Actinomycetes. A group of branching filamentous bacteria,
reproducing by terminal spores. They are common in
the soil. Selected strains are used for production of
certain antibiotics.
Aeration. The mixing of water or other liquid with air,
including the absorption of air through the surface of
the liquid.
Aerobic. A condition involving the presence of free (ele-
mentary) oxygen in a medium such as water or sewage.
Algae (singular, alga). Comparatively simple plants con-
taining photosynthetic pigments. A majority are aquatic
and many are microscopic in size.
Algicide (or algaecide). A chemical highly toxic to algae
and satisfactory for application to water.
Alpha-mesosaprobic zone. Area of active decomposition,
partly aerobic, partly anaerobic, in a stream heavily pol-
luted with organic wastes.
Alternate branching. Only one branch per node or at any
one height on a filament or strand.
Anaerobic. A condition involving the absence of free (ele-
mentary) oxygen in a medium such as water or sewage.
Anterior. The front or forward end of an organism that
is capable of movement.
Aquatic. Living in water.
Arcuate. Moderately curved, like a bow.
Areal standard unit. An area of 400 sq microns, used as a
unit in designating the amount of plankton in water.
Armored flagellates. Flagellates having a cell wall com-
posed of distinct, tightly arranged segments or plates.
The wall is generally thick, rough, and brown.
Aromatic. A fragrant, spicy, or pungent odor.
Attenuation. A continuous decrease in width of a filament,
often to a point or thin hair.
Backwash. The cleaning of a rapid sand or mechanical
filter by reversing the flow of water upward through it.
Bacteria (singular, bacterium). Simple one-celled but often
colonial microorganisms, typically free of chlorophyll,
and rigid in form. Their common method of reproduc-
tion is by cell division. With few exceptions they live
on organic materials.
Benthic. Referring to aquatic organisms growing in close
association with the substrate.
Benthos (or benthon). Aquatic microorganisms capable of
growth in close association with the substrate.
Bioassay. By using algae or other living organisms or cells,
a determination of the biological effect of a substance,
factor, or condition.
Biological. Associated with or caused by living organisms.
Biology. The field of study dealing with living organisms.
It may be divided into the study of plants (botany) and
of animals (zoology).
Blanket algae. A mass of filamentous algae floating as a
visible mat at the surface of the water.
Bloom. A concentrated growth or aggregation of plankton,
sufficiently dense as to be readily visible.
Blue-green algae. The group Myxophyceae, characterized
by simplicity of structure and reproduction, with cells in
a slimy matrix and containing no starch, nucleus, or plas-
tids and with a blue pigment present in addition to the
green chlorophyll.
Bound carbonates. The nearly insoluble monocarbonates
present in water, where a balance is maintained between
the amounts of bound, half-bound, and unbound car-
bonates.
Calibration. Determination of the dimensions of a line,
area, or mass present in an instrument such as a micro-
scope. It is accomplished by measurement with a known
scale.
Calyptra. A cap or lid on some terminal cells in certain
filamentous blue-green algae.
Capitate. Presence of a round cell at the end of a filament;
a cell with a rounded enlarged end.
Cell. The organized ultimate unit of structure and growth
of a plant or animal. It is composed of a protoplast
which, in plants, is generally surrounded by a cell wall.
Cell face. The particular surface of a cell which confronts
a person who is observing it under a microscope.
Cell sap. The watery fluid of a cell which may separate
from the gelatinous protoplasm to form one or more
vacuoles.
Cell wall. The rigid to semirigid, inert, permeable layer of
cellulose, silica, or other material which surrounds, and
is in contact with, the protoplast of plant cells. It is to
be distinguished from the flexible, selectively permeable
surface membrane (ectoplast) of the protoplast, and the
capsule, sheath, or lorica which may be outside of the
cell wall.
Centric. Refers to diatoms which are circular in form in
valve view and have radial striae.
Chlorophyll. Green photosynthetic pigment, present in
plant cells including the algae.
Chromatophore. A color-carrying body within a cell pro-
toplast.
Clean water zone. That area of water, in a polluted stream,
in which self-purification has been completed.
119
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120
ALGAE AND WATER. POLLUTION
Coagulant aid. A substance which, when added with the
coagulant to water, improves the formation of floe.
Coagulation. The agglomeration of suspended or colloidal
matter in a liquid such as water, commonly induced by
addition to the water of a floe-forming chemical.
Coccoid. Round or subspherical cells.
Colloidal. A condition involving particles dispersed in a
medium such as water which do not go into solution
or settle out.
Colony. An isolated group of cells which have developed
together from a single original parent plant or reproduc-
tive cell. Each cell is theoretically capable of life activi-
ties independent of the others.
Constricted. The surface wall of a filament curved inward
to meet the cross walls, thus leaving grooves on the
surface of the filament.
Cooling tower. An enclosure for holding water while its
temperature is decreasing. The cooling tower is part of
a system which involves absorption of heat by the water
from some heat generating apparatus or machinery.
Costae (singular, costa). Thick, rib-like striae in diatom
walls.
Cross walls. Transverse walls in a filament, dividing it into
units or cells.
Crustacea. Aquatic animals with a rigid outer covering,
jointed appendages, and gills. Included are the water
fleas such as Daphnia and the copepoda such as Cyclops.
Cubic standard unit. A volume equal to 8,000 cu microns
and used as a unit in designating the amount of plankton
in water.
Culture. A growth of microorganisms in an artificial me-
dium containing the necessary nutrients.
Desmids. Organisms belonging to the subgroup Desmidi-
aceae of the green algae and characterized by cells of
distinctive shapes one half of which corresponds in
shape, size, and contents to the other half. In many des-
mids the two semicells are connected by a short nar-
row tube (isthmus).
Diatoms. Organisms belonging to the group Bacillariophy-
ceae and characterized by the presence of silica in the
cell walls, which are sculptured with striae and other
markings, and by the presence of a brown pigment asso-
ciated with the chlorophyll.
Dinoflagellate. Motile cells having a transverse groove con-
taining two flagella.
Dissolved oxygen (DO). The amount of elementary oxygen
present in water in a dissolved state. It is commonly
reported in parts per million (by weight), or milligrams
per liter, of oxygen in the water.
Distribution system. Pipes or other conduits through which
a water supply is distributed to consumers.
Ecology. Interrelationships between organisms such as
algae and their environment.
Elliptical. Narrowly oval in form, the greatest width being
across the middle rather than nearer one end.
Enrichment. The addition to water of substances which
increase the amounts of nutrients used by aquatic orga-
nisms in their growth.
Epitheca. The slightly larger half of the two pieces of the
diatom wall. It fits as a flanged cover over the smaller
but otherwise corresponding hypotheca.
Eutrophication. The process of enrichment with nutrients
in a lake, leading to increased production of aquatic
organisms.
Eye piece (or ocular). The short cylindrical frame holding
a lens or combination of lenses, and fitting into the top
of the microscope tube.
Eye Spot. A light-sensitive, red-to-orange body within the
protoplast of a flagellate.
False branching (or pseudobranching). A lateral outgrowth
initiated by a cross breakage of a filament, followed by
the protrusion through the sheath of one or both of the
broken ends of the filament.
False raphe (or pseudoraphe). A longitudinal clear space
on the valve face of a diatom, and bounded on both
sides by lines of striae.
Filament. A linear series of cells, forming a thread, and
held together by their cell walls or sheath.
Filter. A bed of sand or related ingredients through which
water is passed to reduce the amount of solid and col-
loidal material in the water.
Filter clogging. The settling of algae, silt, and other sub-
stances from the water into the pores and on the surface
of a sand or other granular filter bed, thus reducing the
rate of flow of the water through the filter.
Filter run. The time between two successive washing
operations of a rapid sand filter.
Filter skin (or Schmutzdecke). The scum or gelatinous layer
over the top of a slow sand filter and containing various
types of aquatic microorganisms.
Filtration. The process used in water treatment plants o-
passing water through a granular medium such as sane
for the removal or reduction in amount of suspendec
or colloidal matter.
Flagellum. A microscopic whip-like extension present or
many of the motile algae and protozoa.
Flavor. An inclusive term for odor plus the tongue sensa
tions of taste, texture, and temperature of a substance
Flexible. A solid or semisolid body capable of readih
changing its shape when subjected to variations ii
external factors.
Frustule. The cell wall of a diatom.
Fungus (plural, fungi). Simple plants without chlorophyll
in a broad sense they include the bacteria, mold;
yeasts, and mushrooms. The simpler forms are one
celled; the higher forms are branching filaments.
Furrow. A groove or trench on the side of the cell c
certain flagellates.
Fusiform. A shape in which the broadest portion is in th
middle and tapers to both ends.
Gelatinous matrix. Semisolid material surrounding the ce
wall; has a characteristic shape or color in the case (
some algae.
Genus. A group (in the classification system for plants an
animals) into which are placed species that resembl
one another more than they do other species.
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Glossary
121
Girdle view. The side, rather than the front or top, view
of a diatom. It reveals the junction (girdle) of the epi-
theca and hypotheca.
Green algae. Organisms belonging to the class Chlorophy-
ceae and characterized by photosynthetic pigments
similar in color to those of the higher green plants. The
storage food is starch.
Groundwater. Water (excepting capillary water) located
below the surface of the ground, generally limited to that
below the water table.
Gullet. An internal sac-like cavity, open to the outside at
the anterior end of the cell. It is present in certain
flagellates.
Half-bound carbonates. Somewhat soluble bicarbonates
present in water where a balance is maintained between
the amounts of bound, half-bound, and unbound car-
bonates.
Hardness. Ability of water to form a curd-like scum when
soap is added and to form scale in boilers. It is caused
by presence in the water of carbonates, sulfates, and
other related substances.
Hay fever. Allergic symptoms involving the upper respira-
tory tract.
Healthy (portion of) stream. Flowing water in which the
aquatic life has not been adversely affected by human
activities such as pollution or by other relatively recent
changes in the environment.
Heterocyst. A specialized cell in certain filamentous blue-
green algae. It is larger, clearer, and thicker-walled than
the regular vegetative cells.
Heterotrophic. Referring to organisms that for their
metabolism are dependent upon organic matter supplies
from sources outside their own bodies.
Hypotheca. The smaller or bottom half of the diatom cell
wall, its upturned, flanged edge fitting inside of a cor-
responding flange of the epitheca.
Impoundment. A reservoir used for collection and storage
of a water supply and for its controlled release as
required for use.
Impurities in water. Foreign materials present in water,
particularly those impairing its usefulness.
Intercalary. Located between other structures rather than
at the end.
Katarobic zone. That area of a stream which is free of both
organic pollution and its products.
Keel. A ridge present on the valves of some diatoms.
Key. A series of paired, contrasting statements, each pair
leading to other pairs of statements and eventually
revealing the names of organisms. It is for use in the
identification of an alga or other organism.
Lateral. Refers to the side, in contrast to the ends, of the
body of an alga or other organism.
Limnology. The ecology of fresh waters.
.orica. A rigid wall-like covering around a motile cell and
separated by a space from the protoplast or cell wall. An
opening is present at the anterior end, through which
the flagellum extends.
Loss of head. A decrease in water pressure due to friction
and commonly expressed in terms of the difference in
elevations to which water will rise in open tubes.
Mat. A layer of algae, generally of the filamentous type.
The layer may be either floating on the water or cover-
ing a substrate.
Membrane. A wide, flat, thin plant body. A partition or
covering, such as the flexible, selectively permeable
outer surface film of a protoplast.
Metabolic. Referring to the building up (anabolic) and
tearing down (katabolic) processes going on within liv-
ing cells.
Micron. A unit of linear measurement appropriate for
describing the dimensions of microscopic organisms. It
is equivalent to one one-thousandth of a millimeter and
is symbolized by the Greek letter /*.
Microorganism. Any minute organism, either plant or ani-
mal, invisible or barely visible to the unaided eye.
Microscopic. An object too small to be clearly visible
without the aid of a microscope.
Mold. Any fungus, exclusive of the bacteria and yeasts,
which is of concern because of its growth on foods or
other products used by man.
Multicellular. An organism with sufficient specialization to
require more than one cell for its various growth activi-
ties.
Nannoplankton. Unattached aquatic organisms which are
so small that very high magnification with the micro-
scope is required to make them clearly visible. The mag-
nification commonly used for them is 430X to 1,200X.
Naviculoid. Having the form of a ship; pointed or wedge-
shaped at both ends, and widest at the middle.
Node. A swelling, generally occurring at equal distances
along the tube-like strands of certain algae.
Nodule. A lump on the diatom valve located at the center
or at the end.
Nonseptate. A tube-like body that is not divided by cross
partitions.
Nucleus. An organized, specialized body within the proto-
plast and containing the chromatin.
Nuisance organisms. Aquatic organisms that are capable of
interfering with the use or treatment of water.
Nutrient. A substance, such as a nitrate, absorbed by an
organism and essential as a raw material for its growth.
Ocular (or eye piece). The lens or lens combination fitted
into a short cylindric holder which, in turn, fits into the
top of the microscope tube.
Ocular micrometer. A glass disc, marked with a scale, that
fits on the diaphragm of the microscope ocular.
Odor. The property of a substance which permits pleasant
or unpleasant sensations of fragrance or smells to be
recognized.
Oligosaprobic zone. That area of a stream which contains
the mineralized products of self-purification from organic
pollution but with none of the organic pollutants re-
maining.
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122
ALGAE AND WATER POLLUTION
Opposite branching. With branches attached two per node
or at any one height on a filament, tube, or strand.
Organism. A plant or animal. A body that has developed
as a result of being alive.
Outer matrix. The sheath or other cell material outside the
cell wall.
Oxidation pond. An enclosure for sewage designed to pro-
mote the intensive growth of algae. These organisms
release oxygen that stimulates transformation of the
wastes into inoffensive end products.
Oxygenation. The absorption by water of elemental oxygen
which has been released into the water by aquatic plants
as a waste product of photosynthesis.
Parietal. Located near or against the margin. A contrasting
term, "axial."
Pennate diatom. A diatom which is elongate rather than
circular in the valve view. The wall ornamentation is
arranged along the sides of the longitudinal axis rather
than about a central point.
Peripheral. Located at the margin.
Periphyton. Attached microscopic organisms growing on
the bottom or other submerged substrates in a water-
way.
Photosynthesis. Process of manufacture by algae and other
plants of sugar and other carbohydrates from inorganic
raw materials with the aid of light and chlorophyll.
Phytoplankton. Plant microorganisms, such as certain algae,
living unattached in the water. Contrasting term: zoo-
plankton.
Pigmented. Having color, particularly that due to the pres-
ence of photosynthetic colored material in the cells of
algae and other plants.
Pigmented flagellates. Algae that are capable of swimming
and are furnished with one or more flagella. They belong
to a number of classes, including Euglenophyceae, Xan-
thophyceae, Dinophyceae, Chlorophyceae (Volvocales
only), and Cryptophyceae.
Pipe moss. A mat or mass of growth formed by aquatic
organisms that are attached to the inner surface of a
water pipe.
Plankton. Unattached aquatic microorganisms growing as
bodies dispersed throughout the water.
Plastid. A body in a plant cell that contains photosynthetic
pigments.
Pollution. Presence of foreign material in water, particu-
larly that which interferes with its use.
Polysaprobic zone. That area of a grossly polluted stream
which contains the complex organic waste matter that is
decomposing primarily by anaerobic processes.
Posterior. The hind end of the body of a swimming
organism.
Potable. Referring to water which is drinkable as a result
of being free of pathogens, toxic materials, tastes, odors,
color, and other undesirable physical, chemical, and bio-
logical characteristics.
Protoplasm. The gelatinous, colloidal material of plants and
animals in which all life activities occur.
Protoplast. The unit of protoplasm comprising one cell.
Protozoa. Unicellular animals, including the ciliates and
nonchlorophyllous flagellates.
Pseudonodule. A clear area resembling a swelling (nodule)
on a diatom wall.
Pseudoraphe (false raphe). A longitudinal clear space on
the valve face of a diatom and bounded on both sides by
striae.
Pseudovacuoles. Numerous minute bodies, resembling oil
globules, in cells of certain planktonic blue-green algae.
Their function and content are not fully determined. They
appear as black granules under high magnification.
Punctae. Pores (appearing as dots) arranged in rows (striae)
in diatom walls.
Pure culture. A growth in an artificial nutrient medium of
a single kind of microorganism and with no other kinds
of organisms present.
Pyrenoid. A body, often within a plastid, around which
starch granules are aggregated.
Radii (singular, radius). Lines extending from the center of
a circle and at right angles to tangents.
Raphe. A line (cleft) or clear space extending lengthwise on
the valve surface of a diatom. See true raphe and false
raphe.
Rapid sand filter. A bed of sand for water treatment con-
structed to permit a rapid rate of flow of water through
it. The rate is commonly from 2 to 3 gal/min/sqft of
filter surface.
Raw water. Water which is available as a supply for use
but which has not yet been treated or purified.
Reaeration. Contact of air with water permitting absorption
of oxygen into the water from the air.
Recovery zone. The area of a stream in which active, pri-
marily aerobic, decomposition of pollutants occurs.
Red algae. A class of algae (Rhodophyceae) most members
of which are marine. They contain a red pigment in
addition to the chlorophyll.
Red tide. A visible red to orange coloration of an area ol
water caused by the presence of a bloom of certair
armored flagellates.
Reservoir. A basin, lake, pond, tank, or impoundmen
which is used for control, regulation, and storage o
water. It may be either natural in origin or created b}
the building of a dam or retaining wall.
Resting spore. A specialized, thick-walled reproductive
cell, capable of dormancy and of germination, withou
sexual fusion, to form a new plant.
Rhodophyceae. A class of algae popularly called "re<
algae." The cells contain a red pigment in addition to thi
chlorophyll. Mostly marine forms.
Rigid. Fixed, nonflexible.
Rotifer. A microscopic aquatic animal with a ciliated crowi
attached to its head. The cilia give the appearance c
moving in a regular procession around the rim of th
crown.
Sand filter. A bed of sand through which water is permitte
to pass to reduce the amount of silt, plankton, colloid;
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Glossary
123
material, and related substances that were present in the
water. It is in common use in water-treatment plants.
Saprophytic. The capability by some plants, including cer-
tain bacteria and molds, of utilizing dead organic matter
as nutrients.
Schmutzdecke. A German term for filter skin; the gelat-
inous layer over the top of a slow sand filter and con-
taining various types of aquatic microorganisms.
Sedgewick-Rafter method. A procedure for the quantitative
determination of plankton in water, involving the use of
a special funnel and a special counting slide.
Sedimentation. A phenomenon used in water and sewage
treatment in which the rate of flow of the water is re-
duced or stopped, permitting the settling out by gravita-
tion of the suspended particles.
Semicell. One of the two half-cells of the desmid, the two
halves frequently connected by an isthmus.
Semirigid. Capable of limited change in form.
Septum. A cross wall of a filament. A complete or incom-
plete internal wall of a diatom.
Sewage. The spent water supply after it has received the
various household, industrial, and other wastes of a
community.
Sewage treatment. Any artificial process to which sewage
is subjected in order to remove or reduce its objectional
constituents.
Sheath. A covering, usually of mucilage, of one or more
cells or of a colony. It may be hard and wall-like or soft
and transparent.
Slow sand filter. A bed of sand for water treatment con-
structed to permit water to flow through it at a relatively
slow rate. The rate is commonly from 3 to 6 million
gal/day/acre of filter surface area.
Stabilization. Biological transformation of organic wastes
into more durable metabolic end products.
Stabilization pond. An enclosure for sewage designed to
promote the intensive growth of algae. These organisms
provide oxygen that stimulates transformation of the
wastes into inoffensive end products.
Strand. A cylindrical, stem-like plant body that is more
than one cell thick.
Striae. Lines of pores (appearing as dots) arranged in a
regular pattern in the walls of diatoms.
Subspherical. Almost spherical.
Substrate. The substance or base upon which an organism
grows.
Surface water. Water that rests upon the surface of the
earth in contrast to groundwater.
Symmetrical diatom. Correspondence in shape, size, and
relative position of parts of the two longitudinal or trans-
verse halves of a diatom.
Taste. A type of sensation (such as sweet or bitter) that the
tongue recognizes in addition to the texture and tem-
perature of a substance.
raxonomic. Emphasis on the classification and identifica-
tion of organisms.
rhallus. The plant body of an alga or fungus, composed of
one or more cells.
Threshold odor number. A unit designating the intensity
of odor in water as determined by its perception in a
series of dilutions with odor-free water.
Tolerance. Relative capability of algae or other organisms
to endure or adapt to an unfavorable factor.
Tongue sensation. The feel or texture that the tongue
registers when in contact with water containing various
solutes. This is in addition to the sensations of taste and
temperature.
True branching. An elongated lateral growth initiated by
the longitudinal division of a marginal cell or cells in a
filament or strand.
True raphe. A slit (appearing as a line) extending almost
the length of the valve face of a diatom and interrupted
in the middle by a nodular area. The raphe is bounded
by a clear area which, in turn, is bounded by striae.
Tube. A thread-like plant body, one cell wide, that is not
divided into segments by cross walls.
Unbound carbonates. The soluble carbonic acid present
in water where a balance is maintained between the
amounts of bound, half-bound, and unbound carbon-
ates.
Unialgal culture. A growth of only one kind of alga in an
artificial nutrient medium, but not necessarily free of
other types of microorganisms such as bacteria and pro-
tozoa.
Unicell. An organism composed of an isolated single cell.
Unicellular. One-celled.
Unsymmetrical diatom. Lack of correspondence in shape,
size, and relative position of parts in the two longitudinal
or transverse halves of a diatom.
Vacuole. An area within a protoplast which contains a
liquid such as cell sap or oil.
Valve view. The top surface, rather than the side, of the
epitheca or hypotheca of a diatom.
Water mites. Small, sometimes microscopic aquatic orga-
nisms with a more or less round unsegmented body and
with four pairs of legs and one pair of palpi (processes
attached to the mouth).
Water quality. Those characteristics of a supply of water
which are important in determining its purity and use-
fulness to man.
Water table. The surface of a body of groundwater when
its level is not confined by any overlying impermeable
layer of rock or soil.
Whipple micrometer. A subdivided square, marked off on
a glass disc, that fits into the microscope ocular. At a
magnification of 100X, in many microscopes, the square
covers approximately 1 sq mm of the microscope field.
It is designed for use in plankton counting.
Whorled branching. More than two branches per node or
at any one height on a filament or strand.
Yeast. Unicellular fungi which in general commonly repro-
duce by budding, and ferment one or more carbohy-
drates with the production of gas.
Zooplankton. Protozoa and other animal microorganisms
living unattached in water.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/9-77-036
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
ALGAE AND WATER POLLUTION
5. REPORT DATE
December 1977 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
C. Mervin Palmer
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
1BC611
Kendal at Longwood, Box 220
Kennett Square, PA 19348
11. CONTRACT/GRANT NO.
68-03-0232
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory--Cin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final 1973-1976
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Revision and expansion of Dr. Palmer's manual Algae in Water Supplies
16. ABSTRACT
Algae are involved in water pollution in a number of important ways. It requires
a continuous monitoring and study of algae existing in waters of various quality in
order to determine what controls or what changes or what uses can be instituted for
the benefit of man and for conservation of water and of desirable aquatic life.
This manual presents a simplified identification key limited to algal species
of importance in water supplies and associated with pollution. The most important
species are illustrated in three-dimensional drawings in color. The manual also
deals with the ecology and significance of algae and presents information on filter
clogging and mat forming algae, attached forms, algicides and algal control, algae
associated with pollution (both fresh water and estuarine), various uses of algae,
algae of rivers and lakes, eutrophication, algae as indicators of pollution,
methods of recording algae, and the use of algae in waste stabilization lagoons
for the treatment of domestic and/or industrial wastes.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
Algae*
Water pollution*
Identification*
Illustrations*
Fresh water
Estuaries
Systematic key
Colored
13B
06C
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
132
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
124
S GOVERNMENT PR IN T I NG OFFIC E 1978-760 318
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