oEPA
United States
Environmental Protection
Agency
Environmental Research
Laboratory
Corvallis OR 97330
EPA 600 3-79-074
July 1979
Research and Development
Lake and Reservoir
Classification
Systems
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RESEARCH REPORTING SERIES
Research reports o? 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 report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-79-074
July 1979
LAKE AND RESERVOIR CLASSIFICATION SYSTEMS
Editor
Thomas E. Maloney
Freshwater Division
Corvallis Environmental Research Laboratory
Con/all is, Oregon 97330
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330
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DISCLAIMER
This report has been reviewed by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or recom-
mendation for use.
ii
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FOREWORD
Effective regulatory and enforcement actions by the Environmental Protec-
tion Agency would be virtually impossible without sound scientific data on
pollutants and their impact on environmental stability and human health.
Responsibility for building this data base has been assigned to EPA's Office
of Research and Development and its 15 major field installations, one of which
is the Corvallis Environmental Research Laboratory (CERL).
The primary mission of the Corvallis Laboratory is research on the ef-
fects of environmental pollutants on terrestrial, freshwater, and marine
ecosystems; the behavior, effects and control of pollutants in lake and stream
systems; and the development of predictive models on the movement of pollut-
ants in the biosphere.
This report contains a series of articles dealing with the trophic class-
ification of lakes and reservoirs. The papers discuss the history of these
systems and their present day use.
James C. McCarty
Acting Director, CERL
iii
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ABSTRACT
The problem of eutrophication of waters, initially recognized in only a
few countries, was brought into the wide forum of the Organization for Eco-
nomic Cooperation and Development (OECD) in 1967 to be dealt with by inter-
national cooperative action. The first stage was initiated in 1967 with an
overall synthesis of existing knowledge concerning eutrophication. The second
stage consisted of an overall evaluation of eutrophication control strategies,
taking into account their effectiveness, cost and feasibility. In the early
1970's, when it was clear that only an intensive international effort could
produce the needed progress in a reasonable time, a task force working on this
problem came to the conclusion that the experience needed could only be ob-
tained by the close coordination of Member countries. Therefore, in 1973 the
OECD established a Cooperative Program on the Monitoring of Inland Waters for
Eutrophication Control. Eighteen member countries became involved in four
coordinated Regional Projects - Alpine, Nordic, Reservoirs and North American.
Canada and the United State made up the latter.
The main objectives and expected results from the program were:
to obtain a realistic scheme of the development of eutrophication,
in extent and intensity in Member countries and to assess its
spreading rate in various cases.
to better understand the causes and conditions of its development,
which is a prerequisite in taking adequate corrective measures
against the responsible pollutants.
to provide widely applicable guidelines and correlations which will
permit the adoption of control measures of the right order, at the
right time and the right place, thus making their cost/effectiveness
far more satisfactory.
It was recognized early that there was a need to define more precisely
the classical categories of oligo-, meso- and eutrophy. There is no clear
delineation between trophic divisions and often different investigators would
categorize the same body of water as having a different trophic state, depend-
ing to a great extent on their personal experience and on the area where they
live. Recognizing the need for a more quantitative basis for classifying a
l.ake, investigators turned their attention to developing a more quantitative
framework based on correlating variables that reflect lake productivity which
can be expressed in numerical terms.
This report contains the efforts of several of the United States investi-
gators relating to their approaches to the classification of lakes in numeri-
cal terms and represents a part of the United States contribution to the North
American portion of the OECD program.
iv
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CONTENTS
Page
Foreword iii
Abstract iv
A Review of the Philosophy and Construction of Trophic State Indices
Robert E. Carlson 1
The Current Status of Lake Trophic Indices -- A Review
Joseph Shapiro 53
TSI and LCI: A Comparison of Two Lake Classification Techniques
Paul D. Uttormark 101
Trophic Indices and Their Use in Trophic Classification of Lakes
and Reservoirs of North Carolina
Charles M. Weiss 141
A Review of Trophic State Indices For New York State
William R. Schaffner and Ray T. Oglesby 213
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A REVIEW OF THE PHILOSOPHY AND CONSTRUCTION
OF TROPHIC STATE INDICES
Robert E. Carlson
Department of Biological Sciences
Kent State University
Kent, Ohio 44242
INTRODUCTION
The concept of trophic state has been reviewed and discussed many times,
yet the meaning of the concept is still not generally agreed upon. There are
basically two aspects of the concept:
1. It has to do with either supply of nutrients coming into a lake or the
concentration of these nutrients once in the lake. The larger the supply
or concentration, the more eutrophic the lake will be.
2. It has to do with the biology of the lake, either its productivity or
biological structure. The higher the productivity or standing crop, the
more eutrophic the lake.
A compromise view is that trophic state is a multi-variate concept,
incorporating aspects of both nutrients and biology. All three views have
strong philosophical and historical arguments supporting their acceptance.
Interjected into this rather academic argument on the nature of trophic
state is the pressing need to communicate with the public and its governments
concerning the fate of rapidly eutrophying lakes and reservoirs. By communi-
cation I mean the ability to describe the present condition of the lake and
its possible future condition in a simple, straight forward manner that can be
understood easily by the layman. The trophic concept seems ideally suited for
this purpose because in its most basic form "oligotrophic" could mean a clear
lake with many desirable recreational characteristics, and "eutrophic" could
mean a lake with dense algal or macrophyte communities. It is evident that
these terms are already being extensively used in applied limnology. Clearly
defined limits to oligotrophy and eutrophy become far more important when the
terms are to be used as an applied tool rather than an academic discussion.
Unambiguous limits must be set and relationships defined.
The need to be able to classify lakes has long been recognized. Often
the various definitions of trophic state are so inclusive that to measure all
aspects in the concept would be virtually impossible. To simplify the task of
classification, often indicators or indices are used to determine the trophic
state. Used singly or taken as a group average, these indicators have pro-
vided a means for rapid classification without resorting to complex and time-
consuming analysis of all the components of the lake system.
There are fundamental differences as to how these indices are constructed
depending on whether the trophic concept is perceived as a series of "types"
or whether one perceives it as a point on a continuum. These perceptions of
the trophic concept are illustrated in Figure 1.
1
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Naumann (1919) perceived lakes as falling into distinct
classification groups or types of which oligotrophic and eutro-
phic were only two of many possible types. He apparently recog-
nized that there was variation within the groups but that there
were standard lake types about which these variants could be
grouped. In many respects it is similar to the "type species"
used in taxonomy. In this instance, although variation is
acknowledged to exist among individuals of a species, there is
a classification group (i.e., the species) into which these
individuals are placed. It is considered that the variation
among individuals of the same species is less than the difference
among individuals of different species. The type specimen, the
one or two individuals which serve as standards for characteris-
tics of the species, is similar in concept to the standard
attributes which are used to characterize eutrophic and oligo-
trophic lakes.
In contrast to this typological view, the trophic concept
can be viewed as reflecting the attributes of a continuum. Pro-
ponents of this view would argue that there are no distinct tro-
phic "types" of oligotrophic and eutrophic, but a continuous and
infinite variety of trophic possibilities ranging from those with
the general attributes of oligotrophy to those with the general
attributes of eutrophy. Trophic states are recognized along this
continuum, but the number and location of the states are arbitrary.
Viewing the trophic concept as a series of types has resulted
in limits being set to mark the range of values found for each
state. Typological limits can often be recognized by their over-
lapping nature, as the range of values for a given trophic state
may overlap considerably with the values of other states. Exam-
ples of limits of this type are given by Likens (1975) and Wetzel
(1975). The problem with these indices is that they are of little
help in classification. In the range of overlap the lake could be
in either of two conditions, and the index cannot discriminate
between the two. Instead of a single indicator, typological clas-
sification requires the use of several indicators in order to
ascertain trophic status. If the proper criteria could be agreed
upon, then some sort of cluster analysis could be used to facilitate
classification. Shannon and Brezonik (1972) used such a technique
to group 55 Florida lakes, and Sylvester and Hall (1974) used clus-
tering techniques to develop a classification for Maine lakes.
The continuum trophic concept has also produced recommenda-
tions for trophic state limits, but these can be generally recog-
nized because they are non-overlapping. The continuum concept
results in other notable attributes:
1. As trophic states are considered to be arbitrary
divisions of the trophic continuum, a limitation
to two or three classification units (trophic
states) seems unnecessary. Some lakes must be
considered more eutrophic than others, and group-
ing them together results in a loss of information
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TYPOLOGICAL TROPHIC CONCEPT
Mesotrophy
K- -H
Trophic State
CONTINUUM TROPHIC CONCEPT
Oligotrophy
Eutrophy
k-
Trophic
State
Figure 1. An illustration of the differences between the
typological and continuum views of the trophic
state concept.
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about the lakes. Because of this, sensitivity to
change in trophic status becomes an important con-
sideration. Two or three classification units are
sensitive only to the grossest changes. Indices re-
flecting the continuum concept tend to recognize more
nomenclatural classification groups (e.g., Vollen-
weider, 1968) or become numerical.
2. The processes or factors that are considered to be
fundamental to the trophic concept must also be of
a continuous rather than of a discontinuous sort.
Indicators based on the presence or absence of cer-
tain attributes would be of little use, and the
indicators used tend to be of a continuous nature.
For example, orthograde vs. clinograde oxygen curves
might be replaced with rate of hypolimnetic oxygen
depletion, and Tanytarsus vs. Chironomus attributes
might be replaced with indices of relative species
abundance.
3. Unless all aspects of the concept of trophy are
highly correlated and change along the trophic con-
tinuum at the same rate, lakes may still be classi-
fied differently depending on the criteria used.
Solutions to this problem include the minimization
of the number of criteria used in the classification,
the correlation and transformation of all the cri-
teria to the same basis, or the averaging by one
technique or another of the disparate trophic values
in order to obtain an average trophic state value.
This paper will largely deal with indices related to the
continuum trophic concept. This emphasis is because of my own
view that the continuum-type indices appear to be the most
promising of producing a simple yet comprehensive measure of
trophic status.
Five basic types of indices will be examined in this paper:
typological indices, single-variable indices, multi-variable
indices, external loading indices, and indices related to primary
productivity, an often used trophic state criterion. The intent
of the paper is to compare the construction and underlying assump-
tions of these indices and, where possible, describe quantitatively
the relationships among the indices. It is hoped that this review
can serve as a guide to persons in choosing an index to use or in
constructing their own.
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A SINGLE VARIABLE INDEX
Comparison and correlation of the many indices is difficult
because each utilizes different variables for the determination
of trophic state. Some indices use as many as five or six para-
meters while others use only one. Some use transparency, others
use chlorophyll, while others use nutrient concentration. Even
if one could compare the indices by using all the indices on the
same series of lakes, the value of such a comparison is limited
because there is no trophic standard to which the indices can be
compared. In other words, one cannot answer the question, "Which
index best reflects trophic state?", because the current standards
are set up for only two states, eutrophic and oligotrophic, and
there are few, if any, unambiguous trophic criteria even for
these two states. In the absence of unambiguous trophic standards,
the indices can only be compared amongst themselves.
The comparison was done using the index of Carlson (1977) as
the basis for the comparison. This index is based on the amount
of algal biomass present In the surface waters. The index con-
sists of a numerical trophic scale which encompasses most lakes
within values of zero to 110. The scale is based on a Iog2 trans-
formation of the amount of algal biomass as measured by Secchi
disk transparency. The result is a scale where each 10 units
represents a doubling in algal biomass.
Other trophic parameters which are known to correlate with
transparency (at present chlorophyll and total phosphorus) can be
also used to calculate the index using regression equations which
have also been transformed to logo values in the same manner as
was transparency. The index equations are shown in Table 1. In
effect, any of the three parameters can be used independently to
calculate the index value. Because of this, any other index that
utilizes transparency, chlorophyll, or total phosphorus can be
compared with the Carlson index.
According to Carlson (1977) the advantages of this numerical
index are several. Its large number of trophic classes suggests
potential for being sensitive to trophic change. The major tro-
phic divisions are not arbitrary, however, as they represent
doubling in algal biomass. The possibility of using any of three
indices allows a parameter to be chosen that best fits the cir-
cumstances in a particular lake, as well as allowing the number
of parameters measured to be minimized. The scale is absolute
rather than relative. This means that the scale is not limited
to lakes within the original data base. One end of the scale (0)
is beyond all values reported in the literature. The other end
is actually open-ended. By coincidence, however, few lakes have
an index greater than 100, and the mean index value, at least in
Minnesota lakes, appears to be between 40 and 50 (Shapiro, et al.,
1975). As these trophic parameters have a skewed distribution,
the logarithmic transformation apparently is responsible for the
normal distribution observed.
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Table 1. The equations used for calculating
the trophic state index values of
Carlson (1977).
Using Secchi disk transparency (ra)
TSI = 60 - 14.41 In SD
Using Chlorophyll (rag/m^):
TSI = 9.81 In Chi +30.6
o
Using Total Phosphorus (mg/m ):
TSI = 14.42 In TP + 4.15
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As the index utilizes total phosphorus as one of the vari-
ables, it can be coupled with predictive nutrient loading equa-
tions, allowing prediction of changes in trophic state after
changes in nutrient loading.
Brezonik (1976) criticized the Carlson index on several
points. He considered that its simplicity actually detracted
from its utility. He suggested that a multi-variate approach,
which reflects a greater breadth of the trophic concept, is more
useful for management purposes. He suggested that an averaging
of the values might be more appropriate.
This concern with the breadth of the trophic concept that
would be incorporated in an index is a major concern of this
review. The Carlson index only measures open-water nutrient and
biological variables. Brezonik and others have suggested that
the trophic concept is multi-dimensional. The question of whether
these multi-dimensional indices actually measure a greater pro-
portion of the trophic concept will be discussed later. At this
point in the discussion this index serves as an example of a
single-variable index measuring one aspect of the trophic concept.
Its advantage is its simplicity. Whether this simplicity is also
a drawback will be discussed later.
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THE CLASSIFICATION OP OLIGOTROPHY AND EUTROPHY
The terms "oligotrophic" and "eutrophic" are not only classi-
ficatory terms but are also terms describing certain attributes
of lakes. As a description of attributes these terms essentially
serve as two points that can be correlated against the trophic
continuum.
In the same manner as transparency, total phosphorus, and
chlorophyll have been shown to change in relation to the trophic
continuum, the relationship of hypolimnetic oxygen concentration,
phytoplankton species or fish species to the continuum could po-
tentially be examined. At some point on the continuum these
attributes will have values which would coincide with the tra-
ditional idea of oligotrophy, and at some other point the values
will coincide with the traditional idea of eutrophy.
Many authors have given their opinions of what they consider
to be the limits of oligotrophy and eutrophy in reference to
various variables, both biological and chemical. In essence,
they have been comparing single variables against their own con-
ception of oligotrophy and eutrophy. By reversing this order of
thought and utilizing the variables used in the Carlson index,
it is possible to locate on that scale the limits of oligotrophy
and eutrophy.
The trophic limits for values of total phosphorus, chloro-
phyll, and transparency that have been suggested by several authors
are given in Table 2. The corresponding Carlson trophic state
index (TSI) values are also given. The upper limits suggested for
oligotrophy and the lower limits suggested for eutrophy are re-
markably similar among the various authors. The similarity sug-
gests that the changes in trophy are distinct enough that they
can be recognized consistently. The mean TSI value for the upper
limit to oligotrophy is 41 with a standard deviation of 5-75 while
the mean TSI value for the lower limits of eutrophy is 51 with a
standard deviation of 7.61. This means that the two most identi-
fiable lake types are separated by only a single doubling in the
amount of algal biomass in the lake which is brought about by a
doubling in phosphorus concentration in the open water.
Of the whole range of possible locations for these two dis-
parate trophic types, they are located within one doubling of
algal biomass. How could all these changes take place with such
a small change? Several possibilities are possible.
1. To some extent the average trophic limits may mis-
represent the changes in individual lakes. For any
given lake the changes in trophy may take several
doublings of biomass to effect the change from
attributes of oligotrophy to eutrophy.
8
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TABLE 2 A comparison of the trophic limits to oligotrophy and eutrophy as
suggested by several authors. The data is transformed using the
index of Carlson (1977) to provide a uniform basis for comparison.
Author,
Parameter
OLIGO- MESO-
OLIGOTROPHIC MESOTRQPHIC MESOTROPHIC EUTROPHIC EUTROPHIC
Sakamota (1966 a,b)
Chlorophyll
TSI
Total Phosphorus
TSI
Vollenweider (1965)
Total Phosphorus
TSI
Vollenweider (1968)
Total Phosphorus
TSI
Vollenweider (1976)
Total Phosphorus
TSI
Wetzel (1975)
Chlorophyll
TSI
Brezonik (1976)
Chlorophyll
TSI
Transparency
TSI
Total Phosphorus
TSI
Vallentyne (1969)
Chlorophyll
TSI
Transparency
TSI
Nat.Academy of
Science (1972)
Chlorophyll
TSI
Dobson (1974)
Chlorophyll
TSI
EPA Survey (1974)
Chlorophyll
TSI
0.3-2.5
(19-40)
2-20
(14-47)
<37
5
(27)
10-20
(37-47)
5-10
(27-37)
(<37)
0.3-3
(19-41)
1.3-3.2
(33-42)
6.25-3.12
(34-44)
10-18
(37-46)
>5
(46)
>6
(<34)
<4
(<44)
<4.3
(<45)
<7
(50)
1-15
(31-57)
10-30
(37-53)
20-50
(47-61)
10-20
(37-47)
2-15
(37-57)
1.8-9
(36-52)
4.6-1
(38-60)
11-52
(39-61)
5-10
(46-53)
3-6
34-44)
4-10
44-53)
4.3-8.8
(45-52)
7-12
(50-55)
50-100
(61-71)
10-30
(37-53)
5-140
(46-79)
10-90
(37-69)
>100
30-100
(53-71)
>20
(>47)
10-500
(53-92)
3.5-93
(43-75)
1.52-.22
(59-82)
30-900
(53-102)
(>53)
<3
(>44)
(>53)
>8.8
(>52)
(>S5)
Total Phosphorus <10
TSI (<37)
Transparency >3.7
TSI C<41)
10-20
(37-47)
3.7-2.0
(41r50)
>20
(>47)
<2.0
(>50)
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2. The characteristics that observers use to delimit
trophic state may be those that change suddenly
around TSI values of 40-50. I doubt that trophic
state is commonly decided by measuring the concen-
trations of phosphorus and chlorophyll. The changes
in the lake are not so subtle as to require such
sensitive techniques. Between TSI values of 40-50
transparency is halved from four to two meters.
Such a change should be easily noticeable. It may
be also that in this range many lakes become
anaerobic in the hypolimnion. Such a noticeable
change might strongly affect the determination of
trophic state.
3. Rather than a statistical artifact or a subconscious
weighting of trophic criteria, it may be that there are
sudden, discontinuous events occurring as a lake
eutrophies that rapidly shift it from one state to
the other. The most obvious possibility is the loss
of oxygen in the hypolimnion. As the bottom waters
become anaerobic there are dramatic changes in fish
species and bottom fauna. There are also large re-
leases of phosphorus from the sediments as the iron
complexes are reduced. These releases may change the
hypolimnetic phosphorus concentration by ten-fold or
more. Such a change could potentially change the
phosphorus concentration of the epilimnion and thus
change the algal biomass as was suggested by Mortimer
(1941). If this were the mechanism for the rapid
changing of trophic state, then there would be rela-
tively few lakes having trophic index values between
40 and 50. However, Shapiro et al. (1975) found that,
in Minnesota, of 80 lakes measured, the largest number
was in the TSI 40-50 range.
Whatever the reason for the small distance on the trophic
scale between oligotrophy and eutrophy, it emphasizes several
aspects of the study of trophic state. The study of the changes
in lakes with eutrophication has apparently been limited to only
a small portion of the total trophic possibilities. Have we been
too limited in our scope of investigations into trophic changes?
Are there other changes, perhaps not so pronounced, that occur at
other places in the trophic spectrum that remain undiscovered?
Is eutrophication (or oligotrophication) a discontinuous
process? Do lakes suddenly change from oligotrophic to eutro-
phic? Is the change equally suddenly reversible? The evidence
presented suggests that the study of the mesotrophic lake (TSI
40-50) may be extremely important to our understanding of lake
dynamics. The answers to the above questions may have signifi-
cant implications in lake management.
10
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EXTERNAL CLASSIFICATION SYSTEMS
An important observation of Nauman (192?) was that lake types
tended to correlate with the geological structure of the water-
shed. "General eutrophy" dominated in regions of Sweden that were
flooded by the sea after the glacial period and in regions of cal-
careous moraines. In regions of primary rocks and moraines com-
posed largely of primary rocks, "general oligotrophy" dominated.
Although Nauman used this relationship between geology and trophy
to emphasize the importance of the study of regional limnology,
the relationship also emphasizes the importance of the watershed
in the determination of trophic status of the lake.
Hutchinson (1969) suggested that instead of classifying water
types, the watershed-lake-sediment system should be classified. A
eutrophic system would be a system in which the total potential
concentration of nutrients is high. It is possible, according to
Hutchinson, that an oligotrophic lake might exist in a eutrophic
system if the nutrients were tied up in a form or system component
where they were unavailable to the organisms in the lake.
This approach to trophic classification has the advantage
that it is independent of the many biotic and abiotic factors that
may affect the general biological structure of the lake. In
theory at least, it would free the trophic concept from both the
historical and technical encumbrances that have frustrated the
development of simple, uniform classificatory techniques. It also
serves to broaden our scope to include the watershed as an impor-
tant factor in influencing of the chemical and biological structure
of lakes. It implies that the proper unit of study is the water-
shed rather than the lake alone (Odum, 1969).
This emphasis on the watershed-lake system is implicit in
the recent work on nutrient loading models. The measurement of
nutrient export from the watershed could be considered an index
of the potential trophic status system of Hutchinson (1969)- Beeton
and Edmondson (1972) distinguish between oligotrophy and eutrophy
of a lake by the amount of nutrients supplied by the watershed.
They again regard supply as a better indicator of trophic status
than internal measurements because of the uncertainty as to how
the nutrients will be used once in the lake.
Specific nutrient loading (gm nutrient/m2 of lake surface/
year), proposed by Vollenweider (1968), has become a standard term
for nutrient loading. The now-famous graphs of specific loading
versus mean depth (Vollenweider, 1968), of loading versus mean
depth divided by mean hydrologic residence time (Vollenweider,
1975), and mean inflow concentration versus hydrologic residence
time (Vollenweider, 1976) have often been used to classify lakes.
11
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It is sometimes bewildering why people would go to the effort and
expense to construct a nutrient budget, place a single point on a
graph, and then point out that the point's location on the graph
definitely shows that the lake is eutrophic, when much simpler
internal trophic standards are available.
Two reasons for the use of the graphical classification can
be suggested. The graphs provide a recognized and quantitative
method of external lake classification. The graphs are producing
a predicted mean phosphorus concentration. This concentration is
compared against trophic limits which have been previously estab-
lished (10 and 20 mg/m3 total phosphorus). The lakes then are
actually being classified by the "potential" or predicted concen-
tration. Internal factors, other than water residence time, that
might modify that concentration are ignored.
A second possibility for the popularity of such graphs is
that they provide a visual representation of the lake's trophic
status in reference to the trophic limits of oligotrophy and
eutrophy. The distance from those limits by that single point
is an effective indicator of the degree of its trophic status.
The graphs are an exceptionally effective method of communica-
tion, especially with laymen. In instances where lake restora-
tion by nutrient income abatement is being proposed, it is pos-
sible to demonstrate the effect on trophic state of the predicted
diversion.
In 1968, Vollenweider also set tentative limits between
oligotrophy and eutrophy based on specific loading of 0.2-0.5
gm total p/m^/yr and of 5-10 gm total N/m2/yr. Since then, the
use of specific loading alone as an index or standard of trophic
state has been criticized because it incorporates the effects of
both nutrient and water loading (Kerekes, 1975; Dillon, 1975).
Because of this, nutrient incomes consisting of low nutrient con-
centrations but high water inputs could have higher specific
loading values than others having high nutrient values but low
water discharge. An alternate term was introduced by Vollenweider
(1975) to adjust for this hydrologic interference. Termed "average
inflow concentration," the term is actually specific nutrient
loading (Ls) divided by the specific hydrologic discharge from
the lake (qs). Vollenweider's average Inflow concentration is
not the actual incoming concentration as qs does not include the
water loss by evaporation. Carlson (1977) suggested that the
actual mean incoming concentration (Cj) would be useful as a
trophic index. Mean incoming concentration is the concentration
of water as it enters the lake and is defined as
GI = J/Qj
Where:
J = the total nutrient loading (Kg/time)
= the total inflow of water (m3/time)
12
-------
This formulation weighs the actual nutrient concentration from each
source by its relative contribution of water to the total discharge
entering the lake.
The average inflow concentration of Vollenweider (1975) is
related to Cj by the fraction of water lost from the lake by
evaporation.
Ls/qs = GJ (Q!/QO)
Where:
Qo = the total loss of water by means other than evaporation
Mean incoming concentration (Cj) can be used as an external
index of trophic state in several ways:
1. It can be used to classify individual streams and
rivers in order to provide a regional aspect to
the trophic nature of watersheds.
2. It can be used Instead of export "values to classify
the effect of different land uses on nutrient release.
Export values, expressed as Kg nutrient/area/time
suffer the same drawback as specific loading, i.e.,
they incorporate both nutrient and a water loading
into a single value. It may be that although runoff
may vary regionally, that there is considerably less
variation in nutrient concentration for a specific
land use. If this were the case, then changes in a
watershed's Cj could be predicted based on estimated
changes in land use.
3. Mean incoming concentration can also be used to index
the concentration of nutrients entering a specific body
of water. As changes in the concentration of nutrients
entering lakes are a primary cause of eutrophication,
Cj serves as the direct index of these changes.
A major advantage of external trophic classification by means
of incoming concentration is that it could classify a stream, river,
lake, reservoir, or bog. The system could be used in areas where
standing bodies of water are non-existent, yet where the condition
of rivers is a major concern.
External classification does have several disadvantages. The
word "nutrient" includes a large number of elements, any one of
which could potentially be classified. Separate classifications
for all the major and minor nutrients is clearly impossible. At
present, classification appears to be based on the concept of the
limiting nutrient. Phosphorus is often used in loading models
because it Is thought to often be the limiting nutrient. However,
Castle Lake, California is limited by molybdenum (Goldman, I960)
13
-------
and Clear Lake, California is limited by nitrogen (Horne and Gold-
man, 1972). Would separate classifications be made up for each
lake limited by different elements? Implied in the use of the
limiting nutrient concept is knowledge that the biological struc-
ture within the lake is limited by a nutrient. Thus, measure-
ments must be made within the body of water prior to classification,
a clear violation of the intent of external classification.
It may be that Hutchinson's trophic system can be no better
defined nor more easily measured than the trophic concepts based
on within-lake measurements. If this is so, then it might be that
the classification of the watershed system would also require the
use of an index incorporating only a few "indicator" nutrients.
The graphs of Vollenweider (1968, 1975, 1976) or the various nu-
trient loading models that have been proposed might act as external
indices once suitable criteria are established within the lake
(such as Vollenweider's use of 10 and 20 mg/m3 of total phosphorus).
The internal nutrient concentration estimated by the use of the
graphs or nutrient models could be used as a basis for classifica-
tion regardless of the actual concentration found in the lake.
This method would have the advantage suggested by Hutchinson (1969)
and Beeton and Edmondson (1972) of disregarding the internal
dynamics of the lake and concentrating -on its "potential" trophic
state. Such a classification system might be particularly useful
in lakes deviating from the "normal" lakes considered in the
establishment of the trophic criteria, i.e., those that are
either not large, not deep, or not dominated by planktonic growth
forms.
The advantage of the external classification is also its dis-
advantage; it does not classify the lake. Because of internal
modifications, there may be large divergences between predicted
trophic state and observed. If the predicted concentration gives
a mesotrophic classification, yet because of internal loading
there are extensive beds of macrophytes changing the actual lake
condition to eutrophic, of what use is the external classifica-
tion to the cottage owner?
External nutrient loading is presently a viable method for
trophic classification. The models available use total phos-
phorus as the sole parameter for classification, and classifica-
tion is based on a comparison of the predicted internal nutrient
concentration to internal phosphorus concentrations. The most
developed system of this kind is the graphical classification of
Vollenweider (1976). The advantages of such a system are:
1. It emphasizes the importance of external factors on
the internal dynamics of a lake.
2. It rapidly indexes the effects of changes in land
use or nutrient diversion.
3. It avoids problems of the fate of nutrients once
they enter the lake.
14
-------
The disadvantages of the system are:
1. It assumes that nutrients, most often, only phosphorus,
are the limiting factor in the lake. Other possibilities
such as light or temperature are ignored.
2. It is based on a specific nutrient loading model which
assumes, among other things, a completely mixed basin,
a constant sedimentation rate, no sediment nutrient re-
lease, and equal biological activity for all forms of
incoming phosphorus. The model used, however, could
be modified to suit the particular lake that was to be
classified.
3. The system may not be sensitive to the actual condi-
tions within the lake, and therefore, would make it
difficult to use as a tool in classification with the
use-oriented public.
4. The system requires a great deal of data over at least
a year, making it a very expensive classification
system.
15
-------
PRIMARY PRODUCTIVITY AS A TROPHIC INDEX
Productivity, especially primary productivity, has been the
fundamental measurement and index of trophic state since its con-
ception by Naumann in "1919. Oligotrophic lakes are defined as
having low productivity and eutrophic lakes by high productivity.
Rodhe (1969) defines trophy of a lake as "the intensity and kind
of its supply of organic matter."
Primary productivity is commonly reported on an areal basis
(gm/m2) and on either a daily or annual basis. The range of
values for daily areal productivity during the summer range from
less than 35 mg/m2/day in Char Lake, N. W. T. (Kalff and Welch,
197*0 to values higher than 8000 mg/m2/day (Vollenweider, 1968).
Several ranges of areal productivities have been established for
Oligotrophic and eutrophic lakes (Table 3).
Although for theoretical reasons primary productivity may
appear to be the ideal standard for trophic state determinations
(Vollenweider, 1968), it has been under increasing criticism for
a number of reasons. These reasons include problems of tech-
nique, insensitivity, and non-agreement with other trophic
parameters.
Two common methods are employed to measure primary produc-
tivity. The measurement of oxygen released during photosynthesis
is a relatively simple technique requiring little in the way of
equipment or expertise. However, the technique is inaccurate at
low productivities where the changes in ©2 are small. Increasing
the incubation times to increase the total oxygen change also
allows time for the growth of bacterial populations which will
affect the result. The alternative to the oxygen technique em-
ploys the I^Q isotope. The technique is extremely sensitive and
can be used in any type of lake. However, it requires the use of
very expensive equipment and a relatively sophisticated operator
both for reasons of safety and accuracy. The meaning of the
results is also disputed, although the values are thought to
approximate net photosynthesis. There is also criticism of re-
sults in which the possibility of excretion of labeled carbon
products is not included (Vollenweider, 1969).
Insensitivity to trophic change and non-correlation with
other trophic parameters may potentially be the criticism that
will finally effect the greatest change in productivity measure-
ments as they are now reported. Vollenweider (1968) states that
although the high and low ends of the trophic spectrum are ade-
quately predicted by primary productivity, in the intermediate
range (100-1000 mgC/m^/d) there are found inconsistencies between
the trophic states predicted by primary productivity and that pre-
dicted by other trophic parameters. Fee (1973), for example,
found that areal productivity measurements on offshore Lake
Michigan samples indicated that the lake was eutrophic, contrary
to all indications by other criteria.
16
-------
Table 3. Suggested trophic limits based on areal primary
productivity.
Trophic State
Ultraoligotrophic
Oligotrophic
Mesotrophic
Eutrophic
Hypereutrophic
Areal Productivity (mgC/m2/day)
Rodhe, 1969 Likens, 1975 Wetzel, 1975
<50 <50
30 - 100 50 - 300 50 - 300
250 - 1000 250 - 1000'
300 - 1000 600 - 8000 >1000
1500 - 3000
17
-------
The reason for these Inconsistencies in the mid-trophic
ranges may not be because of real differences in the rate of
incorporation of carbon by the algae but by factors not related
to trophic status at all. It may be that what is considered to
be changes in productivity with trophic state are no more than
changes in the optical qualities of the water in which the measure
ments are taken.
Vollenweider (I960) presented the equation
1
TT = P(i) • E • P .
opt
Where:
TT = integral photosynthesis (mg C/m2/day)
F(i) = a function of the photosynthetically active light
E = the attenuation coefficient of the light in
water (1/m)
Popt ~ Productivity (mg C/m3) at optimum light
The productivity at optimum light can be further divided into
p = p p
opt max
Where:
Pmax = the Productivity per unit chlorophyll
(mg carbon/mg Chi/day)
C = concentration of chlorophyll at the depth
of optimum light , _._ , ,N
(mg Chl/m3)
Areal photosynthesis (TT) is then a function of several factors
•not all of which are related to algal biomass '
* = P(1) ' I ' Pmax ' c
The photosynthetic coefficient (Pmax^ or the maximum specific
rate of photosynthesis or the assimilation number is known to vary
with temperature (Schelske et al., 1974; Megard, 1972; Tailing,
1966) and with nutrient depletion (Curl and Small, 1965; Thomas,
1970; Thomas and Dodson, 1972). Megard (1973) found that Pmi->x was
18
-------
positively correlated with extractable cellular phosphorus. Al-
though the range of values can be quite large, there is little
evidence that the mean values are a function of trophic state.
It appears that Pmax is characteristic of the physiological state
of the individual cell and is independent of the number of cells.
Megard et al. (unpublished) considers a value of 50 mg C/mg Chi/
day a "reasonable estimate of the mean value in lakes and oceans
where temperatures are 20°C."
The vertical extinction coefficient (E) in effect decreases
areal productivity as the coefficient increases. The coefficient
can be subdivided into several components. Bannister (197*0 di-
vides it into the extinction of light by water and non-chlorophyll
material (kw) and extinction of light by chlorophyll (kcC). The
resulting term
E = kw + kcC
shows that extinction of light is not just a function of algae
but of water also. If kw is large in comparison to kcC, then
productivlty/m2 will decrease in a non-linear fashion (Megard,
et al., unpublished) as a function of chlorophyll concentration.
This effect on primary productivity is illustrated in Figure 2
assuming a Pmax of 50.
The theoretical upper limit to productivity (nmax) under a
unit area is obtained when light is absorbed solely by chlorophyll
(Bannister, 197*1). It is approached in natural waters as light
extinction by chlorophyll becomes large relative to the extinction
of light by dissolved substances and water. This limit is in fact
not a function of chlorophyll concentration but of the photosynthetic
parameters F(i) and Pmaxa as the chlorophyll potentially could be
widely distributed throughout the water column. Because of this
independence of maximal areal productivity from chlorophyll con-
centration, large areal productivity values could be obtained in
oligotrophic lakes as long as kw were very small. Variations in
kw in oligotrophic and mesotrophic lakes may in fact be the cause
of the wide differences in areal primary productivity reported in
lakes of similar trophic status, as determined by other criteria.
Although the extinction coefficient of water and dissolved
substances (kw) varies at least three orders of magnitude in natural
waters, much of the varience is a function of changes in trophic
state-. Megard (1972) suggested that the material included in kw
(dissolved color, suspended detritus, and zooplankton) may be re-
lated to variations in algal density. Using the data given in
Tables 2 and 3 of Megard et al. (unpublished), it can be shown that
kw and chlorophyll are indeed correlated (Figure 3). This graph
might imply a direct relationship between Kw and chlorophyll con-
centration as if either organic color is produced by the algae
themselves or that Kw is actually measuring the non-chlorophyllous
portions of the cells themselves. Megard et al. (unpublished)
presented evidence that Kw was seasonally constant in a given lake
and independent of the seasonal fluctuation in chlorophyll. This
implies that both Kw and chlorophyll are both independently related
19
-------
10'
CM
E
O)
.SQ 1O'
O
Q_
O 102
CD
10
1
50
Carlson TSI
100
Figure 2.
The relationship between trophic state as reflected
by the Carlson index and integral photosynthesis
(IT). The curves represent K values of 0.03, 0.35
3.0 and a K varying as a function of chlorophyll
(see text).
20
-------
I0r
0-1
In kw = 0.608 In Chlorophyll - 2.02
1O 1OO
CHLOROPHYLL (mg/m3)
10OO
Figure 3- The relationship between extinction of light by
non-chlorophyll substances (K ) and chlorophyll.
21
-------
to a third factor. Two possible suggestions for this unknown
factor are (1) a possible relationship between phosphorus con-
centration and color in the incoming waters and (2) the contri-
bution of color from the decaying organic matter in the sedi-
ments. At present, there is little data to support or refute
either possibility.
The fact that Kw does vary as a function of chlorophyll does
not produce any problems in the use of areal productivity as a
trophic criterion. However, the indication that Kw and chloro-
phyll are not directly related suggests that an unknown amount of
variation around the regression line may be possible. The darkly-
stained waters of the otherwise oligotrophic dystrophic lakes may
be the extreme of such variation. Differences in Kw between lakes
of similar nutrient and algal biomass could produce widely differ-
ent areal productivity values.
The problems of the insensitivity of areal productivity to
trophic change have been recognized. Rodhe (1958) found that pro-
ductivity per unit volume at the depth of optimal light (POpt)
was more sensitive to regional differences than integral produc-
tivity and suggested it might be used for the "biological" charac-
terization of lakes.
Rodhe (1958) also presented a log-log graph of integral
productivity (IT) against volumetric productivity at optimal
light (P0pt)- There appears to be a good correlation between
the two measurements. Using the equation:
* = z± P0pt
the log form of the equation would be
log IT = log zi + b log Popt
Where:
22
-------
1OOr-
1O
Z:
O-1
0.01
,003
kw dependent
on chlorophyll
lit
50
Carlson TSI
100
Figure 4. The relationship between Z. and trophic state as
reflected by the Carlson index. The curves
represent the same K values described in Figure 2
23
-------
The logarithm of z-^ would be the Intercept, and b would be the
slope of the line. Vollenweider (I960) indicated that instead
of one line as suggested by Rodhe's graphs there are a family of
lines having the same slope, differing only in the intercept z-^.
He indicates that the relationship between these two productivity
parameters (TT and Pgpt) ^s determined by the optical properties
of the water. Fee (1973)» whose values for integral productivity
in Lake Michigan would classify it as eutrophic, suggested that
the ratio TT/POpt> which is really Zj_, may be a more sensitive
indicator of trophic state than integral photosynthesis.
Figure 4 is a graph of the relationship between z-^ and trophic
state. A Popt of 50 is assumed. The extinction of light by non-
chlorophyll material is represented as a constant (kw = .03, 0.3,
and 3-0) and as a variable dependent on chlorophyll concentration.
The graph indicates that z^ would only be a sensitive index of
trophic state if kw does change as a function of chlorophyll. The
z-^ calculated with the variable kw does decrease significantly as
trophic state increases suggesting that it could be a sensitive
indicator of trophic state.
Megard, et al. (unpublished) has suggested that the ratio of
measured integral productivity to maximal potential productivity
(the productivity obtained as kw approaches zero (Bannister 197^),
could be used as an alternative to other trophic indices. Rela-
tive integral photosynthesis (irrei or 'n'/'n'max) ^s a measurement of
how photosynthetically active radiation (PHAR) "is partitioned be-
tween the phytoplankton and the environment." From equation 28 of
Bannister (1974) it can be shown that
ir rel =
TT kwChl
ir max
and that irrei is the fraction of PhAR that is absorbed by chloro-
phyll. Megard et al. (unpublished suggests that the ranges of
""rel can be associated as follows with the traditional trophic
types: oligotrophic (fTrei < 0.1), eutrophic (iirel = 0.1-0.5), and
polytrophic (irrei > 0.5).
A major objection to all these indices presented is that, except
for the use of Popt (Rodhe, 1958) they do not have the dimension
of time; they have ceased to measure productivity. As such they
have lost the essence of the reasoning behind measuring produc-
tivity; that is, that it is a measurement that gives insight into
the dynamics of the aquatic system. If integral productivity is
insensitive to trophic change, then it seems appropriate to
modify the dynamic measurement rather than to abandon it for
a static one. The use of Popt as a dynamic index
24
-------
would seem to be appropriate, but Its relationship to integral
productivity is affected by light absorption in the water column
and by itself it appears to have little meaning in the understand-
ing of the dynamics of the lake. Indeed, the dynamic component of
P0pt is the productivity per unit chlorophyll (Pmax) which is not
thought to vary as a function of trophic state. The other component
of POpt which does vary with trophic state is chlorophyll concen-
tration, a static variable.
Horne et al. (1975) critized the whole assumption that primary
productivity is best measured on an areal basis. The original in-
tent of the use of th.e primary productivity as the trophic cri-
terion was that the measurement would imply the condition of the
total lake biology (Naumann, 1927). In the argument of Horne et al.
(1975) areal primary productivity would not accomplish this because
zooplankton feed on a volumetric rather than an area basis. If, as
has been applied, in this paper, similar primary productivity values
are possible in lakes different of widely different concentrations
of algal biomass, then similarly low correlations should be found
between areal productivity and secondary production, which is also
a function of biomass concentration.
A possible alternative to areal primary productivity was sug-
gested by Palalas (1975). He found that Integral productivity is also
misleading in shallow lakes where the total possible integral pro-
ductivity was never reached because the euphotic zone is greater
than the depth of the lake. He suggested that productivity should
be based on the amount of carbon fixed per unit volume of the lake.
This can be calculated by weighing the rates of carbon assimilation
at each depth by the volume of the same strata and dividing their
sum by the total lake volume. In very large lakes he suggested that
the division of the integral productivity by the mean depth would be
acceptable.
Expression of productivity in terms of lake volume eliminates
the problems found using integral productivity both in shallow lakes
and in those with low kw, and therefore, with potentially deep
euphotic zones. In addition, expressing productivity on a volumet-
ric basis allows it to be used directly in models of secondary pro-
ductivity. It might be expected that estimates of secondary pro-
ductivity will relate better to this volumetric measurement than
to the areal representation.
25
-------
MULTI-VARIABLE INDICES
Single variable indices have been criticized for lack of
sensitivity to the total complexity of the concept of trophic
state (Brezonik and Shannon, 1971). The concept is said to be
hybrid, incorporating aspects of both nutrient status and pro-
ductivity. Therefore, in order to reflect the totality of the
concept, many or all of the criteria used to differentiate
trophic state must be incorporated into the index.
Many of the multi-variable trophic indices have been re-
viewed by Shapiro (1975) . In this report three indices will be
reviewed, each differing fundamentally in its construction.
Several points about the construction of the indices will be
raised:
1. Do the indices accomodate lakes outside their
original data base?
2. If correlated parameters are used, does the index
recognize the correlation? If the relationships
among the parameters is non-linear, does the index
compensate for this?
3. Do the multi-variable indices indeed reflect a
greater part of the trophic concept than do single
indices?
4. As the addition of more variables costs money,
does the increase in accuracy justify the expense?
The Michalski-Conroy Index
The first multi-variable index to be discussed was con-
structed by Michalski and Conroy (1972). The index is numerical,,
ranking lakes between values of zero to ten. Zero represents the
"worst" value found in the lakes examined, and ten represents the
"best." Intervening values are calculated using the equation
Rank = 10g<*-y> where
x is the value for a given lake
y is the minimum value for all lakes in the data set
z is the maximum value for all lakes in the data set
The result is a ranking index which linearly divides the trophic
spectrum between the highest and lowest values for each parameter
used. The separate variable indices are then averaged to obtain
a single index value for the lake.
26
-------
The index includes mean depth, a morphometric variable which
is considered to be of importance in determining lake productivity
(Rawson, 1955; Vollenweider, 1968, 1976). Secchi disk trans-
parency and chlorophyll are used to indicate the amount of algal
biomass. The morpho-edaphic index (Ryder, 1965) has been used to
predict fish productivity. The shape of the oxygen curve and the
Pe:P ratio in the bottom waters are used to indicate hypolimnetic
changes. No index of macrophytes is included.
Because the ranking system depends on the range of values
found in the present data base, additions of lakes with values
outside the present maximum and minimum values requires that every
lake in the data set would have to be reclassified. In the index
presented in 1972 the chlorophyll values range from 1.1 to 18.3
mg/m3 and transparency from 1.6 to 8.1 meters. Although this
limited range of values reflects admirably in the status of lakes
in Ontario, the range would have to be expanded considerably
before it could be used worldwide.
A more serious criticism of the index in its present form is
that there is no consideration of correlated variables. It is
either assumed that none of the variables are correlates (i.e.,
that they all change independently of the others) or that cor-
related variables are related linearly so that a given degree of
change in one will correspond to the same degree of change in the
other. Chlorophyll and Secchi disk transparency are known to be
correlated variables, but the relationship between them is not
linear. As the index does assume linearity, the result is a
hyperbolic relationship between the index ranks (Figure 5).
The discrepancies that develop with this treatment of the data
are not the result of any real differences within the lake be-
tween the degree of transparency and the amount of chlorophyll
but only the result of how the index handles non-linearly cor-
related variables.
The correlation of the Michalski—Conroy index values with
the Carlson index values are listed In Table 4. The correlation
coefficients are high. Slightly higher correlation coefficients
are obtained if the two Carlson index values are averaged. The
regression line relating the Chlorophyll TSI with the Michalski-
Conroy Index (Pig. 6) shows the effect of the limited data base.
The scale has an effective range only from TSI's of 29 to 67.
Many lakes are excluded on both ends of the scale.
The Environmental Protection Agency Index
The Environmental Protection Agency (1974) devised a lake
classification Index to use in conjunction with their National
Eutrophication survey. Like the Index by Michalski and Conroy
(1972), this index is also relative, with the extreme's of the
index being dependent on the original data base (in this case,
200 lakes).
27
-------
c
o
cr
X
•0
u
C
o
Q.
C
0
£
10
8
6
4
2
s
s
s
_ X
X ^
' m.
/ •
J^^^. M
\P> • •
&X ^ 0
G ' • ^
*\*xX
X •
X
X
X
X
' 1 1 1 1 1 1 1 1 1 — -J
2 4 6 8
Chlorophyll Index Rank
1O
Figure 5-
The relationship of the Michalski-Conroy index
values for chlorophyll and Secchi disk transparency
28
-------
Table 4. A comparison of the Michalski-Conroy index with
the trophic state index of Carlson (1977).
Carlson Index Correlation Regression
Variable Coefficient Equation
Chlorophyll 0.86 In Y = 4.05 - 0.060 (TSI)
Transparency 0.83 In Y = 4.80 - 0.082 (TSI)
Average Index 0.89 In Y = 4.64 - 0.076 (TSI)
Y = Michalski-Conroy index
29
-------
10
20 3O 4O 50 GO
Carlson TSI (Chlorophyll)
Figure 6.
The relationship between the trophic state indices
of Miehalski-Conroy and Carlson. The Carlson index
values was derived from the chlorophyll data.
-------
The index uses six variables. Three of these (total phos-
phorus, dissolved phosphorus, and inorganic nitrogen) are open-
water nutrient variables, two (Secchi disk transparency and
chlorophyll) are open-water biological variables, and one de-
scribes the oxygen concentration in the hypolimnion.
Instead of a linear division of the intervening values be-
tween the maximum and minimum values for each variable, the
index calculates the percentage of the lakes that have higher
values than the value found in a given lake. Values for each
variable can have an index value of 0 to 100. These index
values are simply summed, resulting in the final index having
a range of 0 to 600. If data are obtained that exceed the
maximum or minimum values used in the index, they are simply
assigned values of 600 or 0 under the premise that "the index
would not be sensitive enough to show changes anyway."
The unique method described above for obtaining the initial
index values results in a non-linear relationship between the
variable and index values. This non-linearity is illustrated
for total phosphorus, chlorophyll, and Secchi disk transparency
in Figure 7. This non-linearity apparently provides a correlated
relationship between the index values, but the relationship is
not necessarily the same as that obtained by others for the same
variable. In Figure 8 the relationships between chlorophyll and
Secchi disk transparency and between chlorophyll and total phos-
phorus are graphed using the values corresponding to EPA index
values of 5, 10, 15 etc. for each variable. In both instances a
close log-log relationship is obtained between the variables.
However, when compared to the relationships obtained by Carlson
(1977) for these same variable, it is seen that the relation-
ships relating to total phosphorus are entirely different. A
possible reason for this is that some of the total phosphorus
values are extremely high (1,525 mg/m3) and may actually be not
well correlated with other variables. In Figure 9 the values
of chlorophyll and total phosphorus are plotted and compared with
the regression lines of Carlson (1977) and Dillon and Rigler (1974
The closeness of fit for most of the points to the line suggest
that the procedure of autocorrelating variables used in the EPA
index was not really necessary. The index could have been derived
using simpler regression techniques.
The results of the correlation of the Carlson single variable
index with the multi-variable EPA index (Table 5) indicate that
all of the three variables correlate well with the index. The
regression lines for chlorophyll and Secchi disk transparency
with the EPA index are nearly identical, while the total phos-
phorus line is very different.
The relationships between the EPA index and the Carlson in-
dices of chlorophyll and total phosphorus are shown in Figure 10.
The regression line for the Secchi disk transparency index is also
superimposed on the chlorophyll index graph. This striking dis-
similarity of the total phosphorus index line from the other is
31
-------
10O
% 5O
Chlorc
Tronsf
Total I
P
*•
X •
'* .
* .
-X •
\
- X •
•
- x •
•
X •
* %
*
X
x •
phyl 2O 4O
>arency(in ) 200
3 200 400
° ° o oo o
°0
o
o
o
0
0
0
o
o
0
o
o
o
o
o
0
0
X • x» °
1 1 1 1 1 Jv^ rt 1
6O 8O 1OO
30O 4OO 5OO
60O 8OO 1OOO
Figure 7.
An illustration of the non-linearity in the relation-
ship between the EPA index values (as represented as
% of maximum value) and the values for Secchi disk
transparency (o), chlorophyll (•), and total
phosphorus (x).
32
-------
CO
O)
t
o
I
(J
1
OOO1
Q01 01
Total Phosphorus (g/m3)
o
-------
1OOOr
CO
£
O)
Q.
O
C.
O
6
1OO
1O
I I it \ \ I I I I I I t I I I I x I
10 10O
Total Phosphorus (mg/m3)
100O
Figure 9•
The relationship between total phosphorus and chloro-
phyll obtained using the EPA data. The lines represent
the regression lines obtained between these parameters
by Carlson (solid line) and Dillon and Rigler (dashed
line).
34
-------
6OO
400
u
200
2O
40 60 80
Carlson TSI (Chlorophyll)
1OO
6OO
40O
UJ
2OO
2O
4O 60
Carlson TSI
80
1OO
Figure 10. The relationship between the EPA trophic state index
and the Carlson index. Upper graph: the Carlson index
values are derived from chlorophyll data. The dashed
line represents the Secchi disk regression line.
Lower graph: the Carlson index values are derived from
phosphorus data.
35
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Table 5 . A comparison of the Environmental Protection
Agency index with the trophic state index of
Carlson (1977).
Carlson Index Correlation Regression
Variable Coefficient Equation
Chlorophyll 0.82 Y = 1139 - 15.26 (TSI)
Transparency 0.81 Y = 1166 - 15-58 (TSI)
Total Phosphorus 0.93 Y = 783 - 8.47 (TSI)
Y = EPA index
36
-------
readily seen. The limitations of the EPA index in relation to the
possible range of values actually found is also apparent. The
chlorophyll and transparency regressions suggest its range is
from about 35 to 75 Carlson TSI units, while the phosphorus index
suggests a broader scale from 22 to 102 units. The total index
may have a range somewhere less than indicated by the total
phosphorus variable alone.
The Shannon and Brezonik Index
The index of Brezonik and Shannon (1971) differs markedly
from the other two indices discussed in that it uses principal
component analysis for the original formulation of the index.
Seven indicators used in the formulation of the index are reduced
to a single value by this technique. The first principal com-
ponent is the linear combination of the variables which explains
the maximum variance in the original data (Shannon and Brezonik,
1972).
Of the seven indicators used in the index, one is related to
open-water nutrients (total phosphorus), three are open-water
biomass variables (Secchi disk transparency, chlorophyll a_ and
total organic nitrogen) , two are related to the total ionic con-
tent of the water (specific conductivity and Pearsall's (1922)
cation ratio) and one dynamic biological parameter (primary
productivity) .
The trophic state index values for a given lake are obtained
from the equation:
TSI = 0.94 (PriProd) + 0.92 (1/SD) + 0.90 (TON) + 0.86 (CHA)
+ 0.80 (COND) + 0.74 (TP) + 0.63 (I/Cat Ratio) + 5-19
where the symbols in parentheses represent standardized values
for each parameter. Standardization is accomplished by means of
the equation:
Where:
Y -
1J = 1 value for variable J
Xj = the mean of variable j
aj = the standard deviation of variable j
(Brezonik, 1976)
The values for Secchi disk transparency are corrected for
coloi' using the equation:
1/SD =0.15 (Turbidity) + 0.003 Color
37
-------
The values for the .lakes are scaled to a color of 75 platinum
units (Brezonik, 1976). Because of this correction, actually
twelve variables rather than ten must be measured in order to
-obtain an index value.
The Shannon-Brezonik index correlated well with all three
of the indices in the Carlson index (Table 6) although the total
phosphorus index produced a different slope than did the Secchi
disk transparency and the chlorophyll indices (Fig. 11). The
average index value of the Carlson index slightly improved the
correlation with the index.
The Shannon-Brezonik index in its present form is considered
preliminary. It is a relative index with the index values based
on the original data set used in the first principal component
extraction. As the original data set is from a limited geographi-
cal area (Brezonik, 1976), there may be peculiarities in the data
that may require that the index be first based on a larger data
set.
A major limitation of the Shannon-Brezonik index is the large
number of variables that must be measured in order to produce an
index value. In its present construction, all twelve parameters
must be measured to obtain an index value. Brezonik (1976) acknow-
ledges this fact and suggests that conductivity and the cation
ratio could be eliminated without much loss in discrimination.
He also suggests that the measure of primary productivity is a
"complicated and time-consuming procedure" as well as being cor-
related with other measurements incorporated in the index. He
suggests that it also could be eliminated. With these elimina-
tions, the index would be constructed using transparency, chloro-
phyll, total phosphorus, and total organic nitrogen. As three
variables have already been shown to be correlated (Carlson,
1977), and total organic nitrogen is probably also correlated, the
abilitv of this multivariate index with its present choice of
variables to be more useful than an index using only one of
these variables is questionable.
A comparison of the indices.
Although these three multi-variable indices do not exhaust
the types of indices now used, they represent three of "the most
popular of the indices, and they serve as examples of how multi-
variable indices can be constructed. Let us now consider these
indices in relation to the four questions posed in the beginning
of the chapter.
1. Do the indices accomodate lakes outside their original
data bases? Only the Shannon-Brezonik index does this. Both EPA
and Michalski-Conroy indices are limited by the data bases. In
both of these indices the incorporation of lakes outside the
original data bases requires a reclassification of every lake or
the arbitrary assignment of the highest or lowest index value to
38
-------
Table 6. A comparison of the Shannon-Brezonik index with
the trophic state index of Carlson (1977).
Carlson Index Correlation Regression
Variable Coefficient Equation
Total Phosphorus 0.88 In Y = 0.04 (TSI) - 0.96
Chlorophyll 0.86 In Y = 0.06 (TSI) - 1.6l
Transparency
(Uncorrected for color) 0.84 In Y = 0.06 (TSI) - 1.92
Average Index 0.9^ In Y = 0.06 (TSI) - 2.04
Y = Shannon-Brezonik index
39
-------
100
JC
8
c_
CD
O
U)
10
X
X
4O 60 80
Carlson TSI (Chlorophyll)
100
Figure 11. The relationship between the Shannon-Brezonik index
and the Carlson index. The data points and the solid
curve is derived from chlorophyll data. The other
curves illustrate the regression lines obtained from
Secchi disk transparency ( ) and total phosphorus
(-.-.) data.
40
-------
the lake. These indices are limited to their original data bases
because their scales are constructed using the highest and lowest
values found in the original data base as the maximum and minimum
index values. The Sh'annon-Brezonik index uses instead a mean
value for each index variable as the basis for the scale, and
the scale is open-ended. The Carlson index is open-ended only on
the eutrophic end, but the value of zero chosen for the oligo-
trophic side exceeded all known values so that there would be
no chance that the values for a particular lake could ever exceed
the lower end of the scale.
The Michalski-Conroy and the EPA indices could be constructed
to include all possible values simply by expanding the scales to
include a larger range of variable values, but the problem with
this maneuver is that the median values for most trophic variables
in natural bodies of water are clustered near one end or the other
of the total range of possible values. For instance, total phos-
phorus values might range as high as 20 or 30 mg/1, yet oligo-
trophy and eutrophy are determined at values of 10 to 20 ug/1.
A linear scale including the total range of values would leave
little sensitivity in the range where the changes of interest
take place. The Carlson index overcomes this problem by using
the logarithm to the base two, which tends to normalize the data
(Shapiro, et al., 1975). A logarithmic transformation of the
Shannon-Brezonik index also resulted in near-normal distribution
(Van Belle and Meeter, 1975 as cited in Brezonik, 1976).
2. Does the index use correlated variables, and if so, are
the relationships correctly represented? Correlated variables
are redundant, providing no extra information about the lake and
tend to weight the index. All the indices considered incorporate
at least some correlated variables. Transparency and chloro-
phyll are found as variables in all the indices, yet both measure
algal biomass. The Shannon-Brezonik index also includes organic N
which should be strongly related to algal biomass. Table 7 com-
pares the variables used in the indices. For the most part, how-
ever, the indices avoid known correlated variables, attempting
instead to capture the broadest expression of trophic state using
the fewest number of measurements.
The indices vary in their ability to handle non-linear
relationships among variables. Using its unique ranking system,
the EPA index essentially derives a relationship between all the
variables, although the relationships are not necessarily the
same as found by other people. The Michalski-Conroy index
assumes no relationships among the variables, which causes dif-
ficulties where non-linear relationships actually exist. The
Shannon-Brezonik index assumes a linear relationship among all
the variables except for transparency which is a reciprocal
relationship (1/SD). Both the Michalski-Conroy and Shannon-
Brezonik indices could be easily modified to accomodate non-
linear relationships. The EPA index appears to be unmodifiable
without fundamentally changing its structure.
41
-------
Table 7. A comparison of the trophic components incorporated
in three, multi-variable indices.
Trophic
Component
Open Water
Biomass
Open Water
Nutrients
Hypolimnetic
Productivity
Total Ionic
Content
Michalski-
Conroy Index
transparency
chlorophyll
Pe: P
shape of 02
curve
morpho-edaphic
index
Shannon-
Brezonik Index
transparency
chlorophyll
organic N
total P
primary
productivity
Pearsall ratio
conductivity
EPA
Index
transparency
chlorophyll
total P
inorganic N
dissolved P
minimum Oo
Morphometric mean depth
42
-------
3. Do multi-variable indices reflect a greater part of the
trophic concept than do single variable indices? All of the in-
dices attempt to broaden the scope of classification to include
several facets of the trophic state concept. Open-water algal
biomass and open-water nutrient concentrations are most heavily
emphasized (Table 7). Only the Shannon-Brezonik index utilizes
a measurement of primary productivity, a popular criterion of
trophic state. The Michalski-Conroy and the EPA indices consider
hypolimnetic oxygen concentrations. None of the indices consider
macrophytes which may compose the larger fraction of plant biomass
in smaller lakes.
4. Is their increase in the number of variables justified?
This question is difficult to answer. The correlations with the
single-variable Carlson index are all high. Averaging the three
Carlson variables (essentially making it a multi-variable index)
only slightly increases the correlations. It could be argued
that these high correlations suggest that single-variable indices
are just as efficient at classification as the multi-variable
indices. On the other hand, it might be argued that as the cor-
relations were not perfect, the variance in the correlations is
not just random scatter but real differences in trophic status
that the multi-variable indices were able to detect that went
unnoticed by the single-variable index. This argument can be
effective as there is no trophic standard against which all the
indices can be compared.% There is no way to determine which
argument is correct.
Prom a practical standpoint, my opinion is that the multi-
variable indices have failed to justify the added expense, time,
and additional expertise necessary to produce them. The indices
are simply harder to use. The Michalski-Conroy index is the most
preferable of the indices in that the index can be obtained from
any number of variables, and therefore, it can be adapted to the
facilities and resources of any given user.
In the Shannon-Brezonik and the EPA index, values for all
the variables must be gathered before an index value can be
obtained. If a single analysis of a variable is lost, as does
sometimes happen, the lake could not be classified without a
second visit and a complete reanalysis.
In an earlier chapter I compared various suggestions of the
limits of oligotrophy and eutrophy to the Carlson index. The
results of that comparison suggested that a TSI value of 40 was
the upper range for oligotrophy and a value of 50 was the lower
range for eutrophy. The authors of the three multi-variable
indices have also suggested trophic limits for their indices. I
have transformed their values into Carlson index values in Table
8. Both the Michalski-Conroy and the EPA index indicate limits
that are close to those obtained in the earlier comparison. The
Shannon-Bresonik index tends, to place a better water quality
designation on a given index value than would the other indices.
43
-------
Table 8. A comparison of the trophic state designations
of the multi-variable indices.
Index
Michalski-Conroy Index
Trophic Designation
Excellent Water Quality
Vulnerable Water Quality
Poor Water Quality
EPA Index
Oligotrophic
Mesotrophic
Eutrophic
Brezonik Index
Ultra-Oligotrophic
Oligotrophic
Mesotrophic
Eutrophic
Hypereutrophy
Index
Value
> 6
3-6
< 3
> 500
420-499
< 420
1.3-1.9
2.0-2.9
3.0-6.9
7.0-9-9
> 10
Corresponding
Carlson Index
Value
< 38
38-49
> 49
< 42
42-47
> 47
31-38
39-45
45-59
59-65
> 65
44
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This paper has discussed only several of the many types of
lake indices that are presently available. This diversity of
indices underscores the confusion that exists today as to the
best way to define and describe the concept of trophic state.
These concluding remarks will attempt to set this discussion of
various indices into a larger perspective in order to suggest a
common basis for the understanding of the trophic concept.
By 1927, Naumann had largely formulated the trophic concept.
In a paper published in that year, many of the basic statements
incorporated in the present concept were presented. Four of the
most important of these statements are presented below.
1. The productivity of waters is determined by several
factors but primarily by the concentration of nitrogen
and phosphorus.
2. There are regional variations in productivity which
correlate with the geological structure of the water-
shed.
3- The amount of nutrients affects not only the phyto-
plankton but also the lake biology as a whole.
4. There are certain evolutionary connections between
lakes of the various types.
In these four statements is embodied the essence of the
trophic concept. These statements suggest not a confused or
even controversial issue, but rather a clearly stated conceptual
model of how a lake ecosystem might respond to inputs of nutrients
or other forcing factors. The trophic concept incorporates two
basic aspects of a systems approach: the stimulus or forcing
factor and the system response (changes in lake biological dynamics
and structure). It has been argued by others that the term "trophic
state" should be applied solely to the measurement of the stimulus
(the rate of nutrient supply). On the other hand, it could also
be applied to the system response. The emphasis on response
rather than stimulus allows for the possibility that factors
other than nutrient supply may also effect a system response.
If trophic state determinations are based on the system re-
sponse, then the major problem faced in the construction of an
index is the selection of the variable or variable that ade-
quately reflect the total lake biotic system. Multi-variable
indices appear to be best suited for this purpose as they can
incorporate several disparate aspects of the system, therefore
reflecting a larger fraction of the system's response.
The problem with multi-variate approaches is in the method of
combining the measurements of the various system components. The
methods reviewed in this paper all result in a loss of infor-
mation, and this loss is critical. As the relationships among
45
-------
the system components are assumed to be unknown or to not exist
in these combinations, the indices forfeit the ability to dis-
criminate the individual status of any given component. They
must assume that trophic state is the average response of the
system, even though wide disparities in response may occur in
the separate system components. The ability to use the index
to predict future trophic states is hampered because prediction
assumes the knowledge of the relationships between system com-
ponents. The net effect of the multi-variable index is to pro-
vide a comprehensive lake classification system which provides
an average lake classification, not necessarily correlated well
with any given system component and having little predictive
capability.
The single-variable indices have the opposite problem. Be-
cause they are related to only a single-system component, the
potential for predictability is large. However, the extension
of the prediction to another system components is limited by the
knowledge of the relationships among the components. If, however,
the relationships were known, then the status of all the biotic
components could be estimated. Besides the potential for pre-
dicting future trophic states, the index based on a single com-
ponent or system aspect has the advantage of an ease of inter-
pretation. Unlike the multi-variable index which produces an
average value the single variable index is not an average of
several non-related components and interpretation of the index
value is more direct. The disadvantage of the single variable
index is in the classification of the whole lake system. Although
it may classify one component well, its ability to classify the
entire lake system is dependent on how directly the system com-
ponents are related. The extent to which this will be a problem
has yet to be examined.
Other considerations besides predictability and comprehensive-
ness must be considered in indices. Hooper (1969), Shapiro (1975),
and Brezonik (1976) have suggested various attributes of the per-
fect index. Of their suggestions I would emphasize three criteria:
1. An index should be simple in technology, collection
of data, and interpretation.
2. It should be universally applicable and incorporate
all possible lakes.
3. It should be scientifically valid.
The first criterion is of fundamental importance in an index's
construction. Multi-variable indices could incorporate so many
measurements that the ability to use the index would be limited
to only the best-equipped laboratories and the largest budgets.
Perhaps the simplest index would be the one that incorporates the
fewest necessary components. The index must also be simple in
interpretation. If its explanation is so complex that the lay
public cannot understand it, then it is of little use in communi-
cation.
46
-------
The index must be universal. Any lake or reservoir should
be able to be classified. The indices discussed in this paper
that rely on the original data base clearly cannot meet this
criterion. It would also be desirable if rivers and streams
could also be classified by the same system. Using variables
unique to lakes limits the index to lakes.
The index must also be a means of communicating our scientific
knowledge, thus its basis must be scientifically valid. This means
not only that the index should incorporate known relationships cor-
rectly, but more importantly, the index should be able to grow and
develop as our knowledge of aquatic systems develops. An index
cannot be static, allowing no further development or change beyond
the original chosen variables. An index should be a tool that
stimulates scientific investigation, not having as its sole func-
tion the placing of a name or number on a lake.
47
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BIBLIOGRAPHY
Bannister, T. T. 1974. Production equations in terms of chloro-
phyll concentration, quantum yield, and upper limit to produc-
tion. Limnol. Oceanogr. 19:1-12.
Beeton, A. M. and W. T. Edmondson. 1972. The eutrophication
problem. J. Fish Res. Bd. Can. 29:673-682.
Brezonik, P. L. 1976. Trophic classifications and trophic
state indices: rationale, progress, prospects. Rept. No.
ENV-07-76-01 Dept. of Engineering Sciences, Univ. Florida.
Brezonik, P. L. and E. E. Shannon. 1971. Trophic state of lakes
in north central Florida. Water Resources Res. Center, Publ.
No. 13. Univ. Florida.
Carlson, R. E. 1975. Phosphorus cycling in a shallow eutrophic
lake in southwestern Minnesota. Ph.D. Thesis, Univ. Minnesota.
1977. A trophic state index for lakes. Limnol
Oceanogr. 22:361-369.
Curl, H., Jr. and L. F. Small. 1965. Variations in photosyn-
thetic assimilation ratios in natural, marine phytoplankton
communities. Limnol. Oceanogr. 10(Suppl.):R67-R73.
Dillon, P. J. 1975. The phosphorus budget of Cameron Lake
Ontario: the importance of flushing rate to the degree of eu-
trophy of lakes. Limnol. Oceanogr. 20:28-39.
Dillon, P. J. and F. H. Rigler. 1974. The phosphorus-chlorophyll
relationship in lakes. Limnol. Oceanogr. 19:767-773.
Dobson, H. F., M. Gilbertson, and P. G. Sly. 1974. A summary
and comparison of nutrients and related water quality in lakes
Erie, Ontario, Huron and Superior. J. Fish. Res. Bd. Can.
31:731-738.
Environmental Protection Agency. 1974. An approach to a relative
trophic index system for classifying lakes and reservoirs.
Working Paper No. 24.
1974. The relationships of phosphorus and nitro-
gen to the trophic state of northeast and north-central lakes
and reservoirs. Working paper No. 23.
Fee, E. J. 1973. A numerical model for determining integral
primary production and its application to Lake Michigan. J.
Fish Res. Bd. Can. 30:1447-1468.
Goldman, C. R. 1960. Molybdenum as a factor limiting primary
productivity in Castle Lake, California. Science 132:1016-1017.
48
-------
Hooper, F. F. 1969. Indices of trophic change, p. 225-235. In
Eutrophication: Causes, consequences, correctives. Natl. Acad.
Sci. Publ. 1700.
Home, A. J., J. D. Newbold, M. M. Tilzer. 1975. The productivity,
mixing modes, and management of the world's lakes. Limnol.
Oceanogr. 20:663-666.
Home, A. J. and C. R. Goldman. 1972. Nitrogen fixation in Clear
Lake, California. I. Seasonal variation and the role of
heterocysts. Limnol. Oceanogr. 17:678-692.
Hutchinson, G. E. 1969. Eutrophication, past and present, p.
17-26. In Eutrophication: Causes, consequences, correctives.
Natl. Acad". Sci. Publ. 1700.
Kalff, J. and H. E. Welch. 1974. Phytoplankton production in
Char Lake, a natural polar lake, arid in Meretta Lake, a polluted
polar lake, Cornwallis Island, Northwest Territories. J. Fish.
Res. Bd. Can. 31:621-636.
Kerekes, J. J. 1975a. Phosphorus supply in undisturbed lakes in
Kejimkujik National Park, Nova Scotia (Canada). Verh. Internat.
Verein. Limnol. 19:349-357.
. 1975b. The relationship of primary production to
basin morphometry in five small oligotrophic lakes in Terra Nova
National Park in Newfoundland. Symp. Biol. Hung. 15:35-48.
Likens, G. E. 1975. Primary productivity of inland aquatic
ecosystems, p. 185-202. In Primary productivity of the biosphere
H. Lieth and R. H. Whittaker, eds. Springer-Verlag.
Megard, R. 0. 1972. Phytoplankton, photosynthesis, and phosphorus
in Lake Minnetonka, Minnesota. Limnol. Oceanogr. 17:68-87.
197"3. Rates of photosynthesis and phytoplankton
growth in Shagawa Lake, Minnesota. Publ. No. EPA-R3-73-039.
Ecological Res. Ser. U.S. Envir. Protection Agency.
Megard, R. 0., P. D. Smith, A. S. Knoll, and W. S. Combs, Jr.
Attenuation of light and rates of photosynthesis of phytoplankton.
Unpublished manuscript.
Michalski, M. F. P. and N. Conroy. 1972. Water quality evaluation
for the Lake Alert study. Ontario Ministry of the Environment,
Water Quality Branch.
Mortimer, C. H. 1941. The exchange of dissolved substances between
mud and water. I and II. J. Ecol. 29:280-329.
49
-------
National Academy of Science and National Academy of Engineering.
1972. Water quality criteria, A report of the Committee on
Water Quality Criteria. Washington, B.C.
Naumann, E. 1919. Nagra synpunkter angaende limnoplanktons okologi
med sarskild hansyn till fytoplankton. Sv. Bot. Tidskv. 13:129-163.
1927. Ziel and Hauptprobleme der regionale Limnologie.
Bot. Notiser 1927:81-103.
Odum, E. P. 1969. Air-land-water-an ecological whole. J. Soil and
Water Conservation. 24:4-7.
Pearsall, W. H. 1922. A suggestion as to factors influencing the
distribution of free-floating vegetation. J. Ecology. 9:241.
Rawson, D. S. 1955. Morphometry as a dominant factor in the
productivity of large lakes. Verh. Int. Ver. Limnol. 12:164-175.
Rigler, F. H. The concept of energy flow and nutrient flow between
trophic levels, p. 15-26. In Unifying concepts in ecology.
W. H. Dobben and R. H. Lowe-McConnel, eds. The Hague: Dr. W. Junk.
Rodhe, W. 1958. The primary production in lakes: some results
and restrictions of the 14^ method. Rapp. et Proc. Verb. Cons.
Intern. Explor. de la Mer 144:122-128.
1969. Crystallization of eutrophication concepts in
northern Europe, p. 50-64. In Eutrophication: Causes, consequences,
correctives. Natl. Acad. Sci. Publ. 1700.
Ryder, R. A. 1964. Chemical characteristics of Ontario lakes as
related to glacial history. Trans. Amer. Fish. Soc. 98:260-268.
1965. A method for estimating the potential fish
production of north temperate lakes. Trans. Amer. Fish. Soc.
94:214-218.
Sakamoto, M. 1966. Primary production by phytoplankton community
in some Japanese lakes and its dependence on lak"e depth. Arch.
Hydiobiol. 62:1-28.
Shannon, E. E. and P. L. Brezonik. 1972: Eutrophication analysis:
a multivariate approach. J. Sanit. Eng. Div., Amer. Soc. Civil
Eng. 98:37-57.
Shapiro, J. 1975. The current status of lake trophic indices-a
review. Limnol. Res. Center Interim Rept. No. 15. Univ. Minnesota.
(mimeo)
Shapiro, J., J. B. Lundquist, and R. E. Carlson. 1975. Involving
the public in limnology--an approach to communication. Int. Ver.
Theor. Angew. Limnol. Verh. 19:866-874.
50
-------
Schelske, C. L., E. D. Rothman, E. F. Stoermer and M. A. Santiago.
1974. Responses of phosphorus limited Lake Michigan phytoplankton
to factorial enrichments with nitrogen and phosphorus. Limnol.
Oceanogr. 19:409-419.
Sylvester, H. and M. W. Hall. 1974. A quantitative classification
of Maine lakes. Environ. Studies Center, Univ. Maine. Paper
presented at 37th meeting Amer. Soc. Limnol. Oceanogr. Seattle,
Wash. (mimeo)
Tailing, J. F. 1966. Photosynthetic behaviour in stratified and
unstratified lake populations of a planktonic diatom. J. Ecol.
54:99-127.
Thomas, W. H. 1970. On nitrogen deficiency in tropical Pacific
oceanic phytoplankton: photosynthetic parameters in poor and
rich water. Limnol. Oceanogr. 15:380-385.
Thomas, W. H. and A. N. Dodson. 1972. On nitrogen deficiency in
tropical Pacific oceanic phytoplankton. II. Photosynthetic and
cellular characteristics of a chemostat-grown diatom. Limnol.
Oceanogr. 17:515-523.
Vallentyne, J. R., J. Shapiro, A. M. Beeton. 1969. The process
of eutrophication and criteria for trophic state determination,
p. 58-67. In "Modeling the eutrophication process." Proc. of
a workshop in St. Petersburg, Florida.
Van Belle, G. and D. A. Meeter. 1974. Statistical analyses of
aspects of the trophic state of selected Florida lakes. Florida
State Univ., Dept. of Statistics. Rept. to State of Florida
Dept. Poll. Control.
Vollenweider, R. A. 1960. Beitrage zur kenntnis optischer
eigenschaften der gewasser und primarproduction. Mem. 1st.
Idrobiol. 12:201-244.
Ital
. 1965.
a acque insubriche.
Materiale
Mem. 1st.
ed idee per una
Ital. Idiobiol.
idrochimica delle
1968. The scientific basis of lake and stream
'eutrophication, with particular reference to phosphorus and
nitrogen as eutrophication factors. Technical Report OAS/DSI/68.27.
Organization for Economic Cooperation and Development. Paris. 159 pp
__^ . (ed) 1969. A manual
production in aquatic environments
Scientific Publications.
on methods for
IBP Handbook
measuring primary
No. 12. Blackwell
37:53-84.
1975. Input-output models. Schweiz. Z. Hydrologie
51
-------
. 1976. Advances in defining critical loading
levels for phosphorus in lake eutrophication. Mem. 1st. Ital
Idrobiol. 33:53-83.
Wetzel, R. G. 1975. Limnology. W. B. Saunders. 743 p.
-------
THE CURRENT STATUS OF LAKE TROPHIC INDICES
- A REVIEW -
Joseph Shapiro
Limnological Research Center
University of Minnesota
Minneapolis, Minnesota
INTRODUCTION
The amount of time and effort expended during the last few decades in
attempts to classify water bodies can be appreciated only by one who attempts
to review the subject. Unfortunately the overriding impression one gets is
that of a limnological tower of Babel. Virtually every characteristic of a
water body, be it stream, river, or lake has been used as a basis for a classi-
fication scheme of one sort or another, and virtually every scheme is unique.
It is safe to say that the reason for this outpouring of work lies in the
failure of the traditional classification scheme that divides lakes into
eutrophic, oligotrophic, and more recently mesotropKic, categories. These
categories, whether used in their original sense of nutrient concentration and
supply, or in their later more widely accepted sense as descriptions of the
consequences of low and high nutrient supplies, are inadequate. They are
inadequate for descriptive purposes other than in a very broad manner, and
they are inadequate for communication. This inadequacy for communication
exists not only among limnologists so that one limnologist's eutrophy is
another limnologist's mesotrophy, but it exists also between limnologists and
laymen. The very word "eutrophic" has come to have a negative-connotation to
the public, to large extent because it is without quantification. Thus we
find ourselves, three quarters of a century after Forel, unable to communicate
with each other or with those who depend upon our sciences. This situation
cannot be allowed to continue. If we are to use our information to manage
lakes, to estimate their recreational potential, to estimate their sensitivity
to degradation, to manipulate and restore them, we must have quantitative
indices to characterize them. We can continue for theoretical purposes to
classify lakes in an attempt to discover or describe groupings in which they
or certain of their characteristics fail, but unless we can develop quan-
titative indices our results will languish as philosophical exercises forever
unavailable to the wider world.
This problem has been recognized by others. As Russell Train pointed out
in 1972, when he was chairman of the United States Council on Environmental
Quality, despite the limitations of such indices as those for gross national
product, cost of living, unemployment etc., they are critical factors in both
formulating and evaluating economic and national policy. He states his belief
that we must develop similar sorts of indices for environmental quality if the
level of environmental policy and planning is to be improved.
53
-------
This is what Shapiro had in mind in 1969 when he
suggested that what limnology needed was something analo-
gous to the Richter scale used for earthquakes -- an objective
numerical scale whose derivation might not be known to all
but whose significance has come to be appreciated through
use.
The purpose of this paper is to present those indices
we have been able to find in the literature so that they
may serve as a guide toward development of indices which
will serve us as standards and as means of communication
with others. The discussion will be limited to indices
developed primarily for lakes although a number of indices
applicable to streams and rivers appear in the bibliography.
Furthermore most of the indices to be described deal with
the open waters of lakes as the problem of adequately char-
acterizing the extent and nature of macrophytes has not been
resolved satisfactorily. ( Lind and Cottam, 1969)
As noted above, the array of indices is wide and their
uses diverse. They may be categorized in a variety of ways.
Thus there are whole lake, water quality, and trophic state
indices; there are indices for determining recreational poten-
tial, for management purposes or for scientific studies;
indices may be descriptive or analytical; subjective or objec-
tive; simple or complex; relative or absolute; biological,
physical, or chemical; etc.
54
-------
Which is best? Clearly the answer depends on the pro-
posed use. However, there are certain features that an ideal
index should embody.
1. It should be easy to arrive at through use of
unequivocal data.
2. It should be simple in form.
3. It should be narrow enough in scope to realisti-
cally serve its purpose.
H. It should be objective in that it must contain no
value j udgment.
5. It should be absolute rather than relative so that
it can be used anywhere.
6. It should be scientifically valid i.e. it should
not use nonlinear relationships in a linear manner.
7. It should be retranslatable in the sense that if the
index is a number derived from certain data the data
should be derivable from the number.
8. It should be understandable to the lay public and
to officials dealing with policy matters.
To facilitate discussion of the various indices, they
will be described under four headings:
1. National Water Quality Indices
2. Whole Lake Indices
3. Relative Trophic State Indices
4. Absolute Trophic State Indices
55
-------
The divisions are not perfect but will help in evaluating
the indices.
I. National Water Quality Indices
Such indices have been developed to deal with water use
problems. Probably many exist but two will suffice as examples
1. In 1969 the National Swedish Nature Conservancy
Office published a report describing a means of dividing
waters into classes for three purposes -- bathing, water
supply, and fishing. For their "general pollutional effects"
waters were classed as:
Al unpolluted
A2 slightly polluted
A3 distinctly polluted
A 4 heavily polluted.
Among the criteria used were temperature increase, taste and
odor increase, BOD increase, and increase in total P. Thus
"distinctly polluted" waters had, among other features, an
increase of total phosphorus of 100%. In classifying the
waters for bathing purposes they were categorized as, Bl,
desirable , to B4, nonpermissible. Among the factors 'used
here are Secchi disk transparency so that Bl lakes have a
transparency greater than 3 meters and BM- lakes have a
transparency less than 1 meter.
56
-------
2_^ In 1975 Inhaber proposed a water quality index for
Canada — or actually two indices. Both are numerical and
nondimensional with zero being best, and both use the root
mean square of the values of the parameters to give sensitivity
to extreme values of the indices.
A. In this index constituents are rated relative to
one another on the basis of their estimated importance in
affecting water use for (1) drinking, (2) fish and aquatic
life, (3) recreation. Weighting is done as follows: if
0.015 ppm is the minimum concentration "tolerable" the
weight of an effluent sample would be 66.7, if it took 66.7
liters of the receiving water to dilute 1 ppm of the effluent
to the tolerable 0.015 ppm.
B. This index deals with what is in the water.
1. Trace metal contaminants.
2. Suitability of rivers in terms of turbidity
for drinking supplies and contact recreation.
3. Mercury contamination of fish landed commercially,
Both of these "indices" may be useful in formulating
national policy to a certain extent but they fulfill few of the
criteria suggested above. In fact there is in these "indices"
more than a small measure of "standards".
57
-------
II. Whole Lake Indices
1. Recreational Indices.
An example of a recreational index useful for the spe-
cific purpose of rating lakes for their recreational use is
presented by one constructed by the Department of Natural
Resources of the State of Wisconsin. In principle, eleven
aspects of the lake divided into four categories are given one
of three ratings. The total rating of a possible 72 is the
recreational rating of the lake. An example of the format is
given in Figure 1.
2. Indices of Potential and Actual Lake Conditions
A. Bortleson e_t al. (1974) divided 24 criteria into
three groups.
1. seven parameters affecting potential enrichment
from natural causes
2. four factors affecting potential enrichment from
culturally-related causes
3. thirteen indicators of existing eutrophication
and water quality.
For each lake each criterion is given a rank of 1-5
( 1 is best). For each category the ranks are summed. Ranks
for the three categories are not summed. Twenty-five other
indicators are checked as plus or minus to provide supplemen-
tary information. An example of the ranking of existing water
quality factors is given in Figure 2.
58
-------
Fig. 1. Example -of the application of the recrea-
tional rating system. The lake is Pewaukee Lake,
Wisconsin. (From the Wisconsin DNR, 1970)
Space: Total area - 2,493 acres Total shore length - 13.71 mi.
Ratio of total area to total shore length: 0.284
Quality (18 points for each item)
Fish:
X_9 High production
9 No problems
6 Medium production 3 Low production
y( 6 Modest problems 3 Frequent and
such as infrequent win- overbearing prob-
terkill, small rough lems such as win-
Swimming:
X 6 Sand or gravel
T75% or more)
6 Clean water
6 No algae or
weed problems
Boating:
X 6 Adequate depths
T75% of basin >5')
X 6 Adequate size
for extended boat-
ing ( >1,000 acres)
fish problems
4 Sand or gravel
T25 - 50%)
X 4 Moderately clean
4 Moderate algae
or weed problems
terkill, carp, ex-
cessive fertility
2 Sand or gravel
_ 2 Turbid or
darkly stained
X 2 Frequent algae
or weed problems
4 Adequate depths
TTO-75% of basin
> 51 deep)
4 Adequate size for
some boating (200-1,000 ing challenge and
acres) space (<200 acres)
2 Adequate depths
T5"0% of basin)
2 Limit of boat-
_Good water quality X 4 Some inhibiting fac- 2 Overwhelming inhibit-
tors such as weedy bays ,irTg factors such as
Aesthetics:
algae blooms, etc,
6 Existence of 25% £_4 Less than 25% wild
or more wild shore shore
X 6 Varied landscape 4 Moderately varied
landscape
6 Few nuisances suchj(_4 Moderate nuisance
as excessive algae, conditions
carp dumps, etc.
weed beds throughout
2 No wild shore
2 Unvaried land"
scape
2 High nuisance
conditons
Total quality rating:
57 out of a possible 72
59
-------
Fig. 2. Ratings assigned to eutrophication and
water quality factors for Washington Lakes. 1 is
best, 5 is poorest. CFrom Bortleson et al., 1974)
Tn Hi o^"hr»'pci
Rating
345
2.1-5.0 0.5-2.0
Total phosphorus
upper water (yg/1) <5 5-10 11-20 21-30 >30
Total phosphorus,
ratio of bottom, to
upper waters <1.0 1.0-1.5
Inorganic nitrogen,
upper water (yg/1) <100 100-200
Inorganic nitrogen,
ratio of bottom to
upper waters <1.0 1.0-1.5
Organic nitrogen,
upper water (yg/1) <100 100-200
Specific conductance
(micromhos at 25°C) <20 20-50
Color (Pt-Co units) 0-10 11-20
Secchi-disc (m) >8.0 5.1-8.0
Dissolved oxygen near
bottom (mg/1) >8.0 5.1-8.0
Water temperature
near bottom f°c) <5.0 5.0-7.0
Fecal-coliform bacteria
(colonies per 100 ml;
mean value) <1 1-5 6-50
Percentage of lake
surface occupied by
emergent rooted
aquatic plants <1 1-10 11-25 26-50 >50
Percentage of shoreline
occupied by emergent
rooted aquatic
plants <10 10-25 26-50 51-75 76-100
1.6-3.0 3.1-10
201-300 301-650 >650
1.6-3.0 3.1-10
201-400 401-800 >800
51-100 101-500 >500
21-40 41-60 >60
3.1-5.0 1.0-3.0 <1.0
<0.5
7.1-10.0 10.0-15.0 >15.0
51-240 >240
60
-------
The system, although very detailed, has certain diffi-
culties. Thus, it requires vast amounts of information and
uses highly diverse parameters such as bottom temperature and
fecal coliforms in the same grouping.
B. Bailey (1974) has proposed a three-dimensional lake
classification scheme for lakes in the state of Maine. One
axis would be "trophic status1.' as indicated by indicator
organisms and other indirect measures. One axis would be
"vulnerability to input" due to morphological or hydrological
factors, and the third axis would be "intensity of cultural
activity or impact". Trophic status would be indicated by the
distance from the origin.
C. Uttormark (1974) has proposed a Lake Condition Index.
Four parameters are given numerical ratings. The sum of all ratings
is the index. Zero is satisfactory, 23 equals unsatisfactory.
The parameters and their values are
Dissolved oxygen
Transparency
Fish kills
Use impairment
Possible total
0-6 points
0-4- points
0-4 points
0-9 points
23 points
61
-------
The index does not relate well to specific nutrient loading (Fig. 3);
also it is subjective. However, it is useful for management where alternative
data are not available.
o
Wandavega OLong
o
I
Q.
•O (M
6)
4J O
E
o
Beulah
CranltcO
O
Cedar
Big MoonQ
OB.ar
OKlnfttsulng Q
Silver
(Kenosha)
OFatten
Eagle
Ostaples
ORound
OCono
QLoon
Tig Dardli
. ..,,,
Harsh HlllerQ
EmllyO LipSett0 O Ralnbw
O _ QWhitf Birch
Q Dunha«~ O O Mary I
I Horsenead Maaon
Twenty Six OAmour O |
8 10 12 14
Lake Condition Index
Satisfactory
16 IB 20 22
Unsatisfactory
Fig. 3. Comparison of Lake Condition Index values and
nutrient loadings for Wisconsin Lakes (from
Uttormark and Wall, 1975).
III. Relative Trophic State Indices
All of the indices described here have the disadvantage
that they are relative. That is, the position of any lake
depends on the position of the other lakes in the array. This
problem is less severe the more lakes there are involved but
it does detract from the usefulness of the indices.
1. One of the simplest approaches was that of Lueschow et al.
(1970) who ranked twelve Wisconsin lakes on the basis of the
62
-------
mean annual values of five parameters significant to trophic
status — dissolved oxygen 1 meter above bottom; organic
nitrogen; total inorganic nitrogen; Secchi disk transparency;
and net plankton. The relative composite index is the sum
of the individual ranks. An example is shown in Fig. 4-.
2. A similar approach was used by Rawson (1960) in
comparing twelve lakes in Saskatchewan,except that two rankings
were made for each lake -- one based on five physical parameters
and one based on three biological parameters. The scores are
kept separate.
3. Reimers et al. (1955) used,a proportionate ranking
system to rank lakes on a scale of 10-0 where 10 was best and 0
worst.
Fig. 4. Composite rating of 12 Wisconsin
lakes based on 5 parameters. (From Lueschow
et al., 1970).
Crystal 8
Big Green 17
Geneva - J-7
Trout ___._19
Round -31
Pine -33
Middle — 33
Oconomowoc , — 3^
Mendota ^5
Pewaukee , , 49
Delavan 52
Winnebago , , 52
63
-------
They used several factors and determined the rankings as follows:
For those parameters whose magnitude is directly proportional
to productivity,
, _ 10 (value - minimum value for all lakes)
range for all lakes
For those parameters inversely related to productivity,
,, _ 10 (maximum value for all lakes - value)
ranK — .- _.. L.—.
range for all lakes
4. A similar approach to that of Reimers et al. was used
by Michalski and Conroy (1972) in Ontario, Canada. They used
six parameters — mean depth, Secchi disk transparency, chloro-
phyll a, Ryder's morpho-edaphic index, Fe/P in the hypolimnion,
and dissolved oxygen in the hypolimnion. The final proportionate
ranking, determined as in Reimers et al., was the arithmetic
average of all six ranks. Data used was for June to September.
An example is shown in Fig. 5.
5. A system based on over 200 lakes was devised by the
United States Environmental Protection Agency (1974). In this
scheme the index is the sum of the percentile rankings for six
parameters — median total P, median inorganic N, median dissolved
P, mean chlorophyll a, mean Secchi disk transparency, and mini-
mum dissolved oxygen. Secchi disk transparency was used as
64
-------
Fig. 5. Ranking of ten selected lakes in the Lake Alert
Study area according to proportionate rankings of selected
parameters. (From Michalski and Conroy, 1972).
CTi
cn
PROPORTIONATE RATINGS
Lake
Gold
Anstruther
Mississagua
Catchacoma
Rathbun
Wolf Lake
Beaver Lake
North Rathbun
Loon Call
Cold
Mean
Depth
10.
5.
7.
7.
4.
1.
2.
1.
1.
0.
0
7
1
9
4
1
0
0
3
0
Secchi
disk
7.
10.
6.
5.
6.
0.
5.
1.
4.
0.
4
0
9
6
9
4
2
3
8
0
Chlorophyll
8.
9.
10.
10.
7.
7.
6.
2.
9.
0.
3
7
0
0
8
3
4
3
2
0
Oxygen Morpho-
Distribution edaphic
10.
10.
10.
10.
3.
10.
0.
0.
0.
0.
0
0
0
0
3
0
0
0
0
0
10.
9.
9.
9.
10.
0.
5.
8.
9.
0.
0
3
3
6
0
0
8
0
5
6
Average
Fe/P Rank
9.1
8.9
8.6
8.6
6.4
3. 7
1.8 3.5
8.3 3.4
0.0 3.1
10.0 1.7
-------
500-SD in inches, and dissolved oxygen was converted to
15-DO ppm to make them directly proportional to "trophic state".
The index ranges from 0 which is worst to 594- which is best
(Fig. 6 )• Lakes outside the range of the 200 on which the
index is based are classed as either 0 if they are worse than
any in the system, or 600 if they are better than any in the
system.
In addition to the difficulty of these indices being relative,
they have other problems as well. For example Michalski and
Conroy can use only stratified lakes and certain of their
categories are subjective. The EPA and Lueschow, both of whom
sum their rankings, and Michalski and Conroy who average theirs,
lose information and make it impossible to use the index to derive
the data. All of the above indices lose information by being
multivariate.
IV. Absolute Trophic State Indices
Such indices are arrived at independently for each lake.
1. Single Parameter
A. The areal hypolimnetic oxygen deficit of Hutchinson
(1938) is an example of an index based on a single parameter.
The infrequent use of this as an index may be due to its
restriction to relatively large, deep, stratified lakes or
to the fact that the system breaks down when the population of
66
-------
Fig. 6. Percent of Maine lakes exceeding parameter value of each
lake and the Trophic Index Number of each Maine lake using a data
base of nine lakes. (.From U.S. E.P.A., 1974).
CT)
Lake
Code
2304
2306
2308
2309
2310
2311
2312
2313
2314
Median
Total P
Lake Name Cms/1)
Estes Lake
Long Lake
Mattawamkeag Lake
Moosehead Lake
Range ley Lake
Sebago Lake
Sebasticook Lake
Long Lake
Bay of Naples
0
44
22
77
55
88
11
33
66
Median
Inorg N
(mg/1)
0
77
44
22
55
33
55
11
88
500-
Mean Sec
(inches)
0
55
22
77
66
88
11
33
44
Mean
Chlorophyll
(UK/1)
11
33
55
88
44
77
0
22
66
15-
a Min DO
(mg/1)
0
22
11
66
55
88
33
33
77
Median
Diss P
(mg/1)
0
33
22
66
55
77
11
33
77
Index No.
(Sum of
Percentages)
11
264
176
396
330
451
121
165
418
-------
algae is comprised primarily of blue greens. It does have
the advantage of being easily and unequivocally determined.
B. Another single parameter proposed as an index is
primary production. Rodhe (1958) suggested that all trophic
lake types except oligotrophic and eutrophic be eliminated, and
the rate of primary production be used as the measure of the
degree of oligotrophy or eutrophy. While this approach has
some merit it is difficult for administrators or laymen to
relate to and thus may not be useful in dealing with the problem
of communication.
C. An approach close to that of Rodhe has recently been
suggested by Megard et al.(1975). They have suggested that the
trophic index be that fraction of the photosynthetically active
irradiance that is utilized by natural populations of algae.
Two difficulties come to mind -- determination of the index
depends on determining K , the attenuation of photosynthetically
active light by the water, which is difficult to measure; and
secondly, the index does not provide an intuitive feeling to non-
limnologists.
2. Quotients
A. Various phytoplankton quotients such as that of Nygaard
(1949) have been proposed. However as Brook (1965) points out
they present difficulties. For example it requires a highly
68
-------
specialized knowledge of the phytoplankton to determine such
a quotient and even then other investigators might not agree
on the algal identifications. Furthermore they do not always
work. Brook describes lake fertilizing experiments in which,
even when the algal population was increased eight fold, the
quotient did not change.
B. A similar yet different approach to the algal quotient
index has been made by Stockner (1971). He proposed character-
izing lakes on the basis of the ratio of Araphidinae/Centrales
diatom frustules in the recent sediments. Basing his ideas
on the differences in ratios between lakes of known character-
istics , and on the changes in individual lakes resulting from
fertilization, he proposed the following:
A/C ratio Lake type
0-1.0 oligotrophic
1.0-2.0 mesotrophic
>2.0 eutrophic
Even assuming this system is valid, it requires expertise
to determine the ratio and provides little intuitive feeling
for the condition of the lake.
3. Indices based on lake fauna
A._ Among those indices based on the fauna of lakes is that
of Reynoldson (1958) who set up five categories ranging from
69
-------
extreme oligotrophy to eutrophy based on the characteristic
species of triclad flatworms.
B. A similar approach was used by Jarnefelt (1953) who
classified Finnish lakes on the bases of total bottom fauna,
and Chironomid larve alone.
C. A numerical index based on Chironomid species was
devised by Brinkhurst et al. (1960). The so called "trophic
condition index", which ranges from 2.00 (extreme eutrophy)
to 0 (extreme oligotrophy) is given by the formula:
EnQ + En + En2
Where 2 , E and E are the numbers of intolerant, moderately
tolerant, and tolerant Chironomids per 100 dredge samples.
This index reflects reasonably well the conditions in the
Great Lakes, western Lake Erie having an index of 2.00, Lake
Ontario 1.07, and Georgian Bay, which is oligotrophic, 0.13.
However, extension into other lakes is not likely to be useful
as the relative abundance of the Chironomids is affected by their
geographic range as well as by factors such as depth and water
temperature having little influence on trophic status. In
addition the range is small and Lake Erie which has an index
70
-------
of 2.00 is certainly not the most eutrophic lake in existence.
Finally this index, as the two of Reynoldson and Jarnefelt,
requires considerable expertise to determine and the results
are not particularly intuitive to the layman.
In addition to phytoplankton quotients and indices based
on bottom fauna, various investigators have developed indices using
the fish in lakes.
D. For example in 1965 Ryder described his morpho-edaphic
index, where X = TDS (?Pm> ,, +s
mean depth (feet)
From this rather hybrid index he claims to be able to predict
fish production, Y, using the relation
Y= 2/Xwhere y is in Ibs/acre/yr.
E. A somewhat more elaborate fish productivity index was
published by Hayes in 1957 and modified by Hayes and Anthony
in 1964. In its first form the PI (Productivity Index) is
obtained by listing the recorded fish crop removed from each
lake, summing up the weights of the species into groups with
short, intermediate, and long food chains, and dividing
the weights of each group by a factor given by Carlander
(140, 43, and 16 respectively). The sum of the resulting three
numbers is the Productivity Index,.
This index which may be used to compare one lake with
another may be converted to a Quality Index, QI, to enable
lakes of different depths to be compared more reasonably.
71
-------
Thus ,
QI = pI/m/5
where m = mean depth in meters.
For example lakes Erie and Superior have Productivity Indices of
1.57 and 0.17 respectively, and Quality Indices of 2.92 and
0.90 respectively. In their later paper Hayes and Anthony
modified the PI to take into account area, depth»and water
chemistry as follows;
log PI = -0.236 + 1.H7 x 10' - 0.517 x + 0.287 x
where x, = /, n5 / . , 2
1 10 /area in km
x~ = log depth , m
XQ = log methyl orange alkalinity, ppm
O
Multivariate Indices
Two approaches have been used in constructing absolute
indices based on a number of parameters -- use of several
factors simultaneously .and use of several factors alternatively,
A. Perhaps the best example of the simultaneous use of
multiple factors is in the work of Shannon and Brezonik (1972).
Using annual averages of seven trophic state indicators in
55 lakes in the State of Florida they arrived at a Trophic
State Index through the use of principle component analysis
and other multivariate analytical methods. The parameters
72
-------
used were, primary production, chlorophyll a., total organic
nitrogen, total phosphorus, Secchi disk transparency, specific
conductance, and Pearsall's cation ratio [ ^—+ -, J.
The Trophic State Index or TSI was calculated as TSI = Y +5.19
where Y = 0.919-|=r + 0.800 COND + 0.896 TON
X o U
+ 0.738 TP + 0.942 PP + 0.862 CHA + 0.634 -lw
LK
The validity of the index was demonstrated by the close
relationship of the TSI values to the traditional trophic
categories of lakes. Thus the group of lakes classed as
hypereutrophic (Fig. 7 ) ranged in TSI from 10.5 to 22.1
while those in the ultraoligotrophic group had TSI values from
1.3 to 1.9.
While this index does have the advantage noted i.e. it
seems to work -- it suffers from certain disadvantages. For
example it is difficult to obtain all of the data, particularly
as annual averages, and not all of the data are meaningful
e.g. the cation ratio. Furthermore by using a combination of
factors one loses information. Thus Lake Alice had a TSI
of 10.7 putting it in the category of hypereutrophic, despite
the fact that it had a moderate transparency and a low primary
productivity and chlorophyll concentration. The lake does
have a large population of water hyacinths however.
73
-------
Fig. 7. Fifty-five Florida lakes ranked according
to Trophic State Index CTSI). (From Shannon and
Brezonik, 1972a)
Lake
TSI
Lake
TSI
Hypereutrophic group
Apopka
Twenty
Dora
Bivin's Arm
Griffin
Kanapaha
Alice
Eustis
Eutrophic group
Hawthorne
Clear
Burnt Pond
Wauberg
Newna^s
Mesotrophic group
Twenty-five
Harris
Twenty-seven
Cooter Pond
Lochloosa
Tuscawilla
Calf Pond
Orange
Mize
Watermelon Pond
Little Orange
Weir
Elizabeth
22.1
18.5
18.5
14. 7
13. 7
13.5
10.7
10.5
9.1
8.6
8. 3
7.4
7.1
6.4
6. 3
5.8
5. 3
5.2
4.8
4.6
4.3
4.2
3.6
3.4
3.3
3.2
Ten
Palatka Pond
Seville's Pond
Met a
Oligotrophic group
Jeggord
Moss Lee
Long Pond
Clearwater
Altho
Hickory Pond
Santa Fe
Sugga
Little Santa Fe
Adaho
Wall
Winnott
Ultraoligotrophic group
Still Pond
Kingsley
Geneva
Gallilee
Swan
Anderson-Cue
McCloud
Brooklyn
Cowpen
Long
Sumrer-Lowry
Magnolia
Santa Rosa
3.2
3.2
3.1
3.1
2. 8
2.8
2.8
2.6
2.5
2.5
2.5
2.3
2.3
2.2
2.1
2.0
1.9
1.9
1.8
1.6
1.5
1.5
1.5
1.5
1.5
1.3
1. 3
1. 3
1.3
74
-------
B. In the second approach to using multiple parameters to
construct an absolute index the factors are used alternatively
i.e. the index is obtained from any one of the factors and the
other factors are used as corroboration. This has two advantages
-- it is easier to gather the data, and because of the direct
relationship between the data and the index the data can easily
be translated from the index.
1. One such index has been proposed by Dobson (1974).
Using data from near surface waters of lakes Ontario and Erie
he found relationships between four "diagnostic variables";
30/Secchi disk (m), chlorophyll a, total phosphorus/ participate
organic carbon, Dobson proposed a scale of three aesthetic
categories as follows :
Trophic Assessment
variable
30/SD
Chi a
POC
TP
low and good
0-4.9
0-4. 3
0-270
0-8.6
medium and fair
5.0-9.9
4.4-8.7
280-550
8.7-17.3
high and
10.0 +
8.8 +
560 +
17.4 +
poor
75
-------
All of the variables are numerically related to the 30/Secchi
disk as follows:
variable factor
30/SP
Chi a. 1.14
POC 0.179
TP 0.057
This system has certain disadvantages.
1. The terms "low", "good", etc. are subjective value judgments.
2. There are too few categories for precision.
3. The relationships used are not valid i.e. 30/SD is not
linear and does not relate well to chlorophyll a..
4. The system was built on only two rather unusual lakes.
5. The system is unbalanced i.e. eutrophic is by far the largest
category.
On the other hand this scheme has certain advantages
or potential advantages.
1. Some of the data are easily.arrived at.
2. Alternative parameters can be used.
3. There is an attempt to use defined relationships.
H. The scheme allows some determination of causal effects,
e.g. one can tell, as the parameters are reported separately,
whether a low transparency is due to chlorophyll or to
turbidity.
76
-------
2. A somewhat similar system with far fewer disadvantages
has been proposed by Carlson (1974). Carlson's Trophic State
Index, or TSI, is basically a linear transformation of Secchi
disk transparency such that each major unit in his scale has
half the transparency of the next lower unit . It is derived
as follows :
= 10(6 - log2SD)
where Secchi disk transparency is in meters .
Thus a lake with transparency of 64 m has a TSI of 0 which is
at the low end of the scale. The other end of the scale is
left open but probably does not extend much above 100 (Fig. 8 ).
By using empirically determined relationships between
total phosphorus and transparency and between biomass , as repre-
sented by chlorophyll a. and transparency, Carlson has made it
possible to arrive at the same index value from these data
as well. Thus ,
^;= 10(6 - Iog0 65^]
and
TSI(CHL
where total P and chlorophyll a are in yg/1 .
77
-------
Fig. 8. Transparency, phosphorus and chlorophyll
values corresponding to Carlson's Trophic State
Index values. (From Carlson, 1974).
Surface
Surface
TSI
0
10
20
30
40
50
60
70
80
90
100
Secchi
Disk (m)
64
32
16
8
4
2
1
0.5
0.25
0.12
0.062
Phosphorus
Cmg/m3)
1
2
4
8
16
32
65
130
260
519
1032
Chlorophyll
(mg/m3)
.04
.12
.34
.94
2.6
6.4
20
56
154
427
1183
78
-------
Calculation of the indices is facilitated by using the
following equations:
TSI = 10(6 - ±S_SD }
CSD) ln 2
li
TSI(Tp)= 10(6-12-fP )
TQT - ifUfi 2.0^ - 0.68 in chl a }
TSICCHL)- 10(6 In-2 }
In similar fashion any parameter that can be correlated with
transparency can be used to arrive at the same Trophic State
Index values.
The advantages of this system are:
1. The index uses easily obtained data.
2. It is simple in form,being reported simply as a number.
3. It is narrow enough in scope to be meaningful i.e. it describes
the "trophic" conditions in the open water and does not
attempt to infer health, aesthetic, or other characteristics.
4. It is purely objective. No value judgments are used and
no names are suggested for different ranges of TSI.
5. The TSI values are absolute and, having been derived from
a wide variety of lakes, are applicable to many lakes.
6. The relationships used are valid i.e. transparency is not
79
-------
treated as linear but cognizance is taken of the parabolic
shape of the transparency/biomass relationship.
7. The index does not lose information by mixing up unrelated
or even related parameters.
8. The data can be retrieved from the index.
9. The form of the index allows for an intuitive grasp of it
in much the same fashion as the Richter earthquake scale
does .
10. The index has sufficient categories for fine discrimination
among lakes.
An example of the descriptive use of the index is given
in figure 9 where the changes in Lake Washington over the
period 1950 to 1973 are shown as both raw data and as TSI values.
Although both show the same trends the TSI values are more
sensitive indicators of change in certain instances. For example
the change in chlorophyll concentrations from 1950 to 1960
does not appear to be great but it does represent a significant
change in the value of the index. Another example of the des-
criptive use of the index is given in figure 10. Note that
the TSI values of the Minnesota lakes almost fit a normal
distribution. This is in contrast to a histogram constructed
using equal intervals of Secchi disk transparency in which most
values appear at the low end of the diagram.
80
-------
X
«•
c •>
a *
>-• S*cct)i D«sX Tron>parnncy
• O-B Chlorophy* a
»—x Total Pho»phoru»
7O
60 E
3O «
1
o.
40 £
o
c
u
30?
o
c
o.
10 -
1933 195O
1S«O
tBTO
197O
Figure 9. Top: Average siommer1 values of three parameters in
Lake Washington, Seattle, Washington. Below: The data trans-
formed into Trophic State Index values.
81
-------
co
CD
40
O
30
O
CO
0)
c
c
20
•10
0)
E
ZJ
0
0
\
•10
L. Washington
(-195O a -1974)
Crater L. L, Superior
\
L Erie
(West Basin)
L. Washington
(-1963)
40 50 60
Trophic State Index
70
80
Figure 10. TSI values for a group of Minnesota lakes and for several
other lakes.
90
-------
The index also has value as an analytical tool. Note
in figure 9 that the TSI values determined separately from
the three parameters do not always coincide. This does not
necessarily mean that the index values are wrong but may
indicate instead certain facts about the lake's behavior.
For example if the TSI(Tp) is higher than the TSI.g-p, or
TSI^HLv it could indicate that either the lake is not phosphorus
limited, or that grazing by herbivorous ^ooplankton is
important.
Postscript
The world is becoming quantitative. Of the indices
described here more than half were developed since 1970.
The reason is obvious. There is a need for quantitative
indices to develop quantitative policies and to make national
decisions based on quantitative considerations. There is also
a need for scientists to communicate with each other and with
the public in quantitative terms. Unless the limnological
community takes its task seriously in selecting, quantifying,
or developing specific indices to use on national and inter-
national scales the problem will soon become one of finding ways
to translate the multitude of indices one to another. There
is no single index that will satisfy every need but unless we
are all prepared to compromise we will continue to flounder about
in a mass of qualitative descriptions and the problems will get
worse. 83
-------
BIBLIOGRAPHY
Aukerman R. and G.I. Chesley, 1971.
Classifying water bodies
Feasibility and recommendations for classifying water.
Report to Natural Water Commission by Department
of Recreation Resources, Colorado State University,
Fort Collins Colorado.
Bailey, John, 1974.
A suggested classification system for Maine lakes.
Draft report, Lakes Division, Department of Environmental
Protection, State of Maine. 1974.
Beeton A.M. and W.T. Edmondson, 1972.
The eutrophication problem.
J. Fish. Res.Bd. Canada 29: 673-682.
Bortleson G.E., N.P. Dion, J.B. McConnell, 1974.
A method for the relative classification of lakes in
the state of Washington from reconnaissance data.
USGS Water Resources Investigations, 37-74.
84
-------
Brezonik P.L. and E.E. Shannon, 1969.
Eutrophication factors in north central Florida lakes
Bull. Ser. 134. Eng. Exp. Sta.
University of Florida, Gainesville, 101 pp.
Brezonik P.L. and E.E. Shannon, 1971.
Trophic state of lakes in north central Florida.
Florida Water Resources Research Center Publ. 13, 102 pp,
Brinkhurt R.O., A.L. Hamilton, H.B. Herrington, 1960.
Components of the bottom fauna of the Great Lakes.
Great Lakes Inst., Univ. Toronto, PR 33:49 pp.
Brook A.J., 1965.
Planktonic algae as indicators of lake types
with special reference to the Desmidaceae.
Limnol. Oceanogr. 10; 403-411.
Brown R.M. et al. , 1971.
"A water quality index -- crashing the psychological
barrier".
Paper presented at the 138th meeting of AAAS ,
Phila. Pa. (Dec 28, 1971).
85
-------
Carlson R.E., 1974.
A trophic state index for lakes.
Contribution #ltl, from the Limnological Research Center,
University of Minnesota.
Chandler, J.R., 1970.
A biological approach to water quality management.
Water Pollution Control, No. 4, 415-422.
Chutter F.M., 1972.
An empirical biotic index of the quality of water
in South African streams and rivers.
Water Research £: 19-30.
Dobson H.F.H., 1974.
Personal communication to J. Shapiro entitled
"Development of a water quality scale".
Elster H.J., 1958.
"The limnological system of lake types; survey and
prospectives".
Proc. Int. Assoc. Theor. Appl. Limnol. 13; 101-120.
86
-------
Faegri, K., 1954.
Some reflections on the trophic system in limnology,
Nytt. Mag. for Bot. _3: 43-9.
Feuillade, J., 1972.
Application de la Methode de I1Analyse Factorielle
des Correspondances a la Classification des Lacs en
Fonction de Leur Degre d'Eutrophie.
Chemosphere 2_: 95-100.
Fruh E.G. et al., 1966.
Measurement of eutrophication and trends.
J. Water Poll.Cont. Fed. 38; 1237-1258.
Harkins R.D., 1974.
An objective water quality index
J. Water Poll. Cont. Fed. 46: 588-91
Hayes F.R., 1957.
On the variation in bottom fauna and fish
yields in relation to trophic level and lake
dimensions.
J. Fish. Res. Bd. Canada 14: 1-32.
87
-------
Hayes. F.R.. and E.A. Anthony, 1964.
Productive capacity of North American lakes as related
to the quantity and the trophic level of fish, the lake
dimensions, and the water clarity..
Trans. Am. Fish. Soc, 93; 53-57.
Hooper F.F., 1969.
Eutrophication indices and their relation to other
indices of ecosystem change.
In "Eutrophication: Causes, Consequences, Correctives"
Nat. Acad. Sci., Wash. D.C. pp. 225-235.
Hutchinson G.E., 1938.
On the relation between the oxygen deficit and the
productivity and typology of lakes.
Int. Rev. Gesamt. Hydrobiol. 36: 336-55.
Hutchinson G.E., 1973.
Eutrophication: the scientific background of a
contemporary problem.
Amer. Sci. 61: 269-279.
-------
lilies, J. and L. Botosaneanu, 1963.
Problemes et methodes de la classification et
de la zonation ecologique des eaux courantes
considerees surtout du point de vue faunistique.
Mitt. Int. Verein. fur. Theor. Angew. Limnol. 12; 1-57
Inhaber H., 1975.
An approach to a water quality index for Canada
To be published in Water Research.
Jarnefelt H., 1952.
Plankton als Indikator der Trophiegruppen der Seen.
Ann. Acad. Sci. Fennicae, A. 55; 1-29.
Jarnefelt H. , 1953.
Die Seetypen in Bodenfaunistischer Hinsicht
Ann. Zool. Soc. 'Vanamo'. 15: 6, 37 pp.
Jarnefelt, H., 1958.
On the typology of the northern lakes.
Verh. Internat. Ver. Limnol. 13 : 228-235.
Kendall M.G., 1963.
"A course in multivariate statistics"
Charles Griffin and Co., London, England.
89
-------
Kolkwitz R. and M. Marsson, 1908.
Oekologie der tierischen Saprobien.
Int. Rev. Ges. Hydrobiol. Hydrogr. 2_: 126-152.
Korde, N.V., 1966a.
Algenreste in Seesedimenten.
Zur Entwicklungeschichte der Seen und umliegenden Land-
schaften. Ergeb. Limnol. 3_: 1-38.
Korde N.V., 1966b.
"Constructing a uniform system of lake types, based on
their origins and history."
Ekologiya vodnykh organizov. Akad. Nauk SSSR. Izd. "Nanka",
Moscow, NO. 7, pp. 62-68.
Larkin, P. and T.G. Northcote, 1958.
Factors in lake typology in British Columbia, Canada.
Verh. Internat. Ver. Limnol. 13; 252-263.
Lind, C.T. and G, Cottam, 1969.
The submerged aquatics of University Bay:
A study in eutrophication.
Amr. Mid. Nat. 81: 353-369.
90
-------
Lueschow, L., J. Helm, D. Winter, G. Karl, 1970.
Trophic nature of selected Wisconsin Lakes,
Wis. Acad. Sci. Arts Lett. 58: 237-264.
Margalef R. , 1958.
Trophic typology versus biotic typology as exemplified
in the regional limnology of northern Spain.
Verh. Int. Verein. Theor. Angew. Limnologie,
1_3: 339-349.
Marstrand, P.K., 1974.
Assessing the intangibles in water pollution control.
Intern. J. Env. Studies £: 289-298.
McColl R.H.S., 1972.
Chemistry and trophic states of seven New Zealand lakes,
New Zealand J. Mar. and Freshwater Res. 6_: 3-99-447.
Megard, R.O.,P.D. Smith, A.S. Knoll, W. Combs, 1975.
Attenuation of light and photosynthetic rates of phyto-
plankton. Unpub. Manuscript.
Michalski M. and N. Conroy, 1972.
Water quality evaluation — Lake Alert Study.
Ontario Ministry of the Environment Report 23 pp.
91
-------
Moyle, J.B., 1949.
Some indices of lake productivity
Trans. Am. Fish. Soc. 76: 322-34.
National Swedish Nature Conservancy Office, 1969.
Summary of "Report on water quality criteria
for Swedish surface waters", 1969: 1 E.
Newton, M.E. and C.M. Fetterolf., 1966.
Limnological data from ten lakes, Genessee and
Livingston Counties, Michigan, September 1965.
Nygaard G., 1949.
Hydrobiological study of some Danish ponds and lakes, II.
The quotient hypothesis and some new or little known
phytoplankton organisms.
Kgl. Danske. Videnskab. Selskab, Biol. Skrifter Ti 293 pp
Piwoni M.D. and G.F. Lee, 1974.
A limnological survey of selected impoundments
in central and southern Wisconsin.
Kept, to Wis. DNR, 151 pp.
92
-------
Prati, L., R. Pavanell and F. Pesaria, 1971.
Assessment of surface water quality by a single
index of pollution.
Water Research _5: 741-51.
Rawson D.S., 1956.
Algal indicators of trophic lake types.
Limnol. Oceanogr. !_: 18-25.
Rawson, D.S., 1958.
Indices to lake productivity and their significance
in predicting conditions in reservoirs
and lakes with disturbed water levels.
Rawson, D.S., 1960.
A limnological comparison of twelve large lakes in
northern Saskatchewan.
Limnol. Oceanogr. 5_: 195-211.
Reimers, N., J.A. Maciolek and E.P. Pister, 1955.
Limnological study of the lakes in Convict Creek
Basin,Mono County, California.
U.S. Fish and Wildlife Service, Fishery Bull 103.
Vol. 5^6; H37-503.
Reynoldson, T.B., 1958.
Triclads and lake typology in northern Britain —
qualitative aspects
Verh. Internat.Ver. Limnol. 13: 320-330.
93
-------
Rodhe W., 1958.
Primarproduktion und Seetypen.
Verh. Internat. Ver. Limnol. 13_: 121-141.
Round, F.E., 1958.
Algal aspects of lake typology.
Verh. Internat. Ver. Limnol. 13: 306-310.
Ryder R.A.. 1965 ,
A method for estimating the potential fish
production of north-temperate lakes.
Trans. Amer. Fish. Soc. 9_H: 214-218.
Shannon E.E. and P.L. Brezonik, 1972a.
Eutrophication analysis: a multivariate approach,
J. San. Eng. Div. ASCE, Vol. 98, No. SA 1,
Proc. Paper 8735, Feb. 1972, pp. 37-57.
Shannon E. and P.L. Brezonik, 1972b.
Relationships between lake trophic state and
nitrogen and phosphorus loading rates.
Env. Sci. and Technol. 6: 719-725.
94
-------
Shapiro, J., 1969.
Criteria for assessment of trophic state.
Prepared for eutrophication workshop
St. Petersburg,Florida. Nov. 1969. Mimeo.
Shapiro, J., J.B. Lundquist, R.E. Carlson, 1974.
Involving the public in limnology — an approach to
communication.
To be published in the proceedings of the 19th Congress
of the SIL.
Sheldon, A.L., 1973.
A quantitative approach to the classification of
inland waters.
pp. 205-261 in "Natural environments", studies in
theoretical and applied analysis"
J.V. Krutilla, ed.
Stewart, K.M. and G.A. Rohlich, 1967.
"Eutrophication -- a review"
California State Water Quality Board, Publ. 34.
Stockner J.G., 1971.
Preliminary characterization of lakes in the experi-
mental lakes area, northwestern Ontario, using
diatom occurrence in sediments.
J. Fish. Res. Bd. Canada. 28: 265-275.
95
-------
Swindale, D.N. and J.T. Curtis, 1957.
The phytosociology of large submerged plants in
Wisconsin lakes.
Ecology 3J3: 397-407.
Sylvester H. and M.W. Hall, 1974.
A qualitative classification of Maine Lakes.
Paper presented at 37th annual meeting of American
Society of Limnology and Oceanography, June 1974
Seattle, Washington.
Tarapchak, S.J., 1974.
Studies on phytoplankton distribution and indicators
of trophic state in Minnesota lakes.
Manuscript prepared for a workshop on the North
American Project, CCIW. Burlington Ontario April 1974.
Thomas, W.A., ed. 1972.
Indicators of environmental quality.
Plenum Press, N.Y.
96
-------
Thunmark, S., 1945.
Zur Soziologie des Stisswasser-planktons.
Eine methodologischo'kologische Studie.
Folia Limnoligica Scandinavica _3: 1-66.
Train, Russell E. ,1972.
Science 178: # 4057
Editorial, "The Quest for Environmental Indices."
U.S. Environmental Protection Agency, 1974.
An approach to a relative trophic index system for
classifying lakes and reservoirs.
Working Paper No. 24.
National Eutrophication Survey, Pacific Northwest
Environmental Research Laboratory,
Corvallis, Oregon. Dec. 1974. 44 pp.
Uttormark, P.D., 1974.
A lake condition index.
Paper presented at Conference on Lake Management
Madison,Wisconsin, October, 1974.
Uttormark, P.D. and J.P. Wall, 1975.
Nutrient assessments as a basis for lake management priorities,
pp. 221-240 in "Biostimulation and Nutrient Assessment."
(E.J. Middlebrooks, et al., edit.).
Ann Arbor Science.
97
-------
Uttormark P.D. and J.P. Wall, 1974.
"National Lake Inventory"
Annual Progress Report to Water Resources Center,
University of Wisconsin, 1974.
Vallentyne, J.R. , J. Shapiro, A.M. Beeton, 1969..
The process of eutrophication and criteria for
trophic state determination.
pp. 58-67 in "Modeling the Eutrophication Process."
proceedings of a workshop at St. Petersburg,
Florida, Nov. 19-21, 1969.
Vollenweider, R.A., and P.J. Dillon, 1974.
The application of the phosphorus loading concept to
eutrophication research.
National Research Council of Canada, WRRC Pub. No. 13690
Wilhm J.L. and T.C. Dorris, 1968.
Biological parameters for water quality criteria,
BioScience 18: 477-481.
Winner R.W., 1972.
An evaluation of certain indices of eutrophy and
maturity in lakes.
Hydrobiologia 40: 223-245.
98
-------
Wisconsin Department of Natural Resources, 1970.
Pewaukee Lake, Waukesha County -- An inventory with
planning recommendations.
Land use Kept. No. FX-2, prepared by the Wisconsin
DNR for the Southeastern Wisconsin Regional Planning
Commission.
Woodiwiss F.S., 1964.
A biological system of stream classification.
Chemistry and Industry 14: March, 1964.
Zafar A.R., 1959.
Taxonomy of Lakes
Hydrobiologia 13: 287-299.
Two recent books should be added:
Hart, C.W. and S.L.H. Fuller, Eds.,1974.
Pollution Ecology of Freshwater Invertebrates.
Academic Press, N.Y. 390 pp.
Thomas, W.A., G. Goldstein and W.H. Wilcox, 1974.
Biological Indicators of Environmental Quality.
254 pp.
99
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TSI AND LCI: A COMPARISON OF TWO
LAKE CLASSIFICATION TECHNIQUES
Paul D. Uttormark
Water Resources Center
University of Wisconsin
Madison, Wisconsin 53706
INTRODUCTION
In recent years increasing emphasis has been placed on the development
and use of classification systems for lakes as an integral part of lake
management efforts. By necessity, these systems must have minimal data
requirements if they are to have broad application, because data are lacking
for the majority of lakes. Two approaches proposed recently are based on the
calculation of "Lake Condition Index" values (Uttormark and Wall, 1975) and
"Trophic State Index" values (Carlson, 1974). It has been demonstrated that
each of these indices can be a useful aid for communication and lake
management decision-making. A volunteer lake monitoring program was initiated
in Minnesota in 1973 in which lake residents collected Secchi depth data and
lakes were classified according to the Trophic Status Index (TSI). This index
was useful for comparing different lakes and, also, as a mechanism for
communication with the general public (Shapiro, Lundquist and Carlson, 1975).
In Wisconsin, the Lake Condition Index (LCI) was used to classify the 1150
larger lakes, and the results have also been incorporated into the planning
and priority analysis of the state's lake protection and renovation program
within the Department of Natural Resources (Uttormark and Wall, 1976).
Significantly, the application and evaluation of these techniques have been
limited to a single state, which limits the diversity of lake type, climatic
influence, and public perception of water quality—factors which affect the
usefulness and acceptability of classification results.
The purpose of this report is to apply the TSI and LCI classification
methodologies to a diverse array of lakes representing a broad geographical
area to determine whether under these conditions the two indices provide a
similar measure of lake water quality, and whether they might be useful for
comparing water quality conditions among these lakes. The objective is nar-
rowly focused, and no attempt is made to assess the applicability of either
technique under different circumstances or for other purposes. For this
analysis, two types of comparisons were made between LCI and TSI values, based
on a study set of about 200 lakes.
1. Both index values were calculated for each lake and a plot was
prepared of Trophic State Index versus Lake Condition Index. (This
was possible because each of the classification techniques is
101
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of the independent type—i.e., lakes are ranked according
to an independent scale of reference, and individual
classifications are not dependent on the rank of other
lakes in the array.)
2. Each index is compared separately to the trophic cate-
gories selected by individuals who provided input data
as best describing the character of each of the lakes
in the study set.
It should be noted from the outset that there is no objec-
tive method for assessing the "accuracy" or "validity" of
lake classification systems. At the root of the problem is
the concept of trophic status which has never been quanti-
fied or defined precisely. Consequently, about the only
method of checking classification results is to obtain
subjective evaluations from individuals familiar with the
subject lakes—i.e., determine whether the classification
results agree with preconceived perceptions of lake status.
This approach has considerable shortcomings, particularly
when the study lakes are selected from a large geographical
area over which there may be diverse variations in the
perception of water quality. For a more comprehensive dis-
cussion of classification mechanics, system types and uses
of classification results the reader is referred to Shapiro
(1975) and Uttormark and Wall (1975).
102
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LAKE CONDITION INDEX
A technique for computing "Lake Condition Indices," based
on some of the more readily observable indicators of eutro-
phication, was proposed by Uttormark and Wall (1975). For
this approach, points are assigned to lakes depending on
the degree to which they exhibit undesirable symptoms of
water quality. Four input parameters are used, and ranges
of values for each parameter are specified to depict lake
conditions ranging from desirable to undesirable. The
parameters used and the range of possible points assigned
are listed below.
Table 1. POINT SYSTEM
FOR LAKE CONDITION INDEX
Parameter Points
Hypolimnetic dissolved oxygen
Transparency
Fishkills
Use impairment (extent of
macrophyte or algal growths)
Total
The parameters are treated independently, and composite
lake ratings are determined by summing the number of points
assigned in each of the four categories. The sum is termed
a "Lake Condition Index" (LCI). Thus, if a lake exhibited
none of the specified undesirable symptoms of eutrophica-
tion, it received no points (LCI = 0). Conversely, for a
lake to have an LCI of 23 it would have had to have all
the undesirable characteristics in the most severe degree.
Details of the classification methodology are given in the
appendices.
LCI values were calculated for all (approx 1150) Wisconsin
lakes with surface areas in excess of 100 acres (40 ha).
In an attempt to check the "accuracy" of the results, lakes
were listed regionally according to LCI value, and these
103
-------
lists were reviewed by area managers of the Wisconsin Depart-
ment of Natural Resources. Of the 1150 lakes classified,
303 were reviewed in detail by the area managers. A summary
of their critiques is given in Table 2.
Table 2. SUMMARY OF LCI REVIEW
BY WISCONSIN DNR AREA MANAGERS
Area
number
Total
lakes
LCI number
unchanged
LCI number
changed by
2 or less
LCI number
changed by
3 or more
1
2
3
4
5
6
7
8
9
Totals
9
42
32
62
84
16
21
23
14
2
32
20
52
63
11
5
8
9
303.(100%) 202(66%)
6
4
6
7
11
4
10
9
_3
60(20%)
1
6
6
3
10
1
6
6
2
41(14%)
It was found that 202 (66%) of the LCI values reviewed were
left unchanged; 60 scores (20%) were changed by 2 or fewer
points; and only 41 scores (14%) were considered to be in
error by 3 or more points. (As part of tests conducted
early in the project, it was estimated that LCI values were
reproducible to within ± 2 units when different sources of
input data were used to classify the same lakes.)
Based on these results, it was concluded that the technique
worked reasonably well in Wisconsin considering that data
were lacking for many of the subject lakes. The primary
objective of the classification effort was to obtain an
improved perspective of the lake resources of the state,
and, for that purpose, the results appear to be useful and
are being used to develop management strategies and pri-
orities. It was suggested that this classification approach
might be applicable in other states as well as in Wisconsin,
as shown in Table 3.
104
-------
Table 3. ESTIMATED APPLICABILITY OF THE LCI APPROACH3
Number of
lakesb
Direct applicability - Group 1
Conn, 111', Ind, la, Me, Mass, Mich,
Minn, Neb, NH, NY, ND, Ohio, Penn, 9,503
RI, SD, Vt, Wis
Some modification - Group 2
Calif, Colo, Del, Ida, Kan, Ky, Md,
Mo, Mont, Nev, NJ, NC, Okla, Ore, 2,073
Tenn, Utah, Va, Wash, WVa, Wy
Major changes - Group 3
Ala, Ariz, Ark, Fla, Ga, La, Miss, ~
NM, SC, Tex *
Total 13,599
afrom Uttormark and Wall (1975)
kfiased on a summary of lake inventory data compiled
by individual states. Lakes larger than 100 surface
acres .
105
-------
TROPHIC STATUS INDEX
This classification was developed primarily as an aid for
communication between limnologists and with the general
public, and it is suggested that this index, or a modifica-
tion of it, might serve as a replacement for the poorly-
defined trophic categories which have been used traditionally
(Shapiro, Lundquist and Carlson, 1975). The index is based
on a single parameter, Secchi depth, and is defined as
follows:
TSI = 10(6-log2(SD))
where SD denotes the Secchi depth in meters. This logarithmic
transformation results in a TSI increase of 10 units when the
Secchi depth decreases by a factor of 2. (Corresponding
values of Secchi depth and TSI are given in Table 4.)
Table 4. TROPHIC STATUS INDEX VALUES
AS A FUNCTION OF SECCHI DEPTH
Secchi depth
(meters) TSI
64
32
16
8
4
2
1
0.5
0.25
0
10
20
30
40
50
60
70
80
Because of its simplicity, the TSI has many of the advan-
tages of an "ideal" classification technique: data require-
ments are minimal, the index values are absolute, and the
approach is objective. However, "trophic status" has
traditionally been used as a multidimensional concept
(Shannon and Erezonik, 1972), and one might question the
106
-------
amount of information that can be relayed on the basis of
a single parameter. Nevertheless, it has been shown that/
for many lakes/ there is a definable relationship between
Secchi depth and chlorophyll-a and between Secchi depth and
total phosphorus (Shapiro, Lundquist and Carlson, 1975)
and, alternately, the TSI may be defined in terms of these
input parameters as well.
A volunteer data collection program was undertaken in
Minnesota and, in 1975, 250 lakes were being monitored
to obtain Secchi depth data. A frequency distribution
for about 80 of these lakes showed that the TSI ranged
from about 20 to 90 with the majority of lakes having TSI
values between 40 and 60. The data plot approached a normal
distribution. No attempt was made to compare the TSI rank-
ings to the traditional trophic descriptions, nor were any
names associated with specific ranges of the TSI. This is
consistent with the objectives of the TSI development, in
which an attempt is made to replace the traditional trophic
groupings with a continuous index which, like the Richter
scale for earthquakes, gains meaning and acceptance through
use.
107
-------
DATA COMPILATION AND ANALYSIS
To obtain the basic information necessary for this analysis,
a data form was designed which contained provisions for the
following information:
1. Lake identification, i.e., name, size, etc.
2. Condition characteristics - four questions relating to
DO conditions and extent of "weed"/algal growth.
3. Secchi depths - three or more values obtained during
the growing season.
4. Trophic status - whether, in the opinion of the re-
sponder, the lake is very oligotrophic, oligotrophic,
mesotrophic, eutrophic, very eutrophic.
Data forms were mailed either to the state agency judged to
have lake management responsibilities or to the Water Resources
Research Institute in each state, and it was requested that
information be provided for 10-12 lakes of differing trophic
character. Only one source was contacted in each state.
Excellent cooperation was received in obtaining the desired
lake information. Data sufficient to compute both TSI and
LCI values were received from 21 states relating to more than
200 lakes. Also, partial information was received from an
additional 5 states; unfortunately, time constraints did not
permit the compilation of missing information so these data
could not be incorporated into this report. A number of
other states reported that it was not possible to provide
the desired data because it was not available or because-
time/manpower constraints precluded compilation of the infor-
mation. The data request was unacknowledged for only a few
states.
Data analyses consisted of converting all the input data to
consistent (metric) units, and computing the corresponding
LCI and TSI index values. A tabulation of all the input
data, as well as plots of TSI versus LCI values for each
state, is given in the appendices.
108
-------
It should be noted that all mathematical manipulations relat-
ing to the TSI were made on the Secchi data, not the cor-
responding index values. For example, Secchi depth data
were averaged over the growing season and mean values were
used to compute the TSI for each lake. (A different result
would have been obtained if each Secchi value had been con-
verted to a TSI and then averaged.) Likewise, frequency data
and statistical summaries are based on Secchi data which were
converted to TSI values only as a final step. However, all
graphs are presented linearly with respect to TSI and, there-
fore, logarithmic with respect to Secchi depth.
109
-------
RESULTS
A comparison of TSI and LCI values for each of the lakes in
the data set is given in Figure 1. The open circles repre-
sent data for those states in which the LCI was estimated
to apply directly (see Table 3)/ and the solid symbols refer
to states in which the LCI was thought to apply only with
modification. This data segregation was done in an attempt
to eliminate one source of variation between the two indices.
However, since the distribution for the three data groups
showed considerable overlap, no further distinction of data
groups is made here, and all the data are considered to be
part of a single set.
In comparing TSI with LCI values it should be noted that
Secchi depth is incorporated in both indices, and therefore
some correlation is imposed by definition. For example, for
an LCI of zero, the typical Secchi depth must exceed 7 meters
This is equivalent to a TSI of 32 or less.
If there is very good agreement between the two indices,
then all the data points should fall in a narrow band from
upper left to lower right in Figure 1. This band could have
some type of curvature—a straight line would not be ex-
pected—but if the two indices yield similar measures of
"status" or "condition," a distinct band should result.
This was not the case. Considerable data scatter resulted
when TSI was plotted against LCI. For a given LCI, TSI
values cover a range of about 30-40 units; conversely, for
a given TSI, LCI values spanned nearly the total possible
LCI range. Clearly, the two indices are not indicative of
similar characteristics for the lakes in this study set.
As a second measure of comparison, each of the indices was
compared independently to the trophic category chosen by
individuals who provided the input data for this analysis.
Five trophic categories were provided—very oligotrophic,
oligotrophic, mesotrophic, eutrophic and very eutrophic—-
and responders were asked to select the category which, in
their opinions, best described the lake. No definitions
were given for the different categories. (Several in-
dividuals pointed out that definitions would have been
desirable; some indicated that more than one category could
have been selected depending on whether the selection was
110
-------
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Lake Condition Index
Figure 1: Comparison of Lake Condition Index to Trophic State Index
values for the composite set of study lakes.
Ill
-------
based on nutrient content, algal concentrations or oxygen
conditions; and a few declined to select categories because
definitions were lacking. These responses emphasize the
need for quantification and improved methods for communi-
cation regarding lake characteristics and conditions.)
Frequency distributions for LCI and TSI values as compared
to perceived trophic status of a composite of all .lakes in
the study set are given in Tables 5 and 6, respectively.
The total number of lakes differs between the two tables
because of incomplete data for some lakes. A plot showing
the mean index values and the standard deviation about the
mean for each of the five trophic categories is given in
Figure 2. These data show that mean LCI and mean TSI
values increase as the perceived trophic state progresses
from very oligotrophic to very eutrophic; however/ data
scatter in both cases was fairly large. As shown by
Tables 5 and 6, typically, a given LCI value spans 3 of
the 5 trophic categories; a given TSI value typically spans
4 of the 5 categories. (Note that the selected trophic
category for lakes having an average Secchi depth of 4-5
meters spanned the entire range from very oligotrophic to
very eutrophic.)
112
-------
Table 5. FREQUENCY DISTRIBUTION OF LCI VALUES AS COMPARED TO TROPHIC STATUS DESCRIBED BY RESPONDERS
(COMPOSITE OF ALL LAKES)
Selected
trophic
category
VO
0
H
E
VE
0123456 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
41 1
555742
338598 14 73 1331
3523 577 10 3354331
25 231221 12 1
No.
6
28
68
64
22
Ave
0.6
2.2
6.2
9.5
12.9
0
1.2
1.5
2.8
3.7
3.9
-------
Table 6. FREQUENCY DISTRIBUTION OF AVERAGE SECCHI DEPTHS AS COMPARED TO TROPHIC STATUS
DESCRIBED BY RESPONDERS (COMPOSITE OF ALL LAKES)
Selected
trophic
category
VO
0
M
E
VE
Trophic state index
o o o o o o
ft) ^ m ID r~- co
Average Secchi depth (meters)
HO _ _
H H o> oo rp to in 10 ( i i ~i ~i
HO<7> 00 t-.tOUOitCOCMH.JFJ?
H H
la 311
2 2546322
1 1 2 2 6 13 14 20 5
1 2 1 2 14 25 17 3
22 666
Ave
No. (SD)
6 7.9
26 5,3
64 2.9
65 1.8
22 1.4
Ave
(TSI)
30.2
36.0
44.6
51.5
55.1
a
(SD)
3.7
2.5
1.8
1.2
1.3
SLake Tahoe (SD = 25.6) not included in calcxilations
-------
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o,
sr
o
vo
o J
00
I
o
•
o
m
M
o>
4J
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•
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O
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0)
0)
t>c
0)
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I
0
I
M
i
E
VE
Perceived Trophic State
o.
CM
vn
r-l
oo-
Mean
Value
\
I
I i i i I
VO 0 M E VE
Perceived Trophic State
Figure 2: Comparison of mean TSI and mean LCI values to the
trophic state of the composite study lakes as described by
responders in the various states. (Very oligotrophic,
oligotrophic, mesotrophic, eutrophic, very eutrophic)
115
-------
SUMMARY AND CONCLUSIONS
A comparison of LCI and TSI values for a study set of more
than 200 lakes distributed through the United States showed
little agreement between the two indices. A value of one
index cannot be inferred from knowledge of the other. Even
though Secchi depth, the sole input parameter for the TSI,
is also included in the LCI, the inclusion of information
relating to dissolved oxygen, .fishkills and abundance of
macrophyte and/or algae, masks the interdependence of the
two indices.
Both the LCI and TSI indices were compared to subgroups of
the original data set after it had been divided into 5 sub-
sets according to the trophic categories selected by the
individuals who provided the lake data. The mean values
of each index increased as the trophic category progressed
from very oligotrophic to very eutrophic, however signifi-
cant data scatter resulted within each group. This was due
only in part to the inability of the classification tech-
niques to cleanly sort the data set—of at least equal
importance are the differences in definition of the tradi-
tional trophic categories from individual to individual,
differences which are exaggerated when lakes from a large
geographical area are considered simultaneously. The com-
parisons conducted here demonstrate clearly the communica-
tion difficulties associated with describing lakes according
to the traditional trophic categories.
The TSI approach results in a ranking of lakes according to
mean Secchi depth. The ranking is objective and. is not in-
fluenced by regional differences in terminology. However,
it was found that lakes of widely differing character may
have similar mean Secchi depth, and it is not clear that more
information would be conveyed If TSI values rather than
trophic categories were used.
The LCI approach results in a ranking of lakes according to
several parameters which are considered to be additive.
Consequently, a given LCI may result from different combi-
nations of the input parameters. This does not appear to
induce excessive diversity within LCI ranks when the system
is applied to lakes in a homogeneous climatic region; how-
ever, when the region spans the continental United States,
diversity within ranks becomes larger.
116
-------
It has been demonstrated that both the TSI (in Minnesota)
and the LCI (in Wisconsin) can be used as effective tools
for communication and decision-making when they are applied
under more restrictive conditions than those reported here.
This is a step in the right direction. Improved techniques
for describing lake characteristics are needed, and con-
tinuing efforts should be made to quantify and define more
precisely trophic terminology and concepts.
117
-------
REFERENCES
Carlson, R. E. 1974. A Trophic State Index for Lakes.
Submitted to Limnology and Oceanography; also, Contribution
$141, Limnological Research Center, University of Minnesota.
Shannon, E. E. , and P. L. Brezonik. 1972. Eutrophication
Analysis: A Multivariate Approach. J. Sanitary Engineering
Division, ASCE 98:37-57.
Shapiro, J. 1975. The Current Status of Lake Trophic
Indices—A Review. Interim Report 15. Linmological
Research Center, University of Minnesota. 23 p.
Shapiro, J., J. B. Lundquist, and R. E. Carlson. 1975.
Involving the Public in Limnology—An Approach to Communica-
tion. Verh. Internat. Verein. Limnol. 19:866-874.
Uttormark, P. D., and J. P. Wall. 1975. Lake Classifica-
tion—A Trophic Characterization of Wisconsin Lakes.
EPA-660/3-75-033. Office of Research and Monitoring, U.S.
Environmental Protection Agency, Washington, D.C. 112 p.
Uttormark, P. D., and J. P. Wall. 1976. Nutrient Assess-
ments as a Basis for Lake Management Priorities. In:
Biostimulation and Nutrient Assessment, Middlebrooks, E, J.,
D. H. Falkenborg, and T. E. Maloney, eds. Ann Arbor Science,
Ann Arbor, Michigan, p. 221-240.
118
-------
Appendix 1
METHODOLOGY FOR CALCULATING LAKE CONDITION INDEX VALUES
The technique is based on the assignment of "penalty points"
to lakes depending on the degree to which they exhibit un-
desirable symptoms of eutrophication. Four parameters were
selected for analysis, and ranges of values for each param-
eter were specified which depicted lake conditions ranging
from desirable to undesirable. The parameters used and the
range of possible points assigned are listed below.
POINT SYSTEM
FOR LAKE CONDITION INDEX
Parameter Points
Dissolved oxygen 0-6
Transparency 0-4
Fishkills 0,4
Use impairment 0-9
Total 0-23
The parameters were treated independently, and composite
lake ratings were determined by summing the number of points
assigned in each of the four categories. The sum is termed
a "Lake Condition Index" (LCI).
Dissolved oxygen in the hypolimnion was selected as one
parameter for consideration because depletion of hypolim-
netic oxygen supplies reflects the integral effect of many
lake processes. The classification methodology for DO was
based on the minimum conditions which were expected to occur
in the hypolimnion during the stratified period. Points
were assigned in the following manner:
119
-------
Dissolved oxygen conditions
Dissolved oxygen in hypolimnion
greater than 5 ppm at virtually
all times
Concentrations in hypolimnion
less than 5 ppm but greater
than 0 ppm
Portions of hypolimnion void
of oxygen at times
Entire hypolimnion void of
oxygen at times
Penalty points
Max depth Max depth
<30' >30'
1
3
2
4
As noted in the tabulation above, lake morphometry was taken
into account in an approximate way by assigning more points
to the deeper lakes. The breakpoint of 30 ft {10 m) maximum
depth was selected arbitrarily as an indicator of lake basin
geometry, which separates lakes with "large" or "small" hypo-
limnetic volumes as compared to the volume of the epilimnion.
Lakes which do not stratify can receive few or no penalty
points for dissolved oxygen conditions.
Secchi disk transparency was incorporated into the system by
using typical annual maximum and minimum Secchi depths.
Ranges rather than specific values were used.
Range Typical Secchi depth
1)
2)
3)
4)
The first range represents a condition in which light pene-
tration would be severely limited. Within the second range,
the depth of the photic zone is likely to be less than the
depth of the epilimnion. Conversely, Secchi depths within
the third range are indicative of a photic zone which ex-
tends below the epilimnion except for large lakes.
Points were assigned according to the combination of depth
ranges which encompass the typical maximum and minimum Secchi
depths. In the tabulation below, the above-listed range
0 -
1.5 -
10 -
-
1.5
10
23
>23
ft
ft
ft
ft
(
(0
(
(
0 -
.5 -
3 -
0.5
3
7
>7
m)
m)
m)
m)
120
-------
numbers of 1-4 are used: {Note: A provision is also in-
cluded to cover the possibility that only one range of Secchi
depths would be given.)
Transparency conditions
if both ranges are given
Minimum
range
1
1
1
1
2
2
2
3
3
Maximum
.range
1
2
3
4
2
3
4
3
4
Penalty
points
4
3
2
2
2
1
0
0
0
Transparency conditions
if only one range is given
Secchi
depth range
1
2
3
4
Penalty
points
4
2
1
0
The occurrence of fishkills was considered in the classi-
fication system, but no attempt was made to stipulate
frequency or severity. Lake depth was taken into account
however, and 30 ft (10 m) was again used as the breakpoint,
History of fishkills
None
Yes, max depth <30'
Yes, max depth >30'
Penalty
points
0
3
4
The presence of algal blooms and excessive rooted aquatic
vegetation was approached indirectly through information
describing the severity of recreational use impairment
due to the overadundance of these aquatic plants.
Lakes were penalized least heavily for problems resulting
from "weed" growths; lakes having both "weed" and algae
problems were penalized most severely. This was based on
the rationale that algal blooms often affect an entire
lake whereas the effect of rooted aquatic vegetation is
normally restricted to the periphery. Also, rooted vege-
tation is sometimes more indicative of lake morphometry
than water quality conditions.
121
-------
Recreational Use Impairment
No impairment of use
Very few algae present, no "bloom"
conditions
AND/OR
Very few weeds in littoral zone
Slight impairment of use
Occasional "blooms," primarily green
species of algae
AND/OR
Moderate weed growth in the littoral
zone
Periodic impairment of use
Occasional "blooms," predominantly
bluegreen species
AND/OR
Heavy weed growth in littoral zone
Severe impairment of use
Heavy "blooms" and mats occur fre-
quently, bluegreen species dominate
AND/OR
Excessive weed growth over entire
littoral zone
Penalty points
Weeds Algae Weeds &
only only algae
Lake Condition Indices were calculated by summing the points
received in each of the four categories. Thus, if a lake
exhibits none of the specified undesirable symptoms of eutro-
phication, it would receive no points (LCI = 0). Conversely,
for a lake to receive an LCI of 23 it would have to have all
the undesirable characteristics in the most severe degree.
122
-------
Appendix 2. TABULATED DATA FOR STUDY LAKES
ro
u>
Lake name
California
rtfasitas
H5on Pedro
j^Elsinore
viron Gate
Hxspez
UTower Twin
Hficasio
tflllsbury
Tahoe
VShasta
^Silver
vCpper Twin
Colorado
Canter
Estes
Granby
Grand
Green Mountain
Horsetooth
Lower Agnes
Rawah #3
Rhadaro Moirntain
Sugarbowl
Summit
Upper Camp
Area
(ha)
1,100
5,245
1,050
413
20,600
152
342
811
48,600
11,940
45
107
455
75
2,542
205
820
755
7.8
-
548
3.2
12
15
Depth
Max
86.9
156.
3.7
39.9
45.1
45.4
35.1
36.6
501.
136.
19.2
34.1
52.
15.
60.
81.
74.
62.
20,
-
11.
16.
15.
25.
(m)
Mean
28.6
47.5
-
17.4
16.8
15.2
7.9
14.3
302.
46.3
-
14.3
29.
5.
19.
41.
21.
24,
-
-
4.
-
-
—
LCI points
DO
2
0
0
2
4
0
0
0
0
0
0
0
0
u
2
4
2
4
0
2
0
2
0
2
TRNS
2
1
3
2
1
1
3
3
0
1
1
0
1
1
1
1
1
1
0
1
2
2
1
1
FSKL
0
0
3
4
4
0
4
4.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
IMPR
2
0
4
4
4
2
4
4
0
0
0
2
0
2
4
3
0
4
0
0
4
0
0
0
LCI
6
1
10
12
13
3
11
11
0
1
1
2-
1
7
7
8
3
9
0
3
6
4
1
3
Secchi depth (m)
Ave
2.4
3.1
0.3
1.6
4.6
5.5
0.5
1.0
25.6
3.7
3.7
6.6
2.5
2,0
2.3
1.8
1-7
1.6
6.2
5.1
1.8
2.0
4.2
3,6
Max
4.3
0.5
2.7
-
5.8
0.6
1.8
27.6
5.2
4.1
7.9
4.0
3.5
3.2
3.2
5.3
2.3
8.2
6.2
2.5
2.2
5.0
5.0
Min
«»
2.1
0.3
0.6
-
5.2
0.3
0.2
23.1
2.4
3.2
5.8
1.7
1.0
1.6
1.5
0.9
1.0
4.3
4.2
1.0
1.8
3.6
2.6
Trophic
state*
E
M
E
M
M
0,
E
M
0
M
0
0
M
M
M
M
M
E
0
VO
M
M
VO
0
Trophic state as described by responders
-------
Appendix 2. Con't
Area
Lake name (ha)
Georgia
Allatoona 4,
Brantley
Chief Mclntosh
Clark Hill 28,
Fort Yargo
Hartwell 24,
High Falls
Jackson 1 ,
Seminole 15,
Tobeoskfee
Union
West Point3 10,
al-year-old impoundment
Illinois
Baldwin
Bloomingtona
Cedar
Decatora
East Loon
Highland Silver3
Lou Yaegera
Slocum
Springfield3 1,
Story
Vermilion3
Wonder
800
18
56
300
97
830
243
922
200
708
8
500
800
197
115
114
67
299
572
77
731
53
283
295
Depth
Max-
44.2
6.1
6.0
43.0
9.6
54.9
7.3
27.0
8.5
13.7
16.8
27.4
12.2
10.7
10,7
4,6
6.4
7.3
6,7
1,5
6.1
7.2
4.6
4.
(m)
Mean
9.4
3.0
3.0
10.9
4.0
14.0
3.7
6.9
3.0
-
6.0
7.3
3.1
5.0
1.2
1.4
1.8
4.2
3.3
1.9.
4.0
4,6
1.4
2.5
LCI points
DO TRNS FSKL
4
1
1
2
1
2
3
4
1
4
2
4
2
2
2
1
3
1
1
3
1
3
3
0
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
3
2
3
4
4
3
2
3
3
0
0
0
0
0
0
0
0
0
0
0
4
0
0
0
0
0
0
0
3
0
0
0
3
IMPR
2
2
0
0
0
0
4
7
3
4
0
2
2
0
2
2
3
2
-
9
2
5
0
9
LCI
8
5
3
4
3
4
9
13
6
10
4
12
6
5
6
6
8
6
-
19
6
10
6
15
Secchi depth (m) „
Ave
1.5
0.7
1.4
1.4
1.7
2.0
1.1
0.8
1.4
1.4
1.8
1.3
1.0
0.9
2.5
0.5
1.3
0.3
0.2
0.3
0.4
1.0
0.4
0.4
Max
1.7
0,7
2.2
1.9
1.8
2.4
1.4
1.0
2.1
1.3
-
1.4
1.2
1.8
3.0
0,6
1.5
0,4
0.4
0.4
0.6
1,4
0.6
0,5
Min
1.1
0.6
0.8
1.0
1.4
1.8
0.9
0.4
0.9
1.4
-
0.9
0.9
0.5
1.8
0.4
0.9
0.2
0.1
0.2
0.2
0.8
0.4
0.2
rrophic
state*
M
E
M
M
M
0
E
E
M
E
0
E
E
E
M
E
E
E
E
VE
E
E
E
VE
aTur>bidi-ty due -to suspended inorganic material
-------
Appendix 2. Con't
ro
en
Lake name
Maine
Branch
Bret tons
Coffee
Eagle
Hopkins
Minnehonk
Phillips
Pleasant
Portage
Pushaw
Raymond
Wilson
Maryland
Deep Creek
Johnson
Liberty
Loch Raven
Area
Cha)
1,093
62
55
2,258
178
40
335
741
1,001
2,046
140
194
1,578
42
1,259
767
Depth
Max
37.8
12.8
21.3
42.6
19.8
22.3
32.0
20.4
7.6
8.5
12.8
26.8
21.9
6.1
43.3
21.3
(m)
Mean
9.6
5.5
10.1
13.7
6.7
9.1
9.4*
9.6
2.4
3.0
4.9
8.2
8.1
2.1
12.7
15.2
'LCI points
DO
0
2
0
2
0
0
0
0
0
1
-
2
2
0
2
2
TRNS
0
1
0
1
0
1
0
0
1
1
1
1
1
2
1
2
FSKL
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
IMPR
0
0
0
0
0
0
0
0
0
2
0
0
0
5
4
4
LCI
0
3
0
3
0
1
0
0
1
4
-
3
3
7
7
8
Secchi depth (m)
Ave
8.2
4.0
8.7
4.4
7.5
4.8
7.7
9.7
3.0
3.2
5.2
4.6
3.0
1.2
2.8
1.7
Max
9.0
6:1
10.0
5.6
9.1
5.9
9.1
11.6
3.4
3.7
6.2
5.9
4.3
1.8
5.5
3,0
Min
6.4
3.0
7.5
2.8
5.0
3.7
5.2
6.2
2.7
2.1
4.3
2.4
1.8
0.8
0.5
0.5
Trophic
state*
M
E
M
E
-------
Appendix 2. Con't
9)
Lake name
Massachusetts
Indian
Mattawa
Norton
Nutting
Pearl
Pontoosuc
Quaboag
Quacumquasit
Upper Mystic
Waushakum
Michigan
Bear
Cass
Elk
Cognac
Higgins
Kent
Lansing
Orchard
Silver
Area
(ha)
78
45
214
32
88
189
215
88
68
33
128
518
3-,128
352
3,885
405
183
318
243
Depth
Max
5.5
10.7
2.5
2.4
10.7
10.7
3.7
21.9
25.0
16.2
18.3
39.0
58.5
20.1
40.5
11.6
10.7
33.5
29,3
Cm)
Mean
3.1
-
1.0
1.3
3.7
4.3
1.8
9.9
8.5
4.3
-
-
-
-
-
-
-
-
-
LCI points
DO
1
2
0
0
4
4
0
4
6
4
2
2
0
4
0
2
4
4
4
TRNS
2
1
3
3
1
2
2
1
2
1
0
1
1
2
0
2
2
1
0
FSKL
3
0
3
0
4
0
0
0
4
4
0
0
0
0
0
0
4
0
0
IMPR
5
0
9
6
3
3
0
0
4
3
0
2
0
2
0
5
3
0
2
LCI
11
3
15
9
12
9
2
5
16
12
2
5
1
8
0
9
13
5
6
Secchi depth On)
Ave
1.2
4.1
0.4
0.8
3.8
2.2
1.7
4.3
1.6
3.1
7.4
2.6
4.8
2.8
7.3
1.4
1.5
3.4
6.1
Max
1.7
4-. 7
0.5
1.3
4.4
2.9
2.1
5.5
2.6
3.7
8.5
4.1
3.0
3.2
9.8
2.1
2.3
4.3
7.6
Min
0.9
3.5
0.3
0.3
3.0
1.7
1.5
3.0
0.8
2.9
6.6
1.7
6.7
2.1
4.3
0.8
1.0
2.4
2.9
Trophic
state*
M
0
VE
E
M
E
0
M
E
M
0
M
0
M
VO
VE
E
0-M
M
-------
Appendix 2. Con't
ro
Lake name
Mississippi
Clark
Claude Bennett
Columbia
Jeff Davis
Monroe
Perry
Roosevelt
Ross Barnett
Tippah
Tombigbee
Walthall
Montana
Ashley
Elaine
Blanchard
Echo
Five
Foy
Little Bitterroot
Lower Stillwater
Mary Ronan
Rogers
Swan
Whitefish
Area
(ha)
25
29
36
66
45
51
51
35
61
33
25
1,134
151
59
293
95
110
1,224
100
609
96
1,328
1,355
Depth
Max
2.4
3.7
3.0
5.5
4.9
7.9
3.7
4.6
5.5
3.7
4.3
61.
42.7
9.8
21.
18.9
40,
85.
15.8
14.3
5.8
40.2
67,1
Cm)
Mean
1.5
1.7
1.5
2.6
2.1
2.4
2.4
2.4
3.0
2.1
2.4
27.
16.
3.5
5,5
5.4
16.
31.
4.4
8.6
2.7
18,
33,
LCI points
DO
5
5
5
5
5
5
5
5
5
5
5
0
0
2
2
2
2
0
4
2
1
0
0
TRNS
2
2
2
2
2
2
2
2
2
2
2
0
0
1
0
1
0
0
2
1
1
2
1
FSKL
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
0
0
0
IMPR
2
4
2
4
4
0
2
4
2
4
4
2
0
6
5
0
6
0
2
6
6
2
2
LCI
9
11
9
11
11
7
9
11
9
11
11
2
0
9
7
3
8
0
8
13
8
4
3
Secchi depth (m)
Ave
0.9
0.8
1.0
1.0
0.8
1.2
0.9
1.1
1.2
1.1
1.4
10.0
5.9
4.4
6.3
5,4
3.6
11.9
4.5
4.3
3.9
5.7
6.9
Max
1.2
1..4
1.1
1.2
1.4
1.9
1.5
1.1
1.4
2.1
2.2
11.9
7.0
4.6
8.5
6.4
7.3
13.7
6.1
7.0
4.6
8.5"
11.0
Min
0.8
0.3
0.8
0.9
0.3
0.6
0.3
1.1
1.1
0.7
0.8
6.6
4,6
4.3
4.0
4.0
1.2
9.8
0.1
3.1
3.4
0.3
1.5
Trophic
state*
M
E(?!
VE
E
E
VE
0
E
VE
VE
M
0
-------
Appendix 2. Conft
Lake name
Nebraska
Branched Oak
Holme sa
McConaughy
Pawnee
Stagecoach
Wagon Train^
Area
(ha)
728
45
14,160
299
79
127
Depth
Max
8.
4.
50.
8.
5.
6.
(m)
Mean
4.4
1.9
-
3.7
3.0
2.6
LCI points
DO
0
0
4
0
0
0
TRNS
2
4
1
2
2
3
FSKL
3
0
0
0
0
0
IMPR
5
0
2
9
9
0
LCI
10
4
7
11
11
3
Secchi depth (m)
Ave
1.5
0.3
3.2
1.1
0.8
0.5
Max
4.1
0;6
5.0
3.9
2.5
1.0
Min
0.5
0.2
1.5
0.4
0.3
0.2
Trophic
state*
E
M-E
M-E
VE
VE
E
aTurbidity due to suspended inorganic materials
oo New Hampshire
Glen
Hot Hole
Kezar
Mascoma
Newfound
Ossipee
Pleasant
Province
Rocky Bound
Sunapee
Wentworth
Winnisquam
48
13
73
451
1,662
1,251
200
410
26
1,642
1,221
1,725
16.8
13.1
8.2
20.7
51.2
18.6
19,5
5.2
9.4
43.3
29.9
51.8
8.5
5.7
-
-
19.8
-
-
3.7
6.4
-
-
15.8
2
6
5
2
0
2
4
0
0
2
2
4
2
1
2
1
0
1
0
2
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
4
0
7
4
0
0
0
5
0
0
0
4
8
7
14
7
0
3
4
7
1
3
3
9
1.8
3.8
0.9
3.6
7.3
4.2
7.9
2.1
5.0
6.6
5.3
5.5
2.7
4.0
1.2
5.2
7.6
4.4
9.8
2.7
5.2
6.7
5.5
8.1"
1.1
3.4
0.6
2.4
7.0
3.7
6.1
1.5
4.9
6.4
5.2
2.7
-E
M
E
M
VO
0
M
E
0
0
0
E
-------
Appendix 2. Con't
Lake name
New Mexico
Abiquiu
Bill Evans
Bonito
Caballo
Elephant Butte
Fenton
Heron
Navo j a
Nogal
Snow
UUte
Wall
New York
Canadarago
Clear
Conesus
George
Greenwood
Neversink
Oneida
Raquette
Swinging Bridge
Upper Saranac
Area
(ha)
526
25
18
2,430
4 000-
~ 5 w W v
8,000
7
1,415
5,260
12
40
1,620
7
1,022
40
1,214
11,400
111
471
20,700
2
405
2,059
Depth
Max
27.4
18.3
12.8
15.2
46.
8.5
36.6
76.2
3.3
18.3
24.4
6.1
13.4
20.4
20.1
58.
17.4
50.0
16,8
31.4
36.6
30.5
(m)
Mean
10.7
12.2
8.3
6.1
18.
3.0
15.2
42.7
1.5
5.5
9.1
3.4
7.5
10.1
10.7
18.
-
18.3
6.8
6.1
13,7
-
LCI points
DO TRNS FSKL
2
2
2
2
2
3
0
0
1
4
2
1
6
0
4
0
4
0
4
0
4
2
3
3
2
3
3
3
1
0
3
3
3
3
2 .
0
0
0
1
1
2
1
2
1
0
0
0
0
4
3
0
0
3
4
0
0
4
0
0
0
4
0
0
0
4
0
IMPR
4
2
2
0
4
9
0
0
6
7
0
3
4
0
2
0
3
0
2
0
4
2
LCI
9
7
6
5
13
18
1
0
13
18
5
7
16
0
6
0
12
1
8
1
14
5
Secchi depth (m) „
Ave
0.6
2.0
15.0
5.8
11.1
2,6
4,2
4,1
1,3
2.1
Max
1.0
3.0
6.5
13.5
4.0
4,6
4,9
2.1
2.1
Min
0.3
1.1
5.0
8.5
1.2
3,7
3.0
0.9
2.0
'rophic
state*
M
M
M
M
M
E
0
0
E
M
M
M
E
VO
M
0
E
0
M
0
E
M
-------
Appendix 2. Con't
CO
o
Lake name
North Dakota
Crown Butte
Dion
Gravel
Hooker
Moon
Sakakawea
School Section
Sweetbriar
Upsilon
Ohio
Action
Berlin
Burr Oak
Camden
Findlay #2
Forked Run
Hargus
Kiser
Long
Nettle
Paint Creek
Area
(ha)
13
34
40
14
35
149,021
140
110
168
102
1,477
267
4
259
43
59
156
91
38
473
Depth
Max
9.4
6.4
6.7
8.3
12.8
54.9
4.4
8.5
8.2
10.7
21.3
11.3
4.3
8.7
10.7
17.1
4,0
13.7
8.5
15.2
Cm)
Mean
3.8
3.8
4.0
4.4
5.0
18.9
3.0
2.9
3.4
4.0
5.0
4.3
2.3
7.2
3.7
9.1
2.4
5.0
6.1
5.3
LCI points
DO
4
3
3
5
4
0
5
1
5
4
4
4
3
3
4
4
3
4
3
4
TRNS
3
2
2
3
1
2
2
3
3
3
3
3
3
1
3
3
3
3
3
3
FSKL
4
3
3
3
4
0
3
0
3
0
0
-
0
0
0
0
0
0
0
0
IMPR
5
3
3
5
2
2
2
5
4
3
2
2
3
3
0
2
2
3
3
2
LCI
16
11
11
16
11
4
12
9
15
10
9
-
9
7
7
9
8
10
9
9
Secchi depth (TO)
Ave
1.1
2 '.4
2.6
0.7
3.6
2.1
2.1
0.6
0.7
0.4
0.9
1.1
0.9
2.8
1.8
1.1
0.5
0.9
0.8
0.9
Max
1.8
3'.0
3.5
0.9
2.8
4.0
3.0
1.3
1.1
0.6
1.3
1.5
1.0
3.5
2.3
1.4
0.6
0.9
0.9
2.1
Min
0.3
1.4
1.0
0.3
4.3
0.2
0.6
0.3
0.3
0.3
0.5
0.6
0.8
2.4
1.2
0.7
0,5
0.9
0.6
0.2
Trophic
state*
E
E
E
VE
0
E
VE
E
E
E
M
VE
M
M
M
E
E
M
-------
Appendix 2. Con't
Lake name
Oklahoma
American Horse
Ellsworth
HSufaula
i^Tt. Cbbb
Grand
Greenleaf
vTenkiller
Watonga
Pennsylvania
Allegheny
Beaver Run
Beltzville
Blanchard
Canadohta
Conewago
Conneaut
Greenlane
Harveys
Indian
Naomi
Ontelaunee
Pocona
Pymatuning
Shenango
Stillwater
WallenpaupacTc
Area
(ha)
40.5
2,260
'41,500
1,660
18,800
370
5,120
22.3
4,877
455
383
700
69
138
378
329
267
304
202
438
304
5,645
1,441
141
2,331
Depth
Max
22.9
16.5
26.5
16.2
36.6
14.3
46.0
7.9
39.0
18.3
36.9
9.4
14.3
5.2
20.1
18.9
29.3
18,3
4.9
9.4
7.9
7.6
10.7
2.4
13.4
Cm)
Mean
6.7
5.1
7.1
6.0
10.7
4.9
15.5
3.6
14.4
7.3
12.8
1.6
8.8
2.7
7.3
5.0
11.0
4.3
0.9
3.4
3.7
3.7
2.5
1.0
8.5
LCI points
DO
2
0
4
0
4
4
4
4
0
2
2
3
4
3
4
2
2
2
0
2
1
0
2
0
4
TRNS
1
3
3
3
2
3
1
2
3
2
1
2
2
2
2
3
1
1
2
3
2
^%
c>
2
2
1
FSKL
0
0
0
0
0
0
4
0
0
0
0
. o
0
0
4
0
0
0
0
0
0
0
0
0
0
IMPR
7
2
0
3
0
3
0
7
0
2
0
4
-
5
4
9
0
0
0
9
0
0
-
0
0
LCI
10
5
7
6
6
10
9
13
a
6
3
9
-
10
14
14
3
3
2
14
3
3
-
2
5
Secchi depth (m)
Ave
0.9
-
-
-
-
1.0
1.2
0.8
1.8
3.0
3.5
1.2
1.6
1.2
2.5
1.0
4,1
2.5
1.4
0.8
1.4
0.8
0.9
1.3
2.7
Max
2.1
T
-
-
-
2,7
-
1.5
4.6
4.6
4.6
2.2
1.8
2.1
2.7
1.8
5.8
3.7
1.5
1.1
2.4
1.7
1.2
1.5
4.9
Min
0.4
-
-
-
-
0.3
-
0.3
0.5
2.1
2.7
0.6
1.2
0.5
2.0
0.5
3.0
1.8
1.3
0.3
0.8
0.4
0.6
0.8
1,4
Trophic
state*
E
M
M
E
M
M
M
E
E
M
M
VE
E
E
E
VE
M
M
M
E
M
E
E
M
M
-------
Appendix 2. Con't
CO
INJ
Lake name
South Carolina3
Clark Hill
Fishing Creek
Greenwood
Hartwell
Marion
Koultrie
Murray
Robinson
Saluda
Wateree
aMost turbidity
South Dakota
Big Stone
Clear
Cochrane
East Oakvrood
Enemy Swim
Hendricks
Herman
Kampeska
Norden
Pickerel
Roy
South Red Iron
Area —
(ha)
31,800
1,360
4,600
24,830
44,760
24,450
20,600
910
200
5,548
due to suspended
5,107
441
148
405
858
530
546
1,943
302
386
685
251
Depth
Max
44.2
24.4
21.3
53.3
16.8
19.8
54.9
12.2
12.2
24.4
Cm)
Mean
11.0
7.3
7.0
14.0
4.0
6.1
12.5
4.3
4.0
7.0
LCI points
DO TRNS FSKL
4
2
4
4
2
0
4
2
0
2
1 0
3 0
3 0
1 0
3 0
2 0
2 0
2 0
3 0
3 0
IMPR
0
2
0
0
3
3
0
5
2
0
LCI
5
7
7
5
8
5
6
9
5
5
Secchi depth (m) r
Ave
1.9
0.4
0.8
2.7
0.8
0.9
2.4
1.0
0.7
0.6
Max
2.5
0.-7
1.1
3.6
1.2
1.4
2.7
1.2
0.9
0.8
Min
1.5
0.1
0.4
1.8
0.5
0.3
1.8
0.9
0.5
0.3
frophic
state*
M
E
M
M
E
M
E
M
M
inorganic material
4.9
6.1
8.2
2.7
7.9
2.4
2.1
4.0
4.6
13.2
5.6
4.6
3.4
3.7
3,4
1.5
3.0
1.8
1'.2
2: 5
2.1
6,1
3.3
2.1
0
0
0
3
0
3
3
0
5
0
0
0
3 0
2 0
2 0
3 3
2 0
4 3
3 3
3 0
4 3
2 C
2 0
2 0
9
2
2
5
2
9
9
4
9
2
3
2
12
4
4
14
4
19
18
7
21
4
5
4
1.0
1.8
1-4
O.ii
0.9
0.3
0.6
0.6
0.3
2.3
1.9
1.8
2.7
2.6
2.5
0.5
2.2
0.5
1.6
0.9.
0.3
5.2
2.5
3.2
0.4
1.0
0.8
0.3
1.1
0.2
0.2
0.4
0.3
1.2
1.6
1.1
VE
E
E
VE
E
VE
VE
E
VE
E
E
E
-------
Appendix 2. Can't
CO
Lake name
Washington
Big
Liberty
Long
Loon
Merrill
Moses
Newman
Sammamish
Silver
Steilacoom
Walupt
Wilderness
Wisconsin
Big Green
Crystal
Delavan
Geneva
Mendota
Middle
Oconomowoc
Pewaukee
Pine
Round
Trout
Winnebago
Area
(ha)
221
713
133
457
197
2,758
49 4
1,980
668
128
143
23
2,964
36
839
2,066
3,938
104
310
955
284
43
1,566
55,729
Depth
Max
7.0
9.1
6.4
30.5
23.5
10.7
9.1
32.0
3.0
6.1
89.9
11.6
69.8
21.0
17.1
41.1
25.0
12.8
18.9
13.7
25.9
20.4
35.1
6.4
(m)
Mean
4.3
7.0
3.7
14.0
11.9
5.6
5.8
17.7
1.5
3.4
53.6
6.4
_
-
~
—
-
_
-
—
-
-
-
-
LCI points
DO
1
4
3
6
0
2
4
6
0
1
2
4
2
0
6
2
6
4
4
4
4
4
2
3
TRNS
2
1
1
0
0
3
1
2
3
2
0
1
0
0
1
1
2
1
1
2
1
1
0
3
FSKL
0
(0)
0
0
0
0
0
0
0
0
0
0
0
0
4
0
4
0
0
0
0
0
0
0
IMPR
5
5
9
2
0
7
5
3
9
(4)
0
3
2
0
4
2
5
2
3
9
2
2
0
7
LCI
8
10
13
8
0
12
10
11
12
7
2
8
4
0
15
5
17
7
8
15
7
7
2
13
Secchi depth (m)
Ave
2.0
3.5
2.3
6.8
7.5
0.5
2.7
3.1
1.0
2.0
6.8
3.6
5.4
7.7
1.6
4.6
3.1
4.4
4.4
1.6
2.6
3.9
4.1
0.7
Max
3.8
5.2
3.4
7.3
10.1
0.6
4.0
5.5
2.0
3.0
8.2
5.5
7.6
9.8
2.4
6.1
5.5
5.8
7.3
2.0
4.3
6.1
5.2
1.1
Min
1.4
2.7
1.5
6.4
3.0
0.4
1.8
1.5
0.8
1.2
5.5
1.5
2.7
5.8
0.9
2.7
1.8
3.1
2,7
0.9
1.7
2.4
2.7
0.3
Trophic
state'**
E
E
E
M
0
VE
E
M
VE
E
0
M
0
70
E
0
E
M
M
E
M
M
0
E
-------
Appendix 3. PLOTS OF LCI VERSUS TSI BY STATE
o
o
s§
0
VO
O
o
California
o
*
-
0
o
" 8>
o
o
o
O o
o
CO
~*
o
O CM
o
rH
4-> 2 *^"
cu H
o
°. ^ 0
rH^ ^
CJ
CJ
V
to
o
-
Colorado
"
*•
o
o
0 0
- O _ Q
0° 0°00
oo
1 '
o
o
o
^
JJ
ex
-------
o
o
CM
0
•*
O
VO
0
o
Maine
-
-§
O CD
o o
~
^
•
CO
-
o 8
o
t-t
•a £ °
2. " "*
Q)
O
0
• -rl O
rH JC VD
0
O
0
CO
o
co
"
Maryland
-
-
o
o
o
o
.
rH
o
*
o
^3
^
0)
Q
O
• *r-f
rH ^
0
O
-------
0
0
CM
So
E-i "*
O
vo
o
0
Mississippi
-
•
"
_
"^
o
8 &8P
*^ 00
•
CO
.
o 8
o
r-i
1 ^
-------
o
•tf
o
VC
o .
CO
New York
ro
o
»•
_ o
III!
I I
o
•
o
cu
a)
o
o
o
CO
8 12
LCI
16 20
o
o
CM
§
0
VD
O
B
N. Dakota
-
o
Q
• O O
o
o
—
CO
*™^
0
o
rH
4J
(X
a)
0
o
' -H
«H rC
u
O
G)
CO
H
o
1 1 1 1 t 1 1 1 1 1 1
0 4 8 12 16 20
LCI
o
o
CM
KO
H-*
0
VO
o
•
Ohio
^
0
o
JD -
two
Wr
O
o
CO
-
0
o
.— 1
4J
P.
-------
o
CM
(O
o
NO
o
CO
1
0
( ciinoj' Avail io
8
00° o
8° oo o
0 o
1 1 1 1 1 1 1 1 1 1
4 8 12 16 20
o
0
— 1
§•
0°
• 1-1
u
0)
CO
r-4
o
LCI
o
CM
O
\o
o
CO
S. Carolina
I00
o
o
•
o
.G
4J
P.
0)
U
U
U
CO
till
I I
I I
8 12
LCI
16 20
o
CM
CO
o
\D
O
CO
S. Dakota
0
o
o
0 °
o
»
o
oc
o
1 1 1 1 1 1 1 1 1 t 1
o
o
4J
(X
0)
O
• ll 1
• TP!
U
0
4>
CO
O
0 4 8 12 16 20
LCI
O
CM
I-l
o
VO
O
CO
Washington
b G o
o go
Oo
o -
0
.
o
d
4-1
cx
o
o
o
• vH
•-« .c
u
u
0)
CO
r- 1
o
1 I f t 1 1 1 1 1 II
0 4 8 12 16 20
LCI
138
-------
Wisconsin
O -
CMP ^
O
coOj. 0 O U80 ^ ^
o
CO -H
_ O JZ
O m — . CJ
*°r o -« o
O Q)
O
00
I I I I I t
8 12 16 20
LCI
139
-------
ACKNOWLEDGMENTS
Data necessary for this report were provided
by numerous individuals associated with
state agencies and universities throughout
the United States. Their cooperation and
helpfulness are gratefully acknowledged.
140
-------
TROPHIC INDICES AND THEIR USE IN TROPHIC CLASSIFICATION
OF LAKES AND RESERVOIRS OF NORTH CAROLINA
Charles M. Weiss
Department of Environmental Sciences and Engineering
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina 27514
SUMMARY AND CONCLUSIONS
The trophic state of a lake reservoir is generally measured in terms of
the magnitude of the biomass supported by the nutrient flux. To do this
directly requires systematic determinations of either cell density or cell
volume of the planktonic algae or some other measurement of the organic com-
ponent produced by cell synthesis that utilizes the available nutrients. It
may be expeditious to use indirect determinations of physical, chemical or
biological variables which replace to the biomass created by the combination
of available nutrients and solar energy. In this study both direct and indi-
rect measures of trophic state were examined to establish the basic rela-
tionships and levels of correlation and to use these measures in defining the
trophic state of various bodies of water in North Carolina and bordering
areas.
Based on the assemblage of 854 observations derived from 69 different.
bodies of water or subsegments of reservoirs, considerations were given to a
wide spectrum of trophic state related indices. These included Secchi depth,
chlorophyll a by filtration and solvent extraction, chlorophyll a by Turner
photofluorometry, total phosphorus, trophic state indices (Carlson) derived
from Secchi depth, chlorophyll a, and total phosphorus, the growth response of
reseeded algae into autoclaved or filtered pretreated samples, the Shannon-
Weaver and Evenness diversity indices of the specific sample, the number of
taxa (species) of algae in the sample, the Pollution Index (the proportional
representation in the total population of the rate species associated with
high nutrient conditions), several diatom quotients or percentages that have
been associated with different trophic states, and the productivity or rate of
carbon fixation. All of these indices of trophic condition were related to
cell density and cell volume of the sample and their correlation determined
over the full range of experienced values.
Within the context of the North Carolina surface waters which were sam-
pled for this study it was apparent that the determination of total phos-
phorus, conductivity, Pollution Index and Secchi depth were the variables most
consistently associated with high correlation levels with the total biomass
that was supported by the existing nutrients. Based on the total data pool a
range of values for each of these strongly correlated indices was organized in
six steps of trophic quality associated with existing water uses. The six
level trophic scale was used to describe the trophic condition of 69 lakes.
141
-------
RECOMMENDATIONS
1. The trophic classification of inland waters can be expedited by the use of
water quality parameters which are highly correlated with direct measures of
trophic condition and thus serve as trophic state indices. The determinations
of Secchi disk transparency, conductivity and total phosphorus are suggested
for this purpose. These trophic state indices appear to be particularly
effective in describing changes along the longitudinal axis of the river
impoundments that are characteristic of the southeastern coastal drainages.
2. To strengthen the validity of the information derived from these quality
parameters, determinations should be made at least monthly in the period of
intensive public use, e.g. May through September.
3. Monitoring programs of trophic conditions could be substantially enhanced
if budgetary considerations could allow for the inclusion of the Pollution
Index as a routine analysis.
142
-------
INTRODUCTION
The trophic state of a lake, or impoundment is a characteristic resulting
from the interaction and relationship of many physical, chemical and biological
factors, These have been well illustrated in the analog model first suggested
by Rawson (1930). They have been redefined by other investigators into a
variety of physical, chemical and biological dimensions which may be used in
arriving at an integrated statement of the trophic state of an individual body
of water (Stewart and Rohlich, 1967), the condition which describes its rela-
tive richness with respect to nutrients and organic production. It is not only
the specific quality of the existing body of water that is of concern and inter-
est but those factors which when generated by man's cultural activity may cause
a change in water quality in the direction of reduced usefulness.
The change in trophic state, generally is a result of an increase in the
quantity of algal nutrients,defines the eutrophication of the body of water.
Hutrient enrichment of waters frequently results in an array of symptomatic
changes such as increased production of algae and other aquatic plants, deteri-
oration of fisheries and other changes in water quality which may be objection-
able and impair water use. Although it is recognized that nutrient enrichment
is also a natural process, it is accelerated nutrient enhancement that has
required development of nutrient classification systems, the trophic state,
for lakes and impoundments in order to effect appropriate management procedures.
In an attempt to deal with the complexities of the Rawson model and arrive
at a direct method of describing the trophic state, attempts have been made to
integrate the several variables in the model to produce a numerical scale or
index which could be used for management purposes and to give a more precise
waning to the terms oligotrophic, mesotrophic and eutrophic generally used to
scale the intensity of the trophic state. These developments have included
the phosphorus loading concepts of Vollenweider and Dillon (1974), and Vollenweider
(1975, 1976) which have been instrumental in the development of procedures for
predicting quality based upon rate of phosphorus input, lake volume and reten-
tion time. Another approach has been the use of multivariate analysis of water
Jpiality parameters by Shannon and Brezonik (1972) to classify the lakes of
Florida. A classification system developed for South African impoundments by
Toerien jet^ al. (1975) draws heavily on much of the European and North American
experiences but emphasizes the use of algal growth potential. A statewide
143
-------
effort to classify the trophic characteristics of Wisconsin lakes by Uttormark
and Wall (1975) depends on a point system derived from four parameters; dis-
solved oxygen, transparency, fish kills and use impairment, to derive a lake
condition index. The relationships developed by Dillon and Rigler (1975) sim-
plifies the procedures for predicting the nutrient capacity of a lake for the
surrounding land development, based on measurements of Secchi disk transparency
and chlorophyll a.. The development of a comprehensive data analysis system by
the New York State Department of Health (Reddy, 1976) seeks to minimize errors
inherent in laboratory and field collections in order to facilitate the use of
trophic indicator concept, such as primary productivity, total organic carbon,
total nitrogen and total phosphorus for the natural waters of New York state.
These current efforts have moved from the more simplified examination of spe-
cific nutrient elements, (Sawyer, 1947; Wetzel, 1975) and particularly the
limiting action of phosphorus on the eutrophication process (Weiss, 1969;
Schindler and Lean, 1974).
North Carolina Lake and Reservoir Studies
Recent investigations on individual lakes have included destratification studies
to improve water quality (Weiss and Breedlove, 1973), investigations concerned
with the impact of electric power generating plants using cooling water from
selected lakes and impoundments (Weiss, et^ ,al., 1975a) and specific investiga-
tions to assess the changing trophic state of a newly impounded body of water
to ultimately be used for cooling water purposes (Weiss, et^ jil., 1971, 1972,
1974, and 1975b).
In addition a detailed analysis extending over several years was carried
out on the John H. Kerr Reservoir, a major impoundment on the Roanoke River,
operated by the Corps of Engineers for flood control and hydropower. This
body of water has proved to be of particular significance in characterizing
the trophic state of lakes and impoundments of this area due to the circumstance
of major nutrient input limited to the inflow into the two arms of the lake
each with major differences in retention times. This ultimately converts into
different levels of trophic condition. This particular investigation has been
part of the North American Project, the OECD-EPA sponsored study organized to
examine the Vollenweider concepts on loading. Preliminary reports have con-
sidered the loading rates of phosphorus and nitrogen and their relationship
to the trophic state of this reservoir (Weiss and Moore, 1975).
144
-------
PURPOSE AND OBJECTIVES
A majority of the "lakes" of North Carolina have been formed by the
impounding of rivers at many suitable dam sites in their flow from the western
mountains through the Piedmont to the coastal plain. In many instances these
rivers and their impoundments receive substantial quantities of wastewater
discharges from major urban areas, It was deemed essential that the effect of
these discharges be quantified in terms of their net effect on the trophic
condition of the impounded waters in order to establish the effectiveness of
pollution abatement efforts currently proscribed by water quality management
laws. This baseline datum of water quality for the major inland bodies of
water in North Carolina will provide a reference point for future assessment
as pollution abatement efforts are carried forward.
The contemporary trophic state of North Carolina waters may not always
reflect the magnitude of the nutrient loads that they are currently receiving.
The past several decades have seen not only significant increases in average
water use with parallel increase in wastewater discharges but also the expan-
sion of urban complexes and extension of sewer lines to serve larger popula-
tions. But there are few lakes or impoundments in North Carolina that have
reached the level of nutrient enrichment that can be considered undesirable
in terms of their current water uses. This report (Weiss and Kuenzler, 1976)
is a product of a sampling program integrated with other recent observations
to describe current water quality levels to define the trophic state of North
Carolina lakes and impoundments. In arriving at definitions of contemporary
nutrient levels and associated biological responses the variety of parameters
sampled has permitted evaluation of several indicators as to their accuracy
and usefulness for water quality monitoring.
The data of this investigation has been derived from a 4-year sampling
program of the lakes and impoundments of North Carolina. They are shown for
purposes of location and identification on a county map of the state, Figure
1. The map code is identified on Table 1 which also lists the lakes, their
particular origin,use, location by county, surface area and mean depth where
such information was available. The selection of lakes to provide a cross
section of water characteristics was made not only to include impoundments in
the several physiographic provinces and major drainage basins but also the few
natural lakes mostly identified with the Coastal Plain.
145
-------
J .
r-.
Natural Lakes
M'llpandi
f~) WoUr Supply Impoundm«n1i
/\ Hydroelectric Impoundmenli
V7 Cooling Water Ponds
(Tl) River Segmtnt
JEt TMLtlllFOII KKI
Figure 1. Location and Types of Water Bodies Sampled
-------
Table 1
Surface Waters of North Carolina and Immediate Adjacent Areas
Sampled for Trophic State Analysis
1971-1975
Codes
Surface
Area Mean
Location
Type and Name
Natural Lakes
Black
Jones
Mat tamuskee t
Phelps
Salters
Singletary
Waccamaw
White
Imp oundments
Cooling Water
Belews
Hyco
Water Supply
University
Michie
High Point
Wheeler
Brandt
Burlington
Lexington-Thomasville 50
Townsend
Roanoke River
John H. Kerr
Gaston
Roanoke Rapids
Yadkin River
W. Kerr Scott
High Rock
Tuckerton
Badin
Tillery
Blewett Falls
Map
1
2
3
4
5
6
7
8
9
10
11
12
46
47
48
49
50
51
Computer Acres Depth-Ft.
BL
JO
MA
PH
SA
SL
WA
WH
BC
HY
UN
MC
HP
WE
BR
BU
LT
TO
1,420
225
30,000
16,000
315
570
8,940
1,070
3,700
3,750
200
507
300
540
800
755
785
1,600
-
-
-
-
-
4.9
50.3
20.5
9.4
25.6
13.5
11.4
8.4
13.0
8.3
12.4
Principal County
Bladen
Bladen
Hyde
Washington
Bladen
Bladen
Columbus
Bladen
Stokes, Rockingham
Person
Orange
Durham
Guilford
Wake
Guilford
Alamance
Davidson
Guilford
od Control
28
29
30
22
23
24
25
26
27
KR
GA
RR
KS
HR
TU
BA
TL
BW
48,900
(elev. 300)
22,000
4,900
3,980
15,180
2,530
5,970
5,000
2,500
33.7
18.8
15.8
38.4
16.3
17.0
23.8
33.6
36.0
Mecklenberg, Va.
Vance, N.C.
Warren
Halifax
Wilkes
Davidson, Rowan
Davidson, Rowan
Montgomery, Stanly
Montgomery, Stanly
Richmond, Anson
147
-------
Table 1 (continued)
Type and Name
Catawba River
James
Rhodhiss
Hickory
Lookout Shoals
Norman
Mt. Island
Wylie (N.C.-S.C.)
Fishing Creek (S.C.)20
Wateree (S.C.)
Broad River
Lure
Green River
Adger
Summit
Toxaway River
Toxaway
Hiwassee River
Chatuge
Hiwassee
Codes
Map
13
14
15
16
17
18
19
(20
21
61
62
60
59
56
55
Coratmter
JA
RH
HK
LS
NR
MT
WY
FC
WT
LU
AD
SM
TX
CT
HW
Surface
Area
Acres
6,510
3,515
4,110
1,270
32,510
3,235
12,455
3,370
13,710
1,500
440
325
650
7,150
6,280
Mean
Depth-Ft.
46.1
20.8
31.0
24.5
33.6
17.7
22.5
17.1
22.6
-
26.7
40.7
-
34.5
69.7
Location
Principal County
McDowell , Burke
Caldwell, Burke
Alexander , Catawba
Iredell, Catawba
Catawba, Iredell,
Lincoln, Mecklenberg
Mecklenberg, Gaston
Mecklenberg, Gaston, N.C
York, S.C.
Chester, Lancaster, S.C.
Fair field, Kershaw.S.C.
Rutherford
Polk
Henderson
Transylvania
Clay
Cherokee
Nantahala River
Nantahala
Cheoah River
Santeetlah
54
53
Little Tennessee River
Fontana 52
Highland 57
Tuckaseigee River
Thorpe 58
River Segment
Chowan
(U.S. 13 to
Albemarle Sound)
44
NA 1,605 86.4
SN 2,860 55.2
FO 10,670 135.4
HL 400 est.
TH
CH
1,462 48.4
Clay, Macon
Graham
Graham, Swaim
Macon
Jackson
Hertford, Gates,
Chowan, Bertie
148
-------
Table 1 (continued)
Codes
Surface
Area Mean
Location
Type and Name
Old Kill Ponds (year
Crystal (1885)
Davies (1850)
Finches (1875)
Hodgins (1871)
Jackson (1885)
Johns (1840)
Jones (1810)
Lytches (1870)
McKensie (1860)
McNeils (1870)
Monroe (1825)
Orton (1810)
lull (1875)
Silver (1785)
Map
istri
31
32
33
34
35
36
37
38
39
40
41
42
43
45
Computer
icted)
CL
DM
FH
HO
JK
JH
JP
LY
MK
MN
MO
OR
TM
SI
Acres
100
60
20
100
75
125
75
325
50
100
70
500
180
75
Depth-Ft. Principal County
- Moore
- Lenoir
Wilson
Hoke
Franklin
Scotland
- Scotland
Scotland
Brunswick
Hoke
- Scotland
- Brunswick
- Lenoir
Wilson
149
-------
PROCEDURES
Trophic and Quality Parameters
In the definition of trophic state the task becomes one of quantifying the
magnitude of the biomass supported by the nutrient flux. This measurement may
be made at the primary level either by enumeration of the cell density of the
planktonic algae and/or cell volume. Since this determination is influenced
by the sampling procedures and quantifying techniques it does not necessarily
describe the net integrated effect of primary productivity. Other measures
have also been used to arrive at an assessment of trophic state such as rate of
carbon fixation (primary productivity); the major components of the nutrient
flux, nitrogen, phosphorus and carbon; or the relative transparency of the water
(Secchi disk depth) under the assumption that the degree of turbidity is a
direct indication of the particulate material of biological origin obscuring
the passage of light.
The following definitions or descriptions are of the measured or calcu-
lated water quality parameters used in the assessment of various trophic indices
as to their validity and utility. Each water sample was considered a micro-
cosm, constituting the physical and chemical environment of a specific micro-
flora (planktonic algae). Ultimately a set of 854 observations from all bodies
of water sampled were treated as a data pool for the following comparisons.
Physical and Chemical
Temp. °C; The temperature of the water sample measured in degrees Celsius was
usually obtained with a thermister probe. The value reported is either repre-
sentative of the average value of the epilimnion at the time of sampling or
the specific temperature at the depth that the sample was taken for algal
analysis.
Secchi-Ft.: The Secchi depth at the time of sampling, measured in feet. This
was the calibration used for most of the field of work of this investigation.
The Secchi depth was generally estimated to the nearest half foot.
Secchi-M; Secchi depth in meters as calculated from the field measurement or
in the later stages of the field work measured in the field to the nearest
0.1 M.
NH^-N; Ammonia nitrogen, determined by the automated phenolate method on a
150
-------
Technicon Autoanalyzer (U. S. EPA, 1974). The water sample was pretreated by
filtering through a washed Millipore HA filter.
: Nitrite and nitrate nitrogen, determined by reduction with hydrazine
sulphate (U. S. EPA, 1974). The procedure was carried out on a sample pre-
treated by filtration through a washed Millipore HA filter. The analysis was
made on a Technicon Autoanalyzer with the color being measured at 520 mm.
Kjel-N; Kjeldahl nitrogen, determined on a Technicon Autoanalyzer using the
automated phenolate method on an unfiltered sample. The sample was digested
in a continuous digestor with sulfuric acid containing potassium sulfate and
mercuric sulfate as a catalyst.
Inorg-N ; Inorganic nitrogen, representing the sum of NHg-N and NC^NO^-N in
the sample.
Org-N; Organic nitrogen, representing the difference between Kjel-N and
NHg-N and thus defining the actual nitrogen, found in cellular materials, which
are released by the digestion process.
Total-N: The sum of N02N03~N and Kjel-N.
PO^-P; Orthophosphate phosphorus, determined on a sample filtered through a
washed Millipore HA filter using the automated stannous chloride method (U. S.
EPA,. 1974) in a Technicon Autoanalyzer.
Total Sol-P: Total soluble phosphorus or dissolved phosphorus as determined
in a sample after filtration through a washed Millipore HA filter. The
dissolved or soluble fraction is digested with potassium persulfate and sul-
furic acid followed by the automated stannous chloride method for determination
of the reactive phosphorus.
Particulate-P: The phosphorus component associated with particulate materials
and determined by difference between the Total-P and Total Sol-P.
Total-P : The total phosphorus component determined on an unfiltered water
sample manually digested with potassium persulfate and sulfuric acid to convert
various forms of phosphorus to the orthophosphate with final determination as
PO^-P using the automated stannous chloride method.
TN/TP: The ratio of total nitrogen to total phosphorus.
Inorg-N/Sol-P: The ratio of inorganic nitrogen to total soluble phosphorus.
Alk; Total alkalinity as mgCaCO^ and determined on a 100 ml water sample tit-
rated with .02N HC1. The equivalence point of pH 5.1 is determined potentio-
metrically.
Cond ymhos; Conductivity in micromhos per cm. at 25°C determined either on a
151
-------
water sample returned to the laboratory utilizing a Lab-Line Electro MHO meter
or in the field with a YSI Model 33 field temperature/salinity/conductivity
meter.
Turbidity; Determined on Hach Model 2100 turbidimeter calibrated against a
Formazin standard and reported as Jackson turbidity units (JTU).
Color: Determined on a raw water sample by comparison with potassium chloro-
platinate standards.
Biological
Chlor a; Chlorophyll ^, determined on a water sample filtered onto a Gelman
glass fiber filter and acetone extracted using the techniques of Strickland and
Parsons (1972) and the pheophytin correction equations of Lorenzen (1967).
Absorbance of the acetone extract was determined at wavelengths of 665 my and
700 my (turbidity correction) using a Beckman DB spectrophotometer and 4 cm
absorption cells.
Chlor a-Turner Units: Chlorophyll a^ determined by its fluorescence on exci-
tation with ultraviolet light using a Turner model 110 fluorometer equipped
with a Hamamatsu R136 photomultiplier, a high sensitivity sample holder,
Corning 5-60 primary filter and 2-64 secondary filter. Samples were read
directly on the fluorometer and all results converted to ,the instruments lOx
scale. The Turner chlorophyll values are significantly correlated with chloro-
phyll ji as determined by standard procedures. A conversion of Turner Units
to chlorophyll ji mg/nH can be approximated by multiplying by a factor of .38
in the range of 0-100 Turner Units and .46 in the range of 100-250 Turner Units.
Prod mgCmVhr; The productivity of the water sample, reported in milligrams
carbon fixed per meter^ per hour, was determined on raw samples brought back
to the laboratory, stored overnight in the dark at room temperature and incu-
bated in light/dark bottles under 400 ft. candles of fluorescent "daylight
lamps" at 24°C. Changes in dissolved oxygen over a six hour incubation period
were determined by Winkler titration and converted to carbon equivalence using
a photosynthetic quotient of 1.2. The samples incubater1 for productivity
determination were aliquots of the same water returned for algal cell density
determinations.
152
-------
Cells no. /ml; All cell density determinations were made on live samples, but
if necessary held overnight in a refrigerator. Measured portions (normally
10 ml) from a well shaken sample were placed on a tapered centrifuge tube and
centrifuged at maximum speed in a clinical centrifuge for 15-20 minutes. The
liquid above each concentrated sample was carefully drawn off by pipette until
about .05 ml were left. The concentrated material was resuspended and thorough-
ly mixed in the remaining water. These drops were transferred by pipette to
a clean microscope slide filling the area under a 22 x 22 mm cover glass. The
cover glass was sealed with a paraffin-petroleum jelly mixture to prevent rapid
drying. The live preparation was examined under a Zeiss GFL compound micro-
scope to determine the uniformity of cell distribution and absence of air
bubbles. The preparation was examined at 500 x to identify and enumerate
phytoplankton in selected transects of known width and length using an oil
immersion lens at 1250 x for careful identification and measurement of smaller
species. In the case of colonies and filaments the entire units were counted
making note of the average number of cells per unit. The number of cells in
units/ml in the original sample was calculated from a known area of cover
glass, the area of the transects counted and the original volume of the sample
concentrated under the cover glass.
Biovol; A standard cell volume was determined for each species, calculated
by water displacement of plasticene clay scale models constructed from obser-
vations and average measurements of each taxa. Considerations were given to
the average number of cells per unit of colonial and filamentous forms and
the large central vacuoles of diatoms. The unit volume, mm-Vm^ is equivalent
to mg/m^, I03ji3/mi or 10~^ul/l, other units commonly used for reporting bio-
mass and biovolume.
A detailed description of the phytoplankton population of each of the lakes
on each of the sampling dates was not considered essential for this report in
defining the trophic state. A comprehensive analysis of population characteristics
and associated environmental factors is to be reported elsewhere (Campbell and
Weiss, in preparation).
153
-------
Diversity Indices; The quantitative definitions of population size, such as
cell density and biovolume and proportional representation of specific groups
or classes were used to compute other indices of trophic status. These pro-
vide additional scales for comparative assessment of the trophic level
reached by a specific body of water. Such measures of trophic state include
the Shannon-Weaver (Shannon and Weaver, 1949) and Evenness (Patten, 1962)
diversity indices and the Pollution Index. The Shannon-Weaver (Shan-Wea)
was chosen because of its independence of sample size and sensitivity to
change in evenness of distribution for a small number of species and insensi-
tivity to rarer missing species. It is assumed that values approaching and
surpassing 3.0 are considered indicative of highly diverse systems and these
are generally associated with waters of high quality.
The Evenness index or evenness of distribution of individuals among
species has a range approaching zero for an extremely skewed distribution to
1.0 for a perfectly even distribution e.g. one with the same number of indi-
viduals in each species. Values approaching 1.0 are generally associated with
water of high quality.
The Pollution Index, modified from Palmer (1969) to account for changes
in overall cell density, depends on a scaling of eighty pollution tolerant
species with values assigned by Palmer. The density of their number in the
sample multiplied by the number of units/ml for that species and the accumu-
lated total of the sample divided by the total number of taxa found provides a
numerical index ranging from zero to over 1000 (Weiss et^ al., 1974). This
index has proved to be unusually valuable and sensitive to changes in quality,
the presence of the pollution tolerant species being a key element in nutrient
rich systems.
Phytoplankton Quotients
With the facility of computers to handle large data banks and rapidly cal-
culate the above diversity indices for each sample, it was also possible to
utilize the raw species count and examine other biological indices that have
been used to describe changes in trophic state, Nygaard "(1953), Rawson (1956),
Brook (1965), Stockner and Benson (1967) and Stockner (1972). These relation-
ships were applied to the diatom composition of the contemporary planktonic
populations of the 854 samples of this study. Several of these relationships
have been computed. They are described in Table 2 and are referred to in the
154
-------
Table 2
Biological Indices
Phytoplankton Quotients
Code Class or Group Relationship
BI-A1 Species - Chlorococcales
Species - Desmidiaceae
BI-B2 Species
Cyanophyceae + Chlorococcales 4- Centrales + Eugleniaceae
Desmidiaceae
BI-C2 Species - Centrales
Species - Pennales
BI-D2
Centrales
Centrales + Araphidineae
BI-E3 Centrales
Centrales + Araphidineae
as % C + A (Density)
as % C -I- A (Volume)
Trophic State
<1 oligotrophy
>1 eutrophy
0.0-0.3 dystrophy
<1 oligotrophy
1-2.5 mesotrophy
2.5-5.0 eutrophy
5.0-2.0 hypereutrophy
0-0.2 oligotrophy
0.2-3.0 eutrophy
>50% eutrophy
32-50% mesotrophy
<32% oligotrophy
1 Rawson (1956)
2 Nygaard (1955)
3 Modified from Stockner (1971)
text and other tables by the codes BI-A, BI-B, BI-C, BI-D and BI-E.
Contemporary with the period of water sampling covered in this report
parallel studies, as part of a Federal, University, Industry effort to develop
an .algal assay for limiting nutrients, was part of the ongoing research effort
of this laboratory (Weiss and Helms, 1971: Weiss, 1976). Many of the samples
taken for assay have also been incorporated in the 854 observations of this
report. The weight of the biomass grown with a reseeded species under control
light and temperature conditions, without nutrient enhancement, provided an
indication of the growth potential of the body of the water. In the instance
where the sample was pretreated by autoclaving the total potential for growth
was indicated. In the second case of pretreatment, filtration, the potential
for growth reflects the immediate available nutrients. This control growth
155
-------
has been used as another trophic indicator, reflecting the current net nutrient
level of a body of water as well as the potential for algal growth. The pre-
treatment methods are identified as aut. wgt. and filt. vgt., e.g. weight of
biomass grown in the autoclaved pretreated sample and weight of biomass grown
in the filtered pretreated sample.
Trophic State-Indices (Carlson)
Due to the variation in interpretation of the meaning of the terms associ-
ated with the quality parameters, Carlson (1975) proposed a trophic state index
^
scale (TSI) based on Secchi-disk transparency (meters), chlorophyll a^ (mg/m )
o
and total phosphorus (mg/nr). He established a scale ranging from 0 to 100
based upon lowest and highest reported values in the literature. The major
divisions are grouped into units of 10's (10, 20, 30, etc.). These divisions
correspond approximately to existing concepts of trophic categories. Carlson's
range of values for TSI are shown in Table 3. In each instance 0 represents
the most oligotrophic state and 100 the most eutrophic. Utilizing the data
from the North Carolina lakes, the TSI has been computed for each and included
in the trophic index analysis. These three indices are referred to as the SD-
TSI, CH-TSI and TP-TSI. In addition to the three computed indices the three
original parameters have also been utilized in scaling the quality of the
sampled waters.
Table 3
Trophic State Index (TSI) and
Associated Parameters^
Secchi Disk Surface Total Surface
TSI Depth-Meters Phosphorus (mg/m3) Chlorophyll (mg/m3)
0 64 1 .04
10 32 2 .12
20 16 4 .34
30 8 8 .94
40 4 16 2.6
50 2 32 6.4
60 1 65 20
70 0.5 130 56
80 0.25 260 154
90 0.12 519 427
100 0.062 1032 1183
l-From Carlson (1975)
156
-------
RESULTS AND DISCUSSIONS
Data Analysis
The data of this report, generated from four years of sampling of lakes
and impoundments located in the representative geographic provinces of the
State of North Carolina provided an opportunity to examine the usefulness of
various trophic state indicators for assessment of trophic condition. In all
854 individual observations were sufficiently complete both in terms of
observed or measured data as well as other parameters calculated from the
primary determination to be used in a data pool. This information has been
examined by various sorting and statistical techniques so that the associations
of dependent and independent variables could be examined over the full range
of values.
Many of the impounded basins on the North Carolina river systems receive
point source discharges from municipalities, either by direct discharge to the
reservoir or into the inflowing river or stream. In some instances the river
and its nutrient load creates sharp quality gradients which permits the data
from large impoundments to be examined in subsegments along the longitudinal
axis, essentially testing in situ the mechanisms of quality change and the
associated trophic indicators or scales.
Each of the 854 water samples have been treated as an independent entity
in order to examine the physical, chemical and biological environment of the
specific microcosms. By computer sorting procedures each of the individual
water quality parameters or trophic indicators were rank ordered and listed
with associated variables. In turn the rank orders were divided into a series
of subclasses or subsets of data. These subsets covered value ranges of some
logical interval, such as a doubling sequence or were divided at points in the
rank order where sharp discontinuities were indicated. The mean values of all
other parameters or variables that occurred within the subclass were then cal-
culated. The mean values of each subclass of the independent variable was
then compared to the mean values of all other parameters measured or calculated
under similar associated conditions. From such analyses of the relationships
of the various trophic indices to those recognized dimensions of trophic state
the indices which appear to serve best to describe a trophic scale have been
highlighted.
157
-------
Secchi Depth
The classic procedure for determining water transparency has been to use
the Secchi disk for measuring the depth to which it can be viewed. This depth
is inversely proportional to the suspended particulate material that is pri-
marily of biological origin. The deeper the disk is viewed, the clearer the
water, thus smaller quantities of particulates of biological origin and con-
sequently the general assumption of water of higher trophic state. Over a
range of Secchi depth values from 0.1 to more than 4 meters, in seven subsets,
the values of the other trophic indices are all negatively correlated decreas-
ing as transparency increased (Table 4). However, a few are negatively cor-
related at very significant levels and thus would appear to have a stronger
direct relationship to the Secchi depth than others with poor correlation or
at non-significant levels. For example strong correlation is seen for chloro-
phyll ji, cell density, cell volume, the Shannon-Weaver and Evenness indices
of diversity. However, both of the latter appear to have a sharp divergency
from the regression slope in the deepest range of Secchi values. The pollution
index, taxa and several of the biological indices particularly BI-A, BI-B, BI-C
and BI-E are also significantly correlated (negative) with Secchi depth. The
biological indices do not necessarily agree in scale as to where one trophic
state phases into another but of the five, the BI-E scale would appear to come
closest to the definition of oligotrophy at the deepest Secchi disk readings.
Another anomaly is noted for BI-B. Across the entire range of values, even
through changing systematically with increase of Secchi depth, it still indi-
cates by the magnitude of the index, to be in a state of hypereutrophy. Note
should be made of the very good correlation between Secchi depth and the scale
of the Pollution Index which decreased systematically as the Secchi depth
increased.
The best of these correlations and others, will be compared in a cross
relationship to establish the most consistent of the indices and how they
might be used to define trophic state.
Chlorophyll ji
By the standard determination for chlorophyll, filtration and acetone
extraction followed by absorption photometry, a range of values from as low
as 0.8 to over 160 mg/m3 have been defined in eight subsets. In addition to
158
-------
en
CO
Table 4
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Secchi-Depth-Meters
Range of Values
N*
Secchi-M (x)
Chlor a rag/m3
TP mg/iii3
SD-TSI
CH-TSI
TP-TSI
Color Ft Units
Turb. JTU
Aut. Wgt.
Flit, Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
0.1-0.49
103
0.31
31(30)
117
76.4
57.6
66.5
77(48)
41(58)
14.0(34)
5.5(34)
5657
2875
3.896
.738
113
39
7.9
15.2
1.3
81.8
76.1
0.5-0.98
309
0.75
24(72)
62
63.7
59.2
56.0
49(102)
14(149)
6.1(96)
2.5(96)
6691
2748
3.597
0.659
145
44
8.1
14.3
1.5
84.3
77.2
1.0-1.49
186
1.2
14(39)
30
56.8
54.4
45.2
24(52)
9(83)
2.5(64)
0.9(64)
4549
2144
3.701
0.664
107
46
7.4
12.6
1.4
78.5
69.4
1.5-1.99
134
1.6
10(40)
21
52.1
51.1
41.9
12(39)
7(79)
3.4(38)
1.3(38)
3439
1875
3.634
0.651
77
45
6.1
10.3
1.4
72.6
63.4
2.0-2.99
82
2.3
3.7(20)
15
47.3
41.8
37.7
13.6(17)
4.5(67)
1.8(18)
0.7(18)
2154
1274
3.294
0.641
39
33
5.1
8.0
1.3
70.9
54.8
3.0-3.99
23
3.3
3.2(7)
15
42.6
41.8
37.2
9.7(8)
3.6
0.5(4)
0.4(4)
1093
857
2.997
0.623
49
25
4.8
7.0
1.4
77.7
62.8
>4.0
5
4.7
2.5
13
37.2
39.8
35.8
9.8
2.0
-
—
516
1461
3.567
0.717
6
27
3.5
5.8
0.7
40.0
31.9
Corr.
Coef .
r(xy)**
_
-.85
-.72
-.92
-.91
-.81
-.74
r-,69
-.80
-.78
-.93
-.81
-.98
-.08
-.91
-.82
-.962
-.95
-.75
-.84
-.92
N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.666
1% level of significance >.798.
-------
describing the relationships with the other trophic state indicators, (Table
5) the data analysis has also been extended to include relationship of chloro-
phyll ji to other physical and chemical and biological dimensions that were
determined on each of the water samples (Table 6).
The relationship of chlorophyll a_ to other trophic indicators is obviously
strongest with those parameters either directly related, other cellular
measurements, or chemical constituents which have been shown to be essential in
the growth of algal cells such as phosphorus. The strongest correlations are
with total phosphorus, the trophic indices of Carlson computed from Secchi
depth, chlorophyll and total phosphorus, the relationships to cell density and
biovolume, Pollution Index and the biological indices A, B, D and E.
When the range of chlorophyll values are examined in relationship to other
parameters of the aquatic environment, the strong negative correlation with
temperature is perhaps unique. It would suggest that the optimum for growth
was at somewhat lower temperatures than might be expected. The unusually
strong correlation of kj eldahl-nitrogen and organic nitrogen would indicate
that these determinations described materials directly associated with the
source of chlorophyll. The strong correlations with the phosphorus constitu-
ents and particularly particulate phosphorus argue for a similar source relation-
ship. The strong negative correlations with the ratios total nitrogen/total
phosphorus and inorganic nitrogen/soluble phosphorus, identify the proportions
needed for maximum growth. The strikingly high correlation with conductivity
suggests the use of this determination for monitoring purposes.
Chloro'phyll a-Turner Units
Since the determination of chlorophyll _a by the standard extraction pro-
cedure is time consuming and requires attention to detail that may not be
feasible on all occasions or in all laboratories, chlorophyll by direct photo-
fluorometry was determined on many samples. The range of values for this deter-
mination and relationships to the trophic state indices as well as the other
physical, chemical and biological parameters, are noted in Tables 7 and 8.
The highlights of these comparisons are that the photofluorometric
measurements also produced many relationships with high correlations, although
perhaps not quite as good as those of the extraction procedure. There was indicated
at the lower subclasses of the range of values of associated parameters little
change in proportion to the change in size of the mean Turner value, an
160
-------
CTt
Table 5
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Range of Given Index
Chlorophyll si mg/m3
Range of Values
N*
Secchi-M
Chlor a (x)
Total-P
SD-TSI
CH-TSI
TP-TSI
Color
Turbidity
Aut. Wgt.
Filt. Wgt.
Cell Density
Biovolume
Shan-Wea
Evenness
Pollution Index
Taxa
BI-A
BI-B
BI-C
BI-D
BI-E
0.8-2.0
19
2,1
1.6
37
52.6
35.2
43.5
2(15)
11
0.1(1)
0.1(1)
919
775
3.443
0.694
12
30
3.9
6.5
0.8
60.2
45.7
2.1-5.0
42
1,7
3.4
47
57.4
42.8
49.5
4(34)
7
5.3(2)
0.1(2)
1931
1356
3.421
0.656
30
35
5.3
9.4
1.0
64.5
56.2
5.1-10.0
35
1,3
7.5
57
57.3
50.4
48.4
4(31)
2
0.3(5)
0.2(5)
4532
2300
3.788
0.673
86
49
7.0
12.9
1.3
62.7
57.6
10.1-20.0
51
1,2
15
33
58.7
56.9
48.3
44
9.4
-
-
12149
4057
3.459
0.609
122
51
7.9
14.0
1.2
59.2
44.5
20.1-40.0
42
0,9
27
63
61.9
62.9
55.7
27
4
1.5(1)
0.1(1)
.15981
5407
4.133
0.689
274
64
10.6
17.7
1.5
79.4
69.0
40.1-80.0
15
0,6
51
100
67.7
69.1
64.0
48
17
-
-
19937
. 7650
4.300
.705
591
68
12.8
20.5
1.1
88.4
77.4
80.1-160
8
,4
96
280
74.5
75.1
80.7
30
29
-
-
43845
13065
4.134
0.687
1481
66
14.9
22.5
1.3
96.7
90.0
>160.1
1
.46
204
900
71***
82***
99***
14***
27***
-
-
58965
76008
4.495***
.698***
4132***
86***
10.7***
19.7***
0.9***
99.9***
99.6***
Corr.
Coef,
r(xy)**
-.72
-
.957
.975
.91
.989
-.14
.88
-
-
.965
.950
.74
.35
,99
.76
.90
.88
.38
.93
.91
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.707
1% level of significance >.834.
***Because of smallness of N these values not used in calculating corr. coef.
-------
CD
ro
Table 6
Mean Values of Physical, Chemical and Biological Parameters
of Lake Samples Collected for Trophic Analysis
Within Value Range of Indicated Parameter
Chlorophyll _a mg/m3
Range of Values
N*
Temp °C
Secchl-Ft.
Secchi-M
NH3-N mg/m3
N02N03-Nmg/m3
Kjel-Nmg/m3
Inorg-N mg/m3
Org-N mg/m3
Total-Nmg/m 3
PO^-P mg/m3
Total Sol-Pmg/m3
Sol Org-P mg/m3
Particulate-P mg/m
Total-P mg/m3
TN/TP
Inorg N/Sol P
Alk. mg/1
Cond ymhos
Cell Den no/ml
Biovol mm3/m3
Ln Cell Den
Ln Biovol
0.8-2.0
19
22.3
7.0
2.13
63
86
214
149
151
299
5
10
5
3 27
37
17.6
18.5
10
56(15)
919
775
6.5681
6.3677
Chlor -a- Turner Units 15
Prod mg C/m3/hr
10(13)
2.1-5.0
42
20.7
5.5
1.68
53
113
230
166
177
343
7
17
10
31
47
12.1
11.7
12
56
1931
1356
7.0227
6.7345
21
15(31)
5.1-10.0
35
22.1
4.4
1.33
55
74
265
129
210
339
23
31
8.2
26
57
14.6
11.1
19
106
4532
2300
8.0377
7.507
35
26(32)
10.1-20.0
51
22.8
3.9
1.18
47
71
288
119
240
356
9
12
3.5
21
33
15.3
15.2
20
112
12149
4057
8.8359
7.9639
39
44
20.1-40.0
42
21.3
3.0
0.88
66
77
377
143
311
454
13
22
8.7
41
63
14.4
15.4
23
119
15981
5407
9.2843
8.3003
67
80
40.1-80.0
15
17.9
2.0
0.59
76
•62
532
138
456
594
20
34
14
66
11
11.3
9.3
25
174
19937
7650
9.694
8.753
102
141
80.1-160
8
13.0
1.2
0.4
467
98
1175
565
708
1272
95
158
63
122
280
4.6
4.7
29
308
43,845
13,065
10.4082
9.2905
164
239
>160
1
27*** .
1.5***
.46
100
60
1400
160
1300
1460
115
600
485
300
900
1.6
.27
31
612
58,965
76,008
10.9847
11.2386
182
309
Corr.
Coef .
r(xy **
-.95
-.87
-.72
.36
-.39
.955
.30
1.00
.95
.93
.963
.93
.990
.957
-.92
-.89
.81
.996
.965
.950
.82
.94
.92
.958
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.666, 1% level of significance >.798.
***Not used in calculating corr. coef.
-------
Table 7
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Range of Given Index
Chlorophyll £ Turner Units
CO
Range of Values
N*
Secchi-M
Chlor j*
Total-P
SD-TSI
CH-TSI
TP-TSI
Color
Turbidity
Aut. Wgt.
Filt.
Cell Density
Biovolume
Shan-Wea
Evenness
Pollution Index
Taxa
BI-A
BI-B
BI-C
BI-D
BI-E
7-14
135
1.5
4.9(22)
35
57.1
41.4(22)
47.0
24(32)
8
5.5(28)
3.0(28)
1206
1028
3.226
0.653
62
28
6.0
10.9
1.3
82.6
76.5
15-29
314
1.2
6.3(64)
42
59.6
46. 5 (-64)
48.4
34(99)
18(157)
4.5(92)
1.8(92)
2560
1211
3.613
0.676
61
39
6.5
11.5
1.3
78.3
70.6
30-44
138
1.1
13.9(52)
38
59.9
55.2(52)
50.0
41(70)
13(93)
4.7(54)
1.2(54)
6732
2558
3.644
0.639
124
50
7.9
14.5
1.5
74.5
64.3
45-59
53
1.0
20.2(22)
52
60.0
59.6(22)
52.8
17(23)
13(30)
7.3(18)
2.9(18)
9155
3862
4.020
0.679
220
58
10.0
17.2
1.5
83.1
72.3
60-89
44
0.8
26.5(21)
94
64.5
61.0(21)
61.2
101(23)
15(29)
4.7(12)
2.6(12)
9394
3826
4.040
0.677
239
61
10.1
16.7
1.6
88.2
79.3
90-119
22
0.7
44(18)
114
65.9
66.7(18)
66.4
36(17)
17(20)
9.1(4)
1.2(4)
17194
7713
4.110
0.696
509
60
14.7
23.4
1.6
87.5
78.6
120-179
18
0.5
67(9)
173
69.3
70.8(9)
72.7
67(9)
20(15)
12.5(6)
6.9(6)
25849
8865
4.068
0.681
1046
61
10.4
15.8
2.0
96.3
89.7
180-239
3
0.5
144
460
68.0
78.0(2)
85.3
22
23
-
-
60203
35595
4.170
0.663
2520
77
10.5
17.7
0.8
94.6
87.9
>240
2
0.4
129
297
74.5
80.0
82.0
17
22
6.0(1)
2.1(1)
33680
19197
3.798
0.637
2136
64
30.5
45.0
2.1
99.8
99.8
Corr .
Coef .
r_(xy_)_**
-.90
.94
.85
.967
.93
.95
-.14
.82
.36
.20
.82
.79
.49
-.37
.92
.75
.83
.82
.35
.91
.92
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.754.
1% level of significance >.874.
-------
en
Table 8
Mean Values of Physical, Chemical and Biological Parameters
of Lake Samples Collected for Trophic Analysis
Within Value Ranges of Indicated Parameter
Chlorophyll £ Turner Units
Corr.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Range of Values
N*
Temp. °C
Secchi-Ft.
Secchi-M
NH3-N rag/m3
N02N03-N mg/m3
Kjel-N mg/m3
Inorg-N mg/m3
Org-N mg/m3
Total-N mg/m3
P04-P mg/m3
Total Sol-P mg/m3
Sol Org-P mg/m3
Particulate-P mg/m3
Total-P mg/m3
IN /IP
Inorg N/Sol-P
Alk mg/1
Cond ymhos
Cell Den no/ml
Biovol tnm3/m3
Ln Cell Den
Ln Biovol
Chlor a-Turner Units (x)
Prod mgC/m3/hr
7-14
135
15.8
4.9
1.5
65
197
213
263
148
410
16
23
7
14
35
17.8
18.0
15(55)
65(54)
1206
1028
7.0059
6.0365
12
12(33)
15-29
314
19.6
3.9
1.2
73
163
262
236
189
425
13
21
8
21
42
15.7
16.6
17(141)
72(156)
2560
1211
7.3809
6.6110
21
20(118)
30-44
138
21.1
3.5
1.1
63
135
303
199
240
438
11
18
8
20
38
15.6
15.6
20(79)
103(94)
6732
2558
7.6895
7.4567
36
44(81)
45-59
53
22.5
3.4
1.0
60
116
357
176
297
473
17
26
9
26
52
14.1
12.0
22(25)
141(32)
9155
3862
8.0048
7.8001
51
70(32)
60-89
44
21.4
2.6
0.8
66
144
456
210
391
601
30
47
16
47
94
11.8
9.3
20(26)
102(31)
9394
3826
8.2743
7.9809
76
79(31)
90-119
22
19.2
2.2
0.7
64
90
523
154
459
613
22
41
20
73
114
6.8
6.1
22(17)
154
17194
7713
9.0329
8.7943
103
120
120-179
18
16.9
1.7
0.5
252
92
859
344
608
952
52
92
38
80
173
6.1
4.9
28(11)
243(15)
25849
8865
9.3889
8.7477
144
174(15)
180-239
3
21.2
1.8
0.5
107
88
1227
195
1120
1315
81
267
186
193
460
4.3
2.4
27
508
60203
35595
10.1192
10.1222
184
300
>240 Coef.**
2 r(xy)
15.1 -
1.3 -
0.4 -
200
41 -
900
241
700
941
108
125
18
172
297
3.4 -
2.2 -
27 -
272
33680
19197
10.1596
9.8347
262
243
.37
.90
.90
.71
.90
.88
.14
.81
.85
.966
.74
.47
,93
.85
.78
.92
.31
.82
.82
.79
.957
.92
_
.929
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.666
1% level of significance >.798.
-------
indication of lack of sensitivity at these levels. However, outstanding cor-
relations are noted with the Secchi depth-TSI as well as that of the chloro-
phyll and total phosphorus TSI's. The correlation, significant at the 5%
level, with turbidity would possibly be indicative of a measurement of bio-
logical particulates containing chlorophyll as well as response to other
fluorescing materials. The relation to Pollution Index is also very strong
as well as with the biological indices D and E. The comparisons with the
physical and chemical parameters shows very highly correlated relationships
with PO^-P and particulate-P as well as the measurement of productivity. In
the comparison with conductivity the correlation was not as strong as has been
previously demonstrated with the chlorophyll ji by extraction,although it is
still greater than the 1% level of significance.
Total Phosphorus
A key measure of any aquatic environment and its trophic state is the
quantity of total phosphorus in the system. Although it is widely recognized
that phosphorus cycles rapidly through many forms, it is the total reservoir
of phosphorus that must be available for the nutrient flux required to support
the microflora. In twelve subsets, over a range of 1 to more than 300 rng/m^,
the relationship of total phosphorus to the various trophic indices are
examined (Table 9). The expected negative correlation with Secchi depth is
indicated. It is just at the 5% level of significance primarily because the
changes in quantity with increase in Secchi depth lack resolution above 50
^
mg/m total phosphorus. Extremely high correlation is shown for chlorophyll
ji as well as with the bioassay indices of reseeded algae grown in water samples
pretreated either by autoclaving or filtration. The correlation with cell
density or cell volume are equally striking as well as with the Pollution Index.
Except for the biological index E the others show correlations coefficients
that are above the 1% level of significance. Key to the importance of phos-
phorus as a trophic state indicator is the exemplary correlation relationships
found not only for the direct measures of cell materials, e.g. density and
biovolume as well as the response of the specific population identified in the
Pollution Index but also the manner in which the algal assay procedure responded
to the proportional amount of phosphorus in the test sample.
165
-------
Table 9
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
TP (Total Phosphorus) mg/m3
Range of Values
N*
Sccchl-M
Chlor a mg/m3
TP rac/ra3 (x)
SD-TSI
CIl-TSI
"•* TP-TSI
o> Color Pt Units
Turb. JTU
Aut. Wgt.
File. Wgt.
Cell Den. no. /ml
Shan-Weaver
Pollution Index
TH-A
BI-B
m-r
ni-n
BI-E
1-9
33
2.4
12(16)
6.6
48.2
50.1(16)
26.9
13(13)
6(28)
1.3(8)
0.4(8)
3260
1763
3.372
0.642
84
39
6.6
11.9
1.1
64.6
53.2
10-19
191
1.7
7(49)
13
52.9
47.1(49)
36.5
29(57)
6
1.6(61)
0.3(61)
3090
1802
3.432
0.640
66
39
5.6
9. A
1.5
73.7
67.1
20-29
184
1.4
12(41)
. 21
56.2
52.5(41)
44.9
42(53)
8(98)
3.0(45)
1.1(45)
3820
1560
3.535
0.661
78
40
6.3
10.7
1.3
75.2
63.8
30-39
108
1.1
13(22)
32
59.5
54.2(22)
50.5
20(31)
12(58)
3.8(36)
1.6(36)
4572
2071
3.660
0.666
102
45
7,2
12.2
1.3
78.5
67,3
40-49
65
i.b
21(12)
41
59.9
56.6(12)
54.3
10(17)
11(28)
4.7(22)
1.7(22)
5205
2671
3.643
0.649
166
47
8.1
14.4
1.2
84.1
73.7
50-69
70
0.7
25(15)
56
65.3
59.6(15)
58.8
33(25)
19(43)
8.5(31)
4.0(31)
4551
2071
3.747
0.602
97
44
8.1
15.0
1.5
S3. 4
77.0
70-89
&1
0.6
20(17)
77
68.9
56.2(17)
63.1
34(22)
27(27)
9.9(14)
1.5(14)
4997
2245
3.844
0.704
136
45
8.7
16.3
1.7
84.8
78.7
90-109
97
0.6
17(6)
96
69.2
54.7(6)
66.3
28(9)
42(10)
10.3(10)
4.7(10)
6076
2629
3.780
0.702
119
41
9.7
16.6
1.4
61.7
71,5
110-149
L")
0.5
35(13)
123
70.0
60.8(13)
70.2
83(22)
40(27)
13.0(17)
.5.6(17)
7211
3015
3.984
0.717
244
47
10.1
17.4
1.6
92.5
84,2
150-199
18
0.6
41(7)
168
68.4
62.4(7)
74.4
78(9)
20(12)
12.7(4)
2.2(4)
12569
4318
3.802
O.C94
280
45
9.3
15.4
1.5
90.2
81.8
200-
299
15
0.5
35
235
72.5
56.6
79.0
126
20
14.7(5)
10.0(5)
14739
5161
3.674
0.700
403
44
9.2
14, 8
1.4
B7.B
78. B
>300
11
0.6
102(6)
464
67.3
73.0
84.3
31
41
26.8(2)
15.5(2)
27759
14260
3.747
0.674
1163
52
10.6
17.5
1.3
97.9
95.3
Corr.
Coef .
r(xyj**
-.53
.962
,57
,86
.80
.37
.62
.962
.93
,991
.964
.38
.35
,967
.72
.74
,62
.04
.78
.81
*If N deviates from values shown by more than 10X then actual N ia In parenthesis,
**5% level of significance >,553
12 level of significance >.684,
-------
Conductivity
Conductivity over a range of seven to more than 300 ymhos/cm and divided
into seven subsets of values is examined in its relationship to trophic indices
in Tables 10 and 11. It clearly becomes a candidate as an important trophic
state indicator by the strong correlations shown with the primary measures of
response to nutrient enhancement cell growth and biovolume. Strong correla-
tions are also noted for chlorophyll ja, and the Pollution Index. In Table 11,
the strong correlations are also noted for Kjel-N, organic nitrogen, and total
nitrogen all measures of biological materials. The correlations with chloro-
phyll ja-Turner and productivity are also strong.
Trophic State-Indices (Carlson)
These indices calculated from the basic measurements of Secchi depth,
chlorophyll ji and total phosphorus provide a range of values from 0-100 in 10
unit intervals and are scaled to known trophic conditions. The intent was to
provide a sensitive index each increasing in scale value as the trophic state
changed from water of high quality, oligotrophic to water of low quality, eu-
trophic. Although each is independent, they are parallel in scale and can be
cross compared in their relationships to trophic state. The SD-TSI, CH-TSI
and TP-TSI are compared to other trophic state indices over the range of
values determined in this set of observations (Tables 12, 13, 14). The cor-
relations for the trophic state index computed from Secchi depth tend to be
somewhat low or below significant levels, few attaining any unusual level
except with total phosphorus and with the actual Secchi depth measurement.
The CH-TSI derived from chlorophyll &_ determinations and organized in
subsets of 10 unit intervals is highly correlated with both the direct Secchi
measurement as well as the SD-TSI and the TP-TSI. Very strong correlations
are also noted for cell density although not as good as that with biovolume.
The Shannon-Weaver diversity index is strongly correlated in contrast with the
essentially non-existent correlation of the Evenness Index. The Pollution
Index barely reaches the 5% level of significance but taxa and the biological
indices A, B, C, D and E are all well correlated.
With few exceptions nearly all of the other trophic state indices are
well correlated with the TP-TSI. Exceptions include comparatively poor cor-
relation with Shannon-Weaver, Evenness diversity indices, number of taxa and
the biological index C. The low but still significant correlation with cell
167
-------
CO
Table 10
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Range of Given Index
Conductivity ymho/cm
Range of Values
N*
Secchi-M
Chlor a
Total-P
SD-TSI
CH-TSI
TP-TSI
Color
Turbidity
Aut. Wgt.
Filt. Wgt.
Cell Density
Biovolume
Shan-Wea
Evenness
Pollution Index
Taxa
BI-A
BI-B
BI-C
BI-D
BI-E
7-19
17
3.16
2.9
18
44.1
40.4
40.6
14
3
-
-
999
1571
2.944
0.612
7
24
4.5
7.1
0.9
54.4
39.8
20-49
47
0.99
8.0(23)
85
64.2
47.6(23)
56.4
'47
24
9.1(19)
2.1(19)
2043
2463
3.275
0.659
44
30
4.9
9.3
1.0
55.6
55.3
50-99
245
1.40
13(80)
42
57.4
52.5(80)
48.2
46.5(117)
3
4.3(8)
1.9(81)
4379
1779
3.506
0.662
120
40
7.0
11.9
1.3
77.6
66.4
100-149
120
1.21
18(55)
37
57.9
57.1(55)
48.1
34.8(56)
2
4.9(36)
1.5(36)
8155
3101
3.859
0.663
163
54
7.3
12.9
1.3
74.1
61.1
150-199
17
0.84
38(12)
82
63.5
64.1(12)
60.9
28.3
6
8.4(5)
0.8(5)
10751
5545
4.344
0.727
387
62
11.7
19.4
1.8
70.7
84.4
200-299
19
0.63
49
136
66.7
66.0
66.7
37.8(17)
18
4.4(3)
1.7(3)
24927
9197
3.971
0.674
591
52
13.5
20.9
1.6
91.8
83.2
>300
11
0.47
83(8)
290
70.7
59.9(8)
78.1
17.0(8)
4
15.6(3)
12.7(3)
39697
18767
4.223
0.720
2095
63
10.1
15.2
1.3
78.9
71.8
Corr.
Coef .
r(xy)**
-.63
.981
.954
.72
.84
.90
-.41
-.15
.75
.90
.974
.987
.73
.72
.984
.75
.61
.53
.37
.57
.54
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.707
1% level of significance >.834.
-------
en
10
Table 11
Mean Values of Physical, Chemical and Biological Parameters
of Lake Samples Collected for Trophic Analysis
Within Value Range of Indicated Parameter
Conductivity ymho/cm
Range of Values
N*
Temp °C
Secchi-Ft.
Secchi-M
NH--N mg/m3
i *•!
N02N03~N mg/m3
Kjel-N mg/m3
Inorg-N mg/m3
Org-N mg/m3
Total-N mg/m3
PO^-P mg/m3
Total Sol-Pmg/m3
Sol Org-P mg/m3
Particulate P mg/m3
Total-P mg/m3
TN/TP
Inorg N/Sol P
Alkinity mg/1
7-19
17
24.0
10.4
3.16
22
41
186
63
165
228
4.0
9.4
5.4
8.2
18
14.8
9.5
4.5
Conductivity ymho (x) 14
Cell Density no/ml
Biovolume mm3/m3
Ln Cell Density
Ln Biovolume
Chlor a_ Turner Units
Prod ' mg C/m3/hr
999
1571
6.7028
7.0366
12
5.0(1)
20-49
47
17.9
3.2
0.99
102
192
325
294
223
223
19
39
20
46
85
11.1
11.6
8.1
39
2043
2463
6.7003
6.6053
28
25(19)
50-99
245
19.3
4.6
1.40
60
117
302
177
242
419
12
19
7
23
42
16.4
15.6
19
76
4379
1779
7.5876
6.8200
31(205)
32(174)
100-149
120
21.6
4.0
1.21
57
88
316
145
258
403
11
17
6
21
37
17.3
13.8
27(99)
116
8511
3101
8.2123
7.5607
41(97)
48(95)
150-199
17
17.8
2.8
0.84
66
109
418
175
352
527
15
25
10
57
82
8.9
11.9
24(14)
167
10751
5545
8.1278
8.3980
94
96
200-299
19
18.7
2.2
0.63
140
65
676
205
536
741
39
51
13
84
136
10.8
8.3
25
225
24927
9197
9.6602
8.6439
108
155(17)
>300
11
16.8
1.6
0.47
325
118
1076
474
750
1267
67
166
103
124
290
5.0
3.9
26
510
39697
18767
8.9415
9.3610
142
202
Corr .
Coef .
r(xy)**
-.61
-.62
-.63
.94
.01
.978
.81
.973
.991
.95
.94
.90
.92
.954
-.77
-.77
.64
—
.975
.987
.85
.90
.92
.94
*If N deviates from values shown by more
**5% level of significance >.707
1% level of significance >.834.
than 10% then actual N is in parenthesis,
-------
Table 12
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
SD-TSI (Secchi Depth - Trophic State Index)
Range of Values
N*
Secchi-M
Chlor ji mg/m3
TP mg/m3
SD-TSI (x)
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
30-39
6
3.7
2(4)
20
36.8
38.8(4)
40.5
10(4)
2(4)
2.5(2)
3.2(2)
770
1324
3.426
0.682
29
28
5.9
9.8
1.0
49.4
43.2
40-49
107
2.5
4(28)
15
46.2
41.9(28)
37.8
12(26)
4(91)
1.5(24)
0.6(24)
1914
1179
3.250
0.640
41
32
5.1
8.0
1.3
72.9
57.4
50-59
311
1.4
12(79)
26
54.9
52.8(79)
43.9
19(91)
8
2.9(97)
1.0(97)
4170
2068
3.673
0.657
95
46
6.8
11.4
1.4
75.7
66.5
60-69
318
0.8
24(71)
62
63.6
59.2(71)
55.8
47(101)
15(148)
6.5(99)
2.8(99)
6523
2688
3.607
0.661
159
44
8.2
14.5
1.5
84.6
77.6
70-79
74
0.3
47(24)
117
74.9
60.2(24)
66.4
85(41)
40(50)
11.6(28)
4.2(28)
6648
3538
4.024
0.729
266
45
9.1
16.8
1.1
81.2
74.3
80-89
24
0.2
20(5)
117
81.9
50.6(5)
66.8
35(6)
32(7)
24.4(4)
9.3(4)
3688
1383
3.525
0.753
73
24
4.3
10.1
1.7
82.7
78.7
>90
2
0.5
6.3
140
94.5
44.5
59.0
166
19
-
-
470**'*
76***
2.426
0.724
0
10
1.5
3.5
0.3
25.0
39.3
Corr.
Coef .
r(xy)**
-.89
.38
.958
^
.37
.85
.83
.70
.87
.72
• 18 (.
-.14(.
-.35
.76
.12
-.43
-.39
-.18
-.32
-.21
.14
71)
48)
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.666
1% level of significance >.798.
***Not used in calculating corr. coef. in ( ).
-------
Table 13
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
CH-TSI (Chlorophyll Trophic State Index)
Range of Values
N*
Secchi-M
Chlor ji mg/m^
TP mg/m3
SD-TSI
CH-TSI (x)
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm^/m^
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
29-39
24
2.1
2
37
53.5
35.9
44.0
30(18)
14
3.5(3)
0.1(3)
966
771
3.583
0.708
23
32
4.4
7.5
0.8
64.4
48.0
40-49
48
1.6
4
46
57.3
44.3
48.7
37
16
0.1(1)
0.6(1)
2223
1550
3.373
0.647
33
36
5.4
9.9
1.1
61.9
56.6
50-59
64
1.2
11
45
58.0
54.4
48.8
41
10
0.4(4)
0.1(4)
9358
3396
3.639
0.637
101
52
7.6
13.6
1.2
60.5
48.2
60-69
63
0.9
29
62
62.5
63.2
55.4
39
13
1.5(1)
0.1(1)
15881
5639
4.035
0.675
312
62
16.5
16.6
1.4
77.4
67.4
70-79
12
0.4
79
24
72.3
72.9
76.1
26
27
-
-
36066
9689
4.168
0.686
887
68
17.9
25.6
1.1
94.8
83.2
>80
2
0.4
166
634
74.0
81.0
92.5
15
21
-
-
47313
49835
4.369
0.717
4080
70
17.9
29.4
2.0
100.0
100.0
Corr.
Coef .
r(xy)**
-.984
.88
- .79
.963
-
.92
-.59
.62
-.46
-.29
.956
.76
.93
.33
.77
.975
.969
.978
.80
.90
.91
*If N deviates from values shown by more than 10% then actual N is in parenthesis,
**5% level of significance >.754
1% level of significance >.874
-------
ro
Table 14
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
TP-TSI (Total Phosphorus Trophic State Index)
Range of Values
N*
Secchi-M
Chlor ji mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI (x)
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
20-29
17
2.0
21(7)
5.1
50.6
57.4(7)
23.4
12(7)
5(12)
1.2(4)
0.4(4)
4188
1558
3.654
0.655
104
48
7.5
13.2
1.3
74.8
67.9
30-39
141
1.9
5(27)
11
51.6
44.1(27)
34.0
24(27)
6(85)
1.3(46)
0.3(46)
2596
1358
3.338
0.638
62
35
5.4
9.1
1.5
72.6
65.1
40-49
265
1.4
11(71)
27
56.0
51.1(71)
44.1
39(90)
8(164)
2.9(70)
1.0(70)
3733
1807
3.515
0.655
77
40
6.2
10.4
1.2
75.0
64.5
50-59
207
1.0
18(42)
39
60.6
56.0(42)
53.5
21(59)
11(95)
4.7(65)
2.1(65)
5010
2399
3.720
0.666
131
47
7.8
13.8
1.3
80.7
70.8
60-69
157
0.6
23(36)
82
68.5
57.7(36)
63.6
35(56)
31(68)
10.7(52)
3.8(52)
5216
2286
3.820
0.702
121
43
9.0
16.3
1.6
84.6
77.8
70-79
44
0.5
36(16)
163
70.1
58.3(16)
73.8
94.7(23)
30(33)
4.2(14)
6.8(14)
10912
3968
3.842
0.700
266
46
9.3
15.8
1.5
93.4
85.4
80-89
15
0.5
64(10)
297
71.2
67.1(10)
83.7
104.6
32
21.7(3)
11.2(3)
23845
8087
3.758
0.699
859
48
10.3
16.1
1.4
87.7
82.5
>90
3
0.8
106
733
62.7
67.5
95.7
23.5
15
-
—
22663
27008
3.814
0.651
1543
59
13.6
22.1
1.3
100.0
99.9
Corr.
Coef .
r(xy)**
-*- --rf— g—
.87
.84
.83
.82
.79
_
.54
.69
.80
.92
.86
.74
.70
.48
.81
.66
.88
.84
.14
.93
.91
*If N deviates from values shown by more than 10% than actual N is in parenthesis,
**5% level of significance >.666
1% level of significance >.798.
-------
volume may be due in part to a lack of sensitivity over the range of TP-TSI
scaled.
Color
The color of water and its effect on transparency, its relationship to
humic materials and associations with acidic waters has caused this parameter
to be examined in relationship to the response of the various trophic state
indices. It would appear that color per se has little or no relationship to
any of the other trophic indices (Table 15). However, the relationship to cell
density and biovolume suggest that at higher color levels these decrease in
proportion to the amount of color present. The specialized cases of highly
colored waters and their role in trophic classification is one that generally
requires individual analysis of the particular body of water.
Turbidity
Similar to the rational for the examination of the relationship between
color and the various trophic indices, the data for turbidity was also organ-
ized (Table 16). No attempt was made to discriminate between turbidity due
to biological particulates and that due to suspended sediments. The correla-
tion coefficients suggest that at the higher turbidities, over 40 JTU, this
could very well be primarily sediment particulates. The significant relation-
ship with total phosphorus as well as TP-TSI would also appear to argue that
a proportion of phosphorus and its relationship to turbidity are materials of
nonbiological composition. Except for the Evenness diversity index all the
other biological criteria of changing quality appear to be nonrelated in any
significant way to turbidity. The possibility of the phosphorus relationship
to turbidity may be creating the marginal correlation for the Evenness diver-
sity index and BI-E.
Autoclaved and Filtered Weight, Biomass Determination
In the development of the algal assay procedure for determination of limit-
ing nutrients in surface waters, one important step in the preparation of sample
is the removal of existing viable algal cells. This step can be achieved either
by autoclaving of the raw water sample or filtration through membrane filters.
In the latter procedure the filtrate then becomes a media containing the soluble
173
-------
Table 15
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Color Pt Units
Range of Values
N*
Secchi-M
Chlor ji mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units (x)
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
1*9
70
1.6
8(49)
26
53.6
48.2(49)
45.3
6
7
3.8(12)
0.7(12)
7981
2390
3.627
0.648
99
48
7.3
11.9
1.0
67.0
52.1
10-19
107
1.2
29(87)
67
60.2
59.5(87)
52.4
14
15
3.6(15)
1.1(15)
13234
5512
3.868
0.659
287
57
10.2
17.6
1.3
75.0
65.4
20-39
40
0.7
16(26)
113
69.2
52.5(26)
63.2
28
31
8.5(10)
0.4(10)
9158
3294
3.666
0.682
152
43
8.0
15.0
1.2
75.5
71.3
40-79
30
0.8
18(13)
122
65.1
51.5(13)
62.0
60
33
12.1(13)
4.3(13)
3028
1651
3.500
0.680
100
34
7.7
13.3
1.0
70.0
64.6
80-159
19
0.9
23(8)
44
61.9
54.5(8)
51.8
100
6
2.9(7)
0.9(7)
3040
1849
2.692
0.595
66
23
3.0
5.1
0.8
32.2
34.5
160-299
9
0.7
9(7)
33
69.3
49.3(7)
47.7
207
9
0.0(1)
0.2(1)
911
896
2.856
0.662
6
20
3.6
6.6
0.9
46.1
44.1
>300
5
0.3
23(4)
166
75.6
59.8(4)
79.2
481
7
_
—
3579***
2545***
3.388
0.657
560***
34
7.6
9.2
1.8
97.5
95.1
Corr.
Coef .
r(xy)**
-.76
.14
.55
.77
.44
.69
-
-.41
-.49
-.18
-.53(-.
-.29(-.
-.32
-.04
.67(-.
-.44
-.19
-.48
.66
.25
.53
80)
69)
73)
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.707
n level of significance >.834.
***Value not used in calculating r in parenthesis.
-------
en
Table 16
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Turbidity JTU
Range of Values
N*
Secchi-M
Chlor ji mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU (x)
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
1-5
159
2.1
7(66)
29
51.0
46.3(66)
42.3
60(82)
4
2.2(37)
0.6(37)
2847
1415
3.200
0.632
71
33
5.0
7.7
1.1
63.1
50.8
6-12
159
1.2
17(70)
43
57.8
55.6(70)
48.1
39(89)
9
4.4(54)
1.6(54)
8241
3317
3.659
0.653
145
48
7.8
13.1
1.3
72.9
62.7
13-19
77
0.9
23(40)
57
61.5
59.5(40)
54.1
15(50)
16
7.2(24)
4.6(24)
9438
3899
4.009
0.692
229
54
8.7
15.3
1.6
87.1
74.4
20-29
32
0.6
52(17)
104
67.4
65.7(17)
62.5
21(21)
24
12.3(7)
3.5(7)
13650
6705
4.0347
0.693
398
57
10.3
17.9
1.2
91.2
81.1
30-39
25
0.4
56(10)
142
72.7
60.2(10)
67.5
37(17)
34
11.4(8)
2.8(8)
14166
3933
3.757
0.708
349
43
9.0
15.0
1.1
89.1
83.1
40-69
11
0.3
5(5)
92
75.5
45.6(5)
64.6
31(9)
51
7.7(5)
1.5(5)
1077
835
4.120
0.759
27
42
7.7
15.8
0.9
73.1
65.6
70-89
8
0.3
4.7(4)
115
78.1
46.3(4)
68.5
41(7)
81
16.3(3)
0.1(3)
677
426
4.215
0.807
31
37
6.4
15.6
1.2
91.5
88.9
>90
5
0.3(4)
KD
191
78.3(4)
31.0(1)
73.8
43
121
11.9(3)
0.2(3)
318
242
3.879
0.807
26
26
3.7
10.2
0.9
89.8
86.8
Corr.
Coef .
r(xy)**
-.68
-.42
o c
.85
.84
-.74
.83
.13
f —i
.67
-.55
c o
-. 58
f /%
-.60
/ -j
.47
n /
.94
/ O
-.48
r t
-. 64
C "7
-. 57
r\ —t
- . 07
-. 55
.51
£ O
. 68
*If N deviates from values shown by more than 10% then actual N is in parenthesis,
**5% level of significance >.666
1% level of significance >.798.
-------
nutrients representative of the time of sampling. Subsequent reseeding with a
test species, e.g. Selenastrum capricornutum, and culture under controlled
temperature and light conditions defines by the biomass formed the growth
potential of this nutrient quantity. In the procedure which destroys all viable
cells by autoclaving, a larger nutrient pool is created by the solubilization
of nutrient materials from both cellular as well as non-cellular sources.
This nutrient pool is generally cleansed of residual particulates by a subse-
quent filtration. The reseeding of the autoclaved sample with the test alga
and culture under controlled conditions provides a demonstration of the total
nutrient pool. This assumes that normal processes of biological degradation
or solubilization would have eventually released the nutrient resources for
algal growth. Thus filtration provides the media that reflects the existing
nutrient pool and autoclaving the potential nutrient pool. These control growth
procedures do not include the addition of nitrogen or phosphorus nutrient spikes.
These growth determining procedures may also be used as an indicator of
trophic condition and have been included in Tables 17 and 18 to illustrate the
relationship between their range of values and other trophic indicators. It
is clear that they are highly correlated, at very significant levels, with each
other. The autoclaved control growth also shows high correlation with total
phosphorus, as might be expected due to the treatment procedure, but shows
little or no correlation with any other of the trophic indicators except Secchi
depth. The growth in the filtered sample, reflecting the magnitude of the
existing nutrient pool, is also highly correlated with total phosphorus; some-
what marginally to Secchi depth; fairly significantly with the Evenness diver-
sity index; negatively correlated at significant levels with taxa and the
biological index D.
Over the range of values for growth in either autoclaved or filtered samples
few parallelisms are noted with other trophic indicators that correlate signifi»-
cantly. However, when these same values for both autoclaved and filtered samples
are compared to nutrient levels and other measures of productivity the correla-
tions are strong and more significant (Tables 19 , 20). The noncorrelated rela-
tionships are the exception rather than the rule. The filtered samples show
a series of noncorrelated relationships that includes kjeldahl nitrogen as well
as organic nitrogen. The correlation with ratio of inorganic nitrogen to solu-
ble phosphorus is almost at significant levels. Chlorophyll is noncorrelated
but productivity does show a strong positive correlation. The autoclaved
176
-------
Table 17
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Filtered Weight rog/1
Range of Values
N*
Secchi-M
Chlor a mg/m^
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Flit. Wgt.(x)
Cell Den. no. /ml
Blovol. nun^/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp .
BI-A
BI-B
BI-C
BI-D
BI-E
0.01-0.1
115
1.2
8
33
58.3
47.8(8)
45.9
34(29)
17(58)
3.0
0.09
3502
2266
3.749
0.676
135
45
7.5
13.0
1.5
79.3
73.7
0.2-1.9
72
1.2
9(1)
44
58.8
43.0(6)
48.9
42(21)
14(49)
3.7
0.8
4830
2206
3.790
0.681
262
45
8.2
14.2
1.3
82.5
74.0
2.0-4.9
40
0.9
—
72
62.4
, -
58.2
38(4)
14(22)
7.7
3.2
6328
3839
3.556
0.661
283
51
7.6
13.3
1.4
74.4
67.2
5.0-7.9
9
0.6
—
55
67.0
-
56.9
-
27(3)
10.3
5 6
3345
1964
3.762
0.688
83
42
5.6
10.0
1.3
86.7
78.5
8.0-10.9
5
1.0
_
53
61.2
-
55.2
—
25
9.6
9.7
1656
897
3.661
0.666
93
40
8.4
13.2
1.0
78.9
68.8
11.0-16.9
9
0.5
_
101
70.7
-
64.8
19(1)
22(4)
21.2
14.9
2409
1482
3.616
0.674
143
38
7.7
13.5
1.5
80.1
70.8
17.0-22.9
2
0.6
_
78
66.0
-
62.0
-
-
16.9
18.9
591
396
3.988
0.783
86
31
12.0
21.0
3.8
94.7
97.6
>23.0
3
0.6
_
248
66.7
-
78.0
65(2)
14
39.0
29.4
5312
2137
3.841
0.736
413
37
8.2
11.7
0.8
98.0
85.9
Corr.
Coef .
r(xy)**
-.72
.88
.66
-
.93
.52
-.06
.959
-
-.18
-.19
.43
.69
.35
-.79
.42
.20
.16
.79
.62
*If N deviates from values shown more than 10% then actual N is in parenthesis.
**5% level of significance >.666
1% level of significance >.798.
-------
00
Table 18
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Autoclaved Weight mg/1
Range of Values
N*
Secchi-M
Chlor £ mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. WgC. (x)
Filt. Wgt.
Cell Den. no. /ml
Biovol. tntnVm3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp
BI-A
BI-B
BI-C
BI-D
BI-E
0.01-0.1
47
1.3
6(6)
27
56.6
45.7(6)
41.5
49(13)
7(22)
0.08
0.16
2833
1787
3.709
0.687
111
42
6.1
10.8
1.5
80.3
73.9
0.2-1.9
54
1.5
15(2)
23
55.3
56.0(2)
42.5
19(11)
8(32)
1.1
0,5
5253
2304
3.598
0.643
231
46
7.4
12.0
1.5
76.5
69.5
2.0-4.9
63
1.1
-
46
58.9
-
51.7
50(12)
13(36)
3.2
1.1
3639
2957
3.766
0.679
196
45
7.3
12.7
1.2
75.3
66.7
5.0-7.9
32
0.9
-
68
61.8
-
55.9
41
18
6.3
3.1
7256
3112
3.888
0.697
288
46
8.9
15.9
1.8
88.1
82.0
8.0-10.9
24
0.8
2(1)
55
65.2
39.0(1)
55.5
20(7)
27(16)
9.5
2.5
3429
2370
3.630
0.658
122
42
8.2
15.6
1.2
81.3
75.4
11.0-16.9
19
0.7
-
71
66.7
-
60.4
32(5)
36(8)
13.3
4.4
3327
1377
3.819
0,711
191
40
10.3
16.7
1.5
90.1
88.5
17.0-22.9
5
0.4
_
100
72.2
-
62.4
65
35
19.1
7.4
4794
4735
3.625
0.655
227
46
9.5
18.3
1.3
88.0
69.3
>23.0
10
0.5
151
70.7
_
70.4
67(3)
314(5)
33.4
16.1
3244
1456
3.776
0.719
263
37
8.6
14.4
1.7
77.7
70.3
Corr.
Coef .
r(xy)**
~ w
-.84
-.49
.979
.88
-.74
.93
.59
.78
_
.982
-.20
-.05
.13
.46
.41
-.63
.56
.52
.24
.15
-.04
*If N deviates from values shown more than 10% then actual N is in parenthesis,
**5% level of significance >.666
1% level of significance >,798.
-------
ID
Table 19
Mean Values of Physical, Chemical and Biological Parameters
Derived from Lake Samples Used in the Algal Assay
Value Ranges of Growth in Samples Prepared by Filtration
Range of Values
N*
NH3-N tng/m3
N02N03-N mg/m3
Kjel-N mg/m3
Inorg N mg/m3
Org N mg/m3
Total N mg/in3
POz,-P mg/m3
Total Sol-P mg/m3
Sol Org P mg/m3
Part-P mg/m3
Total-P mg/m3
TN/TP
Inorg N/Sol P
Chlor a-Turner Uni
Prod-nig C/m3/hr.
0.01-0.1
115
63
145
288
209
225
433
7.5
15
7
18
33
19.4
20.3
ts 32
41(50)
0.2-1.9
72
74
136
344
210
270
479
15
23
8.0
21
44
17.4
15.8
37(60)
47(32)
2.0-4.9
40
94
161
572
254
478
732
20
32
12
42
72
15.2
11.4
46(27)
58(34)
mg/1
5.0-7.9
9
56
259
413
316
357
673
18
34
16
21
55
15.3
11.2
34(5)
47(5)
8.0-10.9
5
75
183
356
258
281
539
25
39
14
14
53
13.1
9.3
22(5)
31(2)
11.0-16.9
9
159
391
393
550
234
784
49
70
21
30
101
8.9
10.1
29
56(3)
17.0-22.9
2
160
408
275
568
115
683
32
48
15
30
78
9.5
13.1
14
-
>23.0
3
473
372
967
845
493
1338
150
195
78
53
248
7.1
7.4
68
199(1)
Corr.
Coef ,
r(xy)**
.89
.86
.62
.973
.14
.86
.88
.88
.84
.66
.88
-.94
-.68
.32
.87
*If N deviates from values shown more than 10% then actual N is in parenthesis.
**5% level of -significance >.666
1% level of significance >.798.
-------
co
o
Table 20
Mean Values of Physical, Chemical and Biological Parameters
Derived from Lake Samples Used in the Algal Assay
Value Ranges of Growth in Samples Prepared by Autoclaving
Range of Values
N*
NH3-N mg/m 3
N02N03-N mg/m3
Kjel-N mg/m3
Inorg N mg/m3
Org N mg/m3
Total Nmg/m3
PCty-P mg/m3
Total Sol-P mg/m3
Sol Org P mg/m3
Part-P mg/m3
Total-P mg/m3
TN/TP
Inorg N/Sol P
0.01-0.1
47
50.0
135.1
275.7
185
226
411
11
15
3.7
12
27
22.9
22.9
Chlor a- Turner Units 28
Prod mg C/m3/hr.
31(18)
0.2-1.9
54
58.9
82.6
275.2
141
216
358
6.2
10
4.0
13
23
19.7
17.2
33(48)
36(30)
2.0-4.9
63
71.8
129.8
402.7
202
330
532
14
22
9.4
24
46
16.7
13.6
35(48)
41(33)
mg/1
5.0-7.9
32
81.6
143.7
509.5
225
428
653
.18
29
12
39
68
16.3
12.8
54(23)
93(20)
8.0-10.9
24
80.7
249.7
311.7
330
231
561
12
27
16
29
55
13.6
12.7
32(20)
31(13)
11.0-16.9
19
105.3
293.7
371.6
399
266
665
25
40
15
34
71
11.1
22.9
341(16)
46(6)
17.0-22.9
5
98.0
425.0
512.0
532
414
937
48
63
16
37
100
13.6
15.5
58
77(3)
>23.0
10
317.0
386.5
643.0
704
326
1030
63
100
33
51
151
8.2
11.7
41.9(8)
98(4)
Corr.
Coef .
r(xy)**
.91
.88
.82
.987
.36
.94
.957
.987
.962
.87
.979
— . 88
-.38
.42
.70
*If N deviates from values shown more than 10% then actual N is in parenthesis,
**5% level oif significance >.666
1% level of significance >.798.
-------
treatment shows lack of correlation only with organic nitrogen, the ratio of
inorganic nitrogen to soluble phosphorus and to chlorophyll. All other
measurements are strongly correlated and some at very significant levels. It
would appear that these algal growth indicators, of either existing or poten-
tial nutrients, are effective in describing those values but do not serve well
as a trophic state indicator.
Cell Numbers and Volume
Basic to the use of an indicator of trophic quality or trophic state is
the relationship of any suggested measure to the actual numbers and volume of
cells present under the conditions of growth. The data pool of observations
on cell density and cell volume were organized in 13 subsets for cell density
and 12 subsets for cell volume. These range from as low as 5 cell units/ml
to over 50,000 and for biovolume from a low of 10 mm3/m3 to over 30,000 mm3/
m3 (Tables 21 and 22). It is clear that nearly all of the trophic state
indices are correlated although some at much higher levels of significance.
Cell density is highly correlated with chlorophyll a^ and total phosphorus
and of the three TSI's (Carlson) the relationship is best with TP-TSI. The
unusually good correlation with the pollution index argues again for the mean-
ing rulness of this particular index and its indication of trophic quality.
The correlations of biovolume parallel those of cell density. The exceptions
in both cases being poor or no correlation with aut. wgt. and filt. wgt. and in
the case of cell density with the biological indices. However, improves over
the range of values for biovalue the relationship to the biological indices
and BI-E.
Diversity Indices
The two classic diversity indices describing relationship of different
numbers of species to the total population, Shannon-Weaver and Evenness are
organized in the usual steo sequences through the observed range of values
and related to other indices of trophic quality (Tables 23, 24). It is of
interest to observe that whereas Shannon-Weaver is negatively correlated with
Secchi depth, higher diversity in less transparent waters and is positively
correlated with chlorophyll ji, Evenness has the same negative correlation
with Secchi depth but is not correlated with chlorophyll a. However, its
regression line shows a curvilinear relationship with a peak value in the
181
-------
Table 21
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Cell Density no./ml
Ranpe of Values
N*
Secchi-M
Clilor a rag/m3
TP mg/m3
SD-TS1
CII-TS1
•r* TP-TSl
00 ll laA
ro Color Pt Units
Turb. JTU
Aut . Wfit .
Flit. Wgt.
Cell Den. no. /ml
n to vol. nun3/in
Sii.in-Wcavcr
Pollution Index
DI-A
BI-D
Bl-C
DI-D
BI-E
5-299
42
0.6
3
87
69.9
40.3
60.0
50
34
5.0(21)
1.8(21)
156
1034
3.302
0.714
33
22
3.0
7.5
1.2
71.6
69.0
300-599
111
1.2
4(15)
44
61.2
41.5(15)
50.2
59(34)
19(53)
6.6(26)
2.1(26)
471
503
3.581
0.721
33
28
5.5
10.8
1.3
77.5
71.1
600-
999
135
1.3
6
•36
59,2
44.2
47.6
52
12
7.8(27)
4.1(27)
799
695
3.646
0.703
57
33
6.3
11.6
1.4
65.1
77.5
1000-
1999
190
1.4
5(31)
38
57.0
45.1(31)
46.3
59(38)
12(100)
5.7(63)
2.4(63)
1437
1056
3.663
0.674
59
40
7.0
11.9
1.4
61.0
70.2
2000-
2999
92
1.4
9(19)
35
56.4
49.7(19)
47.5
62(24)
9(52)
3.2(33)
1.3(33)
2439
1624
3.650
0.657
96
46
6.5
10.5
1.5
72.5
63.4
3000-
4999
9fi
1.2
14(22)
40
57.8
55.5(22)
59.1
29(29)
12(53)
3.0(33)
1.2(33)
3838
2278
3.764
0,655
105
51
fl.O
13.6
1.5
78.2
69.1
5000-
7999
53
1.0
20(20)
69
60.8
55.8(20)
54.2
17(27)
12(34)
6.1(20)
2.4(20)
6494
4105
3.653
0.626
196
55
9.7
16.2
1.4
86.6
77.2
8000-
10999
17
1.0
26(21)
49
6UO
61.3(21)
52.6
36(25)
12(29)
4.4(9)
0.6(9)
8999
5008
3.753
0.629
259
59
10.1
17.3
1.1
72.3
62.5
11000-
14999
30
1.0
26(15)
68
60.7
61.1(15)
56.7
23(17)
12(23)
7.5(9)
4.5(9)
12896
4725
3.795
0.639
291
60
10.7
17.6
1.5
73.5
64.3
15000-
19999
27
1.0
33
75
61.0
62.1
55.0
24
14
5.7(B)
1.8(8)
17480
5387
3.360
0.560
316
60
6.9
14.6
1.4
75.6
67.8
20000-
29999
14
0.9
26
63
61.9
60.9
57.1
14
13
5.2(2)
0.3(2)
24735
7803
3.143
0.537
341
54
11.6
19.0
1.6
76.4
66.7
30000-
49999
19
0.8
38(14)
107
64.7
63.9(14)
61.1
15(16)
14
4.2(4)
1.5(4)
38124
10616
3.201
0.540
632
59
11.0
17.5
1.4
76.0
63.4
>50000
H
0.6
02
280
69.3
70.7
74.4
17
23
7.2(1)
2.9(1)
71091
21973
3.311
0.541
1389
67
9.6
15.5
1.1
91.1
80.1
Corr.
Coef.
_r(xy).'
-.64
.963
.92
.59
.79
.88
-.64
.19
.14
.02
-
.991
-.56
-.78
.987
.66
.54
.50
-.30
.45
.26
*If N deviates from values shown by more than 102 then actual N is in parenthesis.
**5Z level of significance >.532
IX level of significance >.661.
-------
Table 22
Mean Values 01 Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Biovolume mraVm3
Range of Values
N*
Secchi-M
Clilor a ng/ra3
TP mg/n\3
SD-TSI
CII-TS1
TP-TSI
Color Tt Units
Turb. JTU
Aut. Wgt.
Flit. Wgt.
Call Den. no. /ml
Dlovol. iwn3/m3(x)
Shnii-Wcnvor
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
10-299
132
1.0
4(11)
67
64,6
42.0(11)
55.6
65(34)
26(60)
10.8(39)
4.4(39)
610
175
3.306
0.692
45
25
5.1
9.8
1.3
79.9
74.2
300-599
150
1.2
5(12)
42
59.7
42.8(12)
49.2
69(25)
14(66)
5.2(28)
3.5(28)
1289
454
3.584
0.689
55
35
6,8
11.9
1.5
84,0
75.6
600-
999
144
1.4
5
34
57.5
43.3
45.9
52
13
4.2(41)
1.2(41)
1793
781
3.546
0.653
56
40
6,9
11.7
1.4
82.7
74.5
1000-
1999
190
1.3
10(11)
35
56.8
50.7(44)
46.6
19(fil)
16(104)
3.7(68)
1.3(68)
3018
1417
3.712
0.665
115
45
7.4
12.9
1.4
79.6
70.3
2000-
2999
67
1.3
16(28)
37
57.9
55.3(28)
47.7
43(30)
20(46)
3.8(23)
1.3(23)
6161
2432
3.85}
0.66S
135
54
7.6
13.2
1.3
74.6
61.2
3000-
4999
78
1.3
23(41)
53
57.9
58.1(41)
51.4
29(43)
11(60)
5.2(25)
1,1(25)
9352
3871
3.894
0.664
181
57
8.5
14,3
1.3
67.8
56.9
5000-
7999
46
0.9
27(24)
68
62.8
62.2(24)
56.7
38(25)
12(36)
6.8(17)
4.2(17)
15241
6049
3.772
0.640
309
58
8.8
15.3
1.4
75.3
64.5
8000-
10999
20
0.8
47(12)
99
63.3
65.2(12)
61.6
28(14)
16(14)
3.6(5)
2.0(5)
23104
9233
3.578
0.611
522
57
11.4
18.2
1.5
86.7
79.8
11000-
14999
12
0.7
29(4)
106
65.2
62.0(4)
62.7
18(4)
18(7)
6.4(6)
1.5(6)
23837
13019
3.547
0.604
991
59
13.2
21.4
1.4
60.1
52.8
15000-
19999
6
0.9
36(3)
85
62.3
63.7(3)
59.8
23(3)
13(4)
4.2(2)
1.5(2)
27758
17280
3.124
0.651
442
47
7.8
12.3
1.0
63.9
61.0
20000-
29999
'7
0.7
69(5)
460
67.3
69.8(5)
68.3
15(5)
20
5.9(2)
1.0(2)
39274
23779
3.584
0.605
1333
62
11.2
16.9
1.3
95.5
88.7
>30000
2
0.8
204(1)
186
64.0
82.0(1)
71.0
15
18
-
-
33809
55744
3.102
0.528
2128
56
6.6
11.6
0.5
50.0
49.8
Corr.
Cocf.
r(xy)**
-.58
.978
.975
.46
.85
.82
-.56
.23
-.19
-.20
.81
-
-.64
-.87
.963
.38
-.001
-.02
-.91
-.80
-.63
*If N deviates from values shown by more than 10X then actual N is in parenthesis,
**5£ level of significance >.553
1% level of significance >.684.
-------
00
Table 23
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Shannon-Weaver Diversity Index
Range of Values
N*
Secchi-M
Chlor ji mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. nunVm3
Shan-Weaver (x)
Evenness
Pollution Index
Taxa , no . sp .
BI-A
BI-B
BI-C
Bl-D
BI-E
.50-1.999
37
1.4
11(14)
31.4
58.1
52.5(14)
46.2
54(25)
6(29)
3.2(8)
1.3(8)
9910
2889
1.521
0.341
92
27
5.5
9.6
1.0
54.7
50.5
2.0-2.999
130
1.4
12(43)
45.1
57.3
50.7(43)
48.6
49(49)
10(84)
4.5(32)
2.7(32)
7245
2529
2.611
0.527
187
33
6.0
10.5
1.2
72.2
65.3
3.0-3.999
393
1.2
14(47)
43.9
59.1
51.1(47)
48.6
55(78)
12(176)
'5.1(120)
1.7(120)
3425
1729
3.541
0.672
95
38
6.5
11.5
1.5
81.6
73.9
4.0-4.999
265
1.0
26(88)
64.0
61.8
56.0(88)
54.3
25(107)
19(161)
6.6(91)
2.6(91)
4999
2723
4.391
0.762
177
53
9.0
15.6
1.4
82.8
72.0
>3.0
27
1.1
22(20)
40.0
58.0
60.0(20)
51.2
12(19)
13(24)
3.8(5)
1.4(5)
7786
3724
5.120
0.809
235
78
9.2
15.2
1.3
78.6
57.7
Corr.
Coef .
r(xy)**
-.89
.86
.52
.41
.77
.82
-.85
.80
.45
.08
-.47
.35
-
.987
.69
.92
.94
.92
.71
.84
.41
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.811
1% level of significance >.917.
-------
oo
Table 24
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Evenness Diversity Index
Range of Values
N*
Secchi-M
Chlor ji mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den, no, /ml
Biovol. mm3/m3
Shan-Weaver
Evenness (x)
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
.013-. 399
39
1.3
11(15)
38
58.4
52.2(15)
49.2
30(22)
8(26)
4.3(6)
1.7(6)
12030
3090
1.545
0.299
104
33
6.9
12.0
1.1
66.0
57.5
.400-. 499
50
1.3
17(19)
43
58.3
55.4(19)
48.3
49(25)
9(36)
2.5(13)
1.7(13)
13081
4378
2.408-
0.454
137
39
6.6
11.5
1.2
70.4
66.2
.500-. 599
125
1.3
17(30)
42
57.0
53.7(30)
47.8
41(35)
9(69)
4.3(42)
2.0(42)
7061
2879
3.011
0.558
134
41
6.2
10.6
1.4
70.6
64.7
.600-. 699
226
1.3
19(35)
45
58.5
51.0(35)
48.1
50(52)
12(101)
5.6(68)
1.8(68)
3608
2108
3.557
0.657
119
41
7.1
11.9
1.5
81.5
73.1
.700-. 799
333
1.1
25(82)
56
60.6
56.6(82)
52.0
37(109)
15(193)
5.8(100)
2.5(100)
3670
1944
4.108
0.750
135
45
8.0
13.9
1.4
83.5
73.0
.800-. 899
78
0.9
12(30)
54
63.3
51.3(30)
54.2
27(35)
25(49)
7.3(26)
2.7(26)
2073
1450
4.466
0.825
93
44
7.0
13.2
1.4
79.3
68.2
>.900
3
0.4
3
168
78.3
35.5(2)
72.3
32(2)
57(2)
6.6(1)
1.8(1)
933
853
4.157
0.927
80
29
5.3
11.2
0.6
67.4
78.0
Corr.
Coef .
r(xy)**
-.80
-.22
.68
.72
-.56
.72
-.27
.77
.82
.53
-.94
-.86
.93
—
-.46
.08
-.19
.27
-.22
.42
.88
*If N deviates from values shown by more than 10% then actual N is in parenthesis,
**5% level of significance >.707
1% level of significance >.834.
-------
.70-.74 range. Shannon-Weaver is well correlated with Evenness but Shannon-
Weaver is poorly correlated with cell number and cell volume in contrast to
the good negative correlations of Evenness. Shannon-Weaver has good correla-
tion with taxa and the biological indices A, B and D whereas Evenness is
poorly correlated with these except for E.
Pollution Index
Due to the wide range of values for the Pollution Index, from less than
1 to over 3,000, 14 subsets of values were examj led for the relationship of
this index and the other trophic state indices viable 25). The highlights are
the unusually high correlations with chlorophyll £, total phosphorus, very
significant correlations with chlorophyll-TSI and total phosphorus-TSI. Very
strong correlations with cell density and biovolume are evident and somewhat
poorer correlations but significant with the biological indices C, D and E.
The relationship of these subsets of values for the Pollution Index to
other nutrient ranges and other measures of trophic level are presented in
Table 26. Strong significant correlations >0.9, when 170 level of significance
is >.641, are noted for Kjel-N, all the phosphorus fractions, conductivity,
chlorophyll ^-Turner and productivity. A good negative correlation is shown
for the rates of inorganic nitrogen/soluble phosphorus and a marginal correla-
tion but significant at the 5% level for N02+N03-N. "Tie degree response of
the characteristic population used to determine the Pollution Index appears
to represent a sensitive indicator of changing quality related to nutrient
levels.
Taxa
Using as a trophic state indicator the changing number of individual
species found in a particular water sample, this variable was examined in
relationship to the other trophic state indices (Table 28). The correlations
were very good with Secchi depth, chlorophyll £, total phosphorus, the direct
determinations of cell quantity, density and volume, as well as with the
Shannon-Weaver, Evenness indices and the Pollution Index. Except for BI-B it
was only marginally if at all correlated with the other biological indices.
186
-------
Table 25
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
PI (Pollution Index)
Range of Values
N*
Sccchl-H
Chlor £ ng/m'
TP mg/m*
SD-TSl
0-0.9
62
1.6
6(23)
30
57.2
CII-TSI 45.2(23)
TE'-TSI
Color Pt Unlta
Turb. JTU
Aut. Wgt .
rue. v.'gt.
Cell Den. no. /ml
Rlnvol. mn3/m3
Shan-Weaver
Evenness
Pollution Index(x)
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D
BI-E
44.5
69(36)
7(47)
1.1(13)
0.6(13)
1720
1200
2.660
0.609
0
20
2.9
5.4
1.0
53.6
48.7
1-9
69
1.6
4(17)
33
55.6
43.5(17)
45.6
44(27)
10(47)
6.0(16)
1.8(16)
1501
1037
3.305
0.663
6
32
4.5
6.0
1.1
71.0
62.2
10-19
78
1.5
5(18)
38
57.1
42.7(18)
46.7
33(21)
15(39)
4.6(15)
2.7(15)
1816
999
3.438
0.654
15
35
5.1
9.5
1.3
79.7
70.9
20-39
129
1.1
7(24)
48
60.7
48.5(24)
49.9
33(36)
17(64)
6.2(38)
2.3(38)
1865
1076
3.649
0.679
29
39
6.5
11.9
1.5
80.0
71.4
40-59
118
1.1
10(15)
48
60.5
49.7(15)
50.5
26(20)
21(56)
6.3(45)
1.8(45)
2233
1307
3.753
0.686
49
43
6.6
11,7
1.4
80.2
72.1
60-79
6B
1.1
11(13)
41
eo.o
53.1(13)
50.1
17(19)
13(27)
4.7(21)
2,5(21)
3027
1308
3.744
0.672
69
45
8.3
14.7
1.4
80.5
71.8
80-99
42
1.1
15(10)
39
59.4
55.6(10)
49.7
13(11)
14(19)
5.1(9)
3.3(9)
3734
1739
3.760
0.669
88
48
9.0
15.8
1.6
83.3
74.5
100-149
B7
1.1
19(16)
38
56.0
58.3(16)
49.2
39(24)
11(42)
3.1(29)
1.2(29)
37671 f
2152
3.701
0.686
121
43
8.7
14. S
1.6
84.6
75.6
150-199
63
1.1.
21(21)
53
59.3
59.4(21)
53.2
57(25)
11(39)
8.3(20)
4,1(20)
8477
3441
3.793
0.659
174
54
9.0
15.2
1.5
81.7
68.0
200-299
45
0.9
23(19)
46
61.4
59.2(19)
51.4
15(21)
16(30)
4.7(14)
1.2(4)
11108
3744
3.833
0.664
245
54
9.5
15.9
1.2
85.1
76.4
300-499
42
1.0
36(15)
8G
61.7
64.0(15)
56.8
46(18)
12(29)
"3.7(19)
1.1(19)
11390
5486
3.939
0.665
361
60
11.3
18. 3
1.9
80.4
70.2
500-999
24
0.8
50(14)
116
65.5
67.1(14)
63.3
27(14)
16(20)
11.2(8)
2.7(8)
19266
7396
3.879
0.673
706
54
12.1
18.9
1.4
90.7
60.3
1000-
2999
12
O.B
61(6)
134
65.0
70.0(6)
67. 3
96(6)
16
10.2(6)
7.1(6)
38124
10538
3.447
0.577
1432
60
•7.8
11.7
1.1
92.7
85.2
Corr.
>3000 Cocf.
5 r(xy)**
0.7
166(2)
351
66.6
81.0(2) •
75.2
15(2) -•
15
3.8(3) -
1.8(3) •
38331*** .
25307
3.753
0.629 -.
4180
60
10.1
15.9
2.3
9B.3
97.6
59
989
991
73
80
88
07
17
05
15
B6(.993)
991
14
45
-
52
36
26
64
61
77
*If N deviates from values shown by more than 102 then actual N !• In parentheali,
**5Z level of significance >.514.
1% level of significance >.641.
***Value not used in calculating r In ( ).
-------
Table 26
oo
Mean Values of Physical, Chemical and Biological Parameters
of Lake Samples Collected for Trophic Analysis
Within Value Range of Trophic Index
Pollution Index
Range of Values
N*
Temp. °C
Secchi-Ft.
Secchi-M
NH3-N mg/m3
N02N03-N mg/m3
Kjel-N mg/m3
Inor"g-N mg/m3
Org-N mg/m3
Total N mg/m3
P04-P mg/m3
Total Sol P mg/m3
Sol Org P mg/m3
Part-P
Total P mg/m3
TN/TP
Inorg N/Sol P mg/m3
Alkalinity mg/1
Cond ijmhos/cm3
Cell Density
Bio volume mm3/m3
Ln Cell Density
Ln Biovol
Chlor &_ Turner Units
Prod mg C/m3/hr
Pollution Index (x)
0-0.9
62
19.2
5.2
1.6
44
100
257
144
213
357
6.6
11.8
5.1
18.4
30.2
18.2
13.7
1-9
69
18.7
5.2
1.6
50
127
250
177
200
376
10.9
18.1
7.1
14.8
32.9
17.9
14.8
9.0(47)16.6(45)
57(46)
1720
1280
6.6820
6.2704
20
11.5
0
86(46)
1501
1037
6.7977
6.4873
21
22.8
6
10-19
78
19.5
4.9
1.5
69
148
262
217
193
410
13.4
21.5
8.6
17.3
38.3
18.6
14.5
17.8(39)
68(39)
1816
999
6.8479
6.4060
21
17.3
15
20-39
129
17.9
3.8
1.1
76
194
280
271
203
474
17.1
27.3
10.3
21.7
48.4
16.0
15.4
19.4(58)
77(61)
1865
1076
6.9849
6.3816
25
22.0
29
40-59
118
19.5
3.7
1.1
70
179
302
249
232
481
13.6
20.5
7.2
28.4
49.2
15.9
16.2
22.3(51)
87.4(55)
2233
1307
7.2648
6.6793
26
26.1
49
60-79
68
19.2
3.5
1.1
77
178
273
255
195
451
15.1
22.7
7.8
18.9
40.6
16.8
20,4
20.7(21)
99.7(26)
3027
1308
7.4462
6.7527
29
39.4
69
80-99
42
19.6
3.6
1.1
66
150
298
216
232
448
13.1
21.4
8.3
18.3
38.9
15.5
15.5
25.7(19)
18.8(22)
3734
1739
7.7511
6.9853
28
43.4
88
100-149
97
19.0
3.7
1.1
69
159
271
228
203
429
12.1
19.3
7.3
19.5
38.2
15.7
17.3
20.7(35)
113.4(44)
3767
2152
7.6281
7.0719
32
44.9
121
150-199
63
21.0
3.7
1.1
67
147
359
214
292
506
16.2
28.3
11.8
25.8
52.7
15.6
12.7
21.8(31)
95.4(41)
8478
3441
8.5289
7.6877
46
55.1
174
200-299
45
20.7
3.1
1.0
63
95
352
158
289
446
12.6
18.2
5.6
28.0
46.3
14.9
13.4
22.2(28)
113.9(29)
11108
3744
8.6812
7.7247
51
79.8
245
300-499 500-999
42 24
21.5 16.8
3.2 2.6
1.0 0.8
84 172
101 125
528 565
185 297
443 393
631 690
29.0 39.0
42.7 64.4
13.7 25.3
43.3 52.0
85.9 116.4
14.7 9.1
12.6 11.5
24.2(24) 22.9(15)
168.1(20) 241.0
11390 19266
5486 7396
8.8152 9.5436
8.2724 8.6078
70 84
97.5(28) 118.3
381 706
1000-
2999 >3000
12 5
25.4 20.2
2.8 2.3
0.8 0.7
100 102
50 80
762 940
150 182
662 838
812 1020
34.0 77.0
56.4 182.0
15.7 105.0
77.4 168.6
133.8 350.6
9.1 11.0
3.6 2.9
24.9 27.0
241.0 347.2
38124 38331
10538 25707
9.2060 9.9092
8.7921 9.4572
105 181
145.1 263
1432 4180
Corr.
Coef .
r(xy)
.27
-.61
-.61
.40
-.56
.90
-.23
.92
.91
.952
.980
.965
.992
.991
-.63
-.82
.51
.93
.86
.991
.70
.78
.95
.94
-
*lf N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.514
1% level of significance >.641.
-------
oo
10
Table 27
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Taxa (species)
Range of Values
N*
Secchi-M
Chlor a_ mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU 3.
Aut. Wgt. 1.
Filt. Wgt.
Cell Den- no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.(x)
BI-A
BI-B
BI-C
BI-D
BI-E
1-19
60
1.2
7
55
61.9
46.1
51.0
83
6(15)
6(15)
1.6
972
495
2.460
0.611
15
14
2.4
5.0
1.0
57.3
53.3
20-29
159
1.4
6(28)
39
58 .7
45.4(28)
47.8
42(34)
5.9(31)
2.9(31)
3.1(23)
1238
1227
3.230
0.669
89
25
5.3
9.7
1.2
77.7
70.2
30-39
192
1.3
10(26)
47
58.9
47.5(26)
48.3
89(44)
7.7(59)
3.4(59)
3.2(44)
2058
1279
3.509
0.666
91
34
6.5
11.6
1.5
85.1
79.3
40-49
162
1.2
15(31)
39
58.9
53.0(31)
48.6
24(48)
4.3(65)
1.6(65)
1.3(43)
6242
2000
3.640
0.651
112
44
8.1
14.1
1.5
80.7
70.7
50-59
135
1.0
20(33)
55
60.2
54.5(33)
53.3
19(38)
5.3(50)
.1.8(50)
1.9(37)
6428
3038
3.896
0.664
181
54
8.5
14.6
1.4
79.4
69.0
60-69
83
1.1
24(35)
63
60.2
58.5(35)
54.2
13(38)
4.2(21)
1.5(21)
1.8(18)
9248
3585
4.190
0.690
285
64
9.8
16.1
1.5
76.5
62.9
70-79
40
1.0
31(26)
73
61.1
61.5(26)
55.5
16(28)
5.9(10)
1.1(10)
1.2(8)
12740
6055
4.467
0.711
314
74
11.7
19.4
1.4
82.6
72.6
80-98
23
09
42(18)
89
61.8
64.2(18)
54.5
14(19)
2,2(5)
0.8(5)
1.0(4)
17445
8452
4.901
0.759
552
86
8.6
14.4
1.2
85.4
66.9
Corr.
Coef .
r(xy)**
-.84
.97
..81
.37
.981
.79
-.78
.41
-.34
-.66
.969
.94
.982
.90
.94
-
.54
.85
.35
.63
.21
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.666
1% level of significance >.798.
-------
Biological Indices, Phytoplankton Quotients
Each of these indices subdivided into 9 or 10 subsets of values describe
changes in population composition based on the relative numbers of specific
classes of planktonic algae. The quotient of percentage appear to be biased
to trophic levels, ultra oligotrophic, which are seldom observed in the waters
of this region. They would also appear to lack sensitivity to changes in
nutrient level even though they show good step relationships, in some instances
over the entire scale of changing quality as indicated by the other indices
(Tables 28-32). To summarize the key relationships, Table 33 has been pre-
pared which examines the magnitude of correlation determined for each of these
five, with each other and with chlorophyll a_, total phosphorus, cell density,
biovolume and the Pollution index.
It would appear that the biological indices BI-A and BI-B are well related
to chlorophyll £, total phosphorus, cell density, biovolume and the Pollution
Index and to each other. The latter might be expected since their basic rela-
tionships are quite similar, in both instances the number of Desmidiaceae
being the denominator. The BI-C quotient, one based on differences in morphol-
ogy of two general classes appears to have little or no correlations with
chlorophyll a, total phosphorus, cell density and biovolume but a reasonably
good one with the Pollution index. Both good and excellent BI-D, based on
cell density and BI-E, based on cell volume, show good and excellent correla-
tion with chlorophyll a.. Only BI-E (volume) has a good correlation with total
phosphorus and both have negative correlations to cell density and biovolume
but not significant. Both correlate positively to the Pollution Index but BI-E
has the strongest correlation. The cross correlations of the indices with each
other confirm the similarity of BI-A and BI-B by their very high correlation
and their somewhat lesser degree of correlation with C, D and E. D and E show
reasonably good cross correlation with the other indices whereas C has the
lowest correlations with A, B and D and somewhat stronger with E.
The consistent pattern of strong correlations by trophic index BI-B shown
in Table 33 suggested examination of its relationships to other nutrients and
trophic measures (Table 34). Several features are unique and different from
the correlation patterns noted previously. All the nitrogen parameters are
positively correlated and significant in most instances at the 1% level. All
phosphorus relationships are positively correlated and at even higher levels
than the nitrogen components. One exception to previous analysis of this type
is the non-correlation with conductivity.
190
-------
Table 28
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
BL— A IOXO.LOKI ca± xnoex • „ •; rr Ti, 1
B Species - Desmidiaceae '
Range of Values
N*
Secchi-M
Chlor a mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A (x)
BI-B
BI-C
BI-D
BI-E
0.0-0.9
14
0.9
13(6)
65
63.2
53.8(6)
50.7
84
22
1.4(4)
0.1(4)
771
1820
2.348
0.612
12
14
0.3
1.1
0.2
13.7
13.5
1.0-1.9
41
1.4
3(12)
47
59.2
40.5(12)
49.2
61(17)
16(30)
8.8(9)
3.2(9)
1736
1229
3.157
0.650
36
27
1.4
3.4
1.1
57.3
48.7
2.0-2.9
87
1.6
7(18)
25
55.3
45.1(18)
43.3
44(24)
7(50)
4.1(21)
1.3(21)
2064
1876
3.355
0.648
34
34
2.4
4.6
1.2
67.5
60.1
3.0-3.9
99
1.3
6(16)
45
58.3
46.4(16)
47.8
67(20)
11(49)
5.7(41)
2.6(41)
3646
1769
3.462
0.655
74
37
3.3
5.9
1.3
73.9
65.8
4.0-5.9
182
1.2
13(34)
42
59.4
52.6(34)
48.8
42(44)
13(99)
3.0(49)
1.6(49)
3972
1466
3.605
0.668
98
42
4.8
8.7
1.4
81.1
70.7
6.0-7.9
131
1.1
19(42)
43
50.0
55.6(42)
50.4
30(43)
15(75)
5.8(29)
2.1(29)
6718
2745
3.712
0.674
156
44
6.7
11.8
1.3
82.8
71.8
8.0-9.9
93
1.2
14(25)
49
59.5
51.2(25)
51.7
28(27)
13(50)
4.4(29)
1.8(29)
4640
2398
3.715
0.666
131
46
8.6
15.2
1.5
88.0
80.4
10.0-
14.9
122
1.0
35(32)
70
61.5
61.5(32)
54.7
26(49)
20(59)
8.3(44)
3.1(44)
6753
3227
3.864
0.681
179
49
11.6
20.1
1.5
87.3
80.0
15.0-
19.9
56
1.0
34(19)
59
61.4
62.1(19)
52.7
34(28)
14(33)
6.1(19)
1.9(19)
8653
2826
3.820
0.666
205
52
16.7
27.4
1.7
86.2
77.8
>20
29
0.9
43(9)
114
63.6
64.1(9)
62.2
24(14)
14(17)
6.6(11)
2.4(11)
8360
4244
4.121
0.708
357
55
23.8
37.5
1.8
87.7
77.5
Corr.
Coef.
r(xy)**
-.57
.92
.78
.55
.82
.85
-.72
.01
.37
.30
.90
.91
.77
.82
.975
.83
—
.999
.74
.61
.63
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.602
1% level of significance >.735.
-------
Table 29
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
Range of Values
N*
Secchi-M
Chlor a mg/tn3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Ft Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
7T? Biovol. nan3/tn3
l\) Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B (x)
BI-C
BI-D
BI-E
0.0-0.9
10
0.8
18(3)
23
63.2
59.0(3)
45.2
107
4
1.4(4)
0.1(4)
862
937
2.213
0.602
0
12
0.3
0.3
0.1
0.4
0.2
BI-B (Bl<
1.0-2.5
18
1.8
6(9)
29
54.8
43.3(9)
45.4
63(10)
8(15)'
5.4(3)
2.1(3)
2851
2665
2.725
0.570
47
26
1.2
1.8
0.5
27.1
13.5
nogicai inae
2.6-3.9
42
2.0
4(10)
32
52.0
41.6(10)
42.4
84(16)
11(32)
2.2(9)
1.2(9)
1872
2259
3.103
0.623
31
30
2.1
3.2
0.9
53.3
44.1
IX, — •
4.0-5.9
114
1.5
10(17)
38
56.3
46.4(17)
45.0
71(23)
9(63)
6.4(34)
2.4(34)
3082
1772
3.400
0.649
102
37
2.9
4.8
1.4
77.0
70.1
Desmidlaceae '
6.0-7.9
113
1.2
7(24)
41
59.2
48.2(24)
49.1
46(31)
12(62)
4.4(42)
2.0(42)
4045
1507
3.56]
0.664
135
40
3.9
6.7
1.2
75.5
67.2
8.0-9.9
99
1.3
19(26)
47
58.3
54.2(26)
48.6
25(27)
14(62)
3.0(26)
1.0(26)
5648
2047
3.680
0.673
183
44
5.0
8.7
1.4
80.7
66.4
10.0-
14.9
190
1.1
16(48)
41
60.1
54.2(48)
50.3
20(54)
12(94)
4.9(47)
2.7(47)
4903
2250
3.691
0.676
135
43
6.7
12.0
1.4
84.4
75.8
15.0-
19.9
116
0.9
32(31)
75
63.0
58.7(31)
56.6
31(39)
25(56)
8.5(40)
3.2(40)
6236
2920
3.827
0.683
193
47
9.6
17.2
1.5
87.8
79.8
20.0-
29.9
111
1.0
24(31)
61
61.9
59.1(31)
52.6
31(49)
17(59)
5.8(36)
1.4(36)
5662
2419
3.879
0.687
144
49
13.8
23.8
1.7
87.8
80.7
>30.0
41
0.9
39(14)
83
63.2
62.8(14)
59.7
21(21)
15(23)
6.5(15)
2.3(15)
10201
4312
3.852
0.662
313
54
21.7
36.7
1.7
86.1
77.1
Corr.
Coef.
r(xy)**
-.53
.85
.93
.59
.71
.85
-.70
.62
.56
.36
.93
.81
.71
.60
.88
.81
.999
-
.74
.63
.65
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.602
12 level of significance >.755.
-------
Table 30
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
BI-C (Biological Index, |PJL^es " Centrales
^ ° ' SnerlpH - Ppnnalos '
Range of Values
N*
Secchi-M
Chlor a. mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C (x)
BI-D
BI-E
0.0-0.2
50
1.0
11(19)
38
62.1
50.3(19)
50.1
76(32)
6(35)
8.1(17)
2.2(17)
2949
3099
2.688
0.575
47
25
3.6
5.7
0.0
2.7
2.5
0.3-0.5
57
1.6
9(21)
57
57.6
44.3(21)
49.0
32(26)
17(48)
2.5(13)
1.5(13)
4438
1849
3.395
0.670
111
34
5.2
8.5
0.4
54.1
39.0
0.6-0.8
105
1.2
11(23)
48
59.9
50.2(23)
50.0
22(41)
18(70)
7.7(37)
3.5(37)
4711
1782
3.637
0.664
112
44
7.4
12.5
0.7
75.7
63.1
0.9-1.1
184
1.3
27(53)
53
58.7
55.8(53)
49.5
37(67)
13(116)
4.8(57)
2.0(57)
5604
2742
3.736
0.6797
157
45
7.0
11.8
1.0
80.6
69.1
1.2-1.4
138
1.0
21(35)
40
60.5
57.3(35)
49.6
21(41)
15(56)
4.9(39)
1.3(39)
6643
2572
3.728
0.667
149 •>
46
7.7
13.6
1.3
89.0
80.6
1.5-1.7
109
1.1
21. (25)
49
59.4
57.6(25)
51.7(108)
18(30)
15(50)
5.9(35)
2.3(35)
2276
3.670
0.666
158
45
7.9
14.2
1.6
90.0
81.3
1.8-2.1
110
1.2
19.9(20)
57
59.1
55.1(20)
51.1
72(25)
12(57)
3.7(19)
1.5(19)
3713
1532
3.639
0.672
166
41
7.2
12.9
1.9
90.3
84.4
2.2-2.9
45
1.0
11.5(8)
52
61.7
53.4(8)
53.0
19(8)
15(13)
4.1(8)
0.6(8)
3095
2187
3.927
0.703
121
47
10.7
19.3
2.5
94.5
89.5
>3.0
29
1.0
18(4)
53
61.4
55.2(4)
51.7
58(5)
11(11)
6.9(13)
3.5(13)
4817
2117
3.597
0.662
260
41
8.2
14.7
5.0
95.4
95.8
Corr.
Coef .
r(xy) **
-.43
.23
.34
.35
.45
.56
.04
-.09
.02
.26
.12
-.26
.44
.37
.87
.39
.66
.64
-
.63
.73
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.632
1% level of significance >.765.
-------
Table 31
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
. _ . Centrales _ . „ . . . _ .
Range of Values
N*
Secchi-M
Chlor £ mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3
Shan-Weaver
Evenness
Pollution Index
Taxa, no. sp.
BI-A
BI-B
BI-C
BI-D (x)
BI-E
0.0-0.9
48
1.1
10(20)
38
61.5
49.4(20)
49.9
75(33)
6(35)
8.4(16)
2.4(16)
2786
3294
2.594
0.562
46
23
3.3
5.2
0.0
0.0
0.0
BI-D (I
1.0-9.9
12
1.9
7(7)
21
56.1
46.4(7)
41.5
34(7)
7(8)
3.6(4)
2.8(4)
4482
2401
3.251
0.67.0
49
39
5.6
11.4
0.5
5.2
5.0
lloiogicai uiaex, Centrale8 + Araphidineae * « i. -r A Dy «>n Density
10.0-29.9
28
1.5
11(15)
40
55.5
52.5(15)
47.2
18(18)
8
3.0(5)
0.1(5)
9759
3075
3.249
0.571
93
50
5.6
9.5
0.9
18.9
11.9
30.0-49.9
35
1.6
13(10)
22
54.1
54.2(10)
42.0
19(8)
7(22)
2.6(13)
1.3(13)
6293
3250
3.868
0.682
124
50
5.2
8.3
1.0
40.6
17.1
50.0-59.9
45
1.3
13(17)
35
58.8
53.0(17)
47.3
26(20)
13(29)
1.6(9)
0.7(9)
5274
1801
3.759
0.685
94
45
6.9
12.1
1.0
54.2
40.6
60.0-69.9
34
1.5
10(9)
22
54.8
48.0(9)
41.6
16(13)
8(23)
5.3(8)
3.1(8)
3957
1482
3.719
0.690
68
42
6.2
10.1
1.2
65.4
49.9
70.0-79.9
48
1.5
11(13)
29
55.7
50.5(13)
43.1
32(17)
12(28)
2.8(17)
1.3(17)
3709
1544
3.759
0.680
53
45
6.6
11.1
1.1
75.0
57.0
80.0-89.9
113
1.2
15(29)
41
59.4
52.3(29)
49.1
18(33)
19
3.4(31)
1.7(31)
4250
2209
4.019
0.722
120
47
7.7
13.4
1.3
85.6
73.1
90.0-99.9
403
1.0
29(81)
58
61.1
57.7(81)
52.9
41(110)
17(207)
6.6(122)
2.3(122)
5248
2289
3.655
0.671
190
43
7.9
14.1
1.5
96.3
88.6
>100.0
88
1.2
24(12) .74
77 .57
59.9
55.9(12)
54.4
72(21)
10(42)
6.0(31)
3.1(31)
4339
1983
3.372
0.637
173
39
8.3
13.7
2.4
100.0
100.0
Corr .
Coef .
rCxyl**
-.48
.74
.57
.24
.62
.44
-.02
.72
.01
.20
-.19
-.64
.65
.69
.70
.35
.90
.78
.87
-
.97
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5Z level of significance >.602
1% level of significance >.735,
-------
Table 32
Mean Values of Trophic State Indices
Derived from Lake Samples Collected for Trophic Analysis
Arranged Within Value Ranges of Given Index
o.-r, v^uxu^ax xnae*. Centrale8 + Araphldineae A ™ °J ueil Volume
Range of Values
N*
Secchi-M
Chlor a mg/m3
TP mg/m3
SD-TSI
CH-TSI
TP-TSI
Color Pt Units
Turb. JTU
Aut. Wgt.
Filt. Wgt.
Cell Den. no. /ml
Biovol. mm3/m3-
Shan-Weaver
Evenness
_, Pollution Index
VD Taxa, no. sp.
01 BI-A
BI-B
BI-C
BI-D
BI-E (x)
0.0-0.9
54
1.2
9(22)
38
61.8
49.1(22)
49.9
71(35)
6(37)
8.1(18)
2.7(18)
2936
3295
2.701
0.572
50
26
3.6
5.9
0.1
1.4
0.0
1.0-9.9
39
1.7
11(16)
30
54.1
51.6(16)
44.8
25(18)
5(30)
1.8(11)
1.3(11)
6848
2645
3.494
0.631
84
46.9
5.4
9.4
0.9
29.3
4.9
10.0-29.9
57
1.6
9(21)
28
54.8
49.1(21)
43.6
14(21)
10(41)
3.9(14)
1.6(14)
4770
2430
3.539
0.639
93
44.8
6.3
10.4
1.0
47.6
19.1
30.0-49.9
58
1.5
14(22)
35
55.8
53.2(22)
46.3
17(22)
10(44)
5.8(11)
2.1(11)
3960
1609
3.984
0.719
92
47.4
5.9
9.8
1.1
69.3
40.1
50.0-59.9
37
1.4
20(8)
41
57.5
55.3(8)
49.8
23(12)
11(25)
5.0(12)
4.3(12)
4403
1656
4.080
0.729
154
49.0
8.6
14.2
1.0
78.6
55.0
60.0-69.9
56
1.3
19(18)
44
58.6
56.2(18)
48.5
31(17)
13(33)
6.7(11)
0.9(11)
5141
2445
4.053
0.702
134
53.0
8.6
14.6
1.3
81.3
64.5
70.0-79.9 •
72
1.2
22(19)
51
59.3
.55.4(19)
51.3
14(25)
17(40)
3.3(20)
0.9(20)
5952
2512
3.821
0.691
104
46.5
7.1
12.4
1.3
87.8
76.0
80.0-89.9
122
1.1
25(29)
53
60.7
56.9(29)
52.3
36(46)
17(69)
5.0(45)
1.4(45)
6551
2414
3.665
0.662
200
45.1
7.6
13.4
1.4
90.9
85.3
9.0.0-99.9
268
1.0
27(46)
55
61.9
55.6(46)
51.8
51(64)
20(115)
6.1(79)
2.5(79)
4124
2133
3.600
0.673
178
39.5
7.9
14.2
1.6
95.8
92.2
>100.0
_._9_1._._.
1.2
24(12)
74
59.3
55.9(12)
53.2
71(20)
10(42)
5.8(35)
3.1(35)
4208
1986
3.404
0.643
162"
38.3
8.2
13.7
2.4
99.3
100.0
Corr.
Coef.
r(xy)**
-.70
.964
.87
.54
.90
.78
.18
.78
.13
.08
-.06
-.48
.40
.46
.85
.16
.81
.85
.91
.95
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.602
1% level of significance >.735.
-------
Table 33
Relationship of Biological Indices - Phytoplankton Quotients
and Associated Trophic Indices
Chlor a_
Total-Phosphorus
Cell Density
Biovolume
Pollution Index
BI-A
BI-B
BI-C
BI-D
BI-E
Correlation Coefficients(r)
5% level of significance >.632
1% level of significance >.765
BI-A
.92
.78
.90
.91
.975
-
.999
.74
.61
.63
BI-B
.85
.93
.93
.81
.88
.999
-
.74
.63
.65
BI-C
.23
.34
.12
-.26
.87
.66
.64
-
.63
.73
BI-D
.74
.57
-.19
-.64
.70
.90
.78
.87
-
.97
BI-E
.964
.87
-.06
-.48
.85
.81
.85
.91
.95
-
196
-------
Table 34
Mean Values of Physical, Chemical and Biological Parameters
of Lake Samples Collected for Trophic Analysis
Within Value Range of Trophic Index
Phytoplankton Quotient (BI-B)
Range of Values
N*
Temp.°C
Secchi-Ft.
Secchi-M
NH3-N mg/m3
N02N03-N mg/m3
Kjel-N mg/m3
Inorg N ing An
Org N mg/m3
Total N mg/m3
PO^-P mg/m3
Total Sol P mg/m3
Sol Org P mg/m3
Part P mg/m3
Total P mg/m3
TN/TP
Inorg N/Sol P
Alkalinity mg/1
Cond y mhos /cm
Cell Density
Biovolume mm /m
Ln Cell Den
Ln Biovol
Chlor a_ mg/m3
Prod mg C/m3/hr
BI-B (x)
0.0-0.9
10
18.8
2.6
0.8
42
37
327
79
286
364
5.7
11.0
5.3
11.5
22.5
16.4
7.9
0.2
52
862
937
6.2211
6.2197
28
15.6(5)
0.3
1.0-2.5
18
23.8
5.9
1.8
52
75
279
128
227
350
6.8
15.3
8.8
13.8
29.1
15.2
9.9
9.4
186
2851
2665
7.2080
7.0604
21(14)
16.5(11)
1.8
2.6-3.9
42
23.6
6.5
2.0
48
78
263
126
215
341
8.1
15.3
7.3
16.9
32.2
18.5
12.6
15.1(31)
71(30)
1872
2259
7.0761
6.8009
22(36)
14.8(19)
3.2
4.0-5.0
114
21.4
5.0
1.5
53
112
298
164
246
410
14.8
22.4
7.5
16.8
38.4
19.4
12.6
19.5(61)
83(61)
3082
1772
7.2820
6.7693
27(87)
26.8(44)
4.8
6.0-7.0
113
19.2
3.9
1.2
64
153
285
217
221
438
11.7
18.5
7.0
22.7
41.3
16.6
16.0
19.6(54)
89(64)
4045
1507
7.4359
6.6989
29(95)
31.2(48)
6.7
8.0-9.0
99
19.4
4.4
1.3
60
143
307
204
247
452
17.3
24.6
7.5
21.9
46.5
17.6
15.6
22.2(56)
106(59)
5648
2047
7.4654
6.7622
.33(75)
48.1(42)
8.7
10.0-
14.0
190
18.5
3.6
1.1
63
168
303
230
241
471
12.9
20.1
7.3
20.6
40.6
16.7
15.8
21.3(82)
92(92)
4903
2250
7.5052
6.8947
30(164)
48.3(79)
12.0
15.0-
19.0
116
17.2
3.0
0.9
103
190
364
293
260
554
20.2
36.2
15.3
39.8
75.1
12.2
18.2
20.7(44)
113(61)
6236
2920
7.7444
7.1062
43
73.4(51)
17.2
20.0-
29.0
111
18.2
3.1
1.0
97
165
332
262
235
497
20.5
34.6
14.3
29.4
61.1
14.9
15.2
21.9(54)
107(59)
5662
2419
7.8578
7.1922
40
68.1(46)
23.8
^30
41
21.7
2.8
0.8
89
168
435
257
347
604
24.8
37.5
12.8
45.8
83.3
10.6
11.9
20.7(22)
125(25)
10201
4312
8.6345
7.7809
70
113.3(22)
36.7
Corr.
Coef .
r(xy)
-.22
-.56
-.58
.83
.71
.86
.78
.65
.92
.90
.89
.77
.92
.92
-.78
.31
.56
.24
.93
.81
.90
.86
.94
.974
-
*If N deviates from values shown by more than 10% then actual N is in parenthesis.
**5% level of significance >.602
1% level of significance >.755.
-------
Correlations - Trophic Indices and Mean Values of Associated Indices
Extending the limited comparison of Table 33, Secchi depth, chlorophyll
_a, total phosphorus, cell density, biovolume, Pollution Index and conductivity
are compared in cross reference by their degree of correlation with the entire
list of indices or other parameters of trophic state such as productivity
(Table 35). It is clear from the patterns of both positive and negative
correlation and the levels of significance, several of these water quality
dimensions have consistent patterns of high correlation with either the
direct or indirect determinants of the trophic state. These have been
organized in Table 36. Their range of values 'encountered in this investigation
is also shown. These levels establishe the range of effectiveness for North
Carolina waters as trophic state indicators.
Although Secchi depth is not included in this examination of the cross
relationships of the several indices, its relationship can be noted in Table
35. Its level of correlation is generally somewhat lower although above the
level of 5% significance except in the case of total phosphorus. This low
correlation was due to the lack of sensitivity of Secchi depth (mean values)
to changes in higher phosphorus concentrations (see Table 9). Nevertheless
in the final determination as to what has a practical application for rapid
monitoring purposes as well as the effectiveness of the Secchi measurement,
particularly in waters of low sediment content, three measures of trophic state
were concluded as being best suited for North Carolina waters. These are shown
in Table 37; total phosphorus in the range of <10 to >150 mg/m , conductivity
from <19 to >200 ymhos per cm2 and Secchi depth in the range of 0.1 to more
than 3.0 meters. The range of quality values described in Table 37 defines
for total phosphorus a slight shift to a higher range than was first suggested
by Vollenweider (1968). However, this scale for North Carolina waters
recognizes the local geological and cultural context as well as local water uses.
Trophic Classification
Six levels of trophic state have been defineu for each of these indices
as well as the probable relationship to water quality for contact water sports
and fishing potential. Utilizing this scale of classification 69 bodies of
water in North Carolina lakes, reservoirs or subsegments of large reservoirs
have been classified (Table 38). Details of classification for each body of
water are reported in Weiss and Kuenzler (1976). The relationship
198
-------
Table 35
Correlation Coefficients (r) As Calculated Between
Rank Series of Trophic Indices and Mean Values
of Associated Indices Delermined on the Same Sample*
<£>
<£)
Secchi
Depth
_
-.85
-.72
-.92
-.91
-.81
-.74
-.69
-.80
-.78
-.93
-.81
-.98
(-.08)
-.91
-.82
-.96
-.95
-.75
-.84
-.92
-.87
Chlorophyll a.
-.72
-
.957
.975
.91
.989
(-.14)
.88
—
-
.965
.950
.74
(-35)
.99
.76
.90
.88
(.38)
.93
.91
.958
Tctal
Phosphorus
(-.53)
.962
-
.57
.86
.80
.37
.62
.962
.93
.99
.964-
(.38)
(.35)
.967
.72
.74
.62
(.04)
.78
.81
.94
Cell
Density
-.64
.963
.92
.59
.79
.88
-.64
(.19)
(.14)
(.02)
-
.991
-.56
-.78
.987
.66
.54
(-50)
(-.30)
(.45)
(.26)
.961
Biovolume
-.58
.978
.975
(.46)
.85
.82
-.56
(.23)
(-.19)
(-.20)
.81
-
-.64
-.87
.963
(.38)
(-.001)
(-.02)
-.91
-.80
-.63
.962
Poll.
Index
-.59
.989
.991
.73
.80
.88
(-.07)
(.17)
(.05)
(.15)
.993
.991
(.14)
(-.45)
-
.52
(.36)
(.26)
.64
.61
.77
.94
Conductivity
(-.63)
.981
.954
.72
.84
.90
(-.41)
(-.15)
.75
.90
.974
.987
.73
.72
.984
.75
(.61)
(.53)
(.37)
(.57)
(.54)
.94
Secchi-M
Chlorophyll a_ mg/m3
Total Phosphorus mg/m3
SD-TSI
CH-TSI
TP-TSI
Color PT Units
Turb JTU
Aut. Wgt
Filt. Wgt.
Cell Density no/ml
Biovolume mm3/m3
Shannon-Weaver Index
Evenness Index
Pollution Index
Taxa
BI-A
BI-B
BI-C
BI-D
BI-E
Productivity
( ) Below 5% level of significance.
* Comparison can be made along vertical series since (r) values are taken from the table of each given index.
-------
Table 36
The Correlation of Total Phosphorus, Conductivity and Pollution Index
As Trophic State Indices and
Mean Values of Algal Growth Measures
Correlation Coefficients (r)
ro
a
c
Independent Variable
Stepped Rank
Sets
Dependent Variables
Total Phosphorus
Conductivity
Pollution Index
Cell Density
Biovolume
Chlorophyll a±
Range
Total Conductiv- Pollution Cell Bio- Chlorophyll
Phosphorus ity Index .Density volume A Average
1-500 tng/m3
30-500 umhos/cm .964
0-4000 .991
150-70,000 units/ml .916
10-55,000 mm3/ra3 .975
0.8-200 mg/m3 .957
.982
.914
.993
.833
.996
.967
.978
.987
.963
.989
.991
.971
.993
.980
.965
.964
.989
.991
.991
.950
.962
.978
.989
.963
.978
.973
.976
.976
.970
.946
.971
-------
Table 37
Range of Trophic Classification
Suggested for North Carolina Lakes
ro
o
Total Phosphorus1
mg/in3
Conductivity1
umhos/ctn2
Secchi Depth1.2
Meters
<10
10-19
20-39
40-79
80-150
>150
<19
20-49
50-99
100-150
150-199
>200
>3.0
1.5-3.0
1.0-1.5
0.5-1.0
0.1-0.5
<0.1
Expected Quality of
Recreational Water Usage
Body Contact
Trophic State Water Sports
Oligotrophic Excellent
Oligo-Mesotrophic Excellent
Mesotrophic Good
a-Eutrophic Fair
g-Eutrophic Poor
Hypereutrophic Undesirable
Probable
Fishing Potential
Poor
Low
Fair
Good
Excellent
Excellent3
of these scales has been prepared independent of the others. They may be generally compared at each
level but should not be directly equated.
2Simple to use but measurements made in waters with heavy sediment loads must be interpreted with care.
3Fish kills may occur because of low oxygen levels at night or following prolonged periods of cloud cover.
This transition in fishing potential generally includes a species shift from those types considered game
(oligotrophic waters) to coarse (eutrophic waters).
-------
Table 38
Surface Waters of North Carolina and
Immediate Adjacent Areas Sampled for
Trophic State Analysis
1971-1975
Type and Name
Natural Lakes
Black
Jones
Mattamuskeet
Phelps
Salters
Singletary
Waccamaw
White
Impoundments
Cooling Water
Belews
Hyco
Water Supply
University
Michie
High Point
Wheeler
Brandt
Burlington
Lexington-Thomasville
Townsend
Lake
Codes
Trophic State - Summer Conditions
Oligo-
mes o-
Com- Oligo- meso- Meso-
Map puter trophic trophic trophic
1
2
3
4
5
6
7
8
9
10
11
12
46
47
48
49
50
51
BL
JO
MA
PH
SA
SL
WA
WH
BC
HY
UN
MC
HP
WE
LT
TO
— X
Eutro-
phic
a S
X
X
Hyper-
eutrophic
— X
X
X
— X
— X
-- X
. .. Y
X
X
— x
Hydroelectric and Flood Control
Roanoke River
John H. Kerr
Roanoke Arm
Above 58-15 bridge
Dam to Buoy 14
Nutbush Arm
Above 1308 bridge
28 KR
——— X
Buoy N to 1308 bridge
Buoy C to Buoy K
X
Gaston
Roanoke Rapids
29
30
GA
RR
X
X
202
-------
Table 38 (cont'd)
Lake
Codes
Trophic State - Summer Conditions
Type and Name
Yadkin River
W. Kerr Scott
High Rock
Tuckerton
Badin
Tillery
Blewett Falls
Catawba Riv r
James
Rhodhiss
Hickory
Lookout Shoals
Norman
Mt. Island
Wylie (N.C.-S.C.)
South Fork
Fishing Creek (S.C.)
Wateree (S.C.)
Broad River
Lure
Green River
Adger
Summit
Toxaway River
Toxaway
Hiwassee River
Chatuge
Hiwassee
Nantahala River
Nantahala
Cheoah River
Santeetlah
Little Tennessee River
Fontana
Highland
Tuckaseigee River
Thorpe
Oligo-
Com- Oligo- meso-
BW
Eutro-
Meso- phic Hyper-
Map puter trophic trophic trophic a g_ eutrophic
22
23
24
25
26
27
13
14
15
16
17
18
19
20
21
JA
RH
HK
•LS
NR
MT
WY
SF
FC
wr
X
X
X
X
X
™«_—._._—.—..-™.——_—— Y
X
X
X
61 LU
— X
62
60
59
56
55
54
53
52
t;7
AD
SM
TV
A A "*
CT
NA
SN
FO
HT
X
X
X
X
X
X
X
,— _— Y
58 TH X
203
-------
Table 38 (cont'd)
Lake Trophic State - Summer Conditions
Codes Oligo- Eutro-
Com- Oligo- meso- Meso- phic Hyper-
Type and Name Map puter trophic trophic trophic a B eutrophic
River Segment
Chowan (U.S. 13 to 44 CH X
Albemarle Sound)
Albemarle Sound AL X
Roanoke River RO X
Old Mill Ponds (year constructed)
Crystal (1885)
Davies (1850)
Finches (1875)
Hodgins (1871)
Jackson (1885)
Johns (1840)
Jones (1810)
Lytches (1870)
McKensie (1860)
McNeils (1870)
Monroe (1825)
Orton (1810)
lull (1875)
Silver (1785)
^,m^^m^_^J |M||, M| ^,|, ,|| M|,|, ,M|. , V"
204
-------
of the trophic state of these lakes and their surface area is shown in Table
39. The mean depth of 41 of the lakes when related to trophic state (scaled
on a digital basis using values of 1-6) are correlated at an (r) of -.934 with
a 1% level of significance >.834, Table 40. It would appear to follow from
this relationship that the deep lakes, (in North Carolina all deep lakes are
impoundments) have a much greater capacity for assimilation of nutrients.
Substances that increase nutrient levels will tend to sink below the euphotic
zone and are removed from significant re-entry into trophogenic levels. In
the North Carolina context lakes shallower than a mean depth of 15-20 ft. would
probably be not very responsive to quality upgrading. Nutrients from non-
point sources are readily available for enhancement of productivity levels.
Table 39
Summary of Trophic Classifications
of North Carolina Lakes and Impoundments*
Surface Area - Acres
<500
500-1000
1000-5000
5000-10000
> 10000
Oli go-
trophic
1
1
3
2
1
Oligo-
meso-
trophic
6
0
7
1
2
Trophic
Meso-
trophic
6
4
6
1
3
Classification
a-Eutrophic
6
3
5
0
2
6-Eutrophic
1
1
0
0
1
Hyper-
eutrophic
2
0
0
0
0
Physiographic
Distribution
Coastal Plain 1577 0 1
Piedmont 0 8 12 9 3 1
Mountain 7310 0 0
*Number identifies either the classification of an entire lake or impoundment
or a subsegment if data was in sufficient detail.
205
-------
Table 40
Relationship of Trophic State and Mean Depth
41 Lakes or Impoundments of North Carolina
Volume
i Depth- Feet- (Surface Area)
N
6
7
6
8
6
5
3
Range
4.9-8.4
9.4-13.5
15.8-18.8
20.5-26.7
31.0-38.4
40.7-55.2
69.7-135.4
Corr. Coef.
Mean
6.8
11.8
17.1
23.4
34'. 5
48.1
97.1
r = -.934
Trophic State (Scaled 1-6)*
N
6
7
6
8
6
5
3
d.f.
Range
3-6
2-4
2-5
2-4
1-3
1-2
1
=6; 5Z level
Mean
4.0
3.3
3.3
3.0
2.3
1.6
1.0
of sig.
slope 3.727 1Z level of sig. >.834
intercept -.031
*1 - Oligotrophic
2 - Oligo-mesotrophic
3 - Mesotrophic
4 - o-Eutrophic
5 - 8-Eutrophic
6 - Hypereutrophic
206
-------
ACKNOWLEDGEMENTS
This investigation is based on data assembled in the period 1971-1975 and
reflects the efforts of many individuals who participated in the collection
and assessment of the quality of the hundreds of water samples. This
information constitutes the data pool of this document. Responsibility for
nearly all of the field work should be identified with Mr. Terry P. Anderson
and Mark Mason. Mr. Anderson's comments, suggestions and review of drafts
have been particularly helpful and should be specifically acknowledged.
Christopher F. Knud-Hansen had the primary responsibility for the collection
samples from the mill ponds and western lakes. Laboratory analyses,
particularly the algal nutrients, were carried out under the supervision of
Ms. Susan Rappaport and Ms. Carol Parker. All of the phytoplankton analyses
were made by Dr. Peter H. Campbell. Coding and checking of the data for
computer processing was the responsibility of Ms. Ann Scott. The typing of
the numerous tables was a task carried out with great patience by Mrs. Elizabeth
Walter.
Over the period of time in which the hundreds of observations of this
report were gathered, there were several organizations and their specific
projects which contributed directly or indirectly to the total data base.
A principal source of data was the project, The Trophic State of North
Carolina Lakes, supported by the Water Resources Research Institute of the
University of North Carolina. However, the data base both preceded and
postdates the period of support of this specific study. Other organizations
and their projects that contributed by the data pool should be acknowledged
as follows. U.S. Army Corps of Engineers, Wilmington District, The John H.
Kerr Reservoir; Duke Power Company, the Lower Catawba Lakes and Belews Lake;
the North Carolina Science and Technology Committee, Taxonomy and Ecology of
the Phytoplankton of North Carolina.
The Central Computing and Data Processing Center, School of Public Health,
under the direction of Mr. Robert Middour should be particularly acknowledged
for their help in carrying out the innumerable data processing runs necessary
for assembly of the key information used in assessing the relationships of
the trophic indices to trophic conditions.
207
-------
REFERENCES
Brook, A. J. "Planktonic Algae as Indicators of Lake Types, With Special
Reference to the Desmidiaceae," Limnology and Oceanography, 10:403-411,
1965.
Campbell, Peter H. and Charles M. Weiss. "The Taxonomy and Ecology of the
Phytoplankton of North Carolina Lakes," (In Preparation).
Carlson, R. E. "A Trophic State Index for Lakes," Limnological Research
Center, University of Minnesota, Minneapolis. Contribution No. 141,
1975, 17 pp.
Dillon, P. J. and F. H. Rigler. "A Simple Method for Predicting the Capacity
of a Lake Trophic Status," Journal of the Fisheries Research•Board.of
Canada. 32:1519-1531, 1975.
Lorenzen, C. "Determination of'Chlorophyll and Pheo-pigments: Spectrophoto-
metric Equations," Limnology and Oceanography, 12:343-346, 1967.
Nygaard, G. "On the Productivity of Five Danish Waters," Vereinigung fur
Theoretische und Angewandte Limnologie, 12:122-133, 1953.
Palmer, C. M. "A Composite Rating of Algae Tolerating Organic Pollution,"
Journal of Phycology, 5:78-82, 1969.
Patten, B. C. "Species Diversity in Net Phytoplankton of Rantan Bay," Journal
of Marine Research. 20:57-75, 1962.
Rawson, D. S. "Some Physical and Chemical Factors in the Metabolism of Lakes."
In; Problems in Lake Biology, editor Forest Ray Moulton. Publications of
the American Association for the Advancement of Science, No. 10, pp. 9-26,
1939.
Rawson, D. S. "Algal Indicators of Trophic Lake Types," Limnology and Ocean-
ography. 1:18-25, 1956.
Reddy, Michael. "Trophic Indicators in Environmental Monitoring," Reprints of
Papers, 171st National Meeting, American Chemical Society, Division of
Environmental Chemistry, 16:200-201, 1976.
Sawyer, C. N. "Fertilization of Lakes by Agricultural and Urban Drainage,"
Journal of the New England Water Works Association, 61:109-127, 1947.
Schindler, D. W. and D. R. S. Lean. "Biological and Chemical Mechanisms in
Eutrophication of Freshwater Lakes," Annals of the New York Academy of
Sciences. 250-129 135, 1974.
Shannon, C. E. and W. Weaver. The Mathematical Theory of Communication.
University of Illinois Press, Urbana, 111. 1949, 117 pp.
208
-------
REFERENCES (Continued)
Shannon, Earl E. and Patrick L. Brezonik. "Eutrophication Analysis: A Multi-
variate Approach," Journal of the Sanitary Engineering Division.
Proceedings American Society of Civil Engineers. 98(SA1):37-57, 1972.
Stewart, Kenton M. and Gerard A. Rohlich. "Eutrophication - A Review. A
Report to the State Water Quality Control Board, California." State
Water Quality Control Board, Sacremento, California, Publication No. 34,
1967, 188 pp.
Stockner, John G. "Paleolimnology as a Means of Assessing Eutrophication,"
Verhandlungen Internationale Vereinigung Limnologie. 18:1018-1030, 1972.
Stockner, John G. and Woodruff W. Benson, "The Succession of Diatom Assemblages
in the Recent Sediments of Lake Washington," Limnology and Oceanography,
12:513-532, 1967.
Strickland, J. D. H. and T. R. Parsons. "A Practical Handbook of Seawater
Analysis," Fisheries Research Board of Canada. Bull. No. 167, pp. 185-
196, 1972.
Toerien, D. F., Kathy L. Hyman and Mariaan J. Brumer. "A Preliminary Trophic
Status Classification of Some South African Impoundments," Water SA,
1:15-23, 1975.
U.S. Environmental Protection Agency. "Methods for Chemical Analysis of Water
and Wastes," EPA Water Quality Office, Analytical Control Laboratory,
Cincinnati, Ohio. 1974, 298 pp.
Uttormark, Paul D. and J. Peter Wall. "Lake Classification - A Trophic
Characterization of Wisconsin Lakes." Ecological Research Series,
National Environmental Research Center, U.S. Environmental Protection
Agency, Corvallis, Oregon, EPA-66013-75-033, 1975, 165 pp.
Vollenweider, Richard A. "Scientific Fundamentals of the Eutrophication of
Lakes and Flowing Waters with Particular Reference to Nitrogen and
Phosphorus as Factors in Eutrophication." Organization for Economic
Co-operation and Development Directorate for Scientific Affairs, OECD
Report No. DACS/CSI/68.27, Paris, France, pp. 63-66, 1968.
Vollenweider, Richard A. "Input-Output Models with Special Reference to the
Phosphorus Loading Concept in Limnology," Schweizerische Zeitschrift fur
Hydrologie, 37:53-84, 1975.
Vollenweider, Richard A. "Advances in Defining Critical Loading Levels for
Phosphorus in Lake Eutrophication," Memorie dell* Istituto Italiano di
Idrobiologia. 33:53083, 1976.
Vollenweider, R. A. and P. J. Dillon. "The Application of the Phosphorus
Loading Concept to Eutrophication Research," National Research Council
Canada, Report No. 13690, 1974, 42 pp.
209
-------
REFERENCES (Continued)
Weiss, Charles M. "Relation of Phosphorus to Eutrophication," Journal American
Water Works Association, 61:387-391, 1969.
Weiss, C. M. "Field Evaluation of the Algal Assay Procedure on Surface Waters
of North Carolina," In: Biostimulation and Nutrient Assessment, E. J.
Middlebrooks, D. H. Falkenborg and T. E. Maloney (eds.). Ann Arbor,
Ann Arbor Sicence Publishers Inc., pp. 29-76, 1976.
Weiss, Charles M., Terry P. Anderson and David R. Lenat. "Environmental
Assessment, Belews Creek - Belews Lake, North Carolina, May 1971-June
1972, Year II," Department of Environmental Sciences and Engineering,
School of Public Health, University of North Carolina at Chapel Hill,
Pub. No. 317, 1972, 232 pp.
Weiss, Charles M., Terry P. Anderson, Peter H. Campbell, David R. Lenat, Julie
H. Moore and Sheila L. Pfaender. "Environmental Comparison, Belews Lake -
Year III and Lake Hyco, North Carolina, July 1972-June 1973," Department
of Environmental Sciences and Engineering, School of Public Health,
University of North Carolina at Chapel Hill. Pub. No. 370, 1974, 509 pp.
Weiss, Charles M., Terry P. Anderson, Peter H. Campbell, David R. Lenat,
Julie H. Moore, Sheila L. Pfaender and Thomas G. Donnelly. "An Assessment
of the Environmental Stabilization of Belews Lake - Year IV and Comparisons
with Lake Hyco, North Carolina, July 1973-June 1974," Department of
Environmental Sciences and Engineering, School of Public Health, University
of North Carolina at Chapel Hill, Pub. No. 416, 1975(a), 500 pp.
Weiss, Charles M. and Benjiman W. Breedlove. "Water Quality Changes in an
Impoundment as a Consequence of Artificial Destratification," Water
Resources Research Institute of the University of North Carolina,
Report No. 80, 1973, 216 pp.
Weiss, Charles M., Peter H. Campbell, Terry P. Anderson and Sheila L. Pfaender.
"The Lower Catawba Lakes, Characterization of Phyto- and Zooplankton
Communities and Their Relationships to Environmental Factors," Department
of Environmental Sciences and Engineering, School of Public Health,
University of North Carolina at Chapel Hill, Pub. No. 389. 1975 (b),
396 pp.
Weiss, Charles M. and Ronald W. Helms. "The Interlaboratory Precision Test,
An Eight Laboratory Evaluation of the Provisional Algal Assay Procedure
Bottle Test." National Eutrophication Research Program, Environmental
Protection Agency, Corvallis, Oregon, October 1971, 70 pp.
Weiss, Charles M. and Edward J. Kuenzler. '*The Trophic State of North Carolina
Lakes." Water Resources Research Institute of the University of North
Carolina, Report No. 119, 1976, 223 pp.
210
-------
REFERENCES (Continued)
Weiss, Charles M. and Julie H. Moore. "The John H. Kerr Reservoir, Virginia-
North Carolina, A Report for the OECD North American Project Defining its
Limnological Characteristics, Productivity, Nutrient Budgets and
Associated Parameters," The Department of Environmental Sciences and
Engineering, School of Public Health, University of North Carolina at
Chapel Hill, Pub. No. 425, 1975, 39 pp.
Weiss, Charles M. , Leonard H. Smock and Jane Hartley, "An Aquatic Environ-
mental Inventory, Belews Creek - Belews Lake, North Carolina August 1970-
April 1971," Department of Environmental Sciences and Engineering, School
of Public Health, University of North Carolina at Chapel Hill, Pub. No. 279,
1971, 99 pp.
Wetzel, R. G. Limnology, Philadelphia W. B. Saunders Co., pp. 352-354, 1975.
211
-------
A REVIEW OF TROPHIC STATE INDICES
FOR NEW YORK STATE
William R. Schaffner
and
Ray T. Oglesby
Department of Natural Resources
New York State College of Agriculture and Life Sciences
Cornell University
Ithaca, New York
INTRODUCTION
Since the early 1950's a number of attempts have been made to develop
simple lake trophic state indices that could be related to such parameters as
phytoplankton standing crop, quantity of benthos, and fish production. Mean
depth was one of the first factors to be examined, with research being con-
cerned with its influence on fauna! production, especially that of fish
(Rawson, 1952, 1955, 1960; Northcote and Larkin, 1956; Hayes, 1957). In some
instances close correlations were obtained with discrete groups of lakes, but
in general, "...the only generalization which seemed justified was that quan-
tities of fauna from lakes of great mean depth were never as high as those in
some lakes of low mean depth" (Northcote and Larkin, 1956). Sakamoto (1966)
obtained a negative correlation between phytoplankton standing crop (log of
the chlorophyll concentration) and log mean depth for a group of Japanese
lakes that ranged from 1 to 65 meters in mean depth. Vollenweider (1968) also
argued that mean depth was an important trophic parameter and included it in
his phosphorus-loading trophic state plots.
The influence of edaphic factors, as represented by total dissolved
solids (TDS) or conductivity, has also been examined. Rawson (1951, I960) and
Northcote and Larkin (1956) examined lakes in central Canada and British
Columbia, respectively, and observed that the production of net plankton,
benthos and fish increased with increasing TDS, although there was con-
siderable scatter except for those lakes with very low dissolved solids
levels.
213
-------
Hayes and Anthony (1964) developed an index of fish productivity
from multiple regressions that included alKalinity (roughly
proportional to TDS or conductivity) as one of the variables.
Earlier, Ball (1945) had found no significant correlation between
alkalinity and fish abundance in thirty-two Michigan lakes.
Ryder (1961, 1965) formulated the morphedaphic index (MEI)
as a means of estimating fish production, basing the index on
the relationships developed by Rawson (1956) and Northcote and
Larkin (1965). The MEI contains an edaphic variable (TDS or
conductivity) and a morphometric variable (mean depth), and is
expressed as the ratio of TDS (or conductivity) to mean depth.
Although initially used to estimate fish production the MEI has
more recently been related, with moderate success, to trophic
conditions of various lakes (Harvey and Fry, 1973; Henderson
et al., 1973; Michalski et al., 1973).
Vollenweider (1968) discussed in some detail the importance
of nutrient input to lakes and its effect on lake trophic state,
pointing out that lake morphometry should be taken into account
when different lakes are being compared. This was accomplished
by calculating nutrient loading on an areal basis, and plotting
this versus mean depth. A graphic representation resulted which
devided the lakes roughly into oligotrophic,mesotrophic and
eutrophic categories. Subsequently, the influence of lake
hydrology as well as morphometry was considered (Vollenweider
and Dillon, 1974; Dillon, 1975; Dillon and Rigler, 1974).
214
-------
Hydraulic retention time (HRT) has been related to lake
productivity, but the actual point at which it becomes a signifi-
cant factor is not well defined, although, some indications do
exist. Dickman (1969) found evidence that HRT could be of
significance to some lakes in his study of a small British
Columbia lake that flushed as often as every 2.5 days during
periods of heavy rainfall. Kerekes (1973, 1975b) noted in his
studies of Newfoundland and Nova Scotian lakes that at HRT's
<0.2-0.4, chlorophyll and total phosphorus concentrations became
a function of the flushing rate. Similarly, Dillon (1975) found
that the phytoplankton standing crop in a rapidly flushed Ontario
lake (HRT <0.1 yr) was lower than expected based on phosphorus
loading data. Vollenweider (1975) has provided a theoretical
basis for the influence of HRT on lake productivity, and later
versions of his phosphorus loading-mean depth-trophic state
graph have been modified to include HRT (Vollenweider and Dillon,
1974) .
Recently, Carlson (1975) presented a system for the trophic
classification of lakes using indices based on single parameters
(Secchi disc transparency, chlorophyll a_ and total phosphorus)
known to be closely affected by changes in trophic state. The
different trophic states are derived for a given index by
division of the range of values obtained for the index parameter.
For example, Secchi disc transparency (SDT) can be related to
algal biomass by using the Beer-Lambert equation for the vertical
extinction of light in water. Based on this fact SDT is used to
delineate the desired trophic categories such that each division
215
-------
represents a doubling in the concentration of algal biomass in
the surface waters, where biomass is defined in terms of trans-
parency. The zero point for the index was chosen at an SDT value
greater than any yet recorded in the literature -64 meters. A
maximum of 41.6 meters was reported in Hutchinson (1957) for Lake
Masyuko, Japan. The total trophic scale ranges from 0 to 100,
with major divisions as follows: 64m = 0; 32m = 10; 16m = 20;
...; 0.062m = 100.
The present report describes the results obtained when the
various trophic state indiced are applied to a relatively diverse
group of New York State lakes.
MATERIALS.AND METHODS
Data were obtained for twenty-seven New York lakes, although
it'was not possible to obtain a complete set of parameters for
each. They are located throughout most of the state, Long Island
excepted, and occur in a variety of geological settings (Table 1) .
Oneida, the largest, receives runoff from three physiographic
provinces: the Appalachian Upland, Erie-Ontario Lowland and Tug
Hill Upland (Greeson, 1971) . One of the lakes (Moraine) is
man-made; the rest occur naturally.
The data came from a number of sources, published and
unpublished; as a result some of the parameters are not always
exactly comparable- In some instances it was necessary to
substitute median values for means. Such modifications are not
thought to greatly affect the outcome of the study. The additional
information outweighing any introduced variability.
216
-------
Table 1. A list of the twenty-seven New York lakes catagorized
as to the physiographic provinces in which their basins
are located. A brief description of each physiographic
province can be found in Table 2.
Adirondack Highlands
Carry Falls Reservoir
George
Lower St. Regis
Mirror
Placid
Sacandaga
Schroon
Upper Saranac
Appalachian Uplands
Canadarago
Canadice
Canandaigua
Cayuga
Chautaugua
Conesus
Hemlock
Honeoye
Keuka
Lamoka
Moraine
Otisco
Otsego
Seneca
Skaneateles
Waneta
Erie-Ontario Lowlands
Oneida
Hudson-Mohawk Lowlands
Saratoga
217
-------
Table 2. A brief description of five of New York's physiographic
provinces (Cressey, 1966; Greeson, 1971).
Adirondack Highlands
Ancient crystalline rocks, similar to those of the
Canadian Shield, prevail. Intense glacial scouring
has removed most of the original soil and smoothed
out the land surface. Some of the erroded material
now chokes the pre-glacial valleys, deranging the
stream patterns and producing numerous lakes.
Appalachian Uplands
The largest land form in New York,-occupying nearly
half of the state. Underlain by Paleozoic sedemen-
tary rocks. Upper Devonian sandstones and shales
are found in the southern portion, changing to
Middle Devonian limestones northward.
Erie-Ontario Lowlands
A relatively flat region bordering Lake Ontario.
The bedrock is composed of shale, limestone and
minor amounts of sandstone, which may be overlain
by up to 30 meters of unconsolidated glacial
deposits.
Hudson-Mohawk Lowlands
The soft sedimentary rocks and overlying glacial
deposits have been erroded to form a variety of
terrain. The region north of Albany is wide and
flat, and is covered with glacial deposits.
Unusual carbonated, saline waters are found in
the Saratoga-Ballston Spa district.
Tug Hill Uplands
A plateau-like outlier of the Adirondack Highlands
underlain by Paleo2oic sandstones, limestones and
shales which dip gently westward. An area of bad
drainage, poor soils and heavy snows, it is one of
the least settled parts of the state.
218
-------
Data for a given lake during different years are not pooled,
but reported separately so as to provide some estimate as to
the natural variability within a lake.
2
Phosphorus loading are in g total P/m lake surface/year.
The other parameters are defined in the appropriate tables.
Carlson's trophic state indices (TSI) were calculated from the
following formulas:
(1) Summer Secchi disc transparency
TSI(SD) =10 (6 - -)
(2) Summer chlorophyll
-------
Table 3. Morphemetrie and hydirologic data, and location of the twenty-seven New York lakes. Data
from Greeson and Robison (1970), and Oblesby and Schaffner (1975).
Lake
1 Canadarago
2 Canadice
3 Canandaigua
4 Carry Falls Res
5 Cayuga
6 Chautaugua
7 Conesus
8 George
9 Hemlock
ro 10 Honeoye
o 11 Keuka
12 Lamoka
13 Lower St Regis
14 Mirror
15 Moraine
16 Oneida
17 Otisco
18 Otsego
19 Owasco
20 Placid
21 Sacandaga
22 Saratoga
23 Schroon
24 Seneca
•25 Skaneateles
26 Upper Saranac
27 Waneta
o
42
42
45
44
42
42
42
43
42
42
42
42
44
44
42
43
42
42
42
44
43
43
43
42
42
44
42
Location
N. Lat W. Long
1 II O , H
47
44
52
25
56
06
50
50
46
47
39
24
25
17
50
14
54
41
54
18
19
06
43
52
56
15
27
24
27
30
55
51
43
04
13
39
00
22
59
52
02
47
20
16
40
12
16
10
10
40
06
42
04
56
75
77
77
74
76
79
77
73
77
77
77
77
74
73
75
76
76
74
76
73
73
73
73
76
76
74
77'
00
34
16
45
44
06
42
25
36
30
03
05
17
58
31
08
18
55
32
59
55
38
48
56
25
17
06
51
20
20
10
09
08
18
50
59
42
40
10
53
56
39
30
47
18
34
43
26
12
42
26
47
48
17
Surf
Elev.
m
389
334
210
116
399
249
97
276
245
245
335
494
566
369
113
240
363
217
567
235
62
246
136
263
480
335
Surf
Area
km2
7.6
2.6
42.3
26.1
172.1
57.2
13.7
114.0
7.2
7.0
47.0
2.3
1.9
0.5
1.1
206.7
7.6
16.6
26.7
11.3
122.0
16.3
16.7
175.4
35.9
3.2
Drain
Area
km2
174
31
453
2261
2106
490
231
492
111
95
484
18
54.9
3579
88
75
539
52
2704
632
1189
1831
189
46
Depth m
max mean
12. C
25.4
38.5
132.6
18.0
57
27.5
9.2
55.8
14.3
16.8
20.1
51.0
54.0
198.4
90.5
8.8
6.7
16.4
38.8
5.4
54.5
6.9
11.5
18
13.6
4.9
30.5
5.0
5.1
6.8
10.2
12.6
29.3
7.6
7.9
14.3
88.6
43.5
3.5
Vol.
km3
0.05
0.04
1.6
0.14
9.4
0.40
0.16
2.1
0.11
•0.04
1.4
0.01
0.01
14.0
0.08
0.21
0.78
0.93
0.13
0.24
15.5
1.6
0.01
WRT
yrs
0.6
4.5
7.4
0.1
12.0
1.4
1.4
2.0
0.8
6.3
0.3
0.6
1.9
3.1
0.5
0.4
0.4
18.1
17.7
Z/T
11.2
3.6
5.2
54.0
4.5
4.9
8.2
6.8
6.1
4.8
17.0
11.3
5.4
9.4
15.2
19.8
35.8
4.9
2.5
-------
range of differences. Saratoga is the lowest with a surface
altitude of 62 meters, and Placid is the highest at 567 meters.
2
Mirror Lake has a surface area of only 0.5 km ; whereas Oneida,
2
the state's largest lake, has an area of 206.7 km . As one might
2
expect, drainage areas also vary considerably. Lamoka's is 18 km
2
while Oneida has a drainage area covering 3579 km . Three other
lakes (Carry Falls Reservoir, Cayuga and Sacandaga) have basins
2
in excess of 2000 km . Volumes differ by over four orders of
magnitude, and mean depths two, from 3.5 meters (Waneta) to 88.6
meters in Seneca, the state's deepest lake. Some of the lakes
are flushed quite rapidly, Carry Falls Reservoir has a mean
hydraulic retention time of 0.1 yrs, and seven others (Canadarago,
Honeoye, Lower St. Regis, Oneida, Sacandaga, Saratoga and
Schroon) flush on the average in less than a year. Seneca and
Skaneateles have mean HRT's on the order of twenty years.
Trophic State Indices
Six trophic state indices plus supportive data are listed in
Table 4.
Carlson's Indices: The first" three indices are those of
Carlson (1975), which are based on the single parameters: Secchi
disc transparency, surface chlorophyll a_ and surface total
phosphorus. These indices are represented on a scale of 0 to 100,
with the most oligotrophic category having a value of zero.
Secchi disc transparencies varied from 1.2 to 9.3 meters.
The index, TSI(SD)f ranges from 28 (George) to 57 (Lower St.
Regis). Most values are in the 30's, 40's, and 50's (Figure 1).
221
-------
Table 4. Trophic state indices and supportive data for the twenty-seven New York lakes.
Lake
1 Canadarago
2 Canadice
? Canandaigua
4 Carry Falls Res
5 Cayuga
6 Chautaugua
7 Conesus
8 George * '
9 Hemlock
10 Honeoye
Year
1973
1973
1972
1973
1972
1965"
1968
1972
1973
1974
1972
1971
1972
1973
1971
1972
1973
1973
SDT
m
5.2
4.5
3.9
2.3
2.4
2.6
1.8
2.3
2.3
2.0
4.5
4.7
5.2
9.3
4.3
2.7
3.0
3.0
TSI
(SD)
36
38
40
48
47
46
52
48
48
50
38
38
36
28
39
46
44
44
Chi
rng/nr
3.2
2.0
4.3
3.0
3.1
6.4
6.2
11.5
6.8
9.5
13.3
5.8
4.2
3.7
5.4
7.6
5.0
25.7
TSI
(Ch)
42
37
45
41
42
49
48
54
49
53
56
48
45
43
47
50
46
62
TP
mg/m1
10.2
9.0
9.2
10.0
18.3
14.6
31.4
28.0
18.3
11.3
10.6
9.2
19.0
TSI TDS MEI Cond.
(TP) mg/1 (TDS) ymhos/cm
174 26
33 76 5
31
32 187 5
33
38 213 4
49
48
42
35 209 18
136 10
34
32
42 119 24
279
115
310
285
50
500
485
150
340'
328
193
166
MEI
(Cond)
42
7
8
7
9
9
9
22
30
29
14
34
T. Alk. Lsp
mg CaCO /I g P/ma/yr
137 1.2, 0.793
32 0.32, 0.36"
111
108 0.42, 0.14'
10 0.71'
105
110 0.86, 0.81',
0.49'
113
49 0.27'
116" 0.67, 1.46.
0.38*
114
0.43
59
62 C.38, 0.83°
-------
>:al).Io 4. Continued
11
12
13
14
15
16
17
IN)
ro
CO 18
19
?.n
21
22
23
Kouka
Lnmoka
Lower St. Regis
Mirror
Moraine
Oneida
Otisco
Otsego
Owasco
Placid
Sacandaga
Saratoga
Schroon
1972 '
1973
1973
1972
1971
1974
1975
196512
1967 *
1968 2
1973
1975"
1965' 2
1973
1973
196512
1971
1972
1973
1971
1972
1972
1972
2.4
7.0
2.0
1.2
4.8
3.2
5.8
1.9
1.9
2.7
5.2
3.0
3.8
3.1
2.5
9,5
3.5
2.5
3.7
47
32
50
57
37
43
35
51
51
46
36
44
41
44
47
28
42
47
41
8.0
1.8
8.7
7.9
14.1
7.4
4.4
8.5
17.1
1.8
1.8
6.6
5.0
4.9
1.3
4.8
11.8
2.1
51
36
52
51
56
50
45
52
58
36
36
49
46
46
33
46
55
38
13. Q
14.2
12.0
17.0
20.3
36.0
41.0
68.4
39.1
9.6
7.1
17.5
9.9
9.0
25.0
4.0
37 165 5
38
36 100 20
41
43
176 26
52 163 24
53
61 194 29
53
194 19
32 183 18
28 1-60 13
160 6
41
33 167 6
31
46
20
241°
276
150
50
278
290
250
302
287
293
238
263
280"
262
50
232
59
8
9
30
10
41
43
37
44
28
29
19
9
10
9
7
29
4
92 0.45f 0.10
76
54
10 0.41"
9
81
0.87, 1.3*
117
133 0.55
101
1078 0.97
113
8
10 0.18C
72 1.6"
10 0.39'
-------
Table 4. Continued
24 Seneca 1965 ' "
1972
1973
25 Skaneateles 1965 12
1971
1972
1973
26 Upper Seranac 1971 '*
27 Waneta 1973
1 Likens (1974) ; Oglesby (MS
ro 2 Greeson (1971)
PO
3.1
1.8
3.6
7.9
6.6
5.2
3.5
1.5
1974)
44
52
42
30
33
36
42
54
4.8
13.0
8.6
1.1
2.6
1.3
23.6
46 22.0
56 15.0
52 10.2
32
40 28.5
33 6.1
26.0
62 23.8
10 Anonymous (1966)
11 Hetling (1974)
39 790' 9 92 0.64, 0.38s
33 276 3 769 9 90
142 3 224 5
48 0.23
26 144 3 275 6 98
47
46 113 32 152 43 52
3 Hetling tnd Sykes (1971)
* Anonymous (1974a)
s Anonymous (1974b)
' Stewart and Markello (1974)
7 Hetling (1974)
9 Anonymous (1975)
' Anonymous (1974c)
13 Dr. E. L. Mills (personal communication)
111 Anonymous (1972)
-------
Cayuga was sampled during five different years for the period
1965-74, and its index values range from 46 to 52.
Chlorophyll concentrations varied from 1.1-25.7 mg/m3; TSI
(Ch) values are distributed in a fashion similar to those of
TSI(SD) (Figure 1). Skaneateles (1971) has the lowest index
(32), but data were not available for Lake George. Waneta and
Honeoye are the highest at 62. Most of the indices are in the
30-60 range. Cayuga varies from 46 to 52. Skaneateles was 32
in 1971, 40 in 1972, and down to 33 in 1973. Seneca had an
index of 46 in 1965 and 56 in 1972.
Total phosphorus concentrations range 6.1 mg P/m in Skaneateles
(1973) to 68.4 mg P/m3 in Oneida (1973). The total P index,
TSI(TP), has the greatest span, from 20 (Schroon) to 61 (Oneida-
1973). Approximately 75% of the values are in the 30's and 40's
(Figure 1). Oneida varied from 52 in 1967 to 61 in 1973, while
Skaneateles went from 48 in 1972 down to 26 in 1973.
Morphoedaphic Index. The MEI's were calculated with total
dissolved solids (TDS) and conductivity. TDS concentrations
range from 76 mg/1 in Canadice to 276 mg/1 in Seneca, and the
resulting 1-lEI's from 3 (Skaneateles and Seneca) to 32 (Waneta).
Five lakes (Canadarago, Honeoye, Lamoka, Oneida and Waneta) are
20 or greater, and eight (Canadice, Canandaigua, Cayuga, Hemlock,
Keuka, Owasco, Seneca and Skaneateles) are 10 or less.
2
Conductivity ranges from 50 micromhos/cm in Lower St. Regis
2
and Sacandaga to 790 microiuhos/cm in Seneca. The MEI's vary from
4 (Schroon) to 44 (Oneida). Three lakes (Canadarago, Oneida and
225
-------
ro
ro
TSI
0-
10-
20-
30-
40-
50 -
60-
70-
80-
90-
•* f\ f\
100 -1
SDT
m
64-
32-
16-
8-
4~
2-
1-
0.5 -
0.25-
0.12-
.05 -1
C
Ch
mg/m
0.04 -i
0.12-
0.34-
0.94 -
wmmmmmmmm
6.4-
20-
56 -
TSI(SD) 154.
427-
1 1 ^ | j 1101 .
) 5 10 15 20 25 C
TP
mg/m3
1 -i
2 -
4-
8-
?f^^^^J
1b -
i::.:S^ iwSM^^l^^^
32 -
•:•: ^i:':::!: S:pw!>$x^:[
bb -
130-
TSKCh) 260 -
519 -
1 ' ' --f 103°
) 5 10 15 20 C
i
UMJ
^i-i-SiiSli^iiSS^^;^
l^iliPP-^
j'l'l'i'ij
TSKTP)
iiii
) 5 10 15 2
Number of Lakes
Figure 1. Frequency distribution of Carlson's Trophic State Indices.
-------
Waneta) are in the 40's, while ten (Canadice, Canandaigua, Carry
Falls, Cayuga, Keuka, Owasco, Sacandaga, Seneca and Skaneateles)
are 10 or less.
Specific Phosphorus Loading. L estimates for a specific
lake may vary considerably when calculated by different researchers,
e.g. the three estimates for Conesus range from 0.38 to 1.4 g P/m2/yr.
Skaneateles has the lowest loading (0.23 g P/m2/yr) and Saratoga
2
the highest (1.7 g P/m /yr). Three other lakes (Canadarago,
Conesus and Oneida) have at least one estimate greater than
2
1.0 g P/m /yr. The phosphorus loading to the various lakes are
plotted on Vollenweider's revised graph which utilizes mean
depth/HRT on the x-axis (Figure 2). The majority of the lakes
fall in the "eutrophic" classification. Three (Chautaugua, Lower
St. Regis and Skaneateles) are classified as "mesotrophic", i.e.
they lie between the permissible and dangerous loading limits,
and three. (Carry Falls, Sacandaga and Schroon) fall into the
oligotrophic category. Two (Canandaigua and Keuka) were ranked
as being both oligotrophic and eutrophic.
Correlations Between Trophic State Indices
Excepting that between the two MEI's, correlations between
the various indices are not high (Table 5). Three combinations:
TSI(SD) VS TSI(Ch), TSI(TP) vs MEI(TDS) and TSI(TP) vs MEI(Cond),
had R values around 0.7, all others were less.
Alkalinity
Total alkalinities are presented for information only, and no
attempt has been made to make trophic interpretations from them.
227
-------
10
1.0
0.1
0.01
I I 1 1 1 1 1
i i i i i i n i i i i i i i L
Eutrophic
'24
^17{
— Dangerous •——«
Permissable —. — —•'
25 i i
22
2|
Oligotrophic
« J i i iiHI I I 1 1 M Ml 1 1 1 tlltt
0.1
1.0
10
100
Z/T
Figure 2.
Specific phosphorus loadings to nineteen New York
lakes. Estimates for the same lake are connected
by a dashed line. Lakes identified by number, see
Table 3 or 4 for identification.
228
-------
Table 5. Correlation coefficients (R) for TSI and MEI values.
TSI(SD)
TSI(Ch)
TSI(TP)
MEI(TDS)
MEI (Cond)
TSI(SD) TSI(Ch) TSI(TP) MEI(TDS)
0.707 0.406 0.447
0.525 0.459
0.725
-
MEI (Cond)
0.274
0.387
0.688
0.988
-
229
-------
Alkalinity ranges from 8 mg CaCO /I in Lake Placid to 137 mg
CaCO^/1 in Canadarago. Lakes located in the Adirondack Mountains
(Carry Falls/ Lower St. Regis, Mirror, Placid/ Sacandaga and
Schroon) had alkalinities that were considerably lower than
those lakes located in other parts of the state, i.e. the former
had alkalinities of about 10 mg CaCO_/l, whereas the latter did
not have concentrations that went below 49 mg CaCO /I.
DISCUSSION
Various trophic state indices and indicators were applied
to a diverse group of New York lakes using both published and
unpublished data from a number of sources.
Total alkalinities are reported where available, and differ
widely in various areas of the state. The differences are more
closely related to edaphic factors than lake trophic state. The
soft waters of the Adirondack lakes have alkalinities of 10 rag
CaCO.,/1 or less, whereas those in the Finger Lakes region can
have concentrations of 100 mg CaCO-./I, or better, due to the
presence of limestone in their drainage basins.
The MEI's calculated from TDS and conductivity suffer from
the same problem as the alkalinity estimates. This is compounded
by the fact that two of the lakes (Cayuga and Seneca) have
elevated sodium chloride levels (Oglesby et al., 1974), although
the great mean depths of the lakes tend to mask the problem
when MEI's are calculated. The reason for the relatively good
correlation between TSI(TP) and the two MEI's remains obscure,
230
-------
although one could argue that phosphorus concentrations in the
water are more closely related to morphoedaphic parameters than
either transparency or chlorophyll. The problem warrents closer
examination.
The trophic state-indices proposed by Carlson (1975) probably
represent the most practical approach when a large number of lakes
are being studied and their trophic status followed over a number
of years, even though there was a lack of strong correlation between
the indices when they were applied to the New York lakes (Table 5).
The necessary data can be gathered with reasonable ease since each
index is based on a single parameter. Secchi disc transparency,
surface chlorophyll a. and surface total phosphorus, each of which
is related to lake trophic state, should reflect any changes
that take place.
The New York lakes fall in the mid-range of Carlson's (1975)
trophic index scale, the maximum range being from 20 to 61. All
of the mean Secchi disc transparencies are between 1 and 10
meters. Mean surface chlorophyll concentrations do not go below
3 3
1 mg/m , with a high of 25 mg/m being observed in Honeoye. The
next two highest chlorophyll concentrations are from Mirror and
Chautaugua, about 14 and 13 mg/m . Transparencies in the three
lakes are not as low as one might expect, at 3.0, 4.8 and 2.0
meters respectively.
Total phosphorus concentrations range over an order of
magnitude, i.e. from 6 to 68 mg P/m . The greatest difference
for a single lake may be found in Skaneateles which went from
'in3
231
28.5 mg P/m3 in 1972 to 6.1 mg P/m3 in 1973. Heavy rains
-------
associated with Tropical Storm Agnes fell on the state in 1972, a
factor that could have influenced lake phosphorus concentrations.
Examination of Table 2 shows that some of the lakes followed a
pattern similar to Skaneateles, but to a much lesser extent.
Chlorophyll levels in Skaneateles were greater in 1972 than 1973
(2.6 vs 1.3 mg/m ), as was transparency (6.6 vs 5.2 m).
The lack of a strong correlation between the three TSI's is
perplexing, but may be explained at least in part by several
factors. The data that were used came from a variety of sources.
In some instances the lakes were sampled on almost a weekly
basis during the summer/ in others only two or three samplings
were conducted. Thus, some of the lakes may not have been
adequately characterized. The data were not truely comparable
in all instances, e.g. median values were at times substituted
for means. In addition, the various lakes may have responded
differently for each of the three parameters, e.g. the phosphorus
values from Skaneateles, and the chlorophyll-transparency
relationships in Honeoye, Mirror and Chautaugua that have
already been mentioned.
Long-term data for the various parameters were not available,
thus it was not possible to trace changes that may have taken
place in trophic state. Carlson (1975) was able to do this with
information from Lake Washington, and demonstrated that the
indices performed adequately. Variations of from 10 to 20 units
were noted in the New York lakes over periods of only a few
years; this may represent the natural range to be expected.
232
-------
Specific phosphorus loading (L ) estimates were available
sp
for nineteen of the lakes. In some instances where more than one
estimate was made for a particular lake, considerable range was
encountered, e.g. the three values for Conesus vary by more than
a factor of three (Table 2). This was most likely due to the way
in which the loading estimates were obtained, and is not thought
to represent actual differences. Stewart and Markello (1974),
and Oglesby and Schaffner (1975) calculated their phosphorus
loadings based on such factors as land use and population size
in the drainage basins, but made different assumptions as to
relative contributions from each. The estimates presented in
Anonymous (1974a, 1974b, 1974c and 1975) were based on stream
and sewage treatment plant measurements. This usually did not
affect the ultimate classification of a lake when the data were
plotted (Figure 2) , just its relative position on the graph.
Two exceptions were Canandaigua and Keuka which were indicated
as being both eutrophic and oligotrophic.
The majority of the lakes are classified as eutrophic when
L was plotted against Z/T (Figure 2). Three (Carry Falls,
Sacandaga and Schroon) are classified as oligotrophic, and fall
into this category by virtue of their short HRT's (0.1-0.5 yrs)
(Table 3). Examination of their other trophic state parameters,
i.e. transparency, chlorophyll and total phosphorus (Table 4),
would tend to place them somewhat higher on the trophic scale.
Skaneateles, classified as mesotrophic, is quite transparent
(Secchi disc: 5.2-7.9m), and has low chlorophyll levels (1.1-2.6
233
-------
mg/m ), but has a long HRT (18 yrs) . Canandaigua and Keuka
should possibly be classified as mesotrophic, although the
latter differed considerably in 1972 and 1973 (Table 4).
If phosphorus loading estimates are to be used for management
purposes they must be quantitatively accurate, or at least
consistent. In addition, they should be related to measurable
trophic state parameters, such as transparency, chlorophyll or
total phosphorus, rather than to subjective terms such as
eutrophic and oligotrophic which in fact represent a whole
continuum of trophic levels. A preliminary attempt at rectifying
some of the inherent problems is discussed in Oglesby and
Schaffner (1975).
234
-------
REFERENCES
Anonymous. 1975. A compendium of lake and reservoir data
collected by the National Eutrophication Survey in the
northeast and. north-central United States. U.S. Environ-
mental Protection Agency, National Eutrophication Survey.
Working Paper No. 474. 210 pp.
Anonymous. 1974a. Report on Keuka Lake. U.S. Environmental
Protection Agency/ National Eutrophication Survey.
Working Paper No. 160. 29 pp.
Anonymous. 1974b. Report on Seneca Lake. U.S. Environmental
Protection Agency, National Eutrophication Survey.
Working Paper No. 170. 57 pp.
Anonymous. 1974c. Report on Cayuga Lake, U.S. Environmental
Protection Agency, National Eutrophication Survey.
Working Paper No. 153. 54 pp.
Anonymous. 1972. Investigation of Upper Saranac and Lower
St. Regis Lakes. New York State Dept. of Health.
Environmental Health Center Spec. Invest. No. 1/72. 37 pp.
Anonymous. 1966. Eutrophication of water resources of New
York State. A study of phytoplankton and nutrients in
Lakes Cayuga and Seneca. Cornell Univ. Water Resources
Center. Publ. No. 14. 24 pp.
Ball, R. C. 1945. A summary of experiments in Michigan lakes
on the elimination of fish populations with rotenone,
1934-1942. Trans. Amer. Fish. Soc. 75:139-146.
Carlson, R. E. 1975. A trophic state index for lakes. Contri-
bution No. 141 from the Limnological Research Center,
University of Minnesota. (rnimeo) 17 pp.
-------
Cressey, G. B. 1966. Land forms, pp. 19-53. In; J. H. Thompson
(ed.) Geography of New York State. Syracuse Univ. Press.
Dickman, M. 1969. Some effects of lake renewal on phytoplankton
productivity and species composition. Limnol. Oceanogr.
14:660-666.
Dillon, P. J. 1975. The phosphorus budget of Cameron Lake,
Ontario: The importance of flushing rate to degree of
eutrophy of lakes. Limnol. Oceanogr. 20:28-39.
Dillon, P. J. and F. H. Rigler. 1974. A test of a simple
nutrient budget model for predicting the phosphorus
concentration in water. J. Fish. Res. Bd. Can. 31:
1771-1778.
Greeson, P. E. 1971. Limnology of Oneida Lake with emphasis
on factors contributing to algal blooms. U.S. Dept. of
the Interior, Geological Survey. Open-File Report. 185 pp.
Greeson, P. E. and F. L. Robison. 1970. Characteristics of
New York lakes. Part I - Gazetteer of lakes, ponds, and
reservoirs. U.S. Dept. of the Interior, Geological
Survey. Bull. 68. 124 pp.
Harvey, H. H. and F. E. J. Fry. 1973. Sport fish index, pp.
139-190. In; The approach, theory, methodology and
application of a lakeshore capacity model. Univ. of
Toronto Environmental Sci. Publ. EG-10.
Hayes, F. R. 1957. On the variation in bottom fauna and fish
yield in relation to trophic level and lake dimensions.
Trans. Amer. Fish. Soc. 14:1-32.
236
-------
Hayes, F. R. and E. H. Anthony. 1964. Productive capacity of
North American lakes as related to the quantity and the
trophic level of fish, the lake dimensions and the water
chemistry. Trans. Amer. Fish. Soc. 93:53-57.
Henderson, J. F. , R. A. Ryder and A. W. Kudhoghania. 1973.
Assessing fishery potentials of lakes and reservoirs. J.
Fish. Res. Bd. Can. 30:2000-2009.
Hetling, L. J. 1974. Observation on the rate of input into
Lake George and its relationship to the lake's trophic
state. New York State Dept. Environmental Conservation
Tech. Paper No. 36. 20 pp.
Hetling, L. J. and R. M. Sykes. 1971. Sources of nutrients
in Canadarago Lake. New York State Dept. Environmental
Conservation Tech. Paper No. 3. 35 pp.
Hutchinson, G. E. 1957. A treatise on limnology. Vol. 1
Geography, physics, and chemistry. John Wiley and Sons,
Inc. 1015 pp.
Kerekes, J. J. 1975. The relationships of primary production
to basin morphometry in five small oligotrophic lakes in
Terra Nova National Park in Newfoundland. Symp. Biol.
Hung. 15:35-48.
Kerekes, J. J. 1973. The influence of water renewal on the
nutrient supply in small, oligotrophic (Newfoundland) and
highly eutrophic (Alberta) lakes. pp. 383-400. In;
Proceedings-symposium on lakes of western Canada. Univ.
of Alberta Water Resources Center Publ. No. 2.
237
-------
Likens, G. E. 1974. Water and nutrient budgets for Cayuga
Lake, New York. Cornell Univ. Water Resources and
Marine Sciences Center Tech. Kept. No. 82. 91 pp.
Michalski, M. F. P., M. G. Johnson and D. M. Veal. 1973.
Muskoka Lakes water quality evaluation. Ontario Min.
of the Environment Rept. No. 3. 84 pp.
Mills, E. L. 1975. Phytoplankton composition and comparative
limnology of four, Finger Lakes, with emphasis on lake
typology. Ph. D. Thesis. Cornell Univ. 316 pp.
Northcote, T. G. and P. A. Larkin. 1956. Indices of pro-
ductivity in British Columbia Lakes. J. Fish. Res. Bd.
Can. 13:515-540.
Oglesby, R. T. MS 1974. The limnology of Cayuga Lake, New
York. Monograph prepared for North American Lakes Project.
Oglesby, R. T. and W. R. Schaffner. 1975. The response of
lakes to phosphorus, pp. 25-57. Chap. 2. In: K. S.
Porter (ed.) Nitrogen and phosphorus: food production,
waste and the environment. Ann Arbor Science Publishers,
Inc.
Rawson, D. S. 1960. A limnological comparison of twelve large
lakes in northern Saskatchewan. Limnol. Oceanogr. 5:195-
211.
Rawson, D. S. 1956. Algal indicators of trophic lake types.
Limnol. Oceanogr. 1:18-25.
Rawson, D. S. 1955. Morphometry as a dominant factor in the
productivity of large lakes. Verh. Intrenat. Verein.
Limnol. 12:164-175.
238
-------
Rawson, D. S. 1952. Mean depth and fish production of large
lakes. Ecology 33:513-521.
Rawson/ D. S. 1951. The total mineral content of lake waters.
Ecology 32:669-972.
Ryder, R. A. 1965. A method for estimating the potential fish
production of north-temperate lakes. Trans. Am. Fish. Soc,
94:214-218.
Ryder, R. A. 1961. Fisheries management in northern Ontario.
Ont. Fish. Wildl. Rev. 1:13-19.
Ryder, R. A., S. R. Kerr, K. H. Loftus and H. A. Regier. 1974.
The morphoedaphic index, a fish yield estimator - review
and evaluation. J. Fish. Res. Bd. Can. 31:663-688.
Sakamoto, M. 1966. Primary production by phytoplankton
community in some Japanese lakes and its dependence on
lake depth. Arch. Hydrobiol. 62:1-28.
Shampine, W. J. 1973. Chemical quality of surfaqe water in
the Eastern Oswego River basin, New York. New York State
Department of Environmental Conservation. Basin Planning
Rept. No. ORB-6. 100 pp.
Stewart, K. M. and S. J. Markello. 1974. Seasonal variations
in concentrations of nitrate and total phosphorus, and
calculated nutrient loading for six lakes in western New
York. Hydrobiologia 44:61-89.
Vollenweider, R. A. 1975. Input-output models with special
reference to the phosphorus loading concept in limnology.
Schweiz. Z. Hydrol. 37:53-83.
239
-------
Vollenweider, R. A. 1968. Scientific fundamentals of the
eutrophication of lakes and flowing waters, with particular
reference to phosphorus and nitrogen as factors in
eutrophication. OECD Tech. Report DAS/CS1/68.27. 159 pp.
Vollenweider, R. A. and P. J. Dillon. 1974. The application
of the phosphorus loading concept to eutrophication
research. Nat. Res. Counc. Can. Publ. No. 13690. 42 pp.
240
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
FPA-finn/3-7Q-074
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Lake and Reservoir Classification Systems
5. REPORT DATE
July 1979 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Thomas E. Maloney (editor)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Environmental Research Laboratory—Corvallis
Office of Research and Development
U.S. Environmental Protection Agency
Corvallis, Oregon 97330
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
same
113. TYPE OF REPORT AND PERIOD COVERED
final
114. SPONSORING AGENCY CODE
EPA/600/02
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This publication contains a series of articles dealing with the trophic
classification of lakes and reservoirs. These articles are concerned with
the history of lake and reservoir classification systems and their present
day use.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
lake restoration
eutrophication
reservoirs
lakes
water pollution
06/F
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
248
Release to Public
20. SECURITY CLASS (This page)
Unclassifiej
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
241
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