PB83-250035
EPA-600/3-83-075
August 1983
EFFECTS OF PHOSPHORUS LOADING
ON PHYTOPLANKTON DISTRIBUTION
AND CERTAIN ASPECTS OF CYTOLOGY
IN SAGINAW BAY, LAKE HURON
by
E. F. Stoermer,
L. Sicko-Goad, and
L. C. Frey
Great Lakes Research Division
The University of Michigan
Ann Arbor, Michigan 48109
Grant No. 802780
Project Officer
Nelson A. Thomas
Great Lakes Research Laboratory
Environmental Research Laboratory - Duluth
Grosse lie, Michigan 48138
ENVIRONMENTAL RESEARCH LABORATORY - DULUTH
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
DULUTH, MINNESOTA 55804
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NOTICE
This document has been reviewed in accordance with
U.S. Environmental Protection Agency policy and
approved for publication. Mention of trade names
or commercial products does not constitute endorse-
ment or recommendation for use.
11
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ABSTRACT
Phytoplankton abundance and species composition in Saginaw Bay reflects
very high nutrient and conservative ion loadings. Typical of nutrient
stressed systems, seasonal succession and areal distribution are highly
variable, and large abundance and composition changes may be generated by
local meteorological events. Spring flora are dominated by diatoms such as
Fragilaria capucina and Stephanodiscus binderanus, which are associated with
the most eutrophied regions in the Great Lakes. Atypically large numbers of
benthic diatoms occur in Saginaw Bay plankton. Following the spring diatom
bloom, assemblages become dominated by blue-green and green algae, apparently
due to rapid silica depletion. Nuisance populations such as Aphanizomenon
flos-aquae and Anacystis cyanea are common. In late summer there is a second
increase in diatom abundance, apparently due to regeneration and recircula-
tion of silica from the sediments. This secondary diatom bloom is composed
of species such as Actinocyclus normanii var. subsalsa and Melosira granulata.
Our results show substantial export of phytoplankton populations from
the bay to Lake Huron. Under average wind conditions, most export occurs
along the southern coast and these populations are then entrained in the
general Lake Huron circulation and spread down the Michigan coast southward
from the bay. Under certain advective conditions, however, phytoplankton may
be discharged from the bay either northward or directly offshore.
Cytological analysis shows that many of the species present sequester
phosphorus in excess of their immediate physiological needs in the form of
polyphosphate bodies. Polyphosphate body formation may be triggered by
conditions which interfere with normal phosphorus metabolism. These include
phosphorus starvation followed by excess resupply, deficiencies in other
essential nutrients, or toxic effects which limit growth but not phosphorus
uptake. All of these conditions may occur in Saginaw Bay. Our analysis
further shows that populations exported from the bay contain excess
phosphorus and this biologically entrained loading may affect other areas of
southern Lake Huron.
Analysis of polyphosphate bodies also shows that significant quantities
of certain toxic trace metals, notably Pb, are incorporated into these
inclusions. The ultimate fate of this material has not been demonstrated,
but it may represent a previously unrecognized type of biological
incorporation and transport important in some areas of the Great Lakes.
We also investigated the relationship of total phytoplankton cell vol-
ume to protoplasmic constituent volume using quantitative morphometric
techniques. This analysis shows that crude cell volume furnishes a poor
estimate of actual living biomass in many populations, and indicates that
more refined techniques are necessary to correctly convert estimates of cell
number to estimates of biomass.
ill
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CONTENTS
Abstract
Figures vi
Tables ix
Introduction 1
Major Components of this Project 4
Section 1 5
Distribution of Major Phytoplankton Groups 5
Materials and Methods 5
Discussion 55
References 62
Section 2 64
Biomass Estimates 64
Introduction 64
Materials and Methods 64
Quantitative Stereological Methods 65
Results and Discussion 69
Descriptive Electron Microscopy 69
Anabaena flos-aquae (Cyanophyceae) 69
Cell Wall -- 69
"Pseudovacuole" 69
Nitrogen Storage 72
Phosphate Storage 72
Stephanodiscus binderanus and Fragilaria capucina
(Bacilliarophyceae) TTT 72
Frustule 72
Vacuole 75
Storage Products 75
Chloroplast 75
Cytoplasm 75
Euglena viridis (Euglenophyceae) 75
Cell Wall 75
Vacuole 77
Storage Products 77
Chloroplast 77
Cytoplasm 77
iv
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Cryptomonas erosa (Cryptophyceae) 77
Cell Wall 77
Vacuole 79
Storage Product 79
Chloroplasts 79
Cytoplasm 79
Peridinium lindemanni (Dinophyceae) 79
Cell Wall -- 79
Vacuole 79
Storage Products 81
Chloroplast 81
Cytoplasm 81
Prymnesiophycean Algae - Two Undetermined Species 81
Cell Wall 83
Vacuole 83
Storage Products 83
Chloroplasts 83
Cytoplasm 83
Quantitative Electron Microscopy 83
Sample Size Determination 83
Filament Analysis 84
General Descriptive Measures 84
Anabaena flos-aquae 87
Stephanodiscus binderanus and Fragilaria capucina 87
Euglena viridis 87
Cryptomonas erosa 90
Peridinium lindemanni 90
Prymnesiophycean Algal Species 1 and 2 90
Discussion 90
References 95
Section 3 100
Luxury Consumption, Storage, and Transport of Phosphorus
in Saginaw Bay 100
Introduction 100
Materials and Methods 101
Light Microscopy 101
X-Ray Energy Dispersive Analysis 101
Phosphate Uptake in Diatoma E1ongatum 101
Results 102
Discussion 105
References 109
Appendix 1. Phytoplankton of Saginaw Bay (Lake Huron), 1974-1976 112
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FIGURES
Number
Section 1
1 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 25 March 1974
2 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 6 April 1974
3 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 28 April 1974
4 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 13 May 1974
5 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 3 June 1974
6 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 17 June 1974
7 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 8 July 1974
8 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 24 July 1974
9 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 25 August 1974
10 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 18 September 1974
11 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 6 October, 1974
12 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 11 November 1974
13 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 16 December 1974
14 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 20 February 1975
15 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 8 April 1975
16 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 28 April 1975
17 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 20 May 1975
18 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 5 June 1975
6
8
9
10
11
12
14
15
16
17
19
20
21
22
24
25
26
27
VI
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19 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 25 June 1975
20 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 11 July 1975
21 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 29 July 1975
22 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 18 August 1975
23 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 3 September 1975
24 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 23 September 1975
25 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 9 October 1975
26 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 27 October 1975
27 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 16 November 1975
28 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 16 December 1975
29 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 27 January 1976
30 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 11 March 1976
31 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 27 April 1976
32 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 12 May 1976
33 Distribution of major phytoplankton groups in Saginaw Bay for
v cruise beginning 1 June 1976
34 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 18 June 1976
35 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 8 July 1976
36 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 28 July 1976
37 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 11 August 1976
38 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 31 August 1976
39 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 18 September 1976
40 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 7 October 1976
41 Distribution of major phytoplankton groups in Saginaw Bay for
cruise beginning 10 November 1976
28
30
31
32
34
35
36
37
39
40
41
43
44
45
46
48
49
50
52
53
54
56
57
VII
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Section 2
Key to Figure Legends 70
1 Anabaena flos-aquae X250 71
2 Anabaena flos-aquae X8600 71
3 Anabaena flos-aquae XI8,800 71
4 Anabaena flos-aquae X27,300 71
5 Stephanodiscus binderanus X980 73
6 Stephanodiscus binderanus X10,000 73
7 Stephanodiscus binderanus XIO.OOO 73
8 Stephanodiscus binderanus X9050 73
9 Fragilaria capucina X750 74
10 Fragilaria capucina X8250 74
11 Fragilaria capucina XI8,200 74
12 Euglena veridis X1060 76
13 Euglena veridis X5280 76
14 Euglena veridis X12,100 76
15 Cryptomonas erosa X2130 78
16 Cryptomonas erosa X12,300 78
17 Cryptomonas erosa X22,900 78
18 Peridinium lindemanni X810 80
19 Peridinium lindemanni X6960 80
20 Peridinium lindemanni X6540 80
21 Haptophyte #1 X25.700 82
22 Haptophyte #2 X31,500 82
23 Cumulative mean (percent volume) as a function of sample size
(number of micrographs) for five cytoplasmic components of
P_. lindemanni and Hap. 1 85
Section 3
1 An undetermined small blue-green alga with large polyphosphate
(PP) bodies in both electron lucent and electron dense regions
of the cell 104
2 Anacystis sp. with polyphosphate bodies (PP) 104
3 Fragilaria capucina with small polyphosphate bodies (pp)
in the vacuole (V), which is surrounded by the chloroplasts (C)
and other cellular organelles.... 104
4 Scenedesmus sp. with large polyphosphate bodies in the vacuole 104
5 Marginal region of the Diatoma tenue var. elongatum cell show-
ing chloroplast (C), mitochondria (M), and the vacuole (V)... 106
6 Vacuolar (V) region of Diatoma tenue var. elongatum cell 106
7 X-ray spectrum of Diatoma tenue var. elongatum
polyphosphate bodies 106
Vlll
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TABLES
Number
Section 2
1 Sampling scheme employed for morphometric analysis 66
2 Cell volume estimates for the eight phytoplankton
spec ies examined 68
3 Analysis of variance (ANOVA) of between and within
filament variance 86
4 Percent volumes of cytoplasmic compartments in eight
phytoplankton species 88
5 Absolute volumes of defined areas in the algae .... 89
Section 3
Distribution of polyphosphate bodies in naturally-occurring
phytoplankton in Saginaw Bay 103
IX
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INTRODUCTION
Saginaw Bay has probably always been one of the more productive regions
within the Great Lakes system. The productivity of the fishery resource was
undoubtedly one of the factors attracting early settlement in the area.
Other natural resources of the drainage basin provided the incentive for
early settlement and substantial economic growth in the region. The timber
resources of the Saginaw River and its tributaries were rich and easily
accessible which led to early development of the area and the establishment
of an early industrial base. Once cleared of its natural vegetation, much of
the land was found suitable for intensive agricultural practices. Finally,
the presence of subsurface resources, primarily petroleum and salt, made
possible the establishment of one of the midwest's centers of chemical
industry. Unfortunately, the development of the Saginaw-Bay City-Midland
industrial complex and intensive regional agriculture proceeded at the
expense of severe deterioration of water quality within Saginaw Bay. At the
present time it is one of the most seriously modified parts of the Great
Lakes system. During the past few decades Saginaw Bay has been beset with
water quality problems including obnoxious algal blooms, taste and odor
problems in municipal water supplies, and fish flesh tainting. The history
of these problems and the context of the present investigation have been
outlined by the International Joint Commission (1976). The literature
pertaining to pollution problems in Saginaw Bay has been reviewed by Freedman
(1974) and need not be extensively recapitulated here. It should be pointed
out, however, that the perturbation of primary producer communities in this
region reflects the effects of many factors. The most obvious of these are
the effects of excessive nutrient loadings. At the present time the waters
of Saginaw Bay are probably the most productive in the entire Great Lakes
system. The composition of the phytoplankton and benthic algal flora also
reflects the effects of extreme conservative element loadings. Although
these loadings have apparently been decreased to some degree in recent years
(Smith et al., 1977), the flora of the bay still contains many elements
usually found in brackish water localities. Finally, although not
experimentally documented, certain population distributions within the bay
can most plausibly be explained by direct toxic effects.
Saginaw Bay is also an extremely dynamic system. There are strong
gradients in almost all factors of physiological interest between the lower
bay and the open waters of Lake Huron. As might be expected, these gradients
are reflected in the population and community responses of the phytoplankton
flora. This situation is complicated by the physical dynamics of the system
(Richardson, 1974). Idealized dilution gradients are grossly modified by
mass transport of water masses and their entrained chemical constituents,
fauna, and flora into and away from the bay. Schelske et al. (1974) have
demonstrated the transport of populations developed in Saginaw Bay into the
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open waters of Lake Huron. One of the most interesting aspects of this study
is the fact that there appears to be considerable selection among the
population components of the assemblage being transported. Certain
populations, primarily blue-green algae, appear to be conserved, in the sense
that their abundance is highly correlated with the concentration of
biologically conservative chemical elements being discharged from the bay.
Other populations, primarily diatoms, are apparently subjected to much
greater losses during transport. Because of the different physical
characteristics of the populations involved, it is attractive to attribute
such losses to sinking. Without further direct evidence, however, other
possible losses, such as predation or direct cell death and lysis, cannot be
excluded. Equally interesting, conservation of mass demands that transient
mass flow export of water from Saginaw Bay be compensated by import of water
masses from Lake Huron. Such water masses contain biological communities
adapted to physical and chemical conditions found in the open lake. As they
are diluted with, and enriched by, Saginaw Bay water such populations might
be expected to undergo variable responses ranging from death to growth
stimulation depending on both their own physiological requirements and the
degree and rate of mixing.
A meaningful analysis of such a dynamic system requires either extremely
intensive sampling, both areally and timewise, or recourse to simulation of
the system from a more limited measurement base. Since a sampling program of
the density demanded is probably beyond the available regional resources, and
the simulation approach offers the additional advantage of making more
reasonable forecast and hindcast projections, the primary emphasis in this
project was directed toward facilitating this type of analysis. A number of
types of information regarding phytoplankton are necessary. Since any
assemblage is likely to contain representatives of several major
physiological groups with differing absolute or relative nutrient
requirements, it is necessary that qualitative information be retained in the
model data input. It is also necessary that the input be in some uniform
measure. Since phytoplankton cells vary considerably in size, even within a
given species, it is highly attractive to rely upon some secondary estimate
of biomass such as total carbon or extracted chlorophyll.
Unfortunately this approach, although the one generally utilized in such
studies, is subject to a number of difficulties and the correlation between
such measures and independent estimates of phytoplankton biomass for
assemblages occurring in the Great Lakes is often surprisingly low
(Vollenweider et al., 1974). Although considerably more laborious, direct
enumeration of the cells present and subsequent reduction of this information
to some standard unit appears to offer a desirable alternative, especially
since qualitative information can be preserved in the resultant data set.
Although perhaps the most desirable approach, this method is not without its
own significant difficulties. The most generally utilized approach is to
estimate the volume of the cells present, then to directly convert the
volumetric estimate to mass. As may be easily appreciated, precise estimates
of volume are difficult to obtain because of the complex form of many species
and the degree of variability present in many populations. A fundamentally
more serious problem is the variation in cytologic structure and composition
between the major physiological groups of phytoplankton or, in some cases,
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within members of a single division. It has long been recognized (Lohmann,
1908) that relatively large proportions of the total volume of the cells of
certain phytoplankton species are constituted by their vacuoles. If the
fractional volume constituted by metabolically inert wall materials is added
to this, it is easy to see that direct conversions from cell volume to
estimates of biomass are difficult to interpret precisely. It is indeed
unfortunate that estimates of phytoplankton abundance in the current
literature are reported in units of "biovolume" since this neither provides
an unambiguous estimate of biomass nor preserves individual population
abundance information. Perhaps the most commonly utilized method of
converting phytoplankton abundance estimates to estimates of biomass is
regression of cell volume or plasma volume estimates on independent estimates
of cell carbon content (Strathmann, 1967). While this method may be
applicable when dealing with relatively homogeneous oceanic phytoplankton
assemblages, it is somewhat questionable in a situation such as Saginaw Bay
which has exceedingly diverse assemblages containing many pseudoplanktonic or
tychoplanktonic populations.
These considerations make it evident that determination of precise
estimates of phytoplankton composition and biomass within the Saginaw Bay
system is a considerable challenge within the inevitable constraints of
available resources. Additional constraints are introduced by consideration
of the overall project objectives. The entire investigation involved the
first really large scale investigation on the Lake Huron system and consisted
of several components. Although each of the components was the prime
responsibility of a separate laboratory, they are linked to the project
reported here through a common sampling base. In some cases the data
generated by this project have been incorporated into the results of other
projects. The major projects interfacing with this one are the following:
1. A study of physical and chemical conditions in Saginaw Bay reported
by Smith et al. (1977).
2. Construction of a process oriented model of Saginaw Bay reported by
Biermann et al. (1980). One of the major efforts in the present
investigation was the generation of phytoplankton volume/abundance estimates
which provided a major input to the above study. The synthesized results of
this effort are reported there.
3. Studies of the distribution of primary consumer organisms in Saginaw
Bay and southern Lake Huron (Gannon, in prep., Stemberger et al. (1979).
4. Studies of physical and chemical conditions and biological
productivity in southern Lake Huron by Schelske et al. (1980).
5. A study of phytoplankton abundance and distribution in southern Lake
Huron by Stoermer and Kreis (1980).
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MAJOR COMPONENTS OF THIS PROJECT
The major effort in this investigation was to provide data on
phytoplankton biovolume to support a model of processes in Saginaw Bay. This
information has been reported by Beirmann et al. (1980). For purposes of the
model, the data were summarized in categories representing the major
physiological groups of phytoplankton which occupy the base. It was felt
that the actual numbers of organisms and the time sequence of development are
also important in interpreting trends within the bay. This information is
reported in the first section of the present report.
The interpretation of cell volumes in terms of biotnass, although
demonstrably preferable to traditional methods of biomass estimation,
contains certain problems which have not been adequately addressed. As part
of this study, we undertook research directed to developing a method of
estimating the actual viable fraction of the cell volumes of representatives
of the various physiological groups of phytoplankton found in Saginaw Bay.
The results of this study are presented in Section 2 of this report.
Relatively early in the project it became apparent that at least certain
populations generated within Saginaw Bay exhibit delayed response to
phosphorus enrichment, or at least thrive far beyond the zones of the bay
most directly affected by high phosphorus loadings. Since some blue-green
algal populations contained polyphosphate bodies apparent at the light
microscope level, we undertook further research to investigate several
questions:
1. Are polyphosphate bodies quantitatively important in some of the
more abundant potential nuisance organisms, particularly species of
bluegreen algae?
2. Are the bodies present in populations advected from the bay in
sufficient quantitatives to allow further growth of potential nuisance
organisms in southern Lake Huron?
3. Are the eukaryotic organisms which display distribution patterns
similar to thse blue-green algal populations also capable of storing excess
phosphorus in areas of high loading and subsequently metabolizing it after
being advected into areas not receiving direct loadings?
The results of this study are reported in Section 3 of this report.
Also, as part of this study, we discovered that appreciable quantities of
certain heavy metals, particularly Pb, are also sequestered in polyphosphate
bodies in Saginaw Bay phytoplankton. These observations have been separately
published (Stoermer et al., 1980).
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SECTION 1
DISTRIBUTION OF MAJOR PHYTOPLANKTON GROUPS
MATERIALS AND METHODS
The samples utilized in this study were taken in conjunction with water
chemistry and zooplankton samples as part of the combined study discussed
above. The general sampling strategy employed has been discussed by Smith
et al. (1977) and will not be recapitulated here.
In most instances phytoplankton samples were taken by submersible pump.
In some cases either Niskin or Van Dorn bottles were used due to mechanical
failures of the pumping system. In all cases the phytoplankton samples were
taken in 125 ml polyethylene bottles and fixed with 4% (vol./vol.)
glutaraldehyde immediately upon collection. Samples were kept on ice in
darkness until they were processed into slides.
Material was prepared for analysis by the membrane clearing technique
(Schelske et al., 1976). In most instances 50 ml of the original fixed
sample was prepared. Due to the extremely dense phytoplankton assemblages
encountered at some stations, it was necessary to reduce the volume filtered
in some preparations to either 25 or 12.5 ml.
Population estimates were developed from replicate 1 mm strip counts of
randomly selected areas of the slide preparations. Populations present were
enumerated and the mean dimensions of the taxa were recorded. Estimates of
the volume of the phytoplankton present were developed from calculations
based on approximate shape formulae of the species present. The volume data
were converted to an estimate of carbon biomass (Bierman et al., 1980).
Material fixed according to the schedule used for preparation for
electron microscopy (see Section 2) was used for verification of
identifications in some instances, since this procedure finishes superior
preservation of cellular structure.
The first sampling cruise took place 25 March. Relatively few stations
were actually sampled due to adverse weather conditions. Diatoms were
dominant in the samples taken, with very large populations present at cne
station in the southeastern sector (Fig. 1). The abundance of diatoms at
this station dominated the total abundance pattern, since other stations had
much smaller phytoplankton densities. Other groups were of minor importance.
Green and blue-green algae were noted at scattered stations, but heterocyst
forming blue-greens were totally absent. Flagellates were present at all
stations, but did not approach diatoms in total numbers.
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Figure 1. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 25 March 1974.
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Much more complete sampling, particularly of the lower bay, was
accomplished during the second cruise which began 16 April (Fig. 2).
Although no station achieved the very high total phytoplankton density noted
during the previous cruise, there was an increase in the average
phytoplankton abundance at the stations sampled. Diatoms again were the most
abundant group, although the abundance of other groups increased
significantly. Isolated large populations of green and blue-green algae were
found, although heterocyst-forming blue-greens were still essentially absent.
The distribution of flagellates was interesting. Largest abundances were
found in the western half of the bay, which was opposite the trend of diatom
abundance.
The fourth cruise began 28 April (Fig. 3). Total phytoplankton
abundance continued to increase, with the largest proportional increases
occurring in the flagellate groups. As had been true during the previous
sampling period, there appeared to be an inverse relationship between the
abundance of diatoms and flagellates. Green algae began to appear in
significant abundance at stations in and near the Saginaw River. The
abundance of blue-green algae remained relatively low, and heterocyst-forming
taxa were still essentially absent.
The fifth cruise was started 13 May (Fig. 4). Overall phytoplankton
abundance continued to increase and extremely large abundances were noted at
stations near the mouth of the Saginaw River. All of the major phytoplankton
groups were abundant at one or more stations in this region. Flagellates
were less abundant at most stations than during the previous cruise, but
green and blue-green algae continued to increase. Relatively large
populations of heterocyst-forming blue-green algae were found for the first
time, particularly at shoreward stations.
The sixth cruise was begun 3 June (Fig. 5). During this cruise, a
distinct change in the distribution and abundance of major phytoplankton
groups became apparent. Diatoms remained abundant at stations in the
vicinity of the Saginaw River, but were generally reduced in abundance at
stations in other parts of the bay. It appeared that populations were
maintained in this region as a direct result of nutrient resupply from the
Saginaw River, while populations in other regions of the bay were becoming
nutrient limited. Green and blue-green algae became more important elements
of assemblages, particularly at stations in the southern and eastern sectors
of the bay. The distributions noted are probably indicative of incipient
secondary silica and nitrogen limitation and transport of excess phosphorus
along the eastern coast of the bay.
The next cruise was undertaken 17 June (Fig, 6). Sampling during this
period showed a substantially different trend in phytoplankton abundance and
distribution than the previous sampling round. Phytoplankton abundance
generally declined and the distribution of major groups was more erratic than
it had been during the previous sampling. Relatively large abundances of
total phytoplankton and particularly diatoms and green algae were found at
stations in the southeastern sector of the outer bay. It appeared that
during this period these populations were being advected from the bay to Lake
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00
Figure 2. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 6 April 1974.
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Figure 3. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 28 April 1974.
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Figure A. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 13 May 1974.
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Figure 5. Distribution of major phytoplankton groups in Saginaw Bay for
beginning 3 June 1974.
cruise
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Figure 6. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 17 June 1974.
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Huron along the southeastern shore. One of the unusual features of this
sample set was the extreme abundance of total phytoplankton and all of the
major groups at Station 44, near Oak Point. The reason for the atypical
abundance at this particular station is not apparent.
Cruise 8 was begun 8 July (Fig. 7). Phytoplankton distribution at this
time was quite different than during the previous sampling period. Total
phytoplankton abundance declined, and high population densities were
restricted mostly to stations in the lower bay and stations along the
southeastern shore. The abundance of diatoms declined sharply except at
stations in the Saginaw River and immediately adjacent to its mouth. Green
and blue-green algae remained relatively abundant, but heterocyst-forming
blue-green algae were restricted to stations in the southeastern segment of
the area sampled. Relatively low abundance of flagellates was noted at all
stations sampled. The most unusual feature of the results from this cruise
is the extremely low abundance of phytoplankton in segment 4 of the sampling
array. As was the case in the previous set, it appeared that phytoplankton
from the lower bay was being transported along the southeastern coast of
Saginaw Bay and into Lake Huron.
The next sampling round was undertaken 24 July (Fig. 8). Phytoplankton
distribution during this sampling period was again markedly different than it
had been during the previous sampling interval. Total abundance increased
somewhat, but abundance consistently declined along the long axis of the bay
and there was no evidence of particularly high abundance along the southern
shore, as there had been previously. Stations along the Lake Huron interface
and most stations in segment 5 had very low phytoplankton abundance. Large
populations of diatoms and heterocyst-forming blue-green algae were
restricted to stations near the mouth of the Saginaw River. Large
populations of diatoms were found at stations in the river, but blue-greens
were not particularly abundant except in the bay.
The next sampling cruise began 25 August (Fig. 9). By this time the
total abundance of phytoplankton had generally decreased. Assemblages were
dominated by blue-green algae, although the abundance of diatoms had
recovered slightly from the levels observed during the previous cruise.
Population distributions of all groups was rather uniform, with a decrease in
abundance from the lower bay to the Lake Huron interface. During this
cruise, greatest phytoplankton abundance occurred at Station 50, the central
station on the Lake Huron interface, rather than at shoreward stations as had
been the general case previously. Flagellate numbers were very low during
this cruise and the largest populations were found in the lower bay.
A further decline in peak phytoplankton abundance was noted during the
next sampling cruise, which began 18 September (Fig. 10). Relatively high
levels of total phytoplankton standing crop extended further toward the Lake
Huron interface however, particularly at stations along the southeastern
shore. The flora was dominated by blue-green algae, particularly taxa which
do not form heterocysts. Significant populations of heterocyst-forming
species were restricted to stations immediately along the southeast shore.
Diatoms were most abundant in the Saginaw River, but significant populations
were present at most stations sampled. Diatoms increased in abundance at
13
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Figure 7. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 8 July 1974.
-------
Figure 8. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 24 July 1974.
-------
Figure 9. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 25 August 1974.
-------
Figure 10. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 18 September 1974.
-------
stations in the Lake Huron interface, but the assemblage in this region
contained a completely different suite of populations than was present in the
Saginaw River or in the lower bay. Green algae were a relatively important
part of assemblages sampled at most stations. Unusually high numbers of
diatoms, green algae, and flagellates occurred at Stations 47 and 48 in
Tawas Bay.
The next sampling cruise was delayed until 6 October (Fig. 11). By this
time the general level of phytoplankton standing crop had increased somewhat
in most areas of the bay. Blue-green algae remained the dominant element of
the flora, but diatoms had increased significantly in abundance, particularly
at nearshore stations. Heterocyst-forming blue-green algae were less
abundant than during the previous sampling period, but populations were
present at most stations sampled. Green algae remained important at most
stations sampled and they, together with diatoms and flagellates, were the
most important components of the Saginaw River flora as it entered the bay.
The relative abundance of flagellates was also high at stations in the Lake
Huron interface, although a different suite of species was present there than
in the river and lower bay.
The next samples were taken 11 November (Fig. 12). Although less than
complete sampling was achieved, a reasonably complete reconstruction of
phytoplankton distribution within the bay can be made. Total phytoplankton
standing crop decreased significantly from levels of the previous month.
Diatoms were the dominant element at most stations sampled, although
blue-green algae remained abundant, particularly at nearshore stations and
stations in the lower bay. The abundance of heterocyst-forming taxa was much
reduced and only small populations were found at scattered stations. Green
algae and flagellates were relatively minor elements of assemblages at
stations sampled. In the lower bay there appeared to be an inverse
relationship between the abundance of these two groups.
Only a very limited number of stations in the lower bay and in the
Saginaw River were sampled on 16 December (Fig. 13). Somewhat surprisingly,
the total abundance of phytoplankton at the stations sampled was relatively
high. The flora was dominated by diatoms, with a minor and approximately
equal contribution of blue-green algae and flagellates. Unlike previous
samples, flagellates were most abundant in samples from the Saginaw River.
Green algae were present, in low abundance, at most stations sampled, but
heterocyst-forming blue-green taxa were not noted in this set of samples.
A similarly small number of stations in the lower bay were sampled on
20 February 1975 (Fig. 14). Surprisingly high total phytoplankton abundance
was found at a series of stations in the western half of segment 1. Diatoms
dominated the flora in this region and in total. Flagellates were relatively
abundant at a number of nearshore stations sampled. Significant quantities
of green algae were found only at Station 59, although a few specimens of
species in this group were noted at most stations sampled. Blue-green algae
were virtually absent, although a small population of Oscillatoria was found
at Station 14.
18
-------
Figure 11. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 6 October 1974.
-------
Figure 12. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 11 November 1974.
-------
Figure 13. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 16 December 1974.
-------
Figure 14. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 20 February 1975.
-------
A more comprehensive set of samples was obtained on a cruise beginning
8 April (Fig. 15). Although the maximum abundance was significantly reduced
from the levels noted during the previous sampling period, relatively high
levels of phytoplankton standing crop were found at stations in the inner
bay. During this period the flora was completely dominated by diatoms,
although green algae and flagellates were found in most assemblages sampled.
Blue-green algae were not present in significant abundance except at
Station 30.
The next cruise in the sequence was undertaken 28 April (Fig. 16).
Total phytoplankton abundance had increased from levels of the previous
month. The flora was still dominated by diatoms, but increasing quantities
of green and blue-green algae were present, particularly at stations in the
lower bay and along the eastern shore. Heterocyst-forming blue-greens were
still virtually absent at all stations sampled. Flagellates were present in
moderate abundance and representatives of this group were generally
distributed at the stations sampled.
By the time the next cruise was undertaken on 20 May (Fig. 17), maximum
levels of phytoplankton abundance in the bay had decreased somewhat. Unlike
the previous month, however, relatively high levels of abundance were found
at shoreward stations in the Lake Huron interface area. This increase was
accounted for mostly by diatoms, which remained the most abundant component
of the flora. Diatoms were abundant in the Saginaw River and at most
stations in the bay. Green and blue-green algae, on the other hand, were
abundant only at stations in the inner bay. Green algae were particularly
abundant at a series of stations just off the mouth of the Saginaw River.
Somewhat atypically, flagellates were abundant in the Saginaw River and
adjacent stations, although certain populations were present at all stations
sampled.
The number of stations sampled was reduced during the next cruise, which
began 5 June (Fig. 18). At this time there was an extreme variance in
phytoplankton abundance among the stations sampled. This was exemplified by
a very high abundance of blue-green algae at Station 34 in Wild Fowl Bay.
Diatoms remained, overall, the most abundant of the major groups. Their
abundance at the stations sampled was quite variable. Atypically high
abundance was found at Station 36, near the mouth of the Au Gres River.
Green and blue-green algae continued to increase in abundance, particularly
at stations in segments 1 and 3 of the sampling array. Representatives of
the flagellate groups remained most abundant at stations in the lower bay.
The next sampling cruise began 25 June (Fig. 19). By this time total
phytoplankton abundance had been somewhat reduced at most open-water
stations, although high total numbers were found at a number of nearshore
stations. The abundance of diatoms was much reduced, except at stations in
and near the Saginaw River and at nearshore Stations 36 and 53. Green and
blue-green algae were abundant at most stations in the lower bay and a
particularly high abundance of this group was again noted at Station 34, in
Wild Fowl Bay. Flagellates remained abundant and were somewhat more
generally distributed than was the case in the previous cruise.
23
-------
hJ
-p-
Figure 15. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 8 April 1975.
-------
S3
Ln
Figure 16. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 28 April 1975.
-------
Figure 17. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 20 May 1975.
-------
Figure 18. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 5 June 1975.
-------
NJ
OO
Figure 19. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 25 June 1975.
-------
During the next cruise, which began 11 July, there was a rather striking
floristic differentiation between the inner and outer segments of the bay
(Fig. 20). During this sampling period total phytoplankton abundance was
markedly lower at stations southwest of Charity Island than in the outer bay.
This trend is accentuated in some of the major phytoplankton groups. Diatoms
were a relatively minor element of the flora during this cruise and there are
two regions of greatest abundance. One is in the Saginaw River and
immediately adjacent stations. The other is in the outer bay. The species
composition of these two regions is almost entirely different. In the other
major groups high abundance is restricted to stations in the lower bay.
Green algae are abundant during this sampling period and are generally
distributed at stations in the lower bay. The blue-green algae were the
dominant element of the flora in terms of peak abundance, but high numbers,
particularly of heterocyst-forming taxa, were more restricted to nearshore
areas. The occurrence of blue-green algae at Stations 44 and 53, along the
southern coast, indicates that these populations may have been transported
toward Lake Huron by shoreline drift. With the exception of one station, the
flagellates constitute a relatively minor fraction of the flora and the
populations present are largely restricted to the lower bay.
The next series of samples was taken beginning 29 July (Fig. 21).
Although total phytoplankton abundance had increased substantially by the
time these samples were taken, distribution of the major groups was somewhat
similar to that observed during the previous cruise. The abundance and
distribution of diatoms was even more strikingly disjunct than it had been
the previous month. Relatively high abundance was found in the Saginaw River
and at stations in segment 4, but the abundance of this group was low in the
rest of the bay. As was the case the previous month, different species
occupied the two regions of maximum abundance. Although green algae were not
as abundant as diatoms, significant populations were present at most stations
in the lower bay and at Stations 43 and 44 and 52 and 53 along the southern
shore of the outer bay. The distribution of blue-green algae was somewhat
irregular during this sampling period, but very large abundances were found
at some stations. Their distribution followed the same general pattern as
the green algae, although large populations of heterocyst-forming species
were found only at shoreward stations along the southern coast of the bay.
Flagellates were present in relatively low abundance and the populations
present were remarkably evenly distributed. Relatively high abundance of
organisms in this group was found at stations in the Saginaw River.
The next cruise in this sequence began 18 August (Fig. 22). Maximum
total phytoplankton abundance declined from levels observed during the pre-
vious sampling period. Greatest total phytoplankton density as found at sta-
tions in segments 3 and 5, along the southeastern coast of the bay.
Blue-green algae were the dominant element of the flora at this time and were
particularly abundant in this region. The distribution of green algae was
somewhat more uniform, and sizable populations of representatives of this
group were found at most stations in the lower bay. Highest green algal
abundance occurred at stations just off the mouth of the Saginaw River. The
abundance of diatoms was more uniform than it had been the previous month,
but there was still a large difference in the species composition of
different areas. Populations in the outer bay were mostly oligotrophic
29
-------
Figure 20. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 11 July 1975.
-------
Figure 21
Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 29 July 1975.
-------
Figure 22. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 18 August 1975.
-------
species common in the Lake Huron flora. Populations in the inner bay were
mostly species which thrive under eutrophic conditions and the populations in
the Saginaw River were taxa tolerant of extreme eutrophication and elevated
salinity. As had been the case during the previous sampling, flagellates
were a relatively minor constituent of the total phytoplankton assemblage and
largest populations were found at stations near the mouth of the Saginaw
River.
The next sampling was undertaken beginning 3 September (Fig. 23).
Maximum total phytoplankton abundance again increased and the flora was
dominated by extremely large concentrations of green and blue-green algae,
particularly at a series of stations in the vicinity of Sand Point. The
distribution of diatoms was essentially opposite that of the green and
blue-green algae, with greatest abundance of this group occurring at stations
along the northern coast of the bay. Some diatom populations were present at
all stations sampled, but there again was a large qualitative difference in
the diatom floras of different parts of the bay.
Only a very limited number of stations were sampled during the next
cruise, which began 23 September (Fig. 24), due to adverse weather
conditions. The stations sampled were all in the northern half of the bay,
in segments 1, 2, and 4. Based on this subset, total phytoplankton abundance
appeared to decline. Diatoms were most abundant, although significant
populations of blue-green algae were present at stations in the inner bay.
The abundance of green algae was much reduced and large populations were
noted only at Station 30. Flagellates were a minor element of most
assemblages sampled. They were most abundant at stations in the Saginaw
River and, as was also the case with the diatoms, different populations were
present in the river and lower bay than in the outer bay.
During the next sampling cruise, which began 9 October (Fig. 25),
phytoplankton distribution in the bay was atypical, compared to other months
sampled. Total phytoplankton abundance increased, and green algae were the
dominant element of the flora at most stations sampled. Large populations
were present in the Saginaw River and at shoreward stations along the
southern coast and this group was atypically abundant at all stations sampled
except for three stations in the Tawas Bay area. Blue-green algae were also
relatively abundant in the lower bay and significant populations occurred
even at the outermost line of stations sampled. During this sampling period
the total abundance of diatoms was relatively uniform throughout the bay, but
different species occupied different regions within the bay. Large
populations of species usually associated with more oligotrophic or open lake
conditions were noted in the Tawas Bay area.
During the next sampling period, which began 27 October (Fig. 26),
several stations in segment 3, which usually have high levels of
phytoplankton standing crop, were not sampled. The omission of these
stations was particularly unfortunate in this case because the highest
abundance of total phytoplankton was found at stations bordering the area
which was not sampled, and it is quite likely that the highest levels of
phytoplankton abundance in the entire bay actually occurred in the area
represented by the missing stations. This supposition is supported, to a
33
-------
Figure 23. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 3 September 1975.
-------
u>
Ol
0 L
Figure 24. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 23 September 1975.
-------
UJ
Figure 25. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 9 October 1975.
-------
Co
Figure 26. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 27 October 1975.
-------
certain extent, by the distribution of the major phytoplankton groups. Green
and blue-green algae are atypically abundant at Stations 42, 43, and 44,
which may indicate that these populations are being generated in the
unsampled area along the southern coast, as was the case in several previous
cruises, and then transported to these stations. The trend in diatom
abundance at these stations is opposite that of the heterocyst-forming
blue-green algae. Diatoms are relatively evenly distributed at the stations
sampled, compared to other groups of phytoplankton, but different species
were present in the outer bay than in the inner bay. Conditions at Stations
42, 43, and 44 are apparently less conducive to the growth of diatom species
occurring in the lower bay than to the green and blue-green algae. The
distribution of flagellates during this sampling period is highly atypical.
Large populations occur in the Saginaw River, but they are a minor component
of phytoplankton assemblages in the rest of the bay.
More complete sampling was achieved during the next cruise, which began
16 November, although some stations along the southeastern shore of the bay
were again omitted (Fig. 27). By this time, total phytoplankton abundance
had increased somewhat at the stations sampled, and the abundance of
phytoplankton was remarkably uniform throughout the bay. The distribution of
major groups during this period was unusual. Green algae were unusually
abundant at this time and very large populations were present at stations in
the outer bay, including some stations in the Saginaw Bay-Lake Huron
interface region. Relatively low abundance of this group was found at
stations in the lower bay, particularly those in the immediate vicinity of
the Saginaw River discharge. The trend in distribution of this group is thus
essentially opposite that observed during most other cruises. The
distribution of blue-green algae was somewhat similar, although the
occurrence of representatives of this group were so scattered that any trend
is somewhat obscured. The abundance of diatoms was again fairly uniform
throughout the bay but different populations were characteristic of different
areas of the bay. Flagellates remained abundant in the Saginaw River, but
were relatively more abundant at other stations than they had been the
previous month. As was the case with the diatoms, different species occurred
in the river than in the rest of the bay, and there was further differ-
entiation between stations in the inner bay and stations in the Lake Huron
interface region.
The next sampling cruise began 16 December (Fig. 28). Due to adverse
weather conditions only a limited number of stations were sampled, all in the
inner bay. Total phytoplankton abundance at the stations sampled was
drastically reduced from levels observed the previous month. Diatoms were
the dominant element of the flora, although significant populations of green
and blue-green algae were found at some stations. Not enough stations were
sampled to establish regional trends.
A similar limited array of stations was sampled during the next cruise,
which began 27 January 1976 (Fig. 29). Total phytoplankton abundance was
further reduced, but there was a trend for highest total phytoplankton
abundance to occur at stations in segment 3. The main group contributing to
this pattern was the green algae which were the dominant element of the flora
during this period. Blue-green algae without heterocysts and flagellates had
38
-------
Figure 27. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 16 November 1975.
-------
Figure 28. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 16 December 1975.
-------
Figure 29. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 27 January 1976.
-------
similar distribution patterns to the green algae, although they were minor
components of the flora at this time. Heterocyst-forming blue-green algae
were very rare. Diatoms were the second most abundant of the major groups
and the trend in abundance of this group was opposite the others.
Seasonal low in total phytoplankton abundance was found on the next
cruise, which began 11 March 1976 (Fig. 30). The abundance of total
phytoplankton was low at all stations sampled and abundance was fairly
uniform. The same series of stations was sampled as in the previous month.
Only scattered populations of green and blue-green algae were noted, with
most occurrences at nearshore stations. Heterocyst-forming blue-green algae
were not noted in any of the samples from this cruise.
During the next cruise, which began 27 April (Fig. 31), and in
subsequent cruises in the sequence, the array of stations sampled in the
project was reduced. Fewer stations were sampled in the lower bay and
intermediate lines of stations in the outer bay were eliminated. This
reduction in station density, and particularly the elimination of stations in
the transitional zone between the lower bay and the Lake Huron interface,
considerably reduced resolution in detecting trends in phytoplankton
abundance. During the 27 April cruise total phytoplankton abundance
increased with highest total abundance occurring at stations in mid-bay. The
flora was dominated by diatoms but green algae were an important element of
assemblages at several stations in the lower bay. Flagellates were widely
distributed, but their abundance was less than diatoms or green algae and, as
had been the case in several previous cruises, the trend in abundance of
flagellates tended to be opposite the trend in abundance of diatoms at
stations in the lower bay. At stations in the Lake Huron interface region
the abundance trends of these two groups were similar.
There was a very striking difference in the abundance and species
composition of phytoplankton assemblages collected at stations in the Lake
Huron interface region versus other stations sampled in the bay during the
next cruise, which began 12 May (Fig. 32). The apparent difference was
enhanced by the fact that the intermediate line of stations was not sampled,
as it had been in previous years. The differences in abundance and species
composition were, however, larger than had been observed in previous spring
sampling periods. Diatoms were the dominant element of the flora at most
stations sampled, although green algae were very abundant at a few mid-bay
stations. Highest numbers of flagellates and blue-green algae were found at
a line of stations southwest of Charity Island. Although the flagellate
groups were considerably more abundant than blue-greens, the similarity in
distribution was striking.
Only a limited number of stations were sampled on the next cruise, which
began 1 June (Fig. 33), due to adverse weather conditions. All of the
stations sampled were in the lower bay. Total phytoplankton abundance
increased at these stations, and extremely dense populations of green algae
were noted at stations in the vicinity of the Saginaw River mouth. Diatoms
remained relatively abundant as did flagellates, and atypically large
populations of flagellates were found at stations in the Saginaw River.
Blue-green algae were a fairly minor component of the flora and their
42
-------
Figure 30. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 11 March 1976.
-------
Figure 31. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 27 April 1976.
-------
Figure 32. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 12 May 1976.
-------
Figure 33. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 1 June 1976.
-------
distribution was scattered. Highest numbers of heterocyst-forming blue-
greens were found at stations near the Saginaw River mouth which had highest
total phytoplankton abundance and highest abundance of green algae.
More complete sampling was obtained on the next cruise, which began
18 June (Fig. 34). Maximum total phytoplankton abundance was reduced from
the extreme levels noted the previous month. Diatoms remained an important
element of assemblages at most stations sampled, although their abundance
relative to other groups was reduced. Highest numbers of diatoms were found
at a station in the Saginaw River. As had been the case in most previous
sampling periods, the species composition of the river station was
substantially different from stations in the bay. Green algae, flagellates,
and blue-green algae all increased in importance. Greens and blue-greens
tended to be most abundant at stations along the southern coast of the bay
while the flagellate groups tended to be most abundant at stations in the
northern sector of the lower bay. During this sampling period many
populations of green and blue-green algae characteristic of eutrophic water
and generally abundant at stations in lower Saginaw Bay were found at the
most southerly station in the Lake Huron interface. It appeared that these
populations were being advected out of the bay along the southern shore as
had been the case in several other summer cruises.
During the next cruise, which began 8 July (Fig. 35), much higher total
phytoplankton abundance was observed, particularly at stations in the lower
bay. Blue-green algae were the dominant component of the flora in the lower
bay. Heterocyst-forming species were a relatively minor fraction of the
total blue-green algae observed, but they were fairly abundant at Stations
13, 24, and 33. Green algae were also very abundant in the lower bay.
Numbers of diatoms reduced at roost stations sampled but large populations
were present in the Saginaw River and at Station 13 near the mouth of the
river. The species present at these stations were mostly small Gentries
tolerant of high conservative ion levels and extremely eutrophic conditions.
During this sampling period there was little evidence of dispersal of
populations generated in the lower bay into Lake Huron. Green algal
abundance was higher at Station 52 than at other stations in the Lake Huron
interface, but other groups did not show this distribution pattern.
During the next cruise, which began 28 July (Fig. 36), the same general
pattern of distribution was observed. Total phytoplankton abundance
continued to increase in the lower bay, and there was an extreme difference
in both abundance and species composition between stations in the lower bay
and stations in the Lake Huron interface region. Blue-green algae continued
to be the dominant element of assemblages at stations in the lower bay,
particularly at stations in the southeastern quadrants. Green algae
increased in relative and absolute abundance and the distribution pattern of
this group was similar to that of the blue-green algae. The abundance of
diatoms and flagellates increased somwhat at stations in the open bay from
levels observed during the previous sampling period. The abundance patterns
for these groups were opposite those of the green and blue-green algae. As
had been the case previously, diatom abundance was highest in the Saginaw
River, but the species composition at this station was strikingly different
from that found at stations in the open waters of the bay. Populations
47
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/ '
-------
Figure 35. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 8 July 1976.
-------
Figure 36. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 28 July 1976.
-------
present at stations in the Lake Huron interface region were different from
those found at stations in the lower bay.
This situation had changed somewhat by the time the next sampling cruise
was undertaken, beginning 11 August (Fig. 37). Average total abundance of
phytoplankton declined, but there was a marked increase in abundance at
stations in the Lake Huron interface region. Unlike previous cruises,
highest total phytoplankton abundance was found at stations on the northern
end of the outer transect. Assemblages in the lower bay continued to be
dominated by blue-green and green algae, but the abundance of diatoms
increased, particularly at stations in the central segment of the bay. There
was more similarity in assemblage composition between stations in the lower
bay and those in the Lake Huron interface region than was the case in most
cruises. Heterocyst-forming blue-green algae were much more abundant at
stations in the lower bay, but small populations of the same species were
found at stations in the Lake Huron interface. The same situation was
typical of other groups as well. The diatom and green algal flora of the
Saginaw River remained distinct, but there was an unusual degree of
similarity in species composition at all other stations sampled. Although
the same suite of species was present, abundance of the flagellate groups
tended to run counter to the trend of the other major groups. The inverse
relationship between the abundance of green algae and flagellates was
particularly notable.
A somewhat more typical pattern was observed during the next sampling
period, which began 31 August (Fig. 38). Total phytoplankton abundance
increased at stations in the lower bay, but decreased slightly at stations in
the Lake Huron interface region. Although there was some overlap of
populations between the two regions, differences were much greater than they
had been earlier in the month. Blue-green algae continued to dominate the
flora at stations in the lower bay, and green algae were an important
component of assemblages sampled in this region. Limited numbers of greens
and blue-greens were found in samples from the outer line of stations, and
highest abundance was noted at the northernmost and southernmost shoreward
stations on this transect. Although this type of pattern might be expected
to occur routinely, this was one of the few instances in which it was
observed during the period in which we sampled the bay. The abundance of
diatoms generally decreased, but their total abundance was more uniform than
it was during the previous sampling period. Distinct suites of populations
were again present at stations in the Saginaw River, the lower bay, and the
Lake Huron interface region. Flagellates were most abundant at stations on
the north side of the bay and the general pattern of abundance of this group
tended to be opposite the abundance pattern of diatoms.
The next cruise in the sequence began 18 September (Fig. 39). Total
phytoplankton abundance was reduced slightly, although high numbers were
present at most stations in the lower bay. The flora of the lower bay
continued to be dominated by blue-green and green algae. The abundance of
diatoms was remarkably uniform throughout the bay, but very high numbers were
present at the station sampled in the Saginaw River. Although numbers were
similar, the species composition of assemblages in the river, the lower bay,
and the Lake Huron interface region was greatly different. During this
51
-------
Figure 37. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 11 August 1976.
-------
Ol
1-0
Figure 38. Distribution of major phytoplankton groups in Saginaw Bay for eruise
beginning 31 August 1976.
-------
Ul
-p-
Figure 39. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 18 September 1976.
-------
sampling period the abundance trends in the flagellate groups were similar to
those of the green and blue-green algae but the difference in species
composition in different regions was similar to that found in the diatoms.
Although some stations were omitted from the next sampling round, which
began 7 October (Fig. 40), a reasonable coverage of the bay was obtained. On
the basis of these samples, phytoplankton distribution within the bay was
substantially similar to the case observed the previous month. Total
phytoplankton abundance was slightly reduced, but very high total abundance
was noted at several stations in the inner bay. Blue-green and green algae
continued to dominate the flora, although population distribution was even
more erratic than had been the case previously. Diatoms were again most
abundant in the Saginaw River, with relatively uniform numbers throughout the
open waters of the bay. The marked distinction in the species composition of
assemblages found in the river, the lower bay, and the Lake Huron interface
stations was maintained. A larger proportion of species tolerant of
hypereutrophic conditions, which were usually found at stations in the inner
bay, occurred at Stations 51 and 52 on the southeastern end of the outer
transect of stations. These stations also contained a higher proportion of
blue-green and green algae than the other stations on this transect, which is
probably indicative of transport of water masses derived from the lower bay
along the southern shore.
The final cruise in the project began 10 November (Fig. 41). Due to
weather conditions at this time of year, a limited number of stations were
sampled, mostly in the inner bay. Total phytoplankton abundance declined
slightly at the stations sampled, and the distribution of major phytoplankton
groups in the inner bay was quite unusual. Extreme abundance of green algae
was noted at Station 56, north of Fish Point. Although representatives of
this group were present at the other stations sampled, population densities
did not approach those found at Station 56. The next highest abundance of
green algae was found at stations near the mouth of the Saginaw River.
Similar species were present at these stations and it is possible that the
very high abundance of green algae at Station 56 is related to the output of
the Saginaw River. Blue-green algae, on the other hand, were much more
abundant at stations in the northern sector of the lower bay. Blue-green
populations consisted of mostly non-heterocyst-forming species, although
relatively low levels of species with heterocysts were found at stations in
the inner bay. During this sampling period the distribution of diatoms ran
counter to the trend observed for the blue-green algae. The highest
population levels observed were found in the Saginaw River, but nearly equal
population densities were found at stations in the inner bay. The highest
abundance of diatoms occurred at stations in the southern sector of the lower
bay. During this sampling period flagellates were present in minimal
abundance and total abundance of the group was quite similar at all stations
in the inner bay.
DISCUSSION
Taken in its entirety, the phytoplankton flora of Saginaw Bay is
extremely diverse (Appendix l). The species encountered in the bay span the
55
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Ln
cr>
Figure 40. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 7 October 1976.
-------
Ol
--J
Figure 41. Distribution of major phytoplankton groups in Saginaw Bay for cruise
beginning 10 November 1976.
-------
entire range of ecological adaptations found in the modern Great Lakes, with
the exception of populations specifically adapted to very oligotrophic
conditions. Part of this variability results from the large number of
quasidiscrete habitats present within the bay. There are a large number of
shallow, very productive areas which may produce local blooms of particular
species which are later entrained into the general water mass and physically
mixed with other populations. There are a number of examples of intense
local blooms of particular populations at a particular station or at a few
stations within a local region. This type of occurrence is most visible in
the earlier sampling rounds which included more stations and particularly
more stations relatively near to shore. The high productivity potential,
particularly in the inner bay, can lead to extreme local differences in both
the numbers and kinds of phytoplankton present. This extreme regional
patchiness is one of the outstanding characteristics of phytoplankton
distribution within the bay.
The overall diversity of the flora also partially results from the fact
that the flora of the bay at any given point in time may be a composite of
populations developed under different conditions. The most obvious source of
atypical populations is Lake Huron. Under certain conditions it appears that
the Lake Huron water mass extends a considerable distance into the bay.
Apparent cases of this situation occurred in April, June, and September 1974
and July and October 1975. In these cases it appeared that a "wedge" of Lake
Huron water extended into the bay. In other cases disjunct populations of
species usually associated with the offshore waters of Lake Huron were noted
at mid-bay stations. The only apparent explanation for such occurrences is
that these populations were entrained in a deep-running counter current of
Lake Huron water which entered the bay and subsequently welled up in the
mid-bay region.
Another source of populations adapted to conditions at the other end of
the spectrum of chemical conditions is the Saginaw River. In most cases
studied, the flora of the river was dominated by species tolerant of highly
eutrophic conditions and extremely high conservative ion concentrations. The
most characteristic populations were several species of small centric
diatoms, including Cyclotella atomus, £. cryptica, Sceletonema potomos, and
J5. subsalsa. The flora of the river was generally distinct from that of the
open bay. It appears that populations in the river are rarely, if ever,
nutrient limited. Large diatom populations were maintained throughout the
summer and heterocyst forming blue-green algae were rarely abundant at
stations in the river. In some instances, populations usually associated
with the river were major dominants at stations in the vicinity of the river
mouth and smaller numbers of these populations were occasionally found at
stations throughout the lower bay.
A third source of assemblage heterogeneity particularly important in
Saginaw Bay is the periodic entrainment of benthic populations. Although
this mechanism is less well documented, it is quite probably an important
factor in the ecology of the region because it furnishes a direct linkage
between the sediment sink for nutrients and toxicants and planktonic food
webs. Several distinctive types of populations are involved. The most
conspicuous elements of this flora are large pennate diatoms. Some of the
58
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characteristic populations are Calone is amphisbaena, Nitzschia sigma,
N. sigmoidea, and several members of the _N. tryblionella complex, Surirella
angusta, _S_. ovalis, and several members of the j^. ovata complex. Although
these species are rarely numerical dominants, they are large cells and they
may constitute an appreciable fraction of the biovolume at stations in the
inner bay. They are all apparently tolerant of highly eutrophic conditions
and high levels of conservative ion contamination. Although there is
admittedly little direct evidence to demonstrate it, we also suspect that at
least some of the filamentous green and blue-green algal populations which
are dominant populations in the bay may be derived from benthic habitats.
These populations occasionally have very erratic distribution patterns,
especially early or late in the season. They also often contain abundant
polyphosphate bodies, indicating growth under high nutrient and/or stress
conditions.
Another group of organisms important in Saginaw Bay, with a similar type
of meroplanktonic growth cycle, are several species of diatoms which have
become noted indicators of eutrophication in the Great Lakes. Included in
this group are species such as Actinocyclus normanii fo. subsalsa and
Melosira granulata. These species are planktonic in the sense that they have
no apparent special adaptation to benthic existence. They, however, are very
heavy-walled forms. They also apparently have a relatively high temperature
requirement in that they are generally most abundant in the summer and fall.
Such species are usually not successful in the offshore waters of the Great
Lakes because they are very susceptible to sinking losses, and nutrient
supply is limited during summer stratification. They do become dominant
populations in areas such as Saginaw Bay, lower Green Bay, and western Lake
Erie. In these relatively shallow areas wind-induced mixing can furnish
sufficient turbulence to resuspend populations and at the same time reentrain
nutrients from the near bottom waters. Although it has not been widely
reported in the literature, our results indicate that such populations may be
able to store internal phosphorus, in the form of polyphosphate bodies, far
in excess of their immediate requirements. The clearest evidence for this is
found in Fragilaria capucina, another meroplanktonic species which is often a
dominant form in highly enriched regions of the Great Lakes. It differs from
the species discussed above in the fact that it is apparently tolerant of low
temperatures and is usually most abundant during spring mixing. As discussed
later, this species has a much larger fraction of its cellular volume in
silica frustule than is the case with species such as Stephanodiscus
binderanus and other euplanktonic forms which bloom under eutrophied
conditions. Although Fragilaria capucina can store excess phosphate, its
dispersion is limited by large sinking losses, except under ideal conditions.
On the basis of our data, it appears that the dispersion of populations such
as Actinocyclus normanii fo. subsalsa and Melosira granulata is even more
limited, although they may be dominant populations in the bay under ideal
conditions.
All of the above factors tend to modify phytoplankton responses to the
overriding factor of extreme nutrient loading to the bay. It is clear that
excessive phosphorus loads lead to silica limitation and consequent reduction
in diatom growth during the summer. It is also clear that at least transient
nitrogen limitation occurs, favoring the growth of heterocyst forming
59
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blue-green algae. On the basis of our results, however, it is apparent that
physical events can act to de-couple nutrient loads from the directly
expected physiological response of phytoplankton within the bay.
The general pattern of phytoplankton succession in the bay is less well
defined than it is in more stable systems, but the following sequence appears
to be characteristic. Phytoplankton assemblages in the bay are dominated by
diatoms and flagellates during the winter circulation. Occasional
populations of green and blue-green algae are noted, but these groups are
generally a minor component of the total assemblage. With increased
insolation during the spring, total phytoplankton abundance increases,
forming the strong spring bloom characteristic of eutrophic systems. The
timing of the maximum spring bloom appears to be variable from year to year
and is undoubtedly controlled by the extent of ice cover in the bay and
turbidity immediately following break-up of the seasonal ice cover. As soon
as the water column begins to stabilize, the spring dominant diatom
populations rapidly become silica limited, allowing increasing abundance of
phytoplankton groups which do not require silica for reproduction.
Phytoplankton succession then proceeds along the path from dominance by green
algae and non-heterocyst-forming blue-green algae toward large populations of
nitrogen-fixing blue-greens. It should be emphasized, however, that the
timing of this sequence and the absolute "switch-over" of physiological
groups characteristic of smaller hypereutrophic lakes is not so clear-cut in
Saginaw Bay. In Saginaw Bay the normal course of events appears to be a
return to a more mixed flora in the late summer and early fall. During this
period three distinctive thermophilic diatom associations may develop in
different regions of the bay. The Saginaw River and stations directly under
the influence of its plume develop an association characterized by
Thalassiosira, Stephanodiscus, and Cyclotella species tolerant of high
temperature, high nutrient and conservative ion levels, and relatively high
turbidity. The extent of penetration of these populations into the open
waters of the bay is highly variable, but some species are commonly found at
stations throughout the lower bay. The lower and mid-reaches of the bay
develop a substantially different association, dominated by species of
Actinocyclus and Melosira, as discussed earlier. In several instances late
summer diatom blooms were also noted at stations in the Lake Huron interface
region. Although assemblages in this region may contain some of the species
found further down in the bay, they are generally dominated by blooms of
Cyclotella comensis. This species has recently become much more abundant in
the upper Great Lakes. In recent years massive, auxospore forming, summer
blooms of this species have been noted in the Saginaw Bay interface and other
relatively heavy-nutrient-load localities (e.g., Thunder Bay). The species
has not been widely reported from the United States, but it apparently has a
high nitrogen requirement and is especially efficient at uptake of silica at
low concentrations.
The most plausible explanation for this somewhat atypical temporal
sequence of major physiological groups is recycling of nutrients,
particularly silica, which were earlier sequestered during the spring bloom.
This explanation is supported by the results of Smith et al. (1977), which
show a detectable increase in soluble reactive Si02 during late summer and
early fall. Direct measurements of silica recycle from Saginaw Bay sediments
60
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(J. A. Robbins, personal communication) show rates which are consistent with
the hypothesis of substantial silica resupply during this period. It is
interesting to note that this apparent nutrient resupply affects both the
composition of the Saginaw Bay flora and the growth potential of populations
more characteristic of open lake conditions which occur in the Saginaw Bay
interface region.
One of the most crucial points in this investigation is the degree and
intensity of effect on Lake Huron resulting from loadings and biological
processes in Saginaw Bay. Our results indicate that substantial effects are
present, but that the region and intensity of effect is highly variable.
In the average case it appears that the southern coast of Saginaw Bay is
most strongly impacted and that export of phytoplankton populations
associated with highly eutrophic conditions usually occurs through the region
represented by the shoreward stations in region 5. This is the case which
would be expected from consideration of circulation in the bay under average
wind conditions (Allender, 1975; Danek and Saylor, 1977). As Danek and
Saylor (1977) emphasized, actual circulation patterns within the bay are
highly variable and show rapid response to both variations to forcing by
ambient wind fields and the general circulation of Lake Huron. This
instability is reflected by phytoplankton distribution. It is quite clear
that meteorological conditions can have a strong influence on the eventual
fate of materials entering the bay and on the fate of phytoplankton
populations generated by nutrient loadings. In this context, further
research should be devoted to the effects of conditions which force strong
advective events on processes in Lake Huron. The results of Stoermer and
Kreis (1980) are in agreement with our observations of typical distribution
patterns in the Saginaw Bay-Lake Huron interface region. Their results show
a general pattern of effects southward along the Michigan coast with large
variations in the area of Lake Huron showing floristic similarities to
Saginaw Bay. In one instance this general pattern is reversed with materials
advected from Saginaw Bay apparently being dispersed northward. Their
results also show that, under certain conditions, populations such as
Aphanizomenon flos-aquae which were most probably generated in Saginaw Bay
may be transported into the international waters of Lake Huron.
61
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INTRODUCTION AND SECTION 1 REFERENCES
Allender, J. H. 1975. Numerical simulation of circulation and advection-
diffusion processes in Saginaw Bay, Michigan. Ph.D. Dissertation,
University of Michigan, Ann Arbor.
Bierman, V. J., D. M. Dolan, E. F. Stoermer, J. E. Gannon, and V. E. Smith.
1980. The development and calibration of a spatially-simplified
multi-class phytoplankton model for Saginaw Bay, Lake Huron.
Great Lakes Environmental Planning Study Contribution No. 33, 126 pp.
Great Lakes Basin Commission, Ann Arbor, Michigan.
Danek, L. J., and J. H. Saylor. 1977. Measurements of the summer currents
in Saginaw Bay, Michigan. J. Great Lakes Res. 3: 65-71.
Freedman, P. L. 1974. Saginaw Bay: An evaluation of existing and histori-
cal conditions. U.S. Environmental Protection Agency, Region V,
Enforcement Division. 137 pp.
Gannon, J. E., F. J. Bricker, and K. Bricker. In preparation. Spatial and
seasonal structure of crustacean zooplankton communities in Lake Huron.
U.S. Environmental Protection Agency, Ecological Research Series.
International Joint Commission. 1976. The waters of Lake Huron and Lake
Superior. Vol. I. Summary and recommendations. International Joint
Commission, Windsor, Ontario. 236 pp.
Lohmann, H. 1908. Untersuchungen zur Festellung des vollstandigen Gehaltes
des Meeres an Plankton. Wiss. Meeresuntersuch. Abt. Kiel, N.F.,
10: 131-370.
Richardson, W. L. 1974. Modeling chloride distribution in Saginaw Bay.
Proc. Seventh Conf. Great Lakes Res. International Association for
Great Lakes Research. pp. 462-470.
Schelske, C. L., L. E. Feldt, M. S. Simmons, and E. F. Stoermer. 1974.
Storm induced relationships among chemical conditions and phytoplankton
in Saginaw Bay and western Lake Huron. Proc. Seventeenth Conf. Great
Lakes Res., International Association for Great Lakes Research.
pp. 78-91.
62
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E. F. Stoermer, J. E. Gannon, and M. S. Simmons. 1976.
Biological, chemical and physical relationships in the Straits
of Mackinac. U.S. Environmental Protection Agency, Ecological Research
Series EPA-600/3-76-095. U.S. Environmental Protection Agency,
Duluth, Minnesota. 267 pp.
, R. A. Moll, and M. S. Simmons. 1980. Limnological condi-
tions in southern Lake Huron, 1974 and 1975. U.S. Environmental Pro-
tection Agency, Ecological Research Series. EPA 600/3-80-74. 178 pp.
Smith, V. E., K. W. Lee, J. C. Filkins, K. W. Hartwell, K. R. Rygwelski and
J. M. Townsend. 1977. Survey of chemical factors in Saginaw Bay (Lake
Huron). U.S. Environmental Protection Agency, Ecological Research
Series EPA-600/3-77-125. 143 pp.
Stemberger, R. S., J. E. Gannon, and F. J. Bricker, 1979. Spatial and
seasonal structure of rotifer communities in Lake Huron. U.S.
Environmental Protection Agency, Research Reporting Series
EPA-600/3-79-085. 160 pp.
Stoermer, E. F., and R. G. Kreis. 1980. Phytoplankton composition and
abundance in southern Lake Huron. Univ. Michigan, Great Lakes Res.
Div., Spec. Rep. No. 65. 382 pp.
, L. Sicko-Goad, and D. Lazinsky. 1980. Synergistic ef-
fects of phosphorus and trace metal loadings on Great Lakes phyto-
plankton. pp. 171-186. Proc. Symposium on the Theoretical Aspects of
Aquatic Toxicology. Borok, Jaroslav., USSR. U.S. Environmental
Protection Agency, Research Reporting Series. EPA 600/9-80-034.
Strathmann, R. R. 1967. Estimating the organic carbon content of phyto-
plankton from cell volume or plasma volume. Limnol. Oceanogr.
12: 411-418.
Vollenweider, R. A., M. Munawar, and P. Stadelmann. 1974. A comparative
review of phytoplankton and primary production in the Laurentian
Great Lakes. J. Fish. Res. Board Can. 31: 739-762.
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SECTION 2
BIOMASS ESTIMATES
INTRODUCTION
Meaningful and reproducible estimation of phytoplankton biomass remains
a remarkably complex problem. In the past few years, several investigators
have returned to estimates of biovolume in an attempt to escape limitations
of traditional secondary measurement techniques. Biovolume estimates based
on species composition, number, and estimated volume have three inherent
problems: (1) There is a lack of accuracy in measuring and computing volumes
of microscopic, irregularly-shaped, complex forms; (2) There are differing
amounts of metabolizing cytoplasm, vacular "dead" volume, and resistant wall
materials found in different divisions of organisms commonly found in
phytoplankton assemblages as well as in different species in any particular
division; and (3) The physiological state of the cell (as a direct result of
environmental conditions such as light, temperature, and nutrients, as well
as the cell cycle of each organism) may affect both cell size and relative
volumes of cytoplasmic constituents within the cell.
Electron microscopic morphometric methods are based on mathematical
developments that consider the probability of obtaining certain
two-dimensional profiles from three-dimensional structures by randomly
cutting those structures. These methods are commonly used to detect
quantitative differences in tissues and cells as an alternative to
qualitative differences that might be noted during routine observation.
During a study of phytoplankton populations from Saginaw Bay, it became
evident that morphometric methods could be successfully applied to some
members of the assemblage in order to arrive at volume estimates of
components of ecological significance such as carbon-containing cytoplasm,
chloroplast, and "inert" structures. We have utilized these methods to
estimate the volume density of cellular components such as cell wall,
chloroplast, vacuole (areas devoid of any discernible cytoplasmic components,
including gullet, reservoirs, or furrows), storage products, and the
remaining cytoplasmic components. The results of the study indicate that the
problems associated with biovolume estimates can be both understood and, in
many cases, minimized.
MATERIALS AND METHODS
All organisms examined in the morphometric analyses were obtained from
nearshore Saginaw Bay field samples. Samples of Anabaena flos-aquae were
collected from a surface bloom on 9 June 1975 at Station 18 (Lat. 43°44.5'N,
64
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Long. 83°46.4'W) approximately 8 mi from the western shore. All other
samples were obtained from collections at Station 56 (Lat. 43°43.8'N, Long.
83°37.7'W) on 10 April 1975, approximately 4.5 mi offshore, and at Station 12
(Lat. 43°38.4'N, Long. 83°39.7'W) on 3 May 1975, approximately 2 mi
offshore. Water chemistry values and phytoplankton species composition were
similar for the two stations during the sampling periods in question. These
samples were particularly well-suited for morphometric analysis since the
major algal divisions were well represented in the samples and many of the
taxa had high standing crops. Water was pumped from a depth of 1 m into
1-liter polyethylene bottles and was fixed immediately by adding sufficient
glutaraldehyde (50%, biological grade) and sodium cacodylate to give a final
concentration of 3% glutaraldehyde and O.lM cacodylate at pH 7.2.
Samples were stored on ice and returned to the laboratory within 24 hr
for further processing. Samples were then concentrated by gentle
centrifugation and rinsed four times in O.lM cacodylate buffer, pH 7.2. The
concentrated cells were post-fixed with 1% Os04 in O.lM cacodylate buffer for
1 hr at 4°C. Cells were then dehydrated in a graded ethanol-propylene oxide
series and embedded in Epon (Luft, 1961). Thin sections for electron
microscopy were cut with a diamond knife, collected on 300-mesh copper grids,
and stained with uranyl acetate (Stempak and Ward, 1964) and lead citrate
(Reynolds, 1963). Organisms were examined at a standard magnification of
either 4,500X or 8,400X, depending on taxon cell size, using a Zeiss EM 9S-2
electron microscope. Magnification calibrations of the microscope were made
by use of a replica grating to determine the stability of the standard
magnifications. The variation was usually less than 2%. Specimens for total
cell volume determination were fixed and dehydrated as outlined above,
mounted in Epon on glass slides, and viewed using a Leitz Ortholux microscope
equipped with a 95X oil-immersion objective, NA 1.30 or greater.
QUANTITATIVE STEREOLOGICAL METHODS
Eight taxa, including representatives from the classes Cyanophyceae,
Bacillariophyceae, Euglenophyceae, Cryptophyceae, Dinophyceae, and
Prymnesiophyceae (Hibberd, 1976), were selected for quantitative analysis.
The sampling scheme employed was as outlined in Table 1. Seventy-five
micrographs were examined for each taxon, except where scarcity of a
particular taxon in the water samples necessitated a somewhat reduced sample
size. In all cases, examination of coefficients of variation and plots of
cumulative means and variances indicated adequate sampling of the material.
A transparent 0.5-cm square sampling lattice was superimposed over the
micrographs for quantitative measurements.
The first identifiable occurrence of each taxon on a grid was
photographed. Identification or selection of organisms was not based on the
presence or absence of particular cellular organelles. However, small
grazing sections may be slightly undervalued in the samples due to problems
associated with species identification. Blocks were retrimmed after each
series of sections was cut, in order to avoid repeated sampling of adjacent
material within the same organism. For filamentous taxa (eg. j?. capucina, S_.
binderanus, A^ f los-aquae), a single cell was randomly selected from each
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TABLE 1. SAMPLING SCHEME EMPLOYED FOR MORPHOMETRIC ANALYSIS
A.
f los-aquae
Number of
Photos Examined 50
Final
Magnification 25,100
Scope
Magnification 8400X
Photographic
Enlargement 3. OX
Average No.
Pts/Photo 450
Total Pts
Counted 23,194
S. F. E. C. P.
binderanus capucina viridis erosa lindemanni Hap 1 Hap 2
46 75 50 75 75 75 75
13,600 25,100 13,600 25,100 13,600 25,100 25,100
4500X 84000 4500X 8400X 4500X 8400X 8400X
3. OX 3. OX 3. OX 3. OX 3. OX 3. OX 3. OX
650 450 750 700 1500 450 250
30,745 33,263 38,448 54,076 111,881 32,715 20,249
-------
filament. The largest cross-sectional area of several of the taxa examined
exceeded the photographic field of view at the standard magnification
chosen. In these cases subsamples of the largest encountered cross-sections
were photographed, using the upper left portion of the first such cell, the
upper right portion of the next, the lower left, then the lower right, etc.
Estimates of volume density, i.e. the fractional volume of a cellular
component related to its containing volume, were obtained using both the
paper profile cut-and-weigh (Delesse, 1847) and grid point-counting
(Glagoleff, 1933; Chalkley, 1943) techniques. Although both methods were
found to yield similar estimates of volume density, point-counting was found
to be easier and faster to implement. Except where specifically indicated,
reported morphometric results will be those derived from the point-counting
technique.
The point-counting method is an extension of the Delesse principle which
states that the areal density of profiles on "two-dimensional" sections is an
unbiased estimate of the volume density of the corresponding structures
within the tissue (Delesse, 1847 cited in Weibel and Bolender, 1973), i.e.
V£ Ai Pi
_ = _ = _ (!)
VT AT PT
where Vj = volume of a component i, Aj = area of i in section, P^ = number of
points falling within the boundary of i, V-j- = total containing volume, etc.
(Notation and definitions are those of Weibel and Bolender, 1973). Thus, by
counting points of a sampling grid striking component i, or by weighing the
area of _i on a two-dimensional section and comparing that quantity with a
containing area measured in the same units, an unbiased estimate of the
volume fraction of component _i in the original tissue can be obtained.
Additional information concerning the more theoretical aspects of stereology
can be found in one of the several excellent reviews on the subject (Loud,
1968; Underwood, 1970; Weibel and Bolender, 1973).
Actual cell volume estimates (jjm^) were obtained from light microscopic
examination of cells obtained from the same assemblages as those used for the
quantitative stereological analysis. Estimates are based on 10 independent
measurements for each taxon, and assume a regular geometric shape for the
taxon (Table 2). Specific geometric formulae used in the volume calculations
are also presented there.
Statistical analyses were performed with the assistance of the MIDAS
statistical routines available through the computing facilities at the
University of Michigan. Parameter estimates are reported as the mean _+ 1
standard error unless specifically designated otherwise.
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TABLE 2. CELL VOLUME ESTIMATES FOR THE EIGHT PHYTOPLANKTON SPECIES EXAMINED
b - breadth, 1 = length, h = height, d = diameter
TAXON
Anabaena flos-aquae
Stephanodiscus binderanus
Fragilaria capucina
Euglena viridis
Cryptomonas erosa
Peridinium lindemanni
Haptophyte 1
Haptophyte 2
Volume ynH
80
830
400
3100
1300
11000
100
70
(SE) Formula
(9) l/^d2h
(92) l/b-nd2h
(37) blh
(450) l/6irZ £> + l/4TrZ7Z?9
(250) l/6vlb2
(2100) l/87rZZ?2t
(20) l/4ird h
(7) l/4ir<5 h
*Euglena was assumed to be a composite geometric shape consisting of a
rotation ellipsoid with major axis of rotation I, and minor axis b,
and a smaller cylinder of height 1~ and average diameter of b~.
Peridinium was assumed to be intermediate in volume between a rotation
ellipsoid with major axis of rotation 1 and a composite shape consisting
of two cones each of height 1/2.
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RESULTS AND DISCUSSION
DESCRIPTIVE ELECTRON MICROSCOPY
The following is a brief description of each of the organisms involved
in this study, with detailed information presented on the ultrastructure of
the organism and how this information can be correlated with physiological
evidence.
Anabaena flos-aquae (Cyanophyceae)
The blue-green alga, Anabaena flos-aquae, was selected to be a
representative nitrogen-fixing organism. The organism was collected as a
surface bloom with the cells forming tangled masses (Fig. l). The cells are
cylindrical co spherical; the heterocysts are usually terminal (Fig. 2).
Blue-green algae are quite distinct, cytologically, from other algal
groups. This is due to the fact that they are prokaryotic, and hence, more
closely aligned with bacteria both in structure and physiology. At the light
microscope level, the structural features that can be observed in the
blue-green algae are the centroplasm or nucleoplasm, the central portion of
the cell which is rich in nucleic acids, and the chromatoplasm, the
peripheral portion of the cell that contains the photosynthetic pigments and
several types of granules. With the aid of the electron microscope (Figs.
3, 4), greater resolution of these features is achieved. The categories of
cellular compartments in the blue-green algae that were included in
quantitative electron microscopy were as follows:
Cell Wall
This consists of four layers, including the peptidoglycan (including
muramic and diaminapimelic acids). Dunn et al. (1971) have estimated that 10
- 20% of the dry weight of Anabaena cylindrica is wall material (exclusive of
mucilage or sheath). For the present study, mucilage was not included in
cell wall volume determinations, since very little was present.
"Pseudovacuole"
The category pseudovacuole in this study collectively refers to both
areas of intrathylakoidal spaces as well as areas of collapsed gas vacuoles.
The intrathylakoidal spaces may be either fixation artifacts (since the cells
were fixed in glutaraldehyde, not the method of choice for prokaryotes) or
real spaces, as these areas can form under certain nutrient conditions
(Jensen and Sicko, 1974; Sicko, 1974). At best, the estimation of vacuolar
space in the blue-green alga is an approximation, since the vesicles were
collapsed. Van Baalen and Brown (1969) and Smith and Peat (1967) have shown
that gas vacuoles may take up as much as 60-70% of the total cell volume.
Gas vacuoles have been demonstrated to be formed when the algae are subjected
to ionic deficiency (Waaland and Branton, 1969). In addition to regulating
buoyancy and consequently environmental conditions, gas vacuoles may also be
a means for concentrating ions within cells by decreasing intracellular
solution volume.
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KEY TO FIGURE LEGENDS
c - cyanophycin granule
cl - chloroplast
cy - cytoplasm
cw - cell wall
e - ejectosome
f - frustule
g - golgi body
gb - girdle band
gu - gullet
gv - gas vacuole
h - heterocyst
ha - haptonema
1 - lipid
m - mitochonchia
mt - microtubules
n - nucleus
p - polyphosphate body
ph - polyhedial body
pa - paramylon
pe - pellicle
Py ~ pyrenoid
s - storage body
su - sulcus
st - suture
sr - starch
t - trichocyst
tp - thecal plate
v - valve
vac- vacuole
70
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Figures 1-4. Anabaena flos-aquae
1
2.
3.
4.
X250
X8.600
X18.800
X27.300
71
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Nitrogen Storage
Cyanophycin granules or structured granules are present in both
vegetative cells and akinetes of blue-green algae. They consist of high
molecular weight copolymers of aspartic acid and arginine (1:1, mol/mol).
This extremely unusual composition reveals them as particularly well suited
to serve as a nitrogen reserve (Simon, 1971a). Simon (1971b) isolated these
granules from nitrate-grown vegetative cells of Anabaena cylindrica, where
they account for up to 10% of the dry weight.
Phosphate Storage
Polyphosphate bodies are present in limited numbers in blue-green algae
unless the algae are subjected to adverse nutrient conditions. Any type of
nutrient imbalance can induce their formation, whether it be the presence of
excess or absence of a particular nutrient. The polyphosphate bodies encoun-
tered in A., flos-aquae were limited in number and, for the most part,
appeared extracted. This again is most likely a result of inappropriate
fixation.
Cytoplasm
The remaining components in the blue-green algae were collectively
counted as cytoplasm. These include the nuclear area, ribosomes, "ground
substance," polyhedral bodies, and thylakoids. No attempt was made to
estimate the thylakoid volume as a separate category comparable to
chloroplast.
Stephanodiscus binderanus and Fragilaria capucina (Bacilliarophyceae)
Fragilaria capucina is primarily benthic in habitat preference, but it
is also a successful facultative plankton. In samples analyzed, j?. capucina
(Figs. 9-11) was one of the most abundant organisms. Stephanodiscus
binderanus (Figs. 5-8) is a euplanktonic species; it was not as abundant as
_F. capucina in the samples examined.
The diatoms are most distinct at the ultrastructural level. This is due
to the siliceous wall or frustule. This same feature (i.e., the siliceous
frustule) also makes diatoms one of the most difficult algal groups to study
at the ultrastructural level because the frustule is very hard, making thin
sectioning difficult. In general, each cell contains two or more
chloroplasts, a nucleus, either a central or two polar vacuoles,
mitochondria, golgi, ribosomes, and endoplasmic reticulum. The following
celular categories were included in the diatom morphometric analysis:
Frustule
The frustules of the two diatoms examined differed significantly in
thickness (Figs. 7, 8, 11). The frustule is easily identified in electron
micrographs as electron dense material, platelike in nature, immediately
outside the plasma membrane. Lewin and Guillard (1963) point out that the
variation in frustule thickness is both intraspecific and interspecific,
ranging generally between 4 and 50%. Because of this variation, estimates of
organic constituents on a dry weight basis from total cell volume estimates
are of doubtful value, and not easily compared with other algal groups.
72
-------
Figures 5-8.
5.
6.
7.
8.
Stephanodiscus binderanus
X980
X10,000
X10,000
X9.050
7 )
-------
Figures 9-11.
9.
10.
11.
Fragilaria capucina
X750
X8.250
X18.200
-------
Vacuole
Vacuoles in diatoms are variable. In S. binderanus (Figs. 7, 8) the
large central vacuole restricts cytoplasmic organelles to the periphery of
the cell. This situation is not common in diatoms, having only been reported
in Melosira varians (Crawford, 1973). In J\ capucina, the vacuolar
arrangement is similar to other naviculoid diatoms, in that the cytoplasm is
H-shaped, with parietal chloroplasts and a central cytoplasmic bridge
(Stoermer et al., 1965; Drum, 1963; Dawson, 1973). Storage products, usually
lipids, are often found within the vacuolar membrane (tonoplast).
Storage Products
The storage product most commonly encountered in both diatoms appeared
to be lipid, located mainly in the vacuoles (Figs. 8, 11). As with many
other algae, storage products accumulate in older cells (Crawford, 1973;
Lewin and Guillard, 1963). It has been demonstrated that, in young diatom
cultures, lipids constitute 5-15% of the dry weight, whereas in N-deficient
cultures it may increase to 40-50%.
Chloroplast
The chloroplasts in both diatom species examined here are similar
structurally to those described in other diatoms. The plastids are bounded
by an envelope composed of two membranes, which in turn is surrounded by a
membrane of endoplasmic reticulum (ER). The plastids contain pyrenoids which
are traversed by a single lamella, composed of three thylakoids. In the
morphometric analysis, the pyrenoid was counted in two categories, total
chloroplast and chloroplast storage. In the final analysis, the pyrenoid
point totals were added to the total storage, since it is believed to be
involved in the conversion and translocation of early photosynthate in
chloroplasts (Griffith, 1970). This function would more closely align it
with storage than with chlorophyll content.
Cytoplasm
Other eukaryotic cell organelles included in this category and in none
of those previously mentioned include nucleus, golgi, ribosomes,
mitochondria, and "ground substance."
Euglena viridis (Euglenophyceae)
Cell Wall-
In E^igLena (Fig. 12), the cell covering is a unique structure termed the
pellicle (Figs. 13, 14). The pellicle is believed to consist of several com-
ponents: 1. plasma membrane, 2. protein layers beneath and parallel to the
plasma membrane, 3. microtubules, and 4. an endoplasmic reticulum cis-
terna. It has been demonstrated (Barras and Stone, 1965) that the pellicle
is composed of approximately 80% protein. Silverman and Hikida (1976) demon-
strated that the pellicle of _E. gracilis was highly resistant to disruptive
treatment, and speculate that the proteins and microtubules in the distinct
pellicle ridges (Fig. 14) perform a cytoskeletal role. For the purpose of
this study, the area counted in the "wall" category included the points
75
-------
12
14
pe
Figures 12-14.
12.
13.
14.
Euglena veridis
XI,060
X5.280
X12.100
76
-------
between the ER cisterna and the external surface of the cell. This area
constitutes the easily identifiable ridge.
Vacuole
The structures in Euglena which, perhaps, are most closely aligned with
the vacuole in the other algae examined are the anterior canal, reservoir,
and contractile vacuole (Fig. 14). The subapical anterior invagination of
the cell from which the flagella emerge is the anterior canal; the flagella
have their bases in the reservoir. The contractile vacuole is located
adjacent to the reservo*ir on the side opposite the eyespot. Since Euglena is
a naked cell, in fresh water it is subject to continuous uptake of water by
osmosis. To prevent the cell from bursting and to enable it to maintain its
normal size and shape, water must be discharged. At discharge, the membrane
between the contractile vacuole and reservoir breaks down, with the water
from the contractile vacuole emptying into the reservoir. This entire area
is surrounded by microtubules, believed to function in closing the canal
(Leedale et al., 1965). Since this area is obviously osmo-regulatory in
function, and contains no discernible organic components within the membranes
(disregarding the flagella), it was counted in a category comparable to
vacuole in other organisms.
Storage Products
The reserve polysaccharide of Euglena is paramylon. It consists solely
of g(l -> 3) linked D-glucose residues and occurs as water insoluble single
membrane-bound inclusions (Craigie, 1974). Carbon starvation of Euglena
results in the rapid disappearance of paramylon; restoration of a carbon
source leads to a complete reversal to normal morphology (Malkoff and Buetow,
1964; Leedale and Buetow, 1970). The degradation of paramylon is
photoregulated (Schwartzbach et al., 1975). In the presence of sufficient
nutrients and no light, carbon is used for cell growth. When light is the
major energy source and no external carbon is supplied, paramylon is
degraded. This degradation ensures sufficient carbon and energy for plastid
development when the cells are exposed to light.
Chloroplast
Euglena generally contains numerous chloroplasts. The chloroplasts
contain thylakoids which are not arranged as grana; pyrenoids are absent.
Cytoplasm
Other organelles included in this category were nucleus, golgi,
mitochondria, endoplasmic reticulum, ribsomes, and eyespot (adjacent to the
reservoir).
Cryptomonas erosa (Cryptophyceae)
Cell Wall
The cells of Cryptomonas (Figs. 15-17) are bounded by a single membrane
which is regularly indented. The foldings or indentations on the surface are
a result of the periplastial trichocysts (Gantt, 1971). The trichocysts
themselves are contained within single membrane-bound vesicles and are not
77
-------
Figures 15-17.
15.
16.
17.
Cryptomonas erosa
X2,130
X12,300
X22,900
78
-------
generally considered part of the periplast. Since the wall is essentially a
membrane, no estimation was made of its volume component.
Vacuole
The area included in the morphometric analysis as vacuole in Cryptomonas
roughly corresponds to similar structures in Euglena, namely, an anterior
furrow from which the flagella emerge (Figs. 15,16), a gullet (Fig. 17)
comparable to, but not identical with, the reservoir, and a contractile
vacuole or a series of small vacuoles of unknown function. Since these areas
do not appear to contain any organelles or inclusions, the area point totals
were equated with vacuole in other algae.
Storage Product
The main storage product in Cryptomonas is starch. The starch generally
occupies a position between the chloroplast envelope and the endoplasmic
reticulum which encloses the chloroplast (Fig. 17). It appears as a
polysaccharide cap around the pyrenoid, but is not actually part of the
chloroplast (Dodge, 1969; 1973).
Chloroplast
Cryptomonas contains two parietal chloroplasts. These chloroplasts
contain many lamellae which consist of two thylakoids. The pyrenoid is most
often not large, and is of the stalked variety (Dodge, 1973).
Cytoplasm
The remaining cytoplasmic components in this category include golgi,
mitochondria, ribosomes, "ground substance," and ejectosomes.
Peridinium lindemanni (Dinophyceae)
Peridinium lindemanni (Figs. 1820) was found in large numbers in the
April station selected for analysis. It also proved to be fairly abundant,
though not in as large numbers in the May sample. The cellular components
analyzed were the following:
Cell Wall
The dinoflagellates possess a complex cell covering termed the theca or
amphiesma (Loeblich, 1970). The theca consists of an outer membrane,
flattened vesicles or thecal plates, and an inner membrane (Fig. 20). There
are often subthecal microtubules which are sometimes evenly dispersed and
arranged in pairs (Dodge, 1971). The thecal plates are organic in nature;
thick microfibrils appear to be the main component and show random
orientation (Dodge, 1965). At division, dinoflagellates share old plates,
then synthesize new plates to complete their theca. Thus, it is possible to
differentiate between newly divided and more mature cells (Dodge, 1971).
Vacuole
Two types of vacuole or vacuole-like areas are commonly found in
dinoflagellates, food vacuoles, and the pusule. Food vacuoles, either empty
or with recognizable substances, have been described in Ceratium (Dodge and
Crawford, 1970) and Oxyrrhis (Dodge and Crawford, 1974). The pusule is a
79
-------
Figures 18-20.
18.
19.
20.
st
Peridinium lindemanni
X810
X6.960
X6,540
80
-------
unique osmo-regulatory organelle found in all freshwater dinoflagellate
species examined (Dodge, 1972). It consists of vesicles, collecting
chambers, and canals, and is more highly organized than contractile vacuoles
of other common phytoplankton organisms. In J\ lindemanni, the cells were
highly vacuolated (Fig. 20), although the exact nature of the vacuoles was
not determined.
Storage Products
The main storage products (Fig. 20) of dinoflagellates are fats or oils,
stored in the form of droplets, and starch grains (Dodge, 1973). The storage
products are particularly abundant in organisms that have been fixed from a
natural habitat in which the conditions were very favorable for
photosynthesis (Dodge and Crawford, 1970).
Chloroplast
The dinoflagellate chloroplast is typically bounded by a three membrane
envelope which does not normally have any connections with other cellular
constituents. The lamellae are made of stacks of three thylakoids, but there
is some variability in the arrangement of the lamellae. As with other
Peridinium species (Dodge, 1975), the chloroplasts in P. lindemanni are
discoid (lens-like) in shape, have a radial orientation, are numerous, and
are scattered throughout the cell (Fig. 20). The pryenoids encountered in
Peridinium were small and not easily distinguished due to their location in
the chloroplast lamellae. Consequently no attempt was made to quantitate
their relative volume.
Cytoplasm
Other organelles included in the cytoplasm category were nucleus,
eyespot, trichocysts, mitochondria, golgi, ER, ribosomes, and "ground
substance."
Prymnesiophycean Algae - Two Undetermined Species
A large number of small flagellates were encountered in the two stations
selected for analysis. Although their identification is still undetermined,
we have concluded that they are prymnesiophycean (haptophycean) algae based
on several ultrastructural observations, all of which are characteristic of
this group (Leadbeater, 1971; Manton and Peterfi, 1969; Hibberd, 1976).
1. Oftentimes, sections were taken through three flagella-like basal
body areas.
2. Haptonemas were encountered in cross section in several pictures
(a haptonema is a flagellar-like appendage, consisting of six or
seven (Fig. 22) microtubles, and endoplasmic reticulum [Manton,
1964]).
3. The golgi apparatus is extensive, with dilated cisternae and numer-
ous "hairy" vesicles.
81
-------
21
Figure 21. Haptophyte #1 X25.700
\
Figure 22. Haptophyte #2 X31.500
82
-------
4. At least one of the species (Fig. 21) has unmineralized scales
(confirmed by X-ray energy dispersive analysis). The scales are
obvious in all sections taken through the organisms. There is also a
slight suggestion that the other species might also possess scales,
although the freqency of such observations was considerably less.
When scales were found externally, it was also possible to observe
scales developing in the golgi.
5. Hexagonal arrays of microtubules were also found in sections near the
flagellar apparatus and in close association with the chloroplast at
the apical end of the cell, opposite the nucleus.
The two algae were selected for analysis because they represent both
naked and scaled forms of the group. The following areas were defined for
the morphometric analysis.
Cell Wall
The cell wall was defined as the area outside the plasma membrane. For
species #1 (Fig. 21), this consisted of the unmineralized scales, and dense
osmiophilic bodies. The nature of these bodies is unknown. Since species #2
(Fig. 20) was naked, no wall points were counted.
Vacuole
Clear areas devoid of cytoplasm were usually encountered in the cellular
region adjacent to the flagellar apparatus. The amount of vacuole observed
was highly dependent on section angle, indicating a small, polar vacuole.
Storage Products
Chrysophycean algae store fat and chrysolaminarin, a 6(1 + 3) linked
glucan. These products have not been identified with any certainty in the
Prymnesiophyceae (Hibberd, 1976). Thus for the purpose of analysis,
lipid-like inclusions were counted as storage products.
Chloroplasts
The two prymnesiophycean algae have two parietal chloroplasts per cell.
The pyrenoid is embedded in the chloroplast with no thylakoid lamellae
penetration. The lamellae have three thylakoids.
Cytoplasm
Other organelles included in this category were ribsomes, endoplasmic
reticulum, mitochondria, "ground substance," nucleus, flagellar apparatus,
and the extensive golgi system and vesicles.
Quantitative Electron Microscopy
Sample Size Determination
Plots of the cumulative mean and variance as a function of the number of
micrographs examined were used to evaluate the adequacy of the micrograph
sample size used in the morphometric analysis (Chalkley, 1943). The order of
micrographs was randomized prior to mean calculation and plotting.
Micrographs were then re-randomized and plotted a second time to check that
83
-------
the plateau observed for the mean or variance was in fact stable and not a
function of the order of micrographs. The cumulative means for the largest
organism studied, P. lindemanni, and the smallest, Haptophyte sp#l, are
presented in Fig. 23. Such plots demonstrate that the apparent requisite
sample size will differ from organism to organism and from component to
component within a given organism. Components that tend to be highly
oriented, such as the Haptophyte chloroplast or vacuole, require a large
number of random sections to characterize their volume fraction; components
that tend to be more uniformly dispersed throughout the cell, e.g., the
dinoflagellate chloroplast, seem to stabilize rather quickly. Most cellular
components for the organisms examined in this study were adequately
characterized by 30-50 random micrographs.
Filament Analysis
A preliminary pilot survey utilizing stereological cut-and-weigh
techniques was undertaken to evaluate the bias introduced by sampling more
than one cell from a given filament. Two factors suggest a possible bias in
selecting cells from the same filament: (l) cells in a given filament are
genetically and developmentally related; and (2) since cells in the same
filament have been sectioned at the same angle, the primary stereological
assumption of randomness of sectioning angle has been violated. However,
since ease of sampling favors multiple samples from a single filament, the
question was examined statistically.
Fifty-two electron micrographs representing 13 filaments of the
diatom _£. capucina, with four adjacent cells sampled per filament were
measured using the stereological cut-and-weigh technique. The volume
fractions obtained for frustule, storage, and cytoplasm for each of the
thirteen filaments were compared using a one-way univariate analysis of
variance (four replicates per ANOVA cell). The results are summarized in
Table 3. All three analyses indicate that the between-filament variance is
significantly larger than within-filament variance. Examination of mean
cellular volume fractions for the 52 micrographs compared with means obtained
from a sample of 13 micrographs, one randomly chosen from each filament,
shows little difference between the two parameter estimates. Therefore,
preliminary evidence seems to indicate that multiple samples from a single
filament do not substantially improve volume estimates for the given filament
and may potentially bias the population estimate if differing numbers of
cells are sampled per filament.
General Descriptive Measures
The quantitative results presented in this study describe both physical
and physiological "compartments" of the cell. In general, the following
categories and their limits have been utilized:
*1. WALL/FRUSTULE = area outside of the plasma membrane.
84
-------
0.21
QJ5
009
021
0.15
009
039
033
027
009
003
039
033
0.27
Hap. spec. 1
wal 1
j yvj^-X^^^--^
r
vacuolc
I/
chloroplcst
|
1
LV,
-V-/-WX.
storage
/
I cytoplasm
pV
i
i
0 20 40 60 8
Figure 23. Cumulat
function of sample
five cytoplasmic co
018
Q,2
006
0.18
0.12
006
0.27
021
0.15
Q3O
0.24
0.18
039
0.33
027
0
ive mean (perce
size (number of
mponents of P.
2- lindemonni
wal 1
/ "W-~
vacuole
Vs.
chloroplasr
fv--^^-^-^__
1
. storage
1
cytoplasm
J ^*sJ
0 20 40 ' 60 8lC
nt volume) as a
micrographs) for
lindemanni
and Hap. 1
85
-------
TABLE 3. ANALYSIS OF VARIANCE (ANOVA) OF BETWEEN AND WITHIN
FILAMENT VARIANCE
SOURCE
Anova Frustule fraction
Between filaments
Within filaments
Anova Storage fraction
Between filaments
Within filaments
Anova Cytoplasmic fraction
Between filaments
Within filaments
DF
12
39
12
39
12
39
SUM OF SQUARES
.11900
.036417
1.0297
.037337
1.3666
.15117
MEAN SQUARE
.0099167
.0093377
.085811
.00095737
.11388
.0038762
F-STAT
10.620*
89.631*
29.381*
*Significant at .001 level
*2. VACUOLE = vacuole area of the cell bounded by the vacuolar
membrane (tonoplast). This category may also include storage
located in this region.
2a. VACUOLE STORAGE = that portion of the total vacuole volume which
is storage (generally lipids in the diatoms).
2b. "EMPTY" VACUOLE = total vacuole - vacuole storage.
*3. CHLOROPLAST = chloroplast volume; also includes any pyrenoid and
chloroplast storage products such as lipids and starch, if they
are present.
3a. CHLOROPLAST STORAGE = storage within the chloroplast; pyrenoid
plus starch.
3b. TOTAL CHLOROPLAST - CHLOROPLAST STORAGE.
*4. CYTOPLASMIC STORAGE = storage material (starch, lipids, oils,
paramylon, etc.) located in the cytoplasm. Does not include
vacuole or chloroplast storage.
86
-------
*5. CYTOPLASM = all cellular components not included in one of the
above categories (includes organelles such as golgi, nucleus,
ejectosomes, mitochondria, etc.).
*The sum of the starred components should be 100%.
6. TOTAL STORAGE = sum of 2a, 3a, and 4.
7. TOTAL CARBON-CONTAINING CYTOPLASM = storage + cytoplasm +
chloroplast (3b +5+6); does not include vacuole or wall.
8. "METABOLIZING" BIOVOLUME = cellular components that are active
metabolically; cytoplasm plus chloroplast (does not include
vacuole, wall, or storage).
Summaries of the quantitative results are presented in Tables 4 and 5.
The following points were noted for the individual species:
Anabaena flos-aquae
Inappropriate field fixation and the resultant collapse of individual
gas vesicles probably has led to an underestimation of the relative volume of
the "pseudovacuole" category. No attempt was made to select for cyanophycin
granules or polyphosphate bodies in the micrographs; therefore the values
obtained should be an unbiased estimate of the occurrence of these inclusions
within the field population. The extremely low volume fractions may be
indicative of the environmental conditions at the time of sampling.
Stephanodiscus binderanus and Fragilaria capucina
As might be expected, the volume fraction of frustule was higher in _F.
capucina than in JS. binderanus. Both diatoms have a large volume fraction of
vacuole as well as lipid in the vacuole. Another common feature between the
diatoms is the percentage of carbon-containing cytoplasm, which is slightly
larger than 50%.
Euglena viridis
The most noticeable feature encountered in Euglena was the high
percentage of storage products (paramylon). The reservoir (vacuole) and the
contractile vacuole accounted for a higher volume fraction than was expected
(16%). The pellicular ridges also occupied approximately the same volume
fraction as the frustule in Stephanodiscus and the cell wall in Anabaena.
87
-------
TABLE 4. PERCENT VOLUMES OF CYTOPLASMIC COMPARTMENTS IN EIGHT PHYTOPLANKTON SPECIES
VALUES REPORTED ARE THE MEAN + 1 S.E.
1. Cell Wall
2. Total Vacuole
A. Vac. Storage
B. "Empty" Vac.
3. Total Chloroplast
CO
00
A. Chlor. Storage
B. Chi. -Chi. Stor.
4. Cytoplasmic Stor.
5. Cytoplasm
6. Total Storage
(Carbon)
7. Carbon-Containing
Cytoplasm
8. "Metabolizing"
Biovolume
A. flos-aquae
5.5 +_ 0.27
28.5 ± 1.12
-0-
28.5 +_ 1.12
-0-
1.4 i 0.28 (N)
0.5 ^ 0.13 (F)
64.1 +_ 1.16
-0-
65.5 +. 1.21
64.1 + 1.16
S. binderanus
6.
61.
20.
41.
14.
1.
12.
-0-
17.
22.
51.
29.
8 ^
6 _+
3 +_
3 +_
3 +_
6 +_
6 +
2 jt
0 ^
8 +_
9 +
1.25
2.89
2.30
3.25
1.36
0.26
1.27
2.04
2.32
3.15
2.41
F. capucina
20.3 +_
35.9 1
12.9 i
23.0 +_
18.9 +_
0.4 i
18.5 +_
-0-
24.9 +_
13.3 +_
56.8 +,
43.5 +
0.69
1.91
2.01
1.62
1.53
0.11
1.51
1.27
2.00
1.86
1.98
E. viridis
5.9 ' +_ 0.90
15.8 +_ 1.53
-0-
15.8 _+ 1.53
22.3 +_ 1.61
-0-
-0-
33.6 +_ 2.44
22.4 +_ 1.27
33.6 ^ 2.44
78.3 +_ 1.90
44.6 + 1.93
C. erosa
-0-
8.0 +_ 0.94
-0-
8.0 + 0.94
46.5 *_ 1.82
24.3 +_ 1.56
22.2 _+ 1.19
-0-
45.5 +_ 1.55
24.3 ^ 1.56
92.0 *_ 0.94
67.7 + 1.59
P. lindemanni
11.5 +^1.23
10.2 + 0.84
-0-
10.2 +_ 0.84
18.9 +_ 0.85
-0-
18.9 +_ 0.85
19.7 +_ 1.53
39.7 + 1.57
19.7 +_ 1.53
78.3 + 1.56
58.6 + 1.62
Hap. 1
13.
21.
-0-
21.
26.
3.
23.
3.
35.
7.
65.
58.
3
2
2
7
6
1
6
2
1
5
3
± °
*_ 1
i 1
+_ 1
± °
+_ 1
± °
+ 1
± °
+_ 1
+ 1
.55
.46
.46
.36
.75
.18
.37
.41
.75
.55
.60
Hap. 2
-0-
2.2
-0-
2.2
36.3
8.3
28.0
7.6
53.8
15.9
97.8
81.9
+ 0.23
+ 0.23
*_ 1.10
_+ 0.73
+ 0.86
_+ 0.65
+_ 1.18
_+ 0.94
i 0.23
+ 0.91
-------
TABLE 5. ABSOLUTE VOLUMES OF DEFINED AREAS IN THE ALGAE
NUMBERS WERE CALCULATED USING THE MORPHOMETRICALLY-DERIVED PERCENTAGES
FOUND IN TABLE 4 FOR THESE COMPONENTS, AND THE ABSOLUTE VOLUMES
OF THE ORGANISMS CALCULATED BY ASSUMING A REGULAR GEOMETRIC FIGURE (TABLE 2)
A. S. F. E. C. P.
flos-aquae binderanus capucina viridis erosa lindemanni Hap 1 Hap 2
oo
VO
Total Carbon-
containing
Cytoplasm 52
430 230 2400 1200 8600 66 68
Metabolizing
Biovolume
51
250
170
1400
880
6400
58
57
Naked
Colorplast
100
74
690
290
2100
23
20
-------
Cryptomonas erosa
The three major divisions of cellular compartments accounting for 92%
of the volume of Cryptomonas were cytoplasm, chloroplast, and storage
products. The remaining 8% of the volume was the anterior furrow and
gullet. Consequently, Cryptomonas had one of the highest carbon-containing
cytoplasm values.
Peridinium lindemanni
JP. lindemanni had a total storage volume percent that was near the
middle of the range across all eight species. This was not obvious from the
pictures; the dinoflagellates had many small starch grains and lipid droplets.
Prymnesiophycean Algal Species 1 and 2
The differences between these species were as great as the differences
between the diatoms examined. Total vacuole differed by a factor of 10; the
wall volume percents were 13.3 +_ 0.55 and nil; the total storage differed by
a factor of 2.
DISCUSSION
The fact that environmental factors affect the cytology and
morphological placticity of cells is easily documented in the literature.
Studies of morphological and cytological variations are most easily
accomplished by the use of synchronized cultures. The information derived
from culture studies, supplemented with studies of naturally-occurring
species, can be used to morphologically characterize algal species occurring
in phytoplankton.
One of the most extensive reviews relating cytology to cultural con-
ditions was made by Wilkinson and Duguid (1960) with bacteria. The authors
stress the importance of synchronized cultures for morphological studies
since the cytology is greatly dependent upon the life cycle stage. In addi-
tion, culture conditions, such as excess or absence of nutrients, modify the
cytology, the degree of modification being dependent upon the particular life
cycle. Other examples of cytological modification are abundant. Clear-cut
modifications relating to environmental conditions are most easily demon-
strated in both bacteria and blue-green algae. This is due inherently to the
fact that they are prokaryotes, and have a relatively simple cell organiza-
tion. No organelles are present and a number of storage inclusion bodies can
be present depending on the immediate environment of the cell (Jensen and
Sicko, 1971; 1973; 1974; Sicko, 1974; Sicko-Goad and Jensen, 1976).
Cytological and morphological variation, as a manifestation of changing
environmental conditions, is also evident in organisms that possess more
complex cellular organization (eukaryotes). However, as the cellular
complexity increases, the number of sites that can be affected in the cells
90
-------
also increases. Along with the increase in complexity, there is generally an
increase in cell size. Consequently the effects can be more diverse, and are
located in a much larger volume.
Collyer and Fogg (1955) demonstrated that different species of algae
tend to have similar relative amounts of protein, fats, and carbohydrates
when grown under similar environmental conditions. Fogg (1966) stated that
differences between algal classes in respect to their percent composition
tend to be small when compared to the differences a single algal species may
show during the course of growth in culture. This demonstrates that both the
environment and the growth cycle of the cell are important in determining the
biochemical composition of the cell.
The effects of changes in light intensity on algae have been studied
more extensively than any other parameter. Sorokin and Krauss (1958, 1965)
found that, in five green algae, increasing light intensity during growth
initially favors cell division. After the optimum light intensity is
reached, further increases are inhibitory to cell division.
Brown and Richardson (1968) studied the effects of different growth
light intensities on various physiological processes in a variety of algae.
They found that the volume of both cells and chloroplasts decreased with
increasing light intensity. In most cases, the pigment content varied
directly with chloroplast size. Unlike most studies of light effects, this
study also demonstrates a number of other morphological changes as a result
of varying growth illumination. The most notable of these effects were:
1. Cell vacuolization increased with increasing light intensity in
Amphidinium and Cryptomonas ovata var. palustris.
2. A cell volume maximum was dependent on growth light intensity in
Chlorella.
3. Some species such as Euglena gracilis exhibited a steady
growth increase with increasing illumination, whereas in Nitzschia
closteriutn, growth was light-dependent only at low intensities.
Morphological changes also occur as a result of cell cycle and
nutrients. Messer and Ben-Shaul (1972) demonstrated that, in Peridiniutn,
cell size and chlorophyll content increased during early growth and decreased
with culture age. Aged chloroplasts were narrower, had fewer thylakoids, and
also had a greater association with endoplasmic reticulum and cytoplasmic
ribosomes. They also found that the large number of chloroplasts per cell
correlated with a high chlorophyll content. Holmes (1966) demonstrated that,
in four marine diatoms, nitrate, silicate, and phosphate deficiency resulted
in both a reduction in chlorophyll _a and a concomitant decrease in the number
of chromatophores. The nutrient deficiencies caused a cessation of
chlorophyll synthesis whereas the reduction in chromatophore number was a
result of division failure rather than degeneration.
Atkinson et al. (1974) first utilized electron microscopic morphometric
methods to determine the volume fraction of certain cellular compartments in
91
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Chlorella. They demonstrated that cellular organelles were able to grow
continuously throughout the cell cycle. Consequently, the average volume
percents were 40% for chloroplast, 3% for the mitochondrion, and 10% for
vacuoles and nucleus throughout the cycle. The components that were of
particular interest were the vacuole, starch, and pyrenoid. Because
Chlorella contains no large central vacuole, it had previously been assumed
that the area of the tonoplast was insignificant. The authors confirmed that
the tonoplast has an area equal to at least a third of the plasmalemma area.
This indicates that the small vacuoles randomly scattered throughout the
cytoplasm do contribute significantly to both the total cell volume as well
as to the tonoplast area, which is also believed to contribute to solute
absorption in plant cells (Laties, 1969; Humphreys, 1973).
Atkinson et al. (1974) also correlated starch reserves to respiratory
activity of the cell. Starch appeared to function as a reserve material that
sustained cytokinesis in the absence of photosynthesis. The onset of
photosynthesis resulted in a recovery of starch reserves that were depleted
during cytokinesis in the dark phase of cell synchronization. Consequently,
starch reserves were quite dependent on both the photosynthetic and
respiratory activities of the cell.
Both the qualitative and quantitative results presented in these few
examples indicate that morphological characterization of all algal species is
highly dependent upon a wide variety of parameters. Although these
parameters can be easily regulated in a culture situation, the effects
produced in culture studies are not easily applied to natural assemblages
where a wide variety of parameters may be changing simultaneously. Biovolume
estimates are used to assess the importance of algal species since
phytoplankton standing crop is often converted into biomass through cell
volume determinations (Nalewajko, 1966). Cell volume data are also used to
extrapolate to organic carbon content, ash-free dry weight, and chlorophyll
(Paasche, 1960; Mullin et al., 1966; Strathmann, 1967).
We feel that our results indicate that the inherent cellular
organization of some species contributes significantly to the error of such
biomass calculations. This problem was first recognized by Lohmann (1908)
who indicated that only a small proportion of a large diatom is occupied by
chloroplasts and cytoplasm, with the remainder of the cell being vacuole.
Lohmann (1908) suggested that this should be taken into account when
comparing the productive capacity of cells and their cell volumes, since the
cytoplasm may form only a layer of 2 m around the cell periphery. Paasche
(I960) and Strathmann (1967) have both used such correction factors and found
that cell carbon, in many instances, correlates better with surface area than
cell volume for diatoms. These techniques have also been utilized recently
by Bellinger (1974).
The morphometric methods utilized in the present study demonstrate that
both cell vacuole and cell wall play an important role as "inert" structures
in all the algal species examined, not only the diatoms. In Table 5, we have
calculated the corrected cellular volumes of carbon-containing structures in
the cell, metabolizing biovolume (that portion of the cell other than inert
structures such as cell wall and vacuole, and storage products), and
92
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chloroplast volume. When one does not include cell wall or vacuole in the
volume estimates, the carbon-containing cytoplasm percentage drops
significantly. Consequently, correction factors are not only applicable to
large diatoms. Small vacuoles scattered throughout the cytoplasm may
significantly alter biomass and cell carbon estimates.
One of the most important features of the morphometric study is that
the eight algal species were all taken from water masses with similar
chemical and physical properties. Consequently, the number of environmental
parameters that have been demonstrated in the literature to affect the
cytology of a variety of organisms is reduced. Although we are not sure that
all algal species were growing under optimal conditions, it is likely that
the results presented here more closely resemble the percentages that would
be found in a naturally-occurring assemblage during the spring quarter than
would cultured algal species. In this respect, the corrected biovolume
estimates as presented are better than those derived by use of geometrical
formulae alone.
The most obvious example of corrected biovolume estimates from our data
.is the case of the two diatoms, S. binderanus and F. capucina. The
quantitative results show that, in both species of diatom, over 40% of the
cell is occupied by frustule and vacuole. These two taxa also exhibit large
significant differences in both frustule and vacuole relative volumes, even
though they belong to the same "physiological" group. Such data suggest that
cell volumes derived from geometrical formulae may differ significantly from
the real quantity being sought, such as mg cellular carbon or metabolizing
biomass, and the correction factor is probably not a constant for a given
class of algae. Since, of all the groups examined in this study, wall and
vacuole categories attain their largest cellular fractions in diatoms, errors
in cell volume calculations based on shape will be particularly large in
systems such as the Great Lakes where diatoms comprise a significant part of
the assemblage.
Only a small fraction of the total storage in both diatom species is
associated with the chloroplast. The remaining storage products, 13-20% of
total cellular volume, were localized within the vacuole; approximately half
of the vacuolar area in both taxa was occupied by storage. Since storage
products are known to accumulate in senescent cells, percent storage may be a
useful indicator of cell growth conditions.
We feel that this study of cell volume components is important for
several reasons:
1. The chemical composition across algal phyla varies. This is
especially significant in species that possess non-metabolizable
mineralized scales or walls, which make up a considerable
percentage of the total cell volume.
2. The cytological characteristics of the numerous algal species also
vary. Consequently, the percentage of various components, such as
vacuole, is not consistent either between phyla or between similar
species.
93
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Cytological compartments or volumes are subject to change with
changing environmental parameters. Certain features, such as the
presence of large amounts of storage products, are indicative of
senescent cells. The use of morphometric methods allows one to
detect morphological changes that might otherwise go undetected.
One does not have to rely solely on gross morphological changes to
detect significant differences between cells.
94
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Messer, G., and Y. Ben-Shaul. 1972. Changes in chloroplast structure
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99
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SECTION 3
LUXURY CONSUMPTION, STORAGE, AND TRANSPORT OF PHOSPHORUS IN SAGINAW BAY
INTRODUCTION
Polyphosphates are linear condensed phosphates with an elementary
formula of Mn+2Pn03n+j. They may range in size from a chain length of 2
(Pyrophosphate) to Kurrol's and Maddrell's salts of chain length of around
10^ (Harold, 1966). Polyphosphates are stable in alkali, bul: acid-labile.
Lower plants (Keck and Stich, 1957), bacteria (Harold, 1966),
blue-green algae (Sicko, 1974), and a variety of other organisms are known to
accumulate and store large quantities of polyphosphate when j;rown under
conditions of unlimited available phosphorus. This phenomenon is amplified
when the organisms are grown under conditions of phosphate limitation and
then placed under conditions of available phosphate (Mackerel:h, 1953; Liss
and Langen, 1962; Shapiro, 1967; Sicko-Goad and Jensen, 1976). This type of
storage has been termed "luxury storage" (Shapiro, 1968) and has also been
referred to as the polyphosphate "overplus" phenomenon (Voels; et al., 1966).
The physiological roles of phosphagen (Kornberg, 1957; Winder and
Denneny, 1955; Suzuki et al., 1972) and phosphorus reserve (Voelz et al.,
1966; Harold, 1966; Kaltwasser, 1962) have been ascribed to polyphosphate.
The occurrence of polyphosphate has most often been related to several
physiological conditions:
1. Nutrient imbalance other than phosphate,
2. Restoration of phosphorus supply following phosphorus starvation,
and
3. Nucleic acid imbalance.
The ecological significance of polyphosphate in algal cells is not well
understood. Although its presence has most often been related to nutrient
imbalance, the presence of polyphosphate as a phosphorus storage form in
naturally-occurring species has not been well documented.
During a study of phytoplankton populations from Sagins.w Bay, algal
cells were routinely examined by a variety of microscopic techniques for the
presence of polyphosphate bodies. The results of the survey are presented in
this report.
100
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MATERIALS AND METHODS
Most samples were collected and fixed during the routine cruises
according to the schedule outlined in the previous section. Exception to
this schedule was made in several cases where shoreline samples were obtained
in addition to the routine sampling periods. In these cases., plankton tows
were also fixed by placing the algae in veronal acetate buffer at pH 6.2 for
3 hours at room temperature (Pankratz and Bowen, 1963). The algae were then
dehydrated and embedded in the routine manner.
LIGHT MICROSCOPY
Algal suspensions were stained for polyphosphates by the method of Ebel
et al. (1958) and Jensen (1968). This staining procedure employs the ability
of lead salts to complex with polyphosphate and remain stable at low pH
values. The algae were initially fixed in 3% glutaraldehyde in O.lM
cacodylate buffer adjusted to pH 7.2 for a period of 1 hour t
-------
without phosphate salts, but containing 0.5% soil extract). The cells were
then resuspended in the low phosphate Chu-14 and incubated in a growth
chamber at 20°C with a 16-hour light, 8-hour dark cycle for 68 hours. At the
end of this limited phosphate period, during the 4th hour of the light cycle,
the cells were packed by gentle centrifugation and suspended in medium
containing 7.49 mgP/1. At the end of a 3-hour incubation under the original
light and temperature conditions, the cells were harvested by centrifugation
and fixed for electron microscopy as previously described. The supernatant
culture medium was also analyzed for total phosphorus content.
RESULTS
A survey of both light and electron microscope preparations revealed
that polyphosphate bodies were located in a variety of organisms in all
segments of Saginaw Bay except segment IV. The dates and locations of the
organisms containing polyphosphate bodies are found in Table 1. No samples
were obtained during the first quarter.
In general, the light microscopic techniques involving lead sulfide
precipitation were difficult to utilize for these samples on a routine
basis. Polyphosphate bodies, when they were present, were very small and
difficult to resolve with the light microscope. This was especially apparent
in the granular blue-green algae. Examination with the electron microscope
of the samples suspected to contain these inclusions proved that the
assumption about their small size was correct.
The electron micrographs (Figs. 1-4) demonstrate that the polyphosphate
bodies encountered were morphologically similar to the inclusions described
by other authors. Most notably, the inclusions are electron dense and
exhibit sublimation pockets when exposed to the electron beam for a short
period of time. The polyphosphate bodies were found in a variety of
organisms, but most often in bacteria, green and blue-green iilgae, and in
diatoms. The inclusions were of special interest in the diatoms because they
were most commonly found in the large central vacuoles and w?re sometimes
found in association with polysome-like inclusions.
Since the morphological characteristics of polyphosphate bodies are not
well known for algal species other than blue-green algae, experiments were
undertaken to induce their formation and study their morphological
variability. Cells of Diatoma tenue var. elongatum from an exponential
culture were transferred to a phosphate-limiting culture medium for a period
of approximately 3 days to induce several cell divisions and subsequent
phosphate limitation. The cells were then transferred to Chu-14 medium
containing normal phosphate levels. After 3 hours of incubation in this
medium, the cells contained what appeared to be numerous small polyphosphate
bodies, located in the central vacuole. The inclusions were often found
associated with the polysome-like inclusions present in the vacuole. X-ray
energy dispersive analysis of the vacuolar region demonstrated that this
region contained quantities of both phosphorus and silicon in addition to
lower levels of other background elements. During the 3-hour incubation
period, the phosphorus content of the medium dropped to 6.61 mgP/1. Since
102
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TABLE 1. DISTRIBUTION OF POLYPHOSPHATE BODIES IN
NATURALLY-OCCURRING PHYTOPLANKTON IN SAGINAW BAY
Date Collected
5/3/75
5/3/75
6/9/75
6/27/75
6/27/75
5/14/76
6/17/76
7/16/75
7/16/75
7/31/75
7/31/75
8/19/75
7/8/76
7/7/76
8/5/76
9/1/76
8/30/76
10/5/76
10/5/76
10/8/76
10/7/76
10/7/76
10/8/76
Station
12
52
18
56
12
26
26
12
18
26
52
52
Caseville
7
Port Austin
26
35
7
22
26
51
52
56
Depth
1 m
1 m
surface bloom
(Anabaena)
1 m
1 m
1 m
1 m
1 m
1 m
1 m
1 m
1 M
surface tow
1 m
surface tow
1 m
1 m
1 m
1 m
1 m
1 m
1 m
1 m
Segment
I
V
II
III
I
III
III
I
II
III
V
V
V
I
V
III
II
I
II
III
V
V
III
103
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Figures 1-4. Electron micrographs of polyphosphate bodies in species
of phytoplankton from Saginaw Bay. Magnifications are indicated by bar
in upper left of each figure. Figure 1. An undetermined small
blue-green alga with large polyphosphate (PP) bodies in boi:h electron
lucent and electron dense regions of the cell. Figure 2. Anacystis sp.
with polyphosphate bodies (PP). Figure 3. Fragilaria capucina with
small polyphosphate bodies (pp) in the vacuole (V), which :Ls surrounded
by the chloroplasts (c) and other cellular organelles. Figure 4.
Scenedesmus sp. with large polyphosphate bodies in the vacuole.
104
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the morphological characteristics were similar to the polyphosphate bodies
found in the diatoms collected from natural assemblages, the
naturally-occurring polyphosphate bodies were analyzed in a similar fashion.
The results of these analyses are presented in Figures 5-7.
DISCUSSION
Although the sampling was limited, we found that polyphosphate bodies
were present in a variety of organisms in Saginaw Bay in all segments except
segment IV. The use of lead sulfide precipitation to detect their presence
can be somewhat misleading because the polyphosphate bodies found in these
organisms were quite small and difficult to resolve with the light
microscope. The use of the electron microscope and related techniques were
necessary to confirm their presence.
Additional shoreline samples were obtained during July and August,
1976. This was necessitated by the fact that the routine method of fixation
employing glutaraldehyde in the field changed the morphology of the
polyphosphate bodies, especially in the prokaryotes. Since this was expected
(Jensen et al., 1977), and since a number of extracted polyphosphate bodies
were encountered, especially in Anabaena, shoreline tows were made and the
cells were also fixed in modified osmium, using no glutaraldehyde. This
method of fixation proved to be superior for the prokaryotes.
When inclusions were encountered that were suspected to be
polyphosphate bodies, x-ray energy dispersive analysis was usud to confirm
the presence of phosphorus. This technique was useful when either there was
a large number of bodies located in one central area or the polyphosphate
bodies were large. A few small bodies generally did not provide enough x-ray
emission above background to prove conclusively that phosphorus was present.
Consequently, Table 1 includes only those stations where the presence of
polyphosphate was confirmed and not merely suspected.
The most interesting results of the study were obtained both with
Fragilaria capucina, collected from a natural assemblage, and Diatoma tenue
var. elongatum, a cultured species. _F. capucina had numerous small
polyphosphate bodies located in its vacuole, and often in association with
polysome-like inclusions. The x-ray spectrum of the vacuolar region
demonstrated that phosphorus, osmium, and silicon were present: in this
region. Although the osmium can be accounted for, as a resull: of the
fixative, the silicon remains somewhat puzzling. Since the morphology of the
polyphosphate bodies was not what was expected and since it h.js not been
adequately described in diatoms, attempts were made to induce polyphosphate
body formation in a cultured diatom through phosphate imbalance. The results
of the experiment demonstrated the polyphosphate bodies encountered were
quite similar to those found in the naturally-occurring species. The size
range, location, and x-ray spectrum were all similar. In addition, the
association with polysome-like inclusions was even more frequent. This is
not surprising in view of the literature.
105
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1H'
Figures 5-7. Polyphosphate bodies in Diatoma tenue var. e^.ongatum.
Magnifications of electron micrographs indicated by scale bar in upper
left of figures. Figure 5. Marginal region of the cell showing
chloroplast (C), mitochondria (M), and the vacuole (V). Electron dense
structures in the right of the figure are elements of the siliceous
wall. Figure 6. Vacuolar (V) region of cell. Polyphosphate (PP)
bodies appear to be formed in linear arrays of polysome-like (PI)
bodies. Figure 7. X-ray spectrum of polyphosphate bodies shown in
Figure 6. Phosphorus peak (P) is indicated.
106
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Jensen (1969) demonstrated that, in Plectonema boryanum, polyphosphate
bodies frequently developed in the ribosoraal areas of the cytoplasm. Sicko
(1974) found that, under conditions of phosphate imbalance, polyphosphate
bodies developed in association with strands of DNA in the nuclear area of ]?.
boryanum. It was postulated that the DNA strands, along with short chained
polyphosphates, could serve as primers for the polymerization of the longer
chained acid-insoluble polyphosphates.
The relationship between nucleic acids and polyphosphate is further
complicated by studies which indicate that ribonucleic acid and polyphosphate
may exist as a complex in several organisms. This complex was first
postulated by MacFarlane (1936). RNA-polyphosphate has been demonstrated by
Kulaev and Belozerskii (1958) in Aspergillus niger, by Chayen et al. (1955)
in Torulopsis utilis, by Winder and Denneny (1957) in Mycobacteria, by Ebel
et al. (1958, 1962) in yeast, by Correll and Tolbert (1962, ii964) and by
Correll (1965) in Anabaena and Chlorella. Correll and Tolbert (1962, 1964)
found that, in Anabaena, the complex accounted for 25-35% of the total
phosphorus, and a major portion of the alga's RNA. However, there was an
additional 40-50% of the total phosphorus present as uncomploxed
polyphosphate. The polyphosphate-RNA complex in Chlorella was more variable;
the relative amounts of the complex varied with respect to the synchronized
growth cycle.
The ecological causes and consequences of polyphosphati; storage in
phytoplankton may be important in evaluating the impact areas, such as
Saginaw Bay, on the rest of the Great Lakes system. Although this
preliminary study does not provide sufficient basis to fully determine the
importance of the process, a number of points are evident.
On the basis of the literature and the number of experiments carried
out with phytoplankton species native to the Great Lakes, it is evident that
the accumulation of phosphorus in the form of polyphosphate bodies may be
triggered by any one of a number of mechanisms which interfere with normal
cellular growth processes. In a sense, the process provides a mechanism
whereby organisms may protect their ability to sequester the crucial limiting
nutrient phosphorus even in the presence of other growth limitations. The
most commonly observed condition inducing polyphosphate body formation is
phosphorus limitation followed by resupply of the nutrient af: concentrations
above the immediate growth needs.or capabilities of the cells. The process
may also be induced by conditions where adequate phosphorus supplies are
present, but growth is limited by concentration of some other nutrient or
factor. Polyphosphate body formation may also apparently be initiated by low
level toxic stress on the cells, sufficient to restrict maxinum growth rates.
The observed distribution of phytoplankton populations containing
polyphosphate bodies is consistent with any one, or a combination of, these
mechanisms. On the basis of our limited observations, populations containing
polyphosphate bodies are frequent in segments 1, 3, and 5, rare in segment 2,
and not present in segment 4. These results imply that exposure to factors
inducing polyphosphate body formation is probably greatest in segment 1, and
affected populations are then entrained in the normal circulation pattern of
the bay. It is particularly interesting that the abundance of polyphosphate
107
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bodies corresponds to the usual pattern of greatest total phytoplankton
density and to the most probable area of excursion of materials from the bay.
Within this area the relative abundance of cells containing polyphosphate
bodies appears to be quite uniform.
The most probable consequence of polyphosphate body formation is a
temporal separation of phosphorus uptake from eventual resultant growth. In
some cases cells which have sequestered phosphorus in excess of their
immediate needs may perish before utilizing the reserve. The population, as
a whole, however could be expected to exhibit a delayed growth response.
This phenomenon may account, in part at least, for the persistent pattern of
high phytoplankton abundance at stations along the southern coast of Saginaw
Bay. In a system like Saginaw Bay which has dynamic circulation patterns,
the delayed response also implies responses in areas some distance removed
from the primary source of phosphorus enrichment. This is probably the most
important aspect of the problem in the general case of the Great Lakes.
Potentially obnoxious populations developed in areas of high nutrient loading
could exit the immediate area of effect carrying with them the potential for
growth, even under phosphorus-limited conditions. The largest potential
expression of the effect would be expected to occur in the blue-green algae,
which are apparently subjected to minimal sinking and predation losses. We
regard this mechanism as a probable explanation for the extreme dispersal of
certain blue-green algal populations from Saginaw Bay into Lake Huron
observed by Schelske et al. (1974) and Stoermer and Kreis (1980).
We had previously assumed that polyphosphate body formation was
important only in prokaryotic organisms. The results of this study suggest
that the mechanism is present in most of the major physiological groups
present in the Great Lakes. Notable exeptions seem to be the Cryptomonads
and Dinoflagellates. Although we have not attempted induction in species of
these groups under experimental conditions, none of the wild populations
examined contained polyphosphate bodies. Representatives of all of the other
major algal physiological groups did. Most of the species examined in the
study are usually associated with eutrophied conditions in the Great Lakes
and it is possible that luxury consumption of phosphorus is one of the
factors which confers competitive advantage on these populations. Further
research will be needed to answer this question.
Our results also indicate that heavy metals may also be sequestered in
polyphosphate bodies. This mechanism is physiologically plausible and may be
important in biological transport of toxic materials. We are investigating
this problem at the present time.
108
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SECTION 3 REFERENCES
Chayen, R., S. Choyen, and E. R. Roberts. 1955. Observations on nucleic
acid and polyphosphate in Torulopsis utilis. Biochemic.a Biophysica
Acta. 16:117-126.
Chu, S. P. 1942. The influence of the mineral composition of the medium on
the growth of planktonic algae. J. Ecol. 30:284-325.
Correll, David L. 1965. Ribonucleic acid-polyphosphate from algae. III.
Hydrolysis studies. Plant & Cell. Physiol. 6:661-669.
, and N. E. Tolbert. 1962. Ribonucleic acic.-polyphosphate
from algae. I. Isolation and physiology. Plant Physiol. 37:627-636.
, and . 1964. Ribonucleic acic-polyphosphate
from algae. II. Physical and chemical properties of the isolated
complexes. Plant & Cell. Physiol. 5:171-191.
Ebel, J. P., J. Colas, and S. Muller. 1958. Recherches cytochimiques
sur les polyphosphates. II. Mise au point de methodes: de detection
cytochimiques specifiques des polyphosphates. Exp. Cell. Res. 15:28-36,
, A. Stair, G. Dirheimer, S. Muller-Felter, and M. Yacoub. 1962.
Relations de structure entre acides Ribonucleiques et p>olyphosphates.
Colloq. Intern. Centre Natl. Rech. Sci. 106:545-573.
Harold, F. M. 1966. Inorganic polyphosphates in biology: structure,
metabolism, and function. Bacteriol. Rev. 30:772-794.
Jensen, Thomas E. 1968. Electron microscopy of polyphosphate bodies in a
blue-green alga, Noxtoc pruniforme. Arch. Mikrobiol. 6'2:144-152.
. 1969. Fine structure of developing polyphosphate bodies
in a blue-green alga, Plectonema boryanum. Arch. Mikrobiol. 67:328-338.
, L. Sicko-Goad, and R. P. Ayala. 1977. Phosphate metabol-
ism in blue-green algae. III. The effect of fixation and
post-staining on the morphology of polyphosphate bodies in Plectonema
boryanum. Cytologia 42:357-369.
Kaltwasser, H. 1962. Die rolle der polyphosphate im Phosphatstoffioecasel
eines Knallgas bacteriums (Hydrogenomonas Stamm 20). Archiv.
Mikrobiol. 41:282-306.
109
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Keck, K., and H. Stich. 1957. The widespread occurrence of polyphosphates
in lower plants. Ann. Bot. 21:611-619.
Kornberg, S. R. 1957. Adenosine triphosphate synthesis from polyphosphate
by an enzyme from Escherichia coli. Biochim. Biophys. Acta. 26:294-300.
Kulaev, I. S., and A. N. Belozerskii. 1958. Electrophoretic studies on
polyphosphate-ribonucleic acid complexes from Aspergillus niger. Proc.
Acad. Sci. USSR (English transl.) 120:128-131.
Liss, E., and P. Langen. 1962. Versuche zur polyphosphat-uberkompensation
in befezellen nach phosphatverarmung. Archiv. Mikrobiol. 41:383-392.
MacFarlane, M. G. 1936. Phosphorylation in living yeast. Biochem. Jour.
30:1369-1379.
Mackereth, F. J. 1953. Phosphorus utilization by Asterionella formosa
Hass. J. Exp. Bot. 4:296-313.
Pankratz, H. S., and C. C. Bowen. 1963. Cytology of the blue-green algae.
I. The cells of Symploca muscorum. Amer. J. Bot. 50:387-399.
Schelske, C. L., L. E. Feldt, M. S. Simmons, and E. F. Stoerner. 1974.
Storm induced relationships among chemical conditions and phytoplankton
in Saginaw Bay and western Lake Huron. Proc. l7tn Conf. Great Lakes
Res. pp. 78-91. Internat. Assoc. Great Lakes Res.
Shapiro, J. 1967. Induced rapid release and uptake of phosphate by micro-
organisms. Science 155:1269-1271.
. 1968. Studies on the natural factors affecting phosphate ab-
sorption and its utilization by algae. Water Res. 2:21-23.
Sicko, L. M. 1974. Physiological and cytological aspects of phosphate
metabolism in the blue-green algal, Plectonema boryanum. Ph.D.
Dissertation, The City University of New York, New York.
Sicko-Goad, L., and T. E. Jensen. 1976. Phosphate metabolism in blue-green
algae. II. Changes in phosphate distribution during starvation and
the "polyphosphate overplus" phenomenon in Plectonema boryanum.
Amer. J. Bot. 63:183-188.
Stoermer, E. F., and R. Kreis. 1980. Phytoplankton composition and
abundance in southern Lake Huron. Univ. Michigan, Great Lakes Res.
Div., Spec. Rep. No. 65. 382 pp.
Suzuki, H., T. Kaneko, and Y. Ikeda. 1972. Properties of polyphosphate
kinase prepared from Mycobacterium smegmatis. Biochim. Biophys. Acta.
268:381-390.
110
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Voelz, H., U. Voelz, and R. 0. Ortigoza. 1966. The "polyphosphate overplus"
phenomenon in Myxococcus xanthus and its influence on the architecture
of the cell. Archiv. Mikrobiol. 53:371-388.
Winder, F. G., and J. M. Denneny. 1955. Utilization of metciphosphate for
phosphorylation by cell-free extracts of Mycobacterium smegmatis.
Nature 175:636.
and . 1957. The metabolism of inorganic poly-
phosphate in Mycobacteria. J. Gen. Microbiol. l-7:573-!>85.
Ill
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APPENDIX 1. PHYTOPLANKTON OF SAGINAW BAY (LAKE HURON)., 1974-1976
BACILLARIOPHYTA
Achnanthes affinis Grun.
Achnanthes biasolettiana (Kiitz.) Grun.
Achnanthes bioreti Germain
Achnanthes clevei Grun.
Achnanthes clevei var. rostrata Hust.
Achnanthes exigua Grun.
Achnanthes exigua var. heterovalva Krasske
Achnanthes flexella (Kutz.) Brun
Achnanthes flexella var. alpestris Brun
Achnanthes hungarica (Grun.) Grun.
Achnanthes lanceolata (Breb.) Grun.
Achnanthes lanceolata var. dubia Grun.
Achnanthes lanceolata var. omissa Reim.
Achnanthes lapponica (Hust.) Hust.
Achnanthes lapponica var. ninckei (Guerm. and Mang.) Reim.
Achnanthes linearis (W. Sm.) Grun.
Achnanthes microcephala (Kiitz.) Grun.
Achnanthes minutissima Kiitz.
Achnanthes minutissima var. cryptocephala Grun.
Achnanthes oestrupii var. lanceolata Hust.
Actinocyclus normanii fo. subsalsa (Juhl.- Dannf.) Hust.
Amphipleura pellucida (Kiitz.) Kiitz.
Amphora cruciferoides Stoerm. and Yang
Amphora ovalis (Kiitz.) Kiitz.
Amphora ovalis var. affinis (Kiitz.) V.H.
Amphora ovalis var. pediculus (Kiitz.) V.H.
Amphora perpusilla (Grun.) Grun.
Amphora subcostulata Stoerm. and Yang
Amphora veneta var. capitata Haworth
Anomoeoneis vitrea (Grun.) Ross
Asterionella formosa Hass.
Caloneis alpestris (Grun.) Cl.
Caloneis bacillum (Grun.) Cl.
Caloneis bacillum var. lancettula (Schulz) Hust.
Caloneis sp. #3
Caloneis ventricosa var. #1
Cocconeis diminuta Pant.
Cocconeis fluviatilis Wallace
Cocconeis pediculus Ehr.
Cocconeis placentula Ehr.
Cocconeis placentula var. euglypta (Ehr.) Grun.
Cocconeis placentula var. lineata (Ehr.) V.H.
Cocconeis sp.#2
Cocconeis thumensis A. Mayer
(continued).
112
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APPENDIX 1. (continued).
Cyclotella antiqua W. Sm.
Cyclotella atomus Hust.
Cyclotella comensis Grun.
Cyclotella comta~(₯hr.) Kiitz.
Cyclotella cryptica Reimann, Lewin and Guillard
Cyclotella kuetzingiana Thw.
Cyclotella kuetzingiana auxospore
Cyclotella meneghiniana Kiitz.
Cyclotella meneghiniana var. jplana Fricke
Cyclotella michiganiana Skv.
Cyclotella ocellata Pant.
Cyclotella operculata ( Ag . ) Kiitz.
Cyclotella sp. auxospore
Cyclotella stelligera (Cl. and Grun.) V.H.
Cyclotella stelligera auxospore
Cyclotella temperei M. Perag. and Herib.
Cymatopleura elliptica (Breb. and Godey) W. Sm.
Cymatopleura solea (Breb. and Godey) W. Sm.
Cymatopleura solea var. apiculata (W. Sm.) Ralfs
Cymbella affinis Kiitz.
Cymbella amphicephala Nag.
Cymbella cesatii (Rabh.) Grun.
Cymbella cistula (Ehr.) Kirchn.
Cymbella cuspidata Kiitz.
Cymbella delicatula Kiitz.
Cymbella hybrida Grun.
Cymbella leptoceros var. rostrata Hust.
Cymbella microcephala Grun.
Cymbella microcephala var. crassa Reim.
Cymbella minuta Hilse
Cymbella minuta var. silesiaca (Bleisch) Reim.
Cymbella minuta fo. latens (Krasske) Reim.
Cymbella muelleri fo. ventricosa (Temp, and Perag.) Reim.
Cymbella obtusiuscula Kiitz.
Cymbella parvula Krasske
Cymbella prostrata (Berk.) Cl.
Cymbella prostrata var. auerswaldii (Rabh.) Reim.
Cymbella sinuata Greg.
Cymbella sp. #1
Cymbella sp. #6
Cymbella sp. #10
Cymbella subventricosa Choln.
Cymbella triangulum (Ehr.) Cl.
Cymbella tumida (Breb.) V.H.
Cymbella turgida var. pseudogracilis Choln.
Cymbella ventricosa Ag.
(continued).
113
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APPENDIX 1. (continued).
Denticula tenuis var. crassula (Nag.) W. and G.S. West
Diatoma tenue Ag.
Diatoma tenue var. elongatum Lyngb.
Diatoma tenue var. pachycephala Grun.
Diatoma vulgare Bory
Diploneis boldtiana Cl.
Diploneis oculata (Breb.) Cl.
Diploneis parma Cl.
Entomoneis ornata (J.W. Bail.) Reim.
Epithemia intermedia Fricke
Epithemia sorex Kiitz.
Epithemia turgida (Ehr.) Kiitz.
Fragilaria brevistriata Grun.
Fragilaria brevistriata var. inflata (Pant.) Bust.
Fragilaria capucina Desm.
Fragilaria capucina var. lanceolata Grun.
Fragilaria capucina var. mesolepta Rabh.
Fragilaria construens (Ehr.) Grun.
Fragilaria construens var. binodis (Ehr.) Grun.
Fragilaria construens var. minuta Temp, and M. Perag.
Fragilaria construens var. pumila Grun.
Fragilaria construens var. venter (Ehr.) Grun.
Fragilaria crotonensis Kitton
Fragilaria crotonensis var. oregona Sov.
Fragilaria intermedia Grun.
Fragilaria intermedia var. fallax (Grun.) A. Cl.
Fragilaria leptostauron (Ehr.) Hust.
Fragilaria leptostauron var. dubia (Grun.) Hust.
Fragilaria pantocsekii var. binodis (Pant.) A. Cl.
Fragilaria pinnata Ehr.
Fragilaria pinnata var. intercedens (Grun.) Hust.
Fragilaria pinnata var. lancettula (Schum.) Hust.
Fragilaria vaucheriae (Ktitz.) Peters.
Frustulia vulgaris (Thw.) Del.
Gomphonema acuminatum Ehr.
Gomphonema angustatum (Kiitz.) Rabh.
Gomphonema angustatum var. producta Grun.
Gomphonema intricatum Kiitz.
Gomphonema intricatum var. pumila Grun.
Gomphonema olivaceum (Lyngb.) Kiitz.
Gomphonema parvulum (Kiitz.) Kiitz.
Gomphonema parvulum var. lagenula (Kiitz.) Freng.
Gomphonema subclavata var. mustela (Ehr.) Cl.
Gomphonema sp. #3
Gomphonema truncatum Ehr.
Gyrosigma acuminatum (Kiitz.) Rabh.
(continued).
114
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APPENDIX 1. (continued).
Gyrosigma attenuatum (Kiitz.) Rabh.
Gyrosigma scalproides (Rabh.) Cl.
Gyrosigma spencerii (Sulliv. and Wormley) Cl.
Gyrosigma spencerii var. curvula (Grun.) Reim.
Hantzschia amphioxys (Ehr.) Grun.
Mastogloia smithii Thw.
Melosira distans var. alpigena Grun.
Melosira granulata (Ehr.) Ralfs
Melosira granulata var. angustissima 0. Mull.
Melosira islandica 0. Mull.
Melosira italica subsp. subarctica 0. Mull.
Melosira varians Ag.
Meridion circulare (Grev.) Ag.
Meridion circulare var. constrictum (Ralfs) V.H.
Navicula acceptata Hust.
Navicula anglica var. subsalsa (Grun.) Cl.
Navicula aurora Sov.
Navicula bacillum Ehr.
Navicula capitata Ehr.
Navicula capitata var. hungarica (Grun.) Ross
Navicula capitata var. luneburgensis (Grun.) Patr,
Navicula capitata var. #1
Navicula dementis Grun.
Navicula cocconeiformis Greg.
Navicula confervacea (K'utz.) Grun.
Navicula costula'ta Cl. and Grun.
Navicula cryptocephala K'utz.
Navicula cryptocephala var. intermedia V.H.
Navicula cryptocephala var. veneta (K'utz.) Rabh.
Navicula cuspidata (Kvitz.) Kutz.
Navicula decussis 0str.
Navicula exigua var. capitata Patr.
Navicula explanata Hust.
Navicula gastrum (Ehr.) Kiitz.
Navicula gottlandica Grun.
Navicula gregaria Donk.
Navicula heufleri var. leptocephala (Breb.) Patr.
Navicula integra (W. Sm.) Ralfs
Navicula jaernefeltii Hust.
Navicula lacustris Greg.
Navicula lanceolata (Ag.) Kiitz.
Navicula latens Krasske
Navicula menisculus Schuin.
Navicula'menisculus var. obtusa Hust.
Navicula menisculus var. upsaliensis Grun.
Navicula minima Grun.
(continued).
115
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APPENDIX 1. (continued).
Navicula minuscula Grun.
Navicula mutica K'utz.
Navicula mutica var. cohnii (Hilse) Grun.
Navicula nyassensis fo. minor 0. Mull.
Navicula odiosa Wallace
Navicula ordinaria Bust.
Navicula peregrina (Ehr.) KUtz.
Navicula placentula (Ehr.) K'utz.
Navicula protracta (Grun.) Cl.
Navicula protracta fo. subcapitata (Wisl. and Por.) Hust.
Navicula pupula Klitz.
Navicula pupula var. rectangularis (Greg.) Grun.
Navicula pygmaea KUt z.
Navicula radiosa KUtz.
Navicula radiosa var. tenella (Breb.) Cl. and Moll.
Navicula reinhardtii Grun.
Navicula rhynchocephala Klitz.
Navicula rotunda Hust.
Navicula scutelliodes W. Sm.
Navicula sp. #7
Navicula sp. #35
Navicula sp. #43
Navicula sp. #44
Navicula sp. #55
Navicula sp. #78
Navicula spp.
Navicula stroemii Hust.
Navicula stroesii (0str.) A. Cl.
Navicula subseminulum Hust.
Navicula terminata Hust.
Navicula tripunctata (O.F. Mull) Bory
Navicula tripunctata var. cuneata (Lauby) Stoerm. and Yang
Navicula tripunctata var. schizoneiuoides (V.H.) Patr.
Navicula tuscula Ehr.
Navicula tuscula fo. obtusa (Hust.) Hust.
Navicula vanheurck.il Patr.
Navicula viridula (Kiitz.) Ehr.
Navicula viridula var. linearis Hust.
Navicula viridula var. rostellata (Kiitz.) Cl.
Navicula viridula var. #2
Neidium dubium (Ehr.) Cl.
Neidium dubium fo. constrictum (Hust.) Hust.
Neidium dubium var. #1
Nitzschia acicularioides Hust.
Nitzschia acicularis (KUtz.) W. Sm.
Nitzschia actinastroides (Lemm.) Van Goor
(continued).
116
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APPENDIX 1. (continued).
Nitzschia acula Hantz.
Nitzschia amphibia Grun.
Nitzschia angustata var. acuta Grun.
Nitzschia apiculata (Greg.) Grun.
Nitzschia bacata Hust.
Nitzschia capitellata Hust.
Nitzschia commutata Grun.
Nitzschia confinis Hust.
Nitzschia denticula Grun.
Nitzschia diserta Hust.
Nitzschia dissipata (Kiitz.) Grun.
Nitzschia dissipata var. borneensis Hust.
Nitzschia dissipata var. media (Hantz.) Grun.
Nitzschia filiformis (W. Sm.) Schutt
Nitzschia fonticola Grun.
Nitzschia fonticola var. pelagica Hust.
Nitzschia frustulum (Kiitz.) Grun.
Nitzschia frustulum var. perminuta Grun.
Nitzschia frustulum var. subsalina Hust.
Nitzschia frustulum var. #1
Nitzschia gracilis Hantz.
Nitzschia holsatica Hust.
Nitzschia hungarica Grun.
Nitzschia insecta Hust.
Nitzschia interrupta (Reich.) Hust.
Nitzschia kuetzingiana Hilse
Nitzschia linearis (Ag.) W. Sm.
Nitzschia linearis var. tenuis (Kiitz.) Grun.
Nitzschia longissima fo. parva Grun.
Nitzschia longissima var. reversa Grun.
Nitzschia palea (Kiitz.) W. Sm.
Nitzschia palea var. tenuirostris Grun.
Nitzschia paleacea Grun.
Nitzschia recta Hantz.
Nitzschia sigma (Kiitz.) W. Sm.
Nitzschia sigmoidea (Nitz.) W. Sm.
Nitzschia sp. #1
Nitzschia sp. #2
Nitzschia sp. #5
Nitzschia sp. #6
Nitzschia sp. #8
Nitzschia sp. #9
Nitzschia sp. #10
Nitzschia sp. #11
Nitzschia sp. #17
Nitzschia sp. #18
(continued).
117
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APPENDIX 1. (continued).
Nitzschia sp. #19
Nitzschia sp. #22
Nitzschia sp. #26
Nitzschia spiculoides Hust.
Nitzschia subamphioxoides Hust.
Nitzschia sublinearis Hust.
Nitzschia thermalis (Ehr.) Auersw.
Nitzschia thermalis var. minor Hilse
Nitzschia tryblionella Hantz.
Nitzschia tryblionella var. debilis (Arn.) A. Mayer
Nitzschia tryblionella var. levidensis (W. Sm.) Grun.
Opephora martyi Herib.
Pinnularia brebissonii (Ku'tz.) Rabh.
Pinnularia globiceps Greg.
Pinnularia viridis (Nitz.) Ehr.
Plagiotropis lepidoptera var. proboscidea (Cl.) Reim.
Rhizosolenia eriensis H.L. Sm.
Rhizosolenia gracilis H.L. Sm.
Rhoicosphlenia curvata (Ku'tz.) Grun.
Skeletonema potamos (Weber) Hasle
Skeletonema subsalsum (A. Cl.) Bethge
Stauroneis acutiuscula M. Perag. and Herib.
Stauroneis dilatata Ehr.
Stephanodiscus alpinus Hust.
Stephanodiscus astraea (Ehr.) Grun.
Stephanodiscus binderanus (Kiitz.) Kreig.
Stephanodiscus hantzschii Grun.
Stephanodiscus minutus Grun.
Stephanodiscus niagarae Ehr.
S tephanodiscus sp. auxospore
Stephanodiscus subtilis (Van Goor) A. Cl.
S tephanodiscus tenuis Hust.
Stephanodiscus transilvanicus Pant.
Surirella angusta Ku'tz.
Surirella birostrata Hust.
Surirella biserlata var. diminuta A. Cl.
Surirella linearis var. constricta (Ehr.) Grun.
Surirella ovata Ku'tz.
Surirella ovata var. pinnata (W. Sm.) Rabh.
Surirella ovata var. salina (W. Sm.) Rabh.
Surirella ovata var. #1
Surirella sp. #4
Synedra acus Ku'tz.
Synedra capitata Ehr.
Synedra cyclopum Brutschy
Synedra delicatissima W. Sm.
(continued).
118
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APPENDIX 1. (continued).
Synedra delicatissima var. angustissima Grun.
Synedra filiformis Grun.
Synedra minuscula Grun.
Synedra montana Krasske
Synedra ostenfeldii (Kreig.) A. Cl.
Synedra parasitica (W. Sm.) Hust.
Synedra rumpens Kiitz.
Synedra rumpens var. familiaris (Ku'tz.) Hust.
Synedra tenera W. Sm.
Synedra ulna (Nitz.) Ehr.
Synedra ulna var. chaseana Thomas
Synedra ulna var. claviceps Hust.
Synedra ulna var. danica (Kutz.) V.H.
Synedra ulna var. spathulifera (Grun.) V.H.
Tabellaria fenestrata (Lyngb.) Kutz.
Tabellaria fenestrata var. geniculata A. Cl.
Tabellaria flocculosa (Roth) Kutz.
Tabellaria flocculosa var. linearis Koppen
Thalassiosira pseudonana Hasle and Heim.
Thalassiosira weissflogii (Grun.) Fryxell and Hasle
CHRYSOPHYTA
Chrysochromulina parva Lackey
Chrysochromulina sp. #1
Chrysosphaerella longispina Lautb.
Dinobryon cylindricum Imhof
Dinobryon cylindricum cysts
Dinobryon divergens Imhof
Dinobryon sociale Ehr.
Dinobryon cysts
Hymenomonas roseola Stein
Mallomonas caudata Iwanoff
Mallomonas elongata Reverdin
Mallomonas fastigata Zach.
Mallomonas litomesa Stokes
Mallomonas producta (Zach.) Iwanoff
Mallomonas pseudocoronata Presc.
Mallomonas sp. #1
Mallomonas sp. #3
Mallomonas tonsurata var. alpina (Pasch. and Ruttn.) Kreig.
Mallomonas cysts
Ochromonas sp. #1
Spiniferomonas trioralis Takahashi
Synura uvella Ehr.
Uroglenopsis americana (Calk.) Lemm.
(continued).
119
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APPENDIX 1. (continued).
CRYPTOPHYTA
Cryptomonas erosa Ehr.
Cryptomonas marssonni Skuja
Cryptomonas ovata Ehr.
Cryptomonas sp. //I
Cryptomonas cyst
Chroomonas nordstedtii Hansg.
Rhodomonas minuta Skuja
Rhodomonas minuta var. nannoplanctica Skuja
Undetermined cyst
Undetermined flagellate sp. #1
Undetermined flagellate sp. #2
Undetermined flagellate spp.
CHLOROPHYTA
Actinastrum gracilimum G.M. Sm.
Actinastrum hantzschii Lagerh.
Actinastrum hantzschii var. fluviatile Schroed.
Ankistrodesmus braunii (Nag.) Brunnth.
Ankistrodesmus falcatus (Corda) Ralfs
Ankistrodesmus falcatus var. mirabilis (West and West) G.S. West
Ankistrodesmus gelifactum (Chod.) Bourr.
Ankistrodesmus setigerus (Schroed.) G.S. West
Ankistrodesmus sp. #1
Ankistrodesmus sp. #3
Ankistrodesmus sp. #4
Binuclearia eriensis Tiffany
Borodinella polytetras Miller
Botryococcus braunii Ku'tz.
Cerasterias sp. #1
Characium curvatum G.M. Sm.
Chlamydomonas sp. //I
Chlorella sp. #1
Chodatella ciliata (Lagerh.) Chod.
Cladophora sp. #1
Closteriopsis sp. #1
Closterium aciculare T. West
Coccomyxa minor Skuja
Coelastrum microporum Nag.
Coelastrum proboscideum Bohlin
Coelastrum reticulatum (Dang.) Senn.
(continued).
120
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APPENDIX 1. (continued).
Cosmarium botrytis Menegh.
Cosmarium depressum (Nag.) Lundell
Cosmarium sp. #1
Crucigenia quadrata Morren
Dictyochlorella sp. #1
Dictyosphaerium ehrenbergianum Nag.
Dictyosphaerium pulchellum Wood
Dimorphococcus sp. //I
Elaktothrix gelatinosa Wille
Eudorina elegans Ehr.
Eutetramorus sp. //I
Franceia droescheri (Lennn.) G.M. Sm.
Gloeocystis planctonica (West and West) Lemm.
Gloeocystis sp. #1
Gplenkinia paucispina West and G.S. West
Golenkinia radiata (Chod.) Wille
Gonium pectorale Mull.
Kirchneriella lunaris (Kirch.) Moebius
Kirchneriella obesa var. major (Bernard) G.M. Sm.
Lagerheimia subsalsa Lemm.
Lobocystis sp. #1
Micractinium pusillum Fresenius
Mougeotia sp. #1
Nephrocytium agardhianum Nag.
Nephrocytium limneticum (G.M. Sm.) G.M. Sm.
Oedogonium sp. #1
Oocystis borgei Snow
Oocystis parva West and West
Oocystis solitaria Wittr.
Oocystis spp.
Palmodictyon sp. //I
Pediastrum boryanum (Turp.) Menegh.
Pediastrum duplex Meyen
Pediastrum duplex var. clathratum (A. Braun) Lagerh.
Pediastrum duplex var. cohaerens Bohl.
Pediastrum tetras (Ehr.) Ralfs.
Pedinomomas sp. #1
Phacotus lenticularis (Ehr.) Stein
Planctonema lauterbornii Schmidle
Quadrigula lacustris (Chod.) G.M. Sm.
Saturnella sp. #1
Scenedesmus abundans var. brevicauda G.M. Sm.
Scenedesmus acutiformis Schroed.
Scenedesmus arcuatus var. platydisca G.M. Sm.
Scenedesmus armatus (Chod.) G.M. Sm.
Scenedesmus bicellularis Chod.
(continued).
121
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APPENDIX 1. (continued).
Scenedesmus bijuga (Turp.) Lagerh.
Scenedesmus bijuga var. alternans (Reinsch) Hansg.
Scenedesmus corallinus Chod.
Scenedesmus denticulatus var. australis Playfair
Scenedesmus denticulatus Lagerh.
Scenedesmus dimorphus Kiitz.
Scenedesmus falcatus Chod.
Scenedesmus granulatus West and West
Scenedesmus hystrix Lagerh.
Scenedesmus incrassatulus Bohl.
Scenedesmus intermedius Chod.
Scenedesmus jovis Chod.
Scenedesmus lefervii Defl.
Scenedesmus longus Meyen
Scenedesmus quadricauda (Turp.) Breb.
Scenedesmus quadricauda var. longispina (Chod.) G.M. Sm.
Scenedesmus quadricauda var. maximus West and West
Scenedesmus quadricauda var. parvus G.M. Sm.
Scenedesmus quadricauda var. quadrispina (Chod.) G.M. Sm.
Scenedesmus sempervirens Chod.
Scenedesmus serratus (Corda) Bohl.
Scenedesmus tetradesmiformis (Woloszynska) Chod.
Schroederia setigera (Schroed.) Lemm.
Selenastrum bibraianum Reinsch
Selenastrum westii G.M. Sm.
Selenastrum gracile Reinsch
Sestosoma sp. //I
Siderocystopsis sp. #1
Sorastrum sp. #1
Sphaerocystis schroeteri Chod.
Staurastrum paradoxum Meyen
Tetraedron caudatum (Corda) Hansg,
Tetraedron hastatum (Reinsch) Hansg.
Tetraedron minimum (A. Br.) Hansg.
Tetraedron trigonum (Nag.) Hansg.
Tetraedron trigonum var. setigerum (Archer) Lemm.
Tetrastrum staurogeniaeforme (Schroed.) Lemm.
Trochiscia sp. #1
Ulothrix subconstricta G.S. West
Ulothrix sp. //I
Undetermined green colony sp. //I
Undetermined green colony sp. #2
Undetermined green colony sp. #3
Undetermined green filament sp. //I
Undetermined green filament sp. #4
Undetermined green filament sp. #5
(continued).
122
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APPENDIX 1. (continued).
Westella linearis G.M. Sm.
Xanthidium antilopaeum var. depauperatum West and West
CYANOPHYTA
Agmenellum quadruplicatum (Menegh.) Breb.
Anabaena flos-aquae (Lyngb.) Breb.
Anabaena spiroides var. crassa Lemm.
Anabaena subcylindrica Borge
Anabaena zinserlingii Kossinskaja
Anabaena sp. #2
Anacystis cyanea (Kiitz.) Dr. and Daily
Anacystis dimidiata (Kiitz.) Dr. and Daily
Anacystis incerta (Lemm.) Dr. and Daily
Anacystis thermalis (Menegh) Dr. and Daily
Aphanizomenon flos-aquae (Lyngb.) Bre"b.
Chroococcus dispersus (Keissl.) Lemm.
Coccochloris sp. #1
Dactylococcopsis acicularis Lemm.
Gomphosphaeria aponina Ku'tz.
Gomphosphaeria lacustris Chod.
Gomphosphaeria wichurae (Hilse) Dr. and Daily
Microcoleus vaginatus (Vauch.) Com.
Oscillatoria bornetii Zukal
Oscillatoria limnetica Lemm.
Oscillatoria retzii Ag.
Oscillatoria sp. #1
Oscillatoria sp. #2
Plectonema sp. #1
Schizothrix calcicola (Ag.) Com.
Undetermined blue-green filament #1
Undetermined blue-green filament #2
PYRRHOPHYTA
Ceratium hirundinella (O.F. Mull.) Shrank
Glenodimium sp. #1
Gymnodinium helveticum Penard
Gymnodinium sp. #1
Hemidinium sp. #1
Peridinium aciculiferum (Lemm.) Lemm.
Peridinium cinctum (Mull.) Ehr.
Peridinium lindemanii Lef.
Peridinium sp. #1
Peridinium sp. #2
(continued).
123
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APPENDIX 1. (continued).
EUGLENOPHYTA
Euglena allorgei Defl.
Euglena acus Ehr.
Euglena viridis Ehr.
Lepocinclis sp. #1
Phacus sp. //I
Tracholomonas lacustris Drezep.
Tracholomonas volvocina Ehr.
Trachelomonas sp. #1
SCHIZOPHYTA
Beggiatoa alba (Vauch.) Trev.
124
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TECHNICAL REPORT DATA
(Fttatt read irutrucriom on i>u rrrtnt
1. REPORT NO.
EPA-600/3-83-0.75
2.
RECI'I
'OBW-tCCESaiON NO.
PBF.S 25&035
4. TITL1 AND 3UST1TLI
Effects of Phosphorus Loading on Phytoplankton Distri-
bution and Certain Aspects of Cytology in Saginaw Bay,
Lake Huron
REPORT DATB
August 1983
.PERFORMING ORGANIZATION CODE
. AUTHOR(S)' ~
E. F. Stoermer, L. Sicko-Goad, and L. C. Frey
PERFORMING ORGANIZATION REPORT NO.
. PERFORMING ORGANIZATION NAMI AND ADORES*
Great Lakes Research Division
The University of Michigan
Ann Arbor, Michigan 48109
10. PROGRAM ELEMENT NO.
11. CONTRAC
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Duluth. MM 5580.4
13. TYPE Of REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/60C703
IS. SUPPLEMENTARY NOTES
16
.
Saginaw Bay has always been one of the more productive regions of the Great Lakes system. At the present
time, It Is also one of the most modified. Excessive nutrient and conservative element loadings are
factors which have led to severe perturbation of primary producer communities In the region. Because of
the physical dynamics of the bay region, Idealized dilution gradients are grossly modified by transport of
water masses and their entrained chemical constituents, fauna and flora Into, as well as away from, the ;
bay. However, there appears to ba considerable selection among population components of the assemblages
transported. For example, blue-green algae appear to be conserved In the bay while diatoms are subjected :
to great losses. ' !
The major, effort In this Investigation was to provide data on phytoplankton blovolume which would support
a model of processes occurring In Saginaw Bay. A method of estimating the actual vlaole fraction of the
cell volumes of representatives of the various physiological groups of phytoplankton found in Saginaw Bay
was developed, and polyphosphate body formation was studied.. Results showed that substantial
phytopl ankto'n populations were exported from the bay to Lake Huron. Under average wind conditions, most
export occurred along the southern coast. These populations were then entrained .In the general Lake Huron
circulation and were spread down the Michigan coast southward from the bay. Under certain advectlve
conditions, however, phytoplankton were discharged from the bay either to the north or' directly offshore.
Cytologlcal analysis showed that many species sequestered phosphorus In excess of their immediate >
physiological needs, In the form of polyphosphate bodies. Populations exported from the bay also
contained .these polyphosphate bodies. Analysis of the polyphosphate bodies showed that significant
quantities of certain toxic metals, notably lead, were Incorporated into these Inclusions.
Analysis of the relationship of total phytoplankton cell volume to protoplasmic constituent volume showed
that crude cell volume measurements furnished a poor estimate of actual I I vlng blomass |n many
populations. It was concluded that more refined techniques are required to correctly convert estimates of
number to BStlnmtre nf hlnmasi.
KIY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lOENTIPlERS/OPEN ENDED TERMJI
c. COSATi Field/Croup
It. DISTRIBUTION STATEMENT
JRFLEASE 10 PUBLIC
It. SECURITY CLASS (This Riport)
UNCLASSIFIED
21. NO. OP PAO«f
135
20. SECURITY CLAM (T*il p*f«)
UNCLASSIFIED
22. PRICI
EPA Pm 7HO-1 (Re*. 4-77) PMIVIOUI COITION 11 O«»OI_«T«
------- |