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This is to certify that the
thesis entitled
7 Evaluation of the Ecoregion Concept as

an Inland Lake Management Tool for
Lower Michigan

presented by

Nanette F. Kelly

has been accepted towards fulfillment
of the requirements for '

 

 

Master of Science degree in Fish. & Wildl.

Major professor

March 24, 1995

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EVALUATION OF THE ECOREGION CONCEPT
AS AN INLAND LAKE MANAGEMENT TOOL
FOR IDWER MICHIGAN

By

Nanette Fae Kelly

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE
Department of Fisheries and Wildlife

1995

ABSTRACT
EVALUATION OF THE ECOREGION CONCEPT
AS AN INLAND LAKE MANAGEMENT TOOL
FOR LOWER MICHIGAN
By

Nanette Fae Kelly

There is a need to manage water quality in inland lakes in Michigan to halt
cultural eutrophication and / or restore inland lakes. Evaluation of individual lakes
is a time consuming and expensive process according to state and national
governmental agencies. Ecoregions are becoming accepted as a regional water
quality management tool throughout the United States to predict reasonable
attainable water quality for geographic areas. This paper analyzes the spatial
relationship of chemical and biological attributes of selected inland lakes in Lower
Michigan, and evaluates the ecoregion concept as a possible inland lake
management tool. Possible lake management regions were defined for lakes on
the extreme ends of the trophic scale by combining regions previously defined by
two independent methods. Existing ecoregions do not provide the best lake
management regions, but if based on water quality parameters this concept could

provide useful lake management regions for state water quality managers. '

ACKNOWLEDGMENTS

I would like to thank Dr. Niles Kevern, my major professor, for giving me
the opportunity to do this project and for being so patient and understanding as I
struggled through it. I have gained much knowledge about the workings of lakes
and about Lower Michigan.

I would like to thank Dr. Darrell King for his help in analyzing data,
computer expertise, and making me think a little, also for the moral support that I
often needed. I also want to thank Dr. Scott Witter for his help in this project. I
need to include a thanks to all of the people at the Center for Remote Sensing at
Michigan. State University who helped me with computer problems; Bill Enslin,
Dave Lusch and Brian Buckley.

My biggest thanks go to my husband, who has been my greatest moral
support through, not only my graduate studies, but through my undergraduate
education as well. I could not have done this if he had not been behind me

100%.

iii

TABLE OF CONTENTS

page

ABSTRACT ii
ACKNOWLEDGMENTS iii
LIST OF TABLES vi
LIST OF FIGURES vii
INTRODUCTION 1
Ecoregions 5
Omernik’s Ecoregions 7

Albert’s Ecoregions 8

Objectives 12

‘ METHODS 14
Spatial Analysis 14
Ecoregions 15
Simple Regressions 17
Kruskal-Wallis One-Way Analysis of Variance 17
Carlson’s Trophic State Index 20
RESULTS 22
Spatial Analysis 22
Ecoregions 22

Lakes with Omernik’s Ecoregions 22

Lakes with Albert’s Districts (Ecoregions) 24

iv

page

Statistical Analyses 26
Simple Regressions 30
Kruskal-Wallis One-Way Analysis-of-Variance 32
Carlson’s Trophic State Index 34

DISCUSSION 38

Ecoregions and Spatial Analysis 38
Carlson’s Trophic State Index 47
Simple Regressions 50
Kruskal-Wallis One-Way AN OVA 51
SUMMARY 53

LIST OF REFERENCES 56

Table 1a.

Table 1b.

Table 2.

Table 3.

Table 4a.

Table 4b.

LIST OF TABLES

P33e
Trophic states of lakes based on total phosphorus. 16
Four classes of alkalinity. ‘ 16
Results of simple regressions. 31

H values for Kruskal-Wallis One Way AN OVA. All values are
significant at a=0.01. 31

Kruskal-Wallis. multiple comparison results for Omernik’s
ecoregions. 34

Kruskal-Wallis multiple comparison results for Albert’s Districts. 34

Figure 1.

Figure 2.

Figure 3a.

Figure 3b.

Figure 4a.

Figure 4b.

Figure 5a.

Figure 5b.

Figure 6a.

Figure 6b.

Figure 6c.

Figure 6d.

Figure 7a.

Figure 7b.

LIST OF FIGURES

Forest and agriculture land use by county in Lower Michigan
(Atlas of Michigan 1978).

Ecoregions defined by James Omernik are based on soil type,
landform, vegetation and land use.

Two regions used by Dennis Albert to divide northern and
southern Lower Michigan.

Districts defined by Dennis Albert based on climate,
physiography, soil types and vegetation.

Polygons map for total phosphorus in inland lakes in Lower
Michigan, in mg P/L.

Polygon map for alkalinity in inland lakes in Lower
Michigan, in mg Calcium carbonate/L

The formula for Kruskal-Wallis One Way AN OVA.

The formula for Kruskal-Wallis multiple comparison
(Miller 1980).

The location of oligotrophic lakes with respect to the
ecoregions defined by James Omernik.

The location of mesotrophic lakes with respect to the
ecoregions defined by James Omernik.

The location of eutrophic lakes with respect to the
ecoregions defined by James Omernik.

The location of hypereutrophic lakes with respect to
the ecoregions defined by James Omernik.

The location of oligotrophic lakes with respect to the
districts defined by Dennis Albert.

The location of mesotrophic lakes with respect to the
districts defined by Dennis Albert.

page

10

10

18

18

19

19

LIST OF FIGURES, continued

Figure 7c.

Figure 7d.

Figure 8a.

Figure 8b.

Figure 9a.

Figure 9b.

Figure 10.

Figure 11.

Figure 12a.

Figure 12b.

Figure 120.

Figure 12d.

Figure 13.

The location of eutrophic lakes with respect to the districts
defined by Dennis Albert.

The location of hypereutrophic lakes with respects to the
districts defined by Dennis Albert.

Averaged total phosphorus, by ecoregion, in mg P/ L. (The
numbers above the bars are the n values).

Mean total phosphorus values in mg P/ L, and standard
deviation for four ecoregions defined by James Omernik.
(Ecoregion 57 has only one lake).

Averaged total phosphorus values in mg P/ L (The numbers
above the bar are the n values).

Mean total phosphorus values in mg P/I, and standard
deviation for nine districts defined by Dennis Albert
(Districts 5, 6, and 7 have only one lake in the data set).

Averaged Carlson’s Trophic State Index values for inland
lakes in Lower Michigan, using the ecoregions defined by
James Omernik.

Averaged Carlson’s Trophic State Index values for inland
lakes in Lower Michigan, using the districts defined by
Dennis Albert.

The location of oligotrophic lakes m Lower Michigan,
having < 0.01 mg P/L.

The location of mesotrophic lakes in Lower Michigan, having
0.01-0.03 mg P/L.

The location of eutrophic lakes in lower Michigan, having
0.03-0.05 mg P/L.

The location of hypereutrophic lakes in Lower Michigan,
having > 0.05 mg P/L.

Two lake management regions based on the distribution of

oligotrophic lakes in the north and hypereutrophic lakes in the
south.

viii

page

25

27

27

29

29

35

36

39

39

39

39

43

INTRODUCTION

There has been increased concern over the quality of the surface water in
the United States since the Clean Water Act and it’s amendments in the 1970’s.
Cultural eutrophication of surface waters from additions of fertilizers, animal
wastes, detergents and municipal sewage and septic systems, has contributed to
the decrease of water quality for inland lakes in Michigan.

Michigan has over 35,000 inland lakes (Pringle 1983), over 11,000 are at
least five acres in surface area. There are 712 significant public access lakes in
Michigan, according to the Michigan Department of Natural Resources (MDNR),
many having relatively complete chemical, biological and physical data stored in
STORET, Storage and Retrieval of the United States Environmental Protection
Agency’s (USEPA) water quality datafile.

According to Dorr (1970), the genesis of the underlying area determines
the morphometry and substrate that characterize lakes. Michigan has a history of
glaciation that has repeatedly stripped soils from the bedrock, churned them up
and randomly deposited them. Outwash plains of sand, gravel and silt provided

varying low nutrient subsoil where vegetation was established and contribute to

2
the soil layer. Michigan presently has over 250 soil types that are being mapped

(Mokma, pers. comm.) and that are found in seventy eight soil associations for the
entire state, most of which occur in Lower Michigan (USDA 1981). There is a
division between the Frigid soils in the north which are sandier and have lower
concentrations of nutrients, and the Mesic soils in the south which are more
productive clays and loarns.

The soil types, climate and topography dictate the type of land use for an
area. Areas dominated by forest land uses such as timber or recreation tend to
be in the northern part of Lower Michigan (Figure 1). Agricultural use dominates
the southern part of Lower Michigan and often adds nutrients to surface water in
the form of fertilizer.

There are a number of physical attributes, other than soil types, that
contribute to the similarities and differences in lakes; latitude (Brylinski and
Mann 1973), the proximity of land to large bodies of water (Wetzel 1983), total
dissolved solids (Northcote 1956, Ryder 1965, Ryder 1974), morphometry
(Richardson 1975, Home 1975, Fee 1979), the ratio of surface area to mean depth
(Rawson 1955) and a number of chemical attributes such as phosphorus and
carbon for example (Wetzel 1972).

Total phosphorus was selected for this study because it is usually
considered to be the limiting factor in natural surface waters because of it’s
scarcity (Fee 1979, Richardson 1975, Schaffner and Oglesby 1978, Schindler 1977,
Edmondson 1970, Hsiang and Long 1991). Phosphorus can be added to surface

80-100 % Forest

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4
waters by a number of human activities (Oglesby and Bouldin 1984, Schaffner and

Oglesby 1978). Human populations add phosphorus through sewage wastewater.
Homeowners add phosphorus in the form of lawn fertilizers (Taylor 1977), leaky
septic systems (Tsatsaros 1993 ), and in some states, laundry detergents.
Agriculture adds phosphate from fertilizers and manures (Harrison 1987).
Atmospheric fallout delivers phosphorus to lakes adsorbed to dust particles
(Baudo 1990). Urban centers do not add phosphorus to inland lakes because
sewage is transported through pipes to streams, and runs to the Great Lakes.
Another important consideration is how phosphorus moves in the
environment. Active agricultural practices add larger amounts of nutrients than
inactive agricultural land, which add more than forested landscapes (Harrison
1987, Omernik et al. 1981, Borman 1970). Baudo (1990), however, points out that
soils with high adsorptive capacities for phosphorus, like many of the glacial tills
in southern Lower Michigan, tend to bind phosphorus before it reaches the
surface water. Phosphorus is often used as a measure of the productivity of
surface water. Where it is the limiting factor, the amount of phosphorus available
to plants determines the amount of primary productivity in the water.
Carbonate-bicarbonate alkalinity is a fundamental factor in determining the
potential productivity of lakes as well. The drainage basin within which a lake is
situated has a particular substrate, soil composition and climate. Carbon dioxide
can be consistently made available to plants through the atmosphere in terrestrial

systems but not in aquatic systems. These plants must rely on the supply of

5
carbon dioxide from the carbonate-bicarbonate alkalinity system (King 1970).

Those lakes of low alkalinity tend to have lower productivity than those having
high alkalinity (Barrett 1952, Omernik 1986, Moyle 1956). The alkalinity in lakes
is based on the geology of an area and can vary regionally depending on the type
of substrate. Areas dominated by limestone bedrock have lakes with high
alkalinity. Areas dominated by granite substrate have lakes with low alkalinity.

It could be expected that lakes with similar attributes would occur within
an area of similar terrestrial attributes. It could also be expected that lakes in
close proximity to one another would have similar attributes such as nutrient
levels and biological assemblages compared to lakes spatially removed from one
another (Hughes 1987). These expectations are based on the assumption that
there is relative spatial homogeneity of attributes, and that there is a gradual
change in attributes as physical distance increases between lakes.

The spatial relationship of trophic levels of lakes has relevance to
terrestrial regional variation which will be covered in the section of this thesis on
ecoregions. Water quality in lakes reflects the conditions in the watershed such as
land use, soil type and vegetative cover. Both land uses such as agriculture or
forest, and natural characteristics such as soil type or vegetation, vary among
watersheds thus the lakes within these watersheds vary as well.

Missions
This thesis compares lakes in Lower Michigan to regional areas that have

been defined previously (Omernik 1987, Albert 1986). It considers the possibility

6

of grouping inland lakes in Michigan into areal units, or ”ecoregions" based on
surface water quality for the purpose of lake management. Ecoregions have been
defined by similarities of soil types, land use, climate, physiography, and
vegetation types within areas. Chemical conditions of lakes in close proximity to
one another could be used to define spatial homogeneity of lakes. This could be
used as a guideline for attainable water quality by comparing the water quality of
lakes near the lake in question.

There is a need for a general classification system that can be used for
more than a single purpose in water quality management. Expensive site specific
remedies for problems could be eliminated or reduced using this method of
management. There is interest from the Environmental Protection Agency
(EPA) for this approach to identify areas for monitoring and assessment; the
Environmental Monitoring and Assessment Program (EMAP) (Loehr pers.comm.
1991).

Geographic areas having similar attributes that vary significantly from
adjacent areas can be called ecoregions. Several attempts have been made to
classify areas into ecoregions for the United States and individual states. R. G.
Bailey (1976) produced a map based on climate and vegetation, land surface form,
soils, and fauna delineating areas of similar characteristics as an aid to
environmental management. The climate descriptions used by Bailey were based
on Koppen’s classifications and land surface form and work by E. H. Hammond

as cited in Bailey (1976). James Omernik (1988) published a map of ecoregions

7

of the United States to assist managers of aquatic and terrestrial resources to
understand possible realistic attainable water quality. Omernik (1987) stressed
land use (agriculture or forest), soils, land surface form and potential natural
vegetation. Dennis Albert (1986) produced a map of ecoregions for the state of
Michigan. Albert’s districts are based on climate, soil types, physiography and
vegetation.

There has been support for Omernik’s theory (Hughes and Larsen 1988,
Rohm et al. 1987, Whittier et al. 1988, Hughes et al. 1986, Larsen et al. 1988). A
number of papers have been published defining the theory, and comparing it to
conventional surface water management techniques (Omernik and Gallant 1989,
Hughes et al. 1990, and Omernik and Griffith 1991). Work in Michigan,
Wisconsin and Minnesota mapped total phosphorus alone, or combined with a
number of physical attributes related to lakes (Omernik et al. 1988, Omernik et
al. 1991). The purpose of these maps was to clarify patterns of lake trophic states
based on total phosphorus concentrations in water, to be used to determine

attainable water quality for inland lakes.

Omernik’s Ecoregions

The ecoregions defined by James Omernik are areas of relatively
homogeneous ecological systems. He stresses soil type, land use, potential
natural vegetation and physiography. His ecoregions consist of a core of the most

typical conditions and a transitional area surrounding the core. The relatively

8

small central core consists of a homogeneous combination of all of the attributes
used for the classification, while in the transitional area one or more of the
attributes differed from those in the core. There are parts of five of Omernik’s
ecoregions within Lower Michigan (Figure 2).

Ecoregion 50 is mostly forest and woodland. Soil types are podzolic (Gray-
Brown Podzolic, Podzol, and Brown Podzolic) which have low fertility. Ecoregion
5 1 is mainly orchards, pasture, woodland, and forest. Soils are Gray-Brown
Podzolic which have low fertility. Ecoregion 55 is a small area dominated by
cropland. The Soils are Alfisols Gray-Brown Podzolic/Humic Gley and are
fertile, productive soils. Ecoregion 56 is row crops, pasture, woodland, and forest.
The productive soils of this ecoregion are Gray-Brown Podzolic. Ecoregion 57 is
dominated by cropland. The fertile soils of this ecoregion are Humic Gley, low
Humic Gley, Gray-Brown Podzolic/Humic Gley. There are very few lakes in this
ecoregion because it is a lake plain from the glacial period. As the glaciers
retreated across the large glacial lakes that covered this part of the world, the
chunks of ice that fell from the glacier fell into water and melted leaving no
evidence of this process. This differs from the glacial retreat on land in which the
chunks of ice fell onto rock and were covered with till which melted slowly
forming a depression, or kettle lake.

Albert’s Districts
Dennis Albert (1986) divided Lower Michigan into Region I and Region II

(Figure 3a). This division was based on differences in climate, physiography, soil,

57

 

56

 

Figure 2. Ecoregions defined by James Omernik
are based on soil types, landform, vegetation
and land use.

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11

vegetation and land use. He has divided Lower Michigan into twelve ecoregions.
Three of which I have combined because they have only two lakes from my data
set (Figure 3b).

Region I is southern Lower Michigan where soils are fertile and agriculture
dominates land use. The land use in District 1 is dominated by agriculture with
some fragmented forest and metropolitan areas. Land use in District 2 is
dominated by agriculture with some scattered oak / hickory forest, swamps,
marshes and prairies. Land use in District 3 is dominated by agriculture (fruit),
with scattered remnants of woodlots. Land use in District 4 is dominated by
agriculture and beech/maple forest on uplands and hardwood swamps.

District 5, 6 and 7 surround Saginaw Bay and are combined for this
research because they have a very small sample size, only two lakes from my data.
Districts 5 and 6 are in region 1, district 7 is in region II. Agriculture is the
dominant land use in these districts. District 7 is on the northwest shore of
Saginaw Bay. Land use is mostly agriculture and is probably the major
contributor to phosphorus pollution to surface waters.

Region II is the northern part of Lower Michigan where soils have low
natural fertility and agriculture does not dominate land use. In District 8, 9, 10,

11 and 12 land use is dominated by forest of various compositions.

12
MM
1. Many lakes in Lower Michigan exhibit problems associated with

accelerated eutrophication from human interferences. The first objective of this
thesis is to determine if lakes in Lower Michigan that are being impacted by
cultural eutrophication can be identified spatially on a regional scale, and what
factor or factors are contributing to, or preventing cultural eutrophication of these

lakes.

2. Lake managers in the MDNR are looking for a regional lake management
tool that will allow them to predict possible water quality problems without
requiring expensive site analysis. The second objective of this thesis is to
determine if the ecoregions, that have been defined by James Omernik or Dennis
Albert, can be used as a management tool for inland lakes in Lower Michigan.
James Omernik initiated his work dealing with ecoregions as a method of
determining attainable water quality on a regional scale in response to surface

water quality problems due to pollution from various sources.

3. Michigan has an exceptional water resource in the form of inland lakes
which needs to be managed to preserve water quality for recreational purposes
and ecosystem integrity (Hutchinson 1970, Karr 1991). Is it possible to try to
restore all lakes in Lower Michigan to their original form? Should lakes be

managed to protect water quality in high quality lakes or to restore water quality

13

in lakes that have been impacted? The final objective is to determine where we

should concentrate our inland lake management efforts in Lower Michigan.

METHODS

The data for this study came from several sources. The majority of the
data for my study were EPA quality controlled STORET (Storage and Retrieval)
data for significant, public access lakes in lower Michigan. These data were
chemical, physical and biological attributes for about three hundred inland lakes
in lower Michigan. Many of the maps generated for this thesis came from the
~ Atlas of Michigan (1978). Some maps were reproduced directly from the atlas
while others were the result of combinations of maps. Other maps used the
ecoregions defined by James Omernik or the Districts defined by Dennis Albert.

Lakes that are reservoirs, drowned river mouths or lakes that had
significant point source inputs were excluded from the study. Lakes with
significant inputs of point source pollution represent exceptional human
interferences that often produce abnormally high concentrations of total
phosphorus. Reservoirs are the result of stream impoundment, another type of
human interference. Drowned river mouths are not natural lakes, but are the
shallow waters near the coast of the Great Lakes where streams have become
impounded due to a change in water level. These water bodies do not accurately
represent natural lakes in lower Michigan due to their origin or human

interference.

14

15
Spatial Analysis

Values of total phosphorus from STORET data, for individual lakes were
plotted on a basemap using Freelance Graphics software package. The method of
assigning trophy of surface water is subjective. Physical, biological or chemical
parameters can be used such as Secchi disk depth, chlorophyll a, total phosphorus
or nitrogen. The chosen parameter could be based on a previous scale or
divisions convenient for the purpose at hand. I have used four trophic levels
based on total phosphorus for this study (Table 1a) in divisions similar to those
used by the MDNR.

Lakes having total phosphorus concentrations within the same tr0phic level
were identified and visually clustered into enclosed regions or polygons by
separating lakes of different trophic levels as illustrated in Figure 4a and 4b.
Polygons were created in the same way for the alkalinity concentrations for lakes.
Four divisions of alkalinity were used (Table 1b).

The shape, sizes and direction of the polygons of these two maps were
compared to determine if there was any similarity between the alkalinity polygons
and the total phosphorus polygons. Both polygon maps were then compared to a
map showing county by county percent of land use in agriculture.

Wan:

Previous ecoregion studies by James Omernik (1987), for the conterminous

United States, and another by Dennis Albert (1986), for Michigan, were

considered as possible models on which to base statistical analyses. Each lake

16

Table 1a. Trophic states of lakes based on total phosphorus.

 

 

Trophic State mg POJL
Oligotrophic < 0.01
Mesotrophic 0.01 - 0.03
Eutrophic 0.03 - 0.05
Hypereutrophic > 0.05

 

 

 

Table 1b. Four classes of alkalinity.

 

 

Class mg CaCOalL
low < 50
Moderate 51 - 100

Moderately High 101 - 150
High > 150

 

 

 

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18

was assigned to the appropriate district as defined by Albert or, to ecoregions

defined by James Omernik.

Simple Regressions

Regressions were calculated for total phosphorus concentrations for inland
lakes within each ecoregion or district as the independent variable, and the other
attributes as dependent variables, to determine the extent of the correlation
between total phosphorus and other attributes. The dependent variables selected
for these correlations were chlorophyll a, Secchi disk depth, and alkalinity.
Simple regressions were done on the software lotus 123, version 2.3 for DOS.

The STORET data for total phosphorus values for the inland lakes in
lower Michigan were entered into the spreadsheet software lotus 123. The data
were sorted into subsets by Omernik’s ecoregion or Albert’s district. Averages,
standard deviations, maximum, minimum and the number of lakes in the sample
were calculated and included on the spreadsheet. Bar graphs for mean total
phosphorus, by ecoregion or district, were plotted. I-Iigh-low—Close graphs use
the same data but include the range of the standard deviation to see how much
variation there was for total phosphorus among the lakes within an ecoregion or

district.

Kruskal-Wallis One Way Analysis of Variance

Each of Omernik’s ecoregions and Albert’s districts, having lakes, was

19
analyzed using the Kruskal-Wallis one way analysis of variance (Howell 1989)

(Figure 5a). This nonparametric test does not assume normal distribution. It
tests the hypothesis that all samples were drawn from identical populations. It is
especially sensitive to differences in central tendency. Total phosphorus, Secchi
disk depth, chlorophyll a, and alkalinity were tested separately. Then they were
divided by ecoregion or district and summed.

The data were analyzed using the Kruskal-Wallis multiple comparison test
to determine what was causing the differences among the ecoregions and districts
(Miller 1980) (Figure 5b). This test compares each ecoregion or district to each
of the other ecoregions or districts, for each of the attributes mentioned in the

previous paragraph, to calculate the basis for the differences.

Carlson’s Trophic State Index

Carlson’s trophic state index (TSI) values for Secchi disk depth (SD),
chlorophyll a (Chl a), and total phosphorus (TP) were calculated using the mean
value for each region, for each of these parameters. These regional TSI values
were plotted as bar graphs. The TSI bars for total phosphorus, chlorophyll a, and
Secchi disk were grouped by region. This index should give TSI values for total
phosphorus, chlorophyll a, and Secchi disk which are about the same values for a
given lake, and for a group of similar lakes.

This method of determining the productivity of lakes is used by many state

agencies and citizen monitoring groups throughout the United States. For Secchi

 

 

12 k R,’

=N‘ (N+1) 1.21 1151 -3(N+1)

H

 

 

k = the number of groups
n J: the number of observations in Group j

Rj=thesumoftheranksinGroupj
N= 2n Ttotalsamplesize

 

 

Figure 5a. The forumula for Kruskal-Wallis One Way
Analysis of Variance.

 

IR. RI s<hr.>‘”[1fl1152—i9]” g + if *

 

i - R i' = the rank mean of population tested

ZWI

= total sample size
1 n 1' - the number of observations

b

 

a =
1' k-l X”

 

 

Figure 5b. The formula for Kruskal-Wallis multiple
comparison (Miller 1980).

21
disk depth the equation is:
TSI(SD) = 10 [6 - (lnSD / ln2) 1;
for chlorophyll a (mg/L):
TSI(Chl a) = 10 [6 - (2.04 - (0.68 In Chl a) / ln2) ];
and for total phosphorus (mg P/L):
TSI(TP) = 10 [o - (ln48/TP) / (ln2) ].

RESULTS

Shamanism

There was a general east-west trend for the phosphorus polygons, and a
general north-south trend for the alkalinity polygons (Figures 4a and 4b). There
are some total phosphorus areas that agree with alkalinity areas, such as the band
of hypereutrophic lake polygon in the south thumb area and the northern most
part of the large high alkalinity polygon in southeastern lower Michigan. Some
other small areas overlap as well. Most of the polygons do not agree however,
such as the southern most part of the large high alkalinity polygon which
corresponds with the mesotrophic lake polygon in the southeastern part of lower
Michigan. The level of potential productivity indicated by the alkalinity polygons
is different from the level of productivity of the total phosphorus polygons.

Comparing the total phosphorus polygons to the county by county percent
use in agriculture did show agreement. Where agriculture dominates land use the

total phosphorus in lakes tends to be higher (Figure 1).

mm:
Lakes with Omernik’s Ecoregions

Oligotrophic lakes fall into ecoregions 50 and 51 in northern lower
Michigan, and there are a few lakes scattered through ecoregion 56 (Figure 6a).

Mesotrophic lakes are in every ecoregion except 57 (Figure 6b). Eutrophic lakes

22

 

Figure 6a. The location of Figure 6b. The location of

oligotrophic lakes with mesotrophic lakes with
res ct to the ecoregions res ct to the ecoregions.
de ed by James Omernik de ed by James Omernik.

 

 

A
A ‘ “A A A a
A ‘ A “ A ‘ A ‘ ‘
A M
‘1 ‘ I” ‘5. ‘ m
f‘ m ‘
Figure 6c. The location of Figure 6d. The location of
eutrophic lakes with hypereutrophic lakes with
reagct to the ecoregions res ct to the ecoregions
de ed by James Omernik de ed by James Omernik

24
also are found in all of the ecoregions except ecoregion 57 (Figure 6c).

Hypereutrophic lakes are found for the most part in ecoregion 56, the large
ecoregion that dominates the central and southwestern part of lower Michigan
(Figure 6d). There are two near the Michigan-Ohio border in ecoregion 55, one
just on the edge between ecoregions 57 and 56, and several straddling the border
between ecoregions 50 and 56.

By using the total phosphorus values for inland lakes we could combine
Ornernik’s ecoregions 50 and 51 to have a northern lake management region
because oligotrophic lakes are found almost exclusively in these ecoregions. The
other ecoregions could be a southern lake management region since the
hypereutrophic lakes are found in this area. Several of the hypereutrophic lakes
are near the edge of these two proposed regions which may be due to drawing

CI‘I'OI'.

Lakes with Albert’s Districts (Ecoregions)

The oligotrophic lakes lie within districts 11 and 12, and the northern part
of districts 8 and 9. Of the southern oligotrophic lakes, one is in district 1, one is
in district 4 and the last is between districts 2 and 4 (Figure 7a). The
mesotrophic and eutrophic lakes are in every district (Figures 7b and 7c), however
there is only one eutrophic lake in each of districts 10, 11 and 12. The
hypereutrophic lakes cover areas in districts 2, 3, and 4 (Figure 7d). There are

some along the edges of district 8. There are several in the southern part of

26

district 9, and several along the north and west edge of district 1. There are no
hypereutrophic lakes in districts 10, 11 and 12.

We could almost use Albert’s divisions of Region I and Region II for lake
management purposes (Figure 3a). Region I would need to extend a little further
to the north through Iosco county on the east and Mason or Oceana County on
the west side of lower Michigan. Or we could add District 10 and the northern

parts of District 3 and 9 to Omernik’s ecoregions 50 and 51.

W

The lakes were divided into subsets by ecoregions (Omernik) in which they
lie. The ecoregions have been ranked according to the average concentration of
the total phosphorus in each region (Figure 8a). There are four divisions, because
ecoregion 57 has no lakes from my data set. The ecoregions have been ranked
from the lowest total phosphorus value to the highest. Ecoregion 51 has the
lowest mean value at 0.012 mg P/L, with 31 lakes in the subset. Ecoregion 50 is
next with an average of 0.017 mg P/L, with 66 lakes in this subset. These
ecoregions have mean total phosphorus values that are within the mesotrophic
range as I have defined them. Ecoregion 55 has an average value of 0.027 mg
P/l, with a subset of only 7 lakes (also within the mesotrophic range). Ecoregion
56 has the highest average value at 0.044 mg P/L with 156 lakes in the subset
(which puts it within the eutrophic range).

There appears to be a difference among mean total phosphorus

27

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0 2a Eu 0 26% m.— :5:
nap—080 men—an .3 common 5 cab “Ram:— E .noMmBoo
Sommoueoo .58 .5.“ aerate—o ...—3.83 and . .3 ago—Enos.“ .83 vowflo>< 8w 25w?—
JE we a 8:? engage .53 :82 on 2:5

 

 

 

 

 

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28

concentrations for ecoregions (Figure 8b), but the standard deviation indicates no
statistical difference among ecoregions. Lakes fall over a large range of trophic
levels from mesotrophic to hypereutrophic in ecoregion 55, and oligotrophic to
hypereutrophic in ecoregion 56. For ecoregion 50 the standard deviation is
0.0125, for 51 it is 0.009, for 55 it is 0.026, and for 56 it is 0.046.

There are nine subsets of lakes using Albert’s districts. His districts 5, 6
and 7 have only two lakes from my set. The districts have been ranked from low
to high, using average total phosphorus concentrations (Figure 9a). District 12
has the lowest average with 0.010 mg P/l, and 19 lakes in the subset (just into
the mesotrophic range). District 11 has an average of 0.012 mg P/L with 12 lakes
in the subset. District 8 has an average 0.023 mg P/L with 81 lakes. District 9 .
has an average of 0.025 mg P/L with 16 lakes. Districts 8, 9. 11, and 12 also have
an average that is mesotrophic. District 1 has 0.032 mg P/L with a subset of 29
lakes. District 10 has an average of 0.036 mg P/L with a subset of 10 lakes.
District 2 also has an average of 0.036 mg P/L with a subset of 46 lakes. District
3 has an average of 0.042 mg P/L with 14 lakes. Districts 1, 2 and 10 are in the
eutrophic range. District 4 has an average of 0.065 mg P/ L with a subset of 41
lakes which puts it in the hypereutrophic range.

The ten districts defined by Albert also have large standard deviations.
The standard deviations are as follows; for district 12 it is 0.006, for district 11 it
is 0.010, for district 8 it is 0.024, for district 9 it is 0.024, for district 1 it is 0.029,

district 10 it is 0.046, for district 2 it is 0.032, for district 3 it is 0.021, and district 4

.98 Saw 2: E 83 one baa 26.— 5 98
.o .m gEaE e82 agon— B 8.58
“35% 2:: Hem aerate—o Began 28
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Amen—g .— on... 0.3 .8: 06
A osooe ashes: 25 .E as a case
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I

r

l
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8:35 503me when?
4 ... N a A a w = a e
_ L _ _ _ _ _ 2 _ 8...-
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30
has a standard deviation of 0.071 (Figure 9b). Again, the large standard

deviations show a wide range of trophic levels for all district except 11 and 12.
Using visual comparison, the only statistical difference appears to be between

districts 3 and 12 where the standard deviations do not overlap.

Simple Regressions

The strongest correlation for Omernik’s ecoregions was in ecoregion 55,
between total phosphorus and chlorophyll a with an r2 value of 0.863, with total
phosphorus as the independent factor and chlorophyll a as the dependent factor
(Table 2). This is a very small ecoregion with only seven lakes. The other
comparisons for Omernik’s ecoregions were significantly weaker having r2 values
0.333 or lower.

For Albert’s districts the larger r2 values were 0.756 in district 9, 0.733 in
district 12, and another of 0.614 in district 1, again were for the correlation
between total phosphorus and chlorophyll a. Total phosphorus and chlorophyll a
have been shown to be highly correlated (Dillon and Rigler 1974, Brylinski and
Mann 1973, Fee 1979). The lack of correlation of chlorophyll a to total
phosphorus in other ecoregions or districts could indicate that something other
than phosphorus is limiting in some of these lakes. Nitrogen or carbon can

become limiting when phosphorus is abundant.

31

Table 2. Results of simple regressions.

 

 

 

 

 

 

Ecoregion (Omernik) 50 51 55 56

Phosphorus and Alkalinity 0.013 0.005 0.301 0.002

Phosphorus and Secchi Disk 0.078 0.004 0.110 0.135

Phosphorus and Chl a 0333 0.150 0.863 0.202

District (Albert) 1 2 3 4 8 9 10 11 12
Phosphorus and Alkalinity 0.092 0.246 0.263 0.267 0.017 0.093 0.157 0.076 0.022
Phosphorus and Secchi Disk 0.238 0.017 0.004 0.082 0.140 0.279 0.185 0.099 0.115
Phosphorus and Chl a 0.614 0.436 0.181 0.120 0.392 0.765 0.469 0.467 0.733

 

Table 3. H values for Kruskal-Wallis One Way AN OVA
All values are significant at a- - 0. 01.

 

 

 

Ranked Parameter OMERN'IK ALBERT
Total Phosphorus 95.59 104.81
Chlorophyll a 73.56 68.97
Secchi Depth 40.03 37.00
Alkalinity 29.02 60.84

 

 

 

32
Kruskal-Wallis One Way Analysis of Variance

Using the Kmskal-Wallis one way analysis of variance all of the attributes
were found to have significant differences for all of Omernik’s ecoregions and
Albert’s districts (or = 0.01) (Table 3). We can conclude that the ecoregions are
different based on the parameters used.

The Kruskal—Wallis multiple comparison test determined where the origin
of differences were among ecoregions (Table 4a and 4b). For Omernik’s
ecoregions, there were two differences each, from a possible six combinations,
from total phosphorus, chlorophyll a, Secchi disk depth, and alkalinity. There
were no differences between ecoregions 50 and 51, 51 and 55, or 55 and 56.
There were differences in all cases for ecoregions 50 and 56, and three cases for
ecoregions 51 and 56. Only one difference was determined between ecoregions
. 50 and 55.

For Albert’s districts there were 24 cases, from a possible 36 combinations
of districts, where the differences came from total phosphorus. There were 18
differences due to chlorophyll a, 10 due to Secchi disk depth and 14 due to
alkalinity. There were differences in all of the 4 of the attributes in two
comparisons; between districts 1 and 4, and between districts 4 and 8. There were
differences in three of the attributes in 11 comparisons of districts, total
phosphorus being one of the comparisons in each of the 1 1. Eight combinations
of districts where there were no differences determined were 1 and 2, 1 and 10, 2

and 3, 3 and 4, 8 and 9, Sand 10, 9 and 10, and 11 and 12.

33
Table 4a. Kruskal—Wallis multiple comparison results for Omemik's ecoregions
(259) Indicate that there were four missing values for alkalinity.
* after value indicates a source of difference between ecoregions or districts.

 

 

tot Phos Chl a 8d NR

(259) (259)
R—R groups KW KW KW KW R—Fl
49.79 50—51 29.55 34.76 0.51 36.81 49.16
92.04 50-55 39.22 10.48 34.52 112.46 ' 90.71
33.81 50-56 80.83 * 63.60 " 57.90 ‘ 58.95 ‘ 33.57
96.69 51 -55 68.77 24.28 35.03 75.65 95.22
44.94 51 -56 110.38 * 98.36 ' 58.40 ' 22.14 44.33
89.51 55—56 41.62 74.08 23.37 53.51 88.19

 

 

 

Figure 4b. Kruskal—Wallis multiple comparison results for Albert's Districts.
* after value indicates a source of difference betweem ecoregions or districts.

 

 

 

tot Phos Chl a Sd Alk
(259) (259)

H-R groups KW KW KW KW Fl-R
33.69 1-2 13.17 20.20 0.47 11.09 33.52
43.97 1—3 42.93 19.86 32.43 49.87 * 43.30
33.69 1—4 49.07 * 47.69 ' 41.65 * 40.63 * 33.18
30.13 1—8 25.58 0.04 21.84 90.42 ' 29.71
44.99 1-9 33.57 6.43 0.32 96.04 * 44.29
50.63 1-10 34.67 3.94 17.11 67.51 49.85
48.90 1—11 91.99 ' 81.84 * 36.26 ' 19.45 45.42
42.26 1-12 109.60 * 76.44 * 38.64 49.48 ‘ 42.41
41.47 2—3 29.76 0.34 32.90 38.78 41.11
30.35 2—4 35.90 * 27.49 42.12 ' 29.54 30.27
26.34 2-8 36.75 " 20.24 21.36 79.33 * 26.43
42.54 2—9 46.74 * 26.63 0.15 84.94 " 42.16
48.47 2-10 47.84 24.14 16.63 56.41 * 47.97
43.74 2-11 105.17 * 102.03 * 35.79 8.36 43.34
39.64 2—12 122.77 ’ 96.64 * 38.16 38.39 40.18
41.47 3-4 6.15 27.83 9.22 9.24 40.83
38.63 3—8 68.51 ' 19.90 54.26 ' 40.55 * 38.08
51.07 3-9 76.50 * 26.29 32.75 46.16 50.29
56.11 3-10 77.60 ‘ 23.80 49.53 17.63 55.25
52.08 3-11 134.92 * 101.69 * 68.69 * 30.42 51.28
48.68 3—12 152.53 * 96.29 * 71.06 * 0.39 48.63
26.34 4—8 74.65 * 47.73 " 63.48 * 49.79 * 25.99
42.54 4-9 82.65 * 54.11 * 41.97 55.40 * 41.89
48.47 4—10 83.75 ' 51.63 * 58.76 * 26.88 47.73
43.74 4-11 141.07 * 129.52 * 77.91 " 21.18 43.07
39.64 4-12 158.68 * 124.12 * 80.29 * 8.85 39.89
39.78 8-9 7.99 6.38 21.51 5.62 39.20
46.06 8- 10 9.09 3.90 4.73 22.91 45.39
41.06 8—11 66.42 * 81.79 * 14.43 70.97 * 40.47
36.66 8-12 84.02 ' 76.39 * 16.80 40.94 * 37.06
56.90 9-10 1.10 2.49 16.79 28.53 56.03
52.93 9—11 58.42 ' 75.41 * 35.94 76.58 * 52.12
49.60 9-12 76.03 * 70.01 * 38.32 46.55 49.52
57.81 10-11 57.32 " 77.89 * 19.15 48.05 56.92
54.77 10—12 74.93 * 72.49 * 21.53 18.03 54.55
54.77 11 —12 17.61 5.40 2.38 30.03 50.53

 

tot Phos = total phosphorus, Chl a = chlorophyll a. Sd = Secchi disk depth.

Alk = alkalinity.

 

34
Carlson’s Trophic State Index

TSI values for total phosphorus, Secchi disk and chlorophyll a should be
relatively close to one another for a lake or group of lakes spatially near to one
another (Figure 10). The average TSI values for Omernik’s Ecoregion 51 are the
lowest overall. The Secchi disk T81 is slightly over 40 and phosphorus and
chlorophyll a are about 37 and 39 respectively. In ecoregion 50 the TSI’s are
slightly higher and all three values are very close at about 42. The phosphorus
TSI in ecoregion 55 is higher than the other two TSI values in that ecoregion.
Ecoregion 56 has the highest total phosphorus TSI, about 55, while Secchi disk
and chlorophyll a are lower at about 47 and 48 respectively.

Ecoregion 51 has more lakes in the oligotrophic trophic level than do the
other ecoregions, and the total phosphorus 181 is lower than the Secchi disk and
chlorophyll a TSI values. Ecoregions 55 and 56 have more lakes in the
hypereutrophic trophic level and the total phosphorus TSI values are higher than
the Secchi disk and chlorophyll a TSI values. The TSI values seem to fall within
or near the mesotrophic range on the graph. There are differences among them
however. There are differences among ecoregions for total phosphorus and
chlorophyll a (of five TSI points or more) which indicates a difference among
some ecoregions.

Albert’s district 11 has the lowest TSI values for the three parameters, with
the Secchi disk about 42 and total phosphorus and chlorophyll a about 36 (Figure

11). District 12 has slightly higher values for all three, and again the Secchi disk

35

 

100

T

80

eutrop c

l

60

TSI Values

«+3 i

u’fi'lfizs

o‘s°.'.

mesotrophic

- “-3-:- - x .

; ... I - ... .
Ii." . .'.v- -
‘ . :-: . : " (“-52%

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. "13's ’ . -
+45

20

Ema-s

~ sis s62?
oligotrophic

 

 

 

 

 

 

 

 

Omernik’s Ecoregion

 

 

TSI chlorophyll a I TSI total P

 

 

TSI Secchi disk

 

Figure 10. Averaged Carlson’s Trophic State Indes values
for inland lakes in Lower Michigan, using
the ecoregions defined by James Omernik.

TSI Values

36

 

 

100
80 _
_ p
60 — a
3,,
E-
i
40
_ “a
923..
O
‘3
20 e?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1o

 

 

11 12 9

 

 

Albert’s District
181 Secchi disk TSI chlorophyll a. TSI total P

 

 

 

 

Figure 11. Averafied Carlson’s Tro Ohic State Index values for
akes in Lower chigan, using the districts
defined by Dennis Albert.

37
value is higher. District 9 has better agreement among the three TSI values and

they are higher overall. District 8 has a higher phosphorus TSI, but the Secchi
disk and chlorophyll a are lower than district 9. Higher total phosphorus TSI
values could indicate that phosphorus is no longer the limiting factor. District 10
has relatively good agreement among the TSI values and is slightly higher than
district 8. District 1 has a high phosphorus TSI, over 50, and the others are in the
mid 40’s. District 2 has slightly higher values in a similar arrangement. District 3
has a very high phosphorus TSI of about 58, the chlorophyll a is just below 50 and
Secchi disk TSI is about 48. District 4 has the highest overall average values with
the phosphorus TSI just at 60 and the others following the pattern of district 3.
Districts 1 1 and 12 with more oligotrophic lakes have total phosphorus TSI values
that are lower than the Secchi disk and chlorophyll a TSI values. Districts 1, 2,
3, and 4, which have more hypereutrOphic, lakes have total phosphorus TSI values
that are higher than the Secchi disk and chlorophyll a TSI values. Again, as with

Omernik’s ecoregions there are difierences among some of Albert’s districts.

DISCUSSION

WWW

Soils are one of the most important factors when considering the
productivity of lakes. The soils in Michigan vary widely in color, thickness,
texture, chemical composition, biological properties and productivity. Forestry
dominates northern Lower Michigan where sandy soils have low fertility. Sandy
soils allow leaching of humus, nutrients and other materials. The infiltration rate
for these sandy soils is high, water holding capacity is low. Lakes in these areas
tend to have low productivity because well washed glacial tills do not have
nutrients to add to surface waters.

The oligotrophic lakes, having less than 0.010 mg total P/L are clustered
in the northern tip of Lower Michigan (Figure 12a) where soils are poor and
forestry dominates land use. Agriculture is avoided in these areas because of the
low fertility of the soils and so the lakes do not receive inputs of phosphorus from
agricultural use. Mesotrophic lakes are moderately productive lakes. These lakes
are found throughout Lower Michigan. Eutrophic lakes are more productive and
are also found throughout Lower Michigan. Both mesotrophic and eutrophic
lakes may receive excess nutrients from leaky septic systems of residences around
the lake, lawn fertilizers from residences and golf courses, and local agricultural
nutrient inputs as well such as from feed lots or crop fields. Lakes in northern

Lower Michigan have similarities such as morphometry and sandy soils, but

38

39

 

 

I
I
I
I
—Z>

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

( l;- i.
3:. a a'.
1 I

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

f— .3: g I _.

/. J ..

L—'—-'

 

 

 

 

 

 

 

 

 

 

Figure 12a. The location of a subset Figure 12b. The location of a subset

of oligotrophic lakes in of mesotrophic lakes in
Lower Michigan, having Lower Michigan, having
< 0.01 mg P/L. 0.01 to 0.03 mg P/L

 

Figure 12c. The location of a subset Figure 12d. The location of a subset
of eutrophic lakes in of hypereutrophic lakes in
Lower Michigan, having Lower Michigan, having
0.03 to 0.05 mg P/L. > 0.05 mg P/L.

4o

nutrients from leaky septic systems, lawn fertilizer runoff and agricultural nutrients
will increase productivity because phosphorus does not sorb to the sandy soils.
There are a few hypereutrophic (> 0.050 mg P/ L) lakes in the southern part of
northern Lower Michigan, in Ogemaw and Missaukee Counties (Figure 12d).

Lake Missaukee has a high total phosphoms concentration indicating a
hypereutrophic condition (Figure 12d.). It is a shallow lake about 27 feet deep at
the deepest point and is about 1,880 acres, and alkalinity is somewhat low at 86
mg CaCO3 . Lake City borders the lake on the east. Shallow lakes, which do not
thermally stratify in the summer, can be very productive (Brylinski and Mann
1974) because nutrients are available during these warm periods (thermal
stratification prevents the mixing of nutrients that have settled on the bottom of
the lake). If enough phosphorus is provided, as from agriculture or human wastes,
these lakes could be quite productive.

Lakes in Ogemaw County are mesotrophic, eutrophic and hypereutrophic.
Several lakes in Ogemaw County are hypereutrophic. Soils are a mosaic of clay,
sand, loam, and wet sandy and organic soils. Lakes in Ogemaw County are
densely populated with houses and summer cottages. Old poorly maintained
septic systems leach nutrients into these lakes. Animal waste from feedlots can
contribute significant amounts of nutrients to surface waters in these small
watersheds. Lake George is 48 feet deep and has a relatively high alkalinity value
of 176 mg CaCOa. Tee lake is 62 feet deep and has an alkalinity of 144 mg

CaCO3. George lake has a depth of 90 feet and a moderate alkalinity of 119 mg

41
CaCOa. Hardwood lake is only 35 feet deep and has a moderate alkalinity value

of 128 mg CaCO3. The depth and alkalinity concentration for lakes is relevant in
considering the possibility of a lake being a marl lake. Lakes that are deeper
than neighboring lakes can receive inputs of groundwater that may be
supersaturated with C02. If this groundwater enters a lake that has relatively high
alkalinity (> 150) the C02 can cause CaCO3 (marl) to precipitate. Phosphorus
can sorb to marl in water and become unavailable for primary production,
resulting in an underestimation of phosphonrs loading from the watershed.

Agriculture dominates the southern part of Lower Michigan where the soils
are more fertile. The infiltration rate for these soils is generally lower and the
water holding capacity is greater than for the soils in the upper part of the lower
peninsula. In 1969, 595,000 tons of commercial fertilizer was used mostly in the
southwest portion and eastern side of the state (Atlas of Michigan 1978).

Clearing land for agriculture increases phosphorus loading due to increased
overland flow and sedimentation.

Hypereutrophic lakes are found mostly in southern Lower Michigan where
soils, climate and topography are good for farming. These lakes occur on the
central to southwestern parts of the state because the land has been used for
agriculture for many decades and phosphorus from fertilizers has been added to
these soils and is washed into the lakes. The mesotrophic and eutrophic lakes in
southern Lower Michigan may receive most of their nutrients from agricultural

practices rather than residences on the lake as in northern Lower Michigan. The

42

clay soils in the south will bind more of the phosphorus from septic systems and
prevent it from leaching into lakes.

. There are a few oligotrophic lakes in southern Lower Michigan. Three
lakes from my data set that were classified as oligotrophic are Deer lake in
Oakland County, Littlefield lake in Isabella County, and Fish Lake in Barry
County. These lakes are atypical for their areas. Deer and Fish lakes have
moderately high alkalinity values, 213 and 206 mg CaC03/ L while Littlefield has
161 mg CaCO3/L. They are all relatively deep lakes; 63, 66 and 56 feet deep
respectively. These two measurements could lead us to believe that these lakes,
especially Deer and Fish, may be marl lakes. Again, marl removes phosphorus
through adsorption and makes it unavailable for primary productivity.

Lakes on the extreme ends of the trophic scale, oligotrophic and
hypereutrophic lakes, are spatially separated. The oligotrophic lakes are in the
north and the hypereutrophic lakes are in the south (Figure 13). This results from
a change or transition of soil types, land use or other factors that influences total
phosphorus concentrations in inland lakes. These two regions could provide the
needed lake management regions for highly impacted lakes in the south and
relatively unaltered lakes in the north. Combined ecoregions 50 and 51
(Omernik) fit this northern region quite well.

There is a reasonably good fit for the oligotrophic lakes in Omernik’s
ecoregions 50 and 51 in the north, and for hypereutrophic lakes in ecoregion 56 in

the south. The fit is not as good for the mesotrophic lakes or eutrophic lakes

 

 

43

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

’ OOligotrophic
lakes
‘ OI-Iypereutrophic
: 1' lakes
4—4
g ‘ I 1
' N
r ...- COCO...
.0 0
IO 0 I
4’
41' j
I
I
I
7
O
0' O O .
' ..J
.0 O 6’
l f‘ O O
I O
I
l 00 O
i O o
’8 or} 8 O
I’0 (3 O
00
" <33 03 “‘
0 06C

Figure 13. Two lake management regions based on the

distribution of oligotrohic lakes in the north
and hypereutrophic lakes in the south.

which are in all ecoregions.

Omernik’s ecoregion 51 is in the extreme northwestern part of Lower
Michigan. There are many oligotrophic and mesotrophic lakes, and few eutrophic
or hypereutrophic lakes in this area. The soil types are relatively sandy and low
in natural fertility. Thus there are few nutrients to support agriculture or wash
into surface waters. Land use in this area is dominated by forest and recreation.
Agriculture in this area is dominated by fruit orchards.

Ecoregion 50 is in the extreme northeastern to north central part of Lower
Michigan. The physical, biological and chemical influences are similar to
ecoregion 51. In my set of lakes there are a few eutrophic lakes in this ecoregion,
but only one hypereutrophic lake. Most of the lakes are oligotrophic or
mesotrophic. Omernik even had areas that extend from the body of ecoregion 56
that almost include these productive lakes on the edge of ecoregions 50 and 5 1
(Figures 6c and 6d).

Ecoregion 55 is a small section of Lower Michigan by the Ohio border
(Figure 6). The average value of 0.027 mg P/L indicates lakes that are
mesotrophic and most of the lakes in ecoregion 55 are mesotrophic. This area is
dominated by agriculture which probably has a strong influence on the
productivity of these lakes. The soils have more natural fertility than northern
soils.

Ecoregion 56 has the highest average values for total phosphorus. The

value of 0.044 mg P/ L indicates that the area is dominated by eutrophic lakes.

45

There are only three oligotrophic lakes from my data set but a large number of
mesotrophic, eutrophic and hypereutrophic lakes within this large area. This
ecoregion covers about two thirds of Lower Michigan including most of the urban
centers and agricultural areas of the state. These nutrients are piped into streams
and end up in the Great Lakes.

The districts defined by Albert do not work as well for lake management
purposes as Omernik’s ecoregions. His districts tend to have a north to south
orientation due to the his stress on climate and lake effect which will separate
shoreline areas from interior sections of Lower Michigan. Albert’s Regions I and
11 (Figure 3a) could be used as lake management regions in Lower Michigan.

An alternate approach for lake management regions would combine
Omernik’s ecoregions 50 and 51 and Albert’s district 10 and the northern parts of
districts 3 and 9. Districts 10 and 3 follow the western coast of Lower Michigan
along the Lake Michigan coast. This area is dominated by sand dunes. These
sandy soils, as mentioned before, have few nutrients to leach into lakes. This
suggested area is indicated by the dashed line on Figure 13. There is only one
eutrophic lake in district 10, and 5 in the parts of ecoregions 50 and 51 included
in this lake management region. No hypereutrophic lakes from my data are
within this area.

The polygon map (Figure 5b) based on the total phosphorus values of
inland lakes in Lower Michigan has regions having shape, location and orientation

similar to the county by county percentage of agriculture (Figure 1). The total

45
phosphorus polygons may agree because the soil types are fertile and reflect

natural fertility in inland lakes. The fertile soils contribute nutrients directly to
the surface water providing sufficient nutrients for mesotrophic conditions in
inland lakes. However when this fertile land is deforested for agriculture inputs
of nutrients increase significantly due to increased overland flow and erosion,
resulting in eutrophic and hypereutrophic conditions in inland lakes. Thus total
phosphorus concentrations in inland lakes also reflect the degree of cultural
eutrophication imposed upon lakes.

The total phosphorus concentrations of the lakes increase from their
original levels when humans add phosphorus through agriculture or inefficient
septic systems for houses around lakes. Lakes that have total phosphorus in the
eutrophic or hypereutrophic ranges in southern Lower Michigan, where soils are
fertile, are also receiving phosphorus fi'om agricultural runoff. This study did not
consider whether or not farms used conservation practices. In addition these lakes
have significant residential development and may be receiving nutrients from lawn
fertilizers.

Lakes that have total phosphorus concentrations in the mesotrophic or
eutrophic range in northern Lower Michigan are not receiving as much
phosphorus from agricultural runoff because of limited agricultural practices in
areas where infertile sandy soils do not support agriculture. These lakes receive
additional phosphorus from old, poorly maintained septic systems, fertilizer from

lawns and golf courses, and some from local agriculture. Urban centers and

47

smaller developed communities with sewer systems do not add nutrients to lakes.
These wastewater treatment plants usually discharge effluent into streams that
empty into one of the Great Lakes.

The polygon map based on the alkalinity of water in the inland lakes in
Lower Michigan does not have as good agreement as the total phosphorus
polygon map. Alkalinity reflects the base character of the watershed and lake
while the total phosphorus reflects human influences such as agriculture. Human

influences have masked similarities between alkalinity and total phosphorus.

W

Robert Carlson published a paper in 1977, outlining a numerical lake
classification method that could be used to determine the trophic status of lakes,
the Trophic State Index (TSI). Total phosphorus, chlorophyll a, and Secchi disk
depth readings are manipulated to fit within a 0-100 ranking. TSI values below 39
are considered to be lakes that are oligotrophic, those between 39 and 49 are
mesotrophic and those with TSI values greater than 49 are eutrophic. Carlson’s
trophic state index was used because it has been suggested that there is a
relationship between algal biomass and Secchi disk transparency, total phosphorus
concentrations and chlorophyll a. This index was designed to provide a
continuum of trophic levels rather that three or four separate groupings. This is a

useful method of evaluating the trophic status of lakes when dealing with citizen

monitoring groups.

48
The values for the three parameters for an individual lake should generally

agree. That is, if the TSI for Secchi disk depth and chlorophyll a are both 37 and
the TSI for total phosphorus is 60, there is something causing this discrepancy that
needs to be investigated. There was general agreement in TSI values for
Omernik’s ecoregions except for the high phosphorus values in ecoregion 55 and
56. This could indicate that phosphorus may no longer be limiting in these
systems, and that nitrogen or carbon may now be the limiting factor for primary
productivity. Albert’s districts 1, 2, 3, 4 also had high phosphorus TSI values.
Districts 1, 2, 3 and 4 cover much of the same area as Omernik’s ecoregion 55
and 56 (Figures 1 and 3). Districts 11 and 12 had high Secchi disk TSI values.
These could be reflecting sediment or water highly colored from humic acids,
rather than the presence of algae. Districts 11 and 12 correspond with the
northern most parts of Omernik’s ecoregions 50 and 51.

It should be noted that there are differences in the total phosphorus TSI
value compared to the Secchi disk and chlorophyll a TSI values where either
oligotrophic or hypereutrophic lakes are found. In Omernik’s ecoregion 50 and
51, and Albert’s districts 11 and 12, where we find the oligotrophic lakes, the total
phosphorus T31 is lower than the Secchi disk and chlorophyll a TSI values. Water
can become stained by humic acids in areas dominated by poor sandy soils or
suspended sediments can reduce visibility. For Omernik’s ecoregions 55 and 56,
and Albert’s districts 1, 2, 3, and 4, where hypereutrophic lakes are found in

abundance, the total phosphorus TSI values are higher than the TSI values for

49
Secchi disk and chlorophyll a. Phosphorus has probably been replaced by

nitrogen or carbon as the limiting factor in these cases. This could indicate a
problem with Carlson’s index when it is used on oligotrophic or hypereutrOphic
lakes.

Carlson’s method was developed using a relatively small set of inland lake
in Minnesota and there is some concern that lakes in other states may not have
the same associations. Lillie et al. (1993) have adjusted Carlson’s TSI equations
for use in Wisconsin lakes. Carlson’s equations have been altered to consider
whether lakes are stratified seepage, stratified drainage, mixed seepage, mixed
drainage in the south, central and northern parts of the state. They have twelve
equations for each of total phosphorus, Secchi disk and chlorophyll a. Because
the oligotrophic lakes are in northern Lower Michigan and the hypereutrophic
lakes are in the southern Lower Michigan we might need to consider either
adopting Wisconsin’s method of calculating TSI values or developing our own set
of equations. This may not be the way to compensate for high total phosphorus
TSI values when phosphorus is no longer limiting however. We could use the
Secchi disk and chlorophyll a TSI values without the total phosphorus TSI value
because they are in closer agreement with each other. Alternately, we could use a
TSI formula based on nitrogen when phosphorus is suspected of not being
limiting, in eutrophic and hypereutrophic lakes. Used as is, a high phosphoms
TSI, using Carlson’s equations, may simply indicates phosphorus exceeds a limiting

concentration (is no longer limiting).

50
Simple Regressions

While the mean values for total phosphorus concentrations in inland lakes
show apparent differences among ecoregions, the large standard deviation
indicates that there is a great amount of variation in the total phosphorus values
within a region. This means that there is a wide range of total phosphorus values
within regions. There are lakes with high or low total phosphorus values that
create these large ranges and standard deviations in total phosphorus. These may
be due to a local difference such as a small watershed of a very different soil type
or an unusually deep or shallow lake. We need to be aware of these differences
to be able to base management practices on realistic goals. There are general
trends of similarity that may allow using a regional type of system for a guideline
for inland lake management.

Regressions determine the strength of relationship between two variables.
The good r2 values of total phosphorus and chlorophyll a for ecoregion 55 for
Omernik, and for districts 1, 10 and 12 for Albert support the idea that total
phosphorus and chlorophyll a are highly correlated. However this was only four
of the comparisons analyzed. The other correlations for total phosphorus and
chlorophyll a were lower meaning that these total phosphorus values do not
strongly influence the concentration of algae (chlorophyll a) in the water beyond
certain other limits. There could be a problem with the chlorophyll fluorescence

or phosphorus may not be the limiting factor in these lakes.

51
Kruskal-Wallis One Way Analysis of Variance

The first step in the Kruskal-Wallis analysis determined that there were
differences among the ecoregions (Omernik) or districts (Albert) for alkalinity,
total phosphorus, chlorophyll a, and Secchi disk depth (While alkalinity, total
phosphorus, chlorophyll a, and Secchi disk depth were used in this test only total
phosphorus will be discussed. because of it’s relevance to this thesis). This is a
relatively conservative test which means that it will not detect subtle differences,
but will detect moderate differences among populations.

This test indicates a difference among districts and ecoregions, which
appears to be the opposite of the results of simple regressions which shows few
strong correlations. Simple regressions indicate the degree of difference between
attributes rather than a simple presence or absence of difference as in the
Kruskal-Wallis test. The variation in soil types, land use, other physical, chemical
and biological factors, and the definitions of areas called ecoregions or districts
are supported by the Kruskal-Wallis test.

The second part of the Kruskal-Wallis test, the multiple comparison test,
determines which attributes are the source of differences between two areas. In
the case of Omernik’s ecoregions most of the differences are between ecoregion
56 and 50, and 56 and 51. Differences in productivity indicated by total
phosphorus vary between ecoregions in the north (50 and 51) and those in the
south (55 and 56)..

There are 24 differences between Albert’s districts based on total

52
phosphorus from a possible 36. Again most of the differences are between north-

south rather than east-west spatial relationships. This indicates a north-south
difference in the productivity of inland lakes based on the concentration of total
phosphorus in inland lakes. These north-south differences support the use of a
northern and southern lake management region in Lower Michigan (Figure 13).
Both Omernik’s and Albert’s regions indicate a spatial difference in the
base character of the surface water based on Secchi disk depth, chlorophyll a and
alkalinity. These could be useful attributes on which to base regional inland lake
management regions when there is a question about whether phosphorus is the

best attribute to use because it is no longer limiting.

SUMMARY

Lakes in Lower Michigan that have been impacted by cultural
eutrophication can be identified spatially. Hypereutrophic and many eutrophic
lakes are in the southern part of Lower Michigan where agriculture is the
dominant land use, thus the primary contributor to cultural eutrophication.

Excess phosphorus fertilizers applied to agricultural fields will be washed into
lakes increasing the total phosphorus concentration of the water. Oligotrophic
lakes are in the extreme northern part of Lower Michigan. This is an area where
forest, rather than agriculture, dominates land use due to the nature of the sandy
soils dominating the area. Mesotrophic and the few eutrophic lakes in northern
Lower Michigan have increased nutrients possibly from poorly maintained septic
systems for residences around lakes or lawn fertilizers from residences or golf
courses, rather than from agriculture because the sandy soils do not support
agriculture. ’

Oligotrophic and hypereutrophic lakes fit quite well into ecoregions defined
by James Omernik. The oligotrophic lakes are in northern Lower Michigan,
ecoregions 50 and 51. The hypereutrophic and most of the eutrophic lakes fit into
ecoregion 56. The mesotrophic lakes did not fit exclusively into any one or two
ecoregions, but rather covered all of Lower Michigan. Combining Albert’s district
10 and the northern parts of districts 3 and 9 with Omernik’s ecoregions 50 and

51 makes a logical northern lake management region for regional inland lake

53

54

management. This region is dominated by sand dunes on the west coast of Lower
Michigan and sandy soils in the norther fourth of Lower Michigan. A southern
lake management region covers the remainder of Lower Michigan, ecoregions 55
and 56.. '

While ecoregions and districts can be combined to define general areas
that coincide with lakes of various trophic levels, lake management regions should
be based on water quality parameters rather than broad general terrestrial
parameters. Total phosphorus, alkalinity, Secchi disk depth, chlorophyll a, or
physical parameters that contribute directly to water quality such as soil type and
land use could be used. Watershed analysis could provide nonpoint source
pollution (phosphorus) information regarding land use or septic system inputs of
phosphorus (Tsatsaros 1993). Lake management regions should include the entire
Great Lakes Basin, resulting in a regional Lake Management tool for Michigan,
Wisconsin, Minnesota, northern Ohio and Ontario. These lake management
regions provide a reasonable first step in determining attainable water quality for
inland lakes in Lower Michigan. It could be a useful tool for national or state
water quality managers such as the EPA or MDNR.

We should concentrate our lake management efforts in Lower Michigan to
those lakes that have been impacted the least, the oligotrophic lakes. These lakes
are found mainly in northern Lower Michigan where soils tend to be sandy and
forest dominates land use. As people move north when they retire, and year

round lake use increases due to our increasing mobility, we need to monitor these

55
lakes. The sandy soils that have not supported agriculture in the north also makes

these lakes vulnerable to other sources of phosphorus pollution, such as poorly
maintained septic systems or fertilizers from lawns of riparian residences or golf
courses. Sandy soils do not have the cation exchange capacity that clay soils have,
and so phosphorus will percolate through the soils and run into the groundwater
and lakes.

Mesotrophic lakes are a second priority for management efforts. The
mesotrophic lakes have potential for maintenance of good water quality.
Mesotrophic lakes in southern Lower Michigan might benefit from watershed
analysis to determine the source of nutrient inputs, and Best Management
Practices by agriculture. Mesotrophic lakes in the north would benefit from a
reduction of lawn fertilizer, more frequent septic system maintenance and prudent
placement of new septic systems.

It would have been interesting to see what the inland lakes were like fifty
or sixty years ago, before the impacts of humans. We have to be content with
making assumptions about what these lakes were like before agricultural activity
dominated the landscape. The lakes in southern Lower Michigan may not have
been the clear, blue lakes of the north because of the soils types that dominate
the south. What ever condition the lakes were in and are in now, we should use

preventative methods to conserve this resource.

LIST or REFERENCES

Albert, D., S.R. Denton, B.V. Barnes. 1986. Regional landscape ecosystems of
Michigan. School of Natural Resources, University of Michigan, Ann Arbor
MI. 32 pp. Map suppl., map scale 1:1,000,000.

Atlas of Michigan, 1978. L.M. Sommers ed. Michigan State University Press,
Grand Rapids MI. 242 pp.

Bailey, KG. 1976. Ecoregions of the United States. Map (scale 1:7,500,000). U.S.
Department of Agriculture, Forest Service. Ogden, UT.

Bailey, KG. 1976. Description of the ecoregions of the United States. U.S.
Department of Agriculture, Forest Service, Ogden UT. 77 pp.

Bailey, KG. 1983. Delineation of ecosystem regions. Environmental management
7(4):365-373.

Barrett RH. 1952. Relationships between alkalinity and adsorption and
regeneration of added phosphorus in fertilized trout lakes. Transactions of
the American Fisheries Society 82:78-90.

Baudo, R., J. Giesy and H. Muntau. 1990. Sediments: Chemistry and Toxicity of
In place Pollutants. Lewis Publishers, Inc. Chelsea, MI. 405 pp.

Borman RH. and G.L Likens. 1970. The nutrient cycles of an ecosystem.
Scientific American 223(3):92-101.

Brylinsky M and KH. Mann. 1973. An analysis of factors governing productivity in
lakes and reservoirs. Limnology and Oceanography 18(1):1-14.

Carlson RE. 1977. A trophic state index for lakes. Limnology and Oceanography
22(2):361-369.

Dillon PJ. and RH. Rigler. 1974. The phosphorus-chlorophyll relationship in
lakes. Limnology and Oceanography 19(5):767-773.

Dorr, J .A., and DP. Eschman. 1970. Geology of Michigan. The University of
Michigan Press, Ann Arbor MI. 476 pp.

Edmondson, W.T. 1970. Phosphorus, nitrogen and algae in Lake Washington after
diversion of sewage. Science 169:690-691.

56

57

Fee, EJ. 1979. A relation between lake morphometry and primary productivity
and its use in interpreting whole-lake eutrophication experiments.
Limnology and Oceanography 24(3) 401-416.

Harrison, AR 1987. Soil organic phosphorus, a review of world literature. CAB.
International. Wallingford, United Kingdom. pp 19, 36-46, 61-64.

Hasler, AD. 1947. Eutrophication of lakes by domestic drainage. Ecology
28(4):383-395.

Horne, AJ. 1975. Comment: the productivity, mixing mode, and management of
the world’s lakes. Limnology and Oceanography 20(4):663-666.

Howell, DC. 1989. Fundamental Statistics for the Behavioral Sciences. PWS-
KENT Publishing Company. Boston MA.

Hsiang-Te Kung, and Long-Gen Ying 1991. A study of lake eutrophication in
Shanghai, China. The Geographic Journal. 157 (1):45-50.

Hughes, RM. and D.P. Larsen. 1988. Ecoregions: An approach to surface water
protection. Journal of the Water Pollution Control Federation 60:486-493.

Hughes R.M., D.P. Larsen and J .M. Omernik. 1986. Regional references sites: a
method for assessing stream potentials. Environmental Management
10(5):629-635.

Hughes R.M., E. Rexstad and CE. Bond. 1987. The relationships of aquatic
ecoregions, river basins and physiographic provinces to the
ichthyogeographic regions of Oregon. Copeia 1987(2):423-432.

Hughes, R.M., T.R. Whittier, and CM. Rohm. 1990. A regional framework for
establishing recovery criteria. Environmental Management 14(5):673-683

Hutchinson G.E. 1970. The biosphere. Scientific American 223(3):45-74.

Kart, J .R. 1992. to be published as: Ecological integrity: strategies for protecting
earth’s life support systems, in Ecosystem health: new goals for
environmental management, R. Costanza, B.G. Norton and ED. Haskell
(eds.). Island Press, Washington, DC.

Kevern N.R. Personal communication. Professor, Department of Fisheries and
Wildlife, Michigan State University, East Lansing MI.

58

King L.D.1970. The role of carbon in eutrophication. Journal Water Pollution
Control Federation 42(12):2035-2051.

Larsen D.P., D.R. Dudley and RM. Hughes. 1988. A regional approach for
assessing attainable surface water quality: an Ohio case study. Journal of
Soil and Waster Conservation 43(2): 171-176.

Lillie, R.A., S. Graham and P. Rasmussen. .1993. Trophic state index equations
and regional predictive equations for Wisconsin lakes. N o. 35. Wisconsin
Department of Natural Resources.

Loehr R. and K. Dickinson. 1991. Personal communication to William Reilly,
Administrator U.S. Environmental Protection Agency.

Michigan State University, Cooperative Extension Service and Agricultural
Experiment Station with the USDA Soil Conservation Service. 1981. Soil
association map of Michigan. Extension Bulletin E- 1550, File 32.13. Map
scale 1: 1,000,000.

Miller R.P. 1980. Simultaneous statistical inference. Second ed. Springer-Verlag,
New York NY. 299 pp.

Mokma D. Personal communication. Professor, Department of Soil Science,
Michigan State University, East Lansing MI.

Moyle J .B. 1956. Relationships between the chemistry of Minnesota surface waters
and wildlife management. Journal of Wildlife Management 20(3):303-320.

N orthcote, T.G. and PA. Larkin. 1956. Indices of productivity in British Columbia
lakes. The Journal of Fisheries Research Board of Canada 13(4):515-540.

Omernik, J .M. 1987. Ecoregions of the conterminous United States. Annals of the
Association of American Geographers 77:118-125.

Omernik, J.M., A.R Abernathy and LM. Male. 1981. Stream nutrient levels and
proximity of agricultural and forest land to streams: some relationships.
Journal of Soil and Water Conservation 36(4):227-231.

Omernik, J .M., and AL. Gallant. 1989. Defining regions for evaluating
environmental resources. In: Proceedings of the Global Natural Resource
Monitoring and Assessment Symposium, Preparing for the let Century;
Venice, Italy, September 24-30, pp. 936-947.

S9

Omernik, J .M., and AL. Gallant. 1988. Ecoregions of the Upper Midwest States.
EPA/ 600/ 3-88/ 037. U.S. Environmental Protection Agency,
Environmental Research Laboratory, Corvallis, OR. 56 pp.

Omernik, J .M., and AL. Gallant. 1989. Aggregations of Ecoregions of the
Conterminous United States. U.S. EPA Environmental Research
Laboratory, Corvallis, OR. NSI Technology Services Corp., Corvallis, OR.

Omernik, J .M. and G.E. Griffith. 1986. Total alkalinity surface waters; a map of
the upper midwest region of the United States. Environmental
Management 10(6):829-839.

Omernik, J.M., and G.E. Griffith. 1991. Ecological Regions vs. Hydrologic Units:
A Comparison of Frameworks for Assessing and Monitoring Surface
Waters, Journal of Soil and Water Conservation. 46(5):334-340.

Omernik, J.M., D.P. Larsen, C.M. Rohm, and SE. Clarke. 1988. Summer total
phosphorus in lakes: A map of Minnesota, Wisconsin and Michigan.
U.S.A. (map scale 1:2,500,000). Environmental Management 12:815-825.

Omernik, J .M., C.M. Rohm, R.A. Lillie, N. Mesner. 1991. The Usefulness of
Natural Regions for Lake Management: An Analysis of Variations Among
Lakes in NW Wisconsin. U.S.A. Environmental Management 15:281-293.

Pringle CM. 1983. A classification of Michigan’s lacustrine systems. For the
Michigan natural features inventory program.

Rawson D.S. 1953. The standing crop of net plankton in lakes. Journal of
Fisheries Research Board of Canada 10(5):224-237.

Richardson, J .L 1975 . Comment: morphometry and lacustrine productivity.
Limnology and Oceanography 20(4):661-663.

Rohm M.C., C.W. Giesse and CC. Bennett. 1987. Evaluation of an aquatic
ecoregion classification of streams in Arkansas. Journal of Freshwater
ecology. Map suppl. 4(1):127-139.

Ryder, R.A. 1965. A method for estimating the potential fish production of north-
temperate lakes. Transactions of the American Fisheries Society 94:214-
218.

Ryder, R.A. , S.R. Kerr, K.H. Loftus and HA. Regier. 1974. The morphoedaphic
index, a fish yield estimator-review and evaluation. Journal of Fisheries
Research Board of Canada 31:663-688.

60

Sakamoto, M. 1966. Primary production of phytoplankton community in some
Japanese lakes and its dependence on lake depth. Arch. Hydorbiolol. 62:1-
28. -

Schaffner, W.R. and RT. Oglesby. 1978. Phosphorus loadings to lakes and some
of their responses. Part 1. A new calculation of phosphorus loading and its
application to 13 New York lakes. Limnology and Oceanography
23(1): 120-134.

Schindler, D.W. 1977. Evolution of phosphorus limitation in lakes. Science
195:260-262.

Taylor, R.W. 1977. Phosphorus Adsorption and Movement in Soils. Ph.D.
Dissertation, Department of Crop and Soil Sciences, Michigan State
University, East Lansing MI.

Tomson, MB. and L. Vignona. 1984. in Phosphate Minerals, J .O. Nriagu and RE.
Moore Q.E. (eds.) Springer-Verlag, Berlin.

Tsatsaros, J .H. 1993. The impacts of cultural nutrient inputs on Townline lake.
MS. Thesis, Department of Fisheries and Wildlife, Michigan State
University, East Lansing W.

USDA. 1981. Soil association map of Michigan. Extension Bulletin E-1550. Mich.
Cooperative Extension Service and Agricultural Experiment Station and
USDA Soil Conservation Service, Map.

Wetzel R.G. 1983. Limnology. Saunders College Publishing. Philadelphia PA.
753 pp.

Wetzel, R.G. 1972. The role of carbon in hard-water marl lakes. Nutrients and
Eutrophication, Special Symposia. The American society of limnology and
oceanography, inc. 1:84-97.

Whittier, TR. and S.G. Paulsen. 1992. The surface waters component of the
Environmental monitoring and assessment program (EMAP). Journal of
Aquatic Ecosystem Health 1: 13-20.

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