EFFECTS OF ABIOTIC AND BIOTIC FACTORS ON BLUEGILL REPRODUCTION
AND GROWTH IN SEVEN UNEXPLOITED SURFACE COAL MINE LAKES
by
David Steven Knuth
B.S., Southern Illinois University 2002
A Thesis
Submitted in Partial Fulfillment of the Requirements for the
Master of Science Degree
Department of Zoology
in the Graduate School
Southern Illinois University Carbondale
June 2007
August 2007
THESIS APPROVAL
EFFECTS OF ABIOTIC AND BIOTIC FACTORS ON BLUEGILL REPRODUCTION
AND GROWTH IN SEVEN UNEXPLOITED SURFACE COAL MINE LAKES
By
David Steven Knuth
A Thesis Submitted in Partial
Fulfillment of the Requirements
for the Degree of
Master
in the field of Zoology
Approved by:
Jim Garvey, Chair
Frank Wilhelm
Eric Schauber
Graduate School
Southern Illinois University Carbondale
June 2007
AN ABSTRACT OF THE THESIS OF
DAVID STEVEN KNUTH, for the Master of Science degree in Zoology,
presented on 21 September 2006, at Southern Illinois University Carbondale
TITLE: EFFECTS OF ABIOTIC AND BIOTIC FACTORS ON BLUEGILL
REPRODUCTION AND GROWTH IN SEVEN UNEXPLOITED SURFACE COAL
MINE LAKES
MAJOR PROFESSOR: Jim Garvey
Understanding the density-dependent and density-independent factors that
influence bluegill life histories and recruitment processes are necessary for managing
quality populations. I evaluated the effects of the size structure of adult bluegill and
habitat conditions on their larval production, time of spawning, and survival of seven
unexploited populations in small (2.47-8.67ha) surface coal mine lakes near Sparta, IL,
during the summer of 2003. Lakes were stratified across categories of adult size
structure, the availability of littoral habitat, and other habitat parameters (i.e. mean depth,
shoreline development, and chlorophyll a concentrations). Adult fish community
characteristics were assessed using three-phase boat electrofishing. Larval tows were
conducted weekly in each of the lakes to estimate densities throughout the spawning
season. Littoral habitat and lake morphology characteristics were quantified by
conducting bathymetric surveys with an echosounder. Age-0 bluegill were sampled in
the fall of 2003 to assess survival from the larval stage by estimating swim-up date using
otoliths. Peak and total larval sunfish densities increased with adult size structure. A
positive relationship occurred between summer chlorophyll a concentrations and larval
production. The earliest peak spawning occurred in lakes with large adults. Although
lakes ranged from 9% to 40% littoral volume, littoral volume was not correlated with
i
larval sunfish production among lakes. Juvenile bluegill growth differed among lakes
and was negatively affected by adult density. Survival of larvae to the juvenile stage
differed among lakes and was negatively correlated with larval densities. Densitiydependent factors were mostly responsible for the structuring of bluegill populations in
these seven unexploited surface coal mine lakes and allowed them to reach equilibrium.
Management that encompasses an approach that examines all of these processes will
likely be the most successful in increasing adult size in lakes, by improving reproduction,
recruitment success, and maintaining quality size structure.
ii
ACKNOWLEDGMENTS
I would first like to extend my gratitude to the Illinois Department of Military
Affairs, Southern Illinois University Department of Zoology, and the Fisheries and
Illinois Aquaculture Center for providing the resources for this project during my
graduate career. I would not have been able to accomplish this research without the
professional help and guidance of my major professor James E. Garvey. I would also
like to thank my other committee members Frank M. Wilhelm and Eric M. Schauber for
their assistance. I appreciate the help of Sara Tripp with larval fish identification and
sorting and her assistance in the field. I would also like to thank Katie Emme and all
other graduate students for their assistance in the field. My gratitude also goes to Ron
Brooks and Pat Beck for their help with aging fish, Ryan Lane and Rob Colombo for
their assistance with data analysis, and all other graduate students and faculty who were
there for me during the writing process. Finally, I would like to especially thank my
family and friends for their support and guidance throughout my academic career.
iii
TABLE OF CONTENTS
CHAPTER
PAGE
ABSTRACT..................................................................................................................... i
ACKNOWLEDGEMENTS........................................................................................... iii
LIST OF TABLES...........................................................................................................v
LIST OF FIGURES ....................................................................................................... vi
INTRODUCTION ...........................................................................................................1
METHODS ......................................................................................................................5
Study Site ............................................................................................................5
Adult Fish............................................................................................................5
Lake Bathymetry and Spawning Habitat ............................................................7
Larval Fish ..........................................................................................................8
Juvenile Sunfish ..................................................................................................9
Data Analysis ....................................................................................................10
RESULTS ......................................................................................................................13
Adult Fish Assemblages and Size Structure .....................................................13
Lake Bathymetry and Habitat Conditions.........................................................13
Larval Sunfish...................................................................................................14
Juvenile Bluegill ...............................................................................................15
Adult Size vs. Larval Production and Timing of Spawning .............................16
Habitat Conditions vs. Larval Production.........................................................17
Juvenile Growth and Survival...........................................................................17
DISCUSSION ................................................................................................................19
Adult Bluegill Size Effects ...............................................................................19
Habitat Effects ..................................................................................................21
Growth and Survival .........................................................................................21
Conclusions and Implications ...........................................................................23
LITERATURE CITED ..................................................................................................36
APPENDICES ...............................................................................................................41
VITA ..............................................................................................................................49
iv
LIST OF TABLES
TABLE
PAGE
1.
Catch per unit effort (CPUE), proportional stock density (PSD), and mean
relative weight (Wr) results for bluegill and largemouth bass in 15 surfacemine lakes located near Sparta, IL during fall 2002 and spring 2003. PSD
N and Wr N represent the number of individuals used for those
calculations. The seven bolded lakes were selected to span the adult
bluegill size structure .........................................................................................25
2.
Bathymetric dimensions, shoreline development indices, chlorophyll a
concentrations, and littoral habitat data for the seven study lakes located
near Sparta, IL sampled during the summer/fall 2003.......................................26
3.
Summary of larval sunfish data for the seven study lakes located near
Sparta, IL sampled during the summer of 2003. Total production was
quantified by summing all the weekly densities for each lake. Peak
density in each lake was the highest density which occurred during the
twelve sampling events. Mean densities represent the mean of all twelve
sampling events for each lake ............................................................................27
v
LIST OF FIGURES
FIGURE
PAGE
1.
Aerial photo of 1,133-hectare reclaimed surface coal mining area near
Sparta, IL where all research was conducted from fall 2002 through fall
2003. The yellow line is the property boundary surrounding all 15 lakes
represented in blue. The three larger lakes are labeled L1-L3 and the
twelve smaller lakes are labeled S1-S12. The seven lakes intensively
studied for this study are labeled with lake names inside the yellow boxes......28
2.
Percent frequencies of small (15-30 mm), medium (30-50 mm), and large
(50-80 mm) juvenile (age 0) bluegill collected in October 2003 in the
seven study lakes near Sparta, IL. Relative proportions of these three size
ranges of juveniles differed among the lakes with different adult size
structures. ...........................................................................................................29
3.
Daily growth regressions for juvenile bluegill collected in October 2003 in
the seven study lakes located near Sparta, IL ....................................................30
4.
Relationships between adult bluegill size structures (PSDs) and (A) total
larval sunfish production and (B) peak larval sunfish densities in lakes
near Sparta, IL 2003. Total production for each lake was calculated by
summing all of the weekly larval densities calculated for the twelve
sampling events and was positively related to increasing PSD. Peak
density was considered the time when the average weekly larval density in
each of the lakes was the highest of all twelve sampling events and was
also positively related to increasing PSD...........................................................31
5.
Weekly mean larval sunfish densities with associated standard error bars
for the three different adult size structure categories in the seven study
lakes located near Sparta, IL during the summer of 2003. ................................32
6.
The relationship between mean lake depth (m) and regressed juvenile
bluegill growth (mm/day) for the seven study lakes near Sparta, IL during
the fall of 2003. ..................................................................................................33
7.
The relationship between adult bluegill density (number per hour
electrofished) and regressed juvenile bluegill growth (mm/day) for the
seven study lakes near Sparta, IL during the fall of 2003..................................34
vi
8.
Mean log transformed survival values for three seasons (early, middle,
late) with associated standard error bars calculated for the juveniles
collected in the fall of 2003 for the three different adult size structure
categories. ..........................................................................................................35
vii
INTRODUCTION
Year-class strength in many fish species can vary greatly among years due to
large fluctuations in early life mortality. The point during the first year of life when
mortality transforms from extremely variable to constant is known as recruitment. In
other words, year-class strength is set at this point and year-class size can influence the
dynamics and structure of fish populations. Because of this, interest in early life history
stages of freshwater fishes has increased (Miller et al. 1988). Developing a better
understanding of mechanisms that control recruitment in fishes during early life is a
major issue in fisheries (Miller et al. 1988), because variation in recruitment is affected
by both exploitation and abiotic factors.
In North American inland fisheries, management of important sport fish
populations may benefit from a better understanding of recruitment variability. Bluegills
(Lepomis macrochirus) are key components of many North American fisheries, with total
production often exceeding that of other sport fish species (Cooper et al. 1971; Drake et
al. 1997; Jennings et al. 1997). Therefore, concern over the decline in the size structure
of bluegill populations across North America has led to increased efforts to improve or
maintain quality populations with high proportions of large individuals (Paukert et al.
2002). Consequently, the reproductive behaviors and early life histories of sunfish have
been studied extensively (Breder 1936; Jennings 1997; Garvey et al. 2002). Densitydependence in sunfish populations affects adult size and condition, age of maturity, larval
timing of appearance, competition for food and space, and total production (Cargnelli and
Gross 1996; Garvey and Stein 1998; Garvey et al. 2002; Rettig and Mittelbach 2002).
Density-independent factors including lake morphometry, available littoral habitat, and
1
water chemistry also affect the variability of recruitment in sunfish populations (Latta and
Merna 1977; Wiener and Hanneman 1982; Belk 1995; Claramunt and Wahl 2000;
Tomcko and Pierce 2001). Understanding the relative contributions of these variables on
top-down and bottom-up controls of sunfish early life histories and demographic
processes including recruitment, growth, and mortality, is essential to successfully
manage a fishery (Jennings 1997; Diana 2004).
DENSITY-DEPENDENT AND DENSITY-INDEPENDENT FACTORS
Adult Sunfish Size and Condition
Adult fish density can affect adult size structure, condition, and age of maturity,
which in turn can affect timing of spawning and total production (Cargnelli and Gross
1996; Jennings et al. 1997; Garvey et al. 2002). Sunfish exhibit protracted reproduction,
which involves producing larvae over several spawning bouts in a single year. Protracted
spawning results in a wide range of hatching dates and potential growth opportunities for
young (Cargnelli and Gross 1996). Adult sunfish densities can influence timing of
spawning, which in turn can affect the age of maturation and condition of young. For
example, populations with low adult sunfish densities typically produce larger adult fish
in better condition, which spawn earlier than populations with high densities of adult
sunfish (Drake et al. 1997; Jennings et al. 1997). Early spawning may lead to decreased
competition and longer growing seasons than spawning late, which allows for increased
growth, larger size, avoidance of predation, and better overwinter survival of offspring
(Garvey et al. 2002).
2
Total production can also be greatly influenced by the size of adults in a particular
system. In most fishes, especially in the females, fecundity increases with both size and
age (Roff 1983). Populations with a large number of stunted females generally deposit
fewer eggs than a population of non-stunted females (Aday et al. 2002). This can result
in less production and a possible decrease in recruitment in lakes with a small adult size
structure than in lakes with a large adult size structure.
Lake Morphometry and Physical Conditions
The littoral zone is defined as the portion of the lake bottom and water column in
which light penetration is sufficient for macrophyte growth and is used by many pelagic
and littoral fishes during some part of their life (Hayes et al. 1999). For sunfish in lentic
systems, littoral habitat provides habitat for spawning, a source of invertebrates as forage,
and refuge from predation (Lemly and Dimmick 1982; Hayes et al. 1999). A potential
problem in many surface coal mine lakes is the lack of littoral habitat. These lakes are
generally steep-sided with little structure and limited shallow area in relation to volume
(Rold et al. 1996). This reduced littoral zone and shallow area may greatly reduce the
overall production of the fishery (e.g., Bell 1956; Gash and Bass 1973; Claramunt and
Wahl 2000).
Water temperature, nutrients, turbidity, and pH can influence lake productivity
and fish yields (Belk 1995). Water temperature in lakes and reservoirs can be greatly
influenced by depth and the amount of dissolved organic material or turbidity (Wetzel
2001). Water temperature can affect sunfish growth, energy allocation, and timing of
spawning, which in turn can affect recruitment success (Belk 1995). For example, cold
water temperatures can lead to slow growth and late spawning. High amounts of
3
dissolved organic material (i.e., nutrients) can increase lake productivity (e.g.,
chlorophyll a) and food availability for larval sunfish upon hatching, and thus positively
affect their survival (Claramunt and Wahl 2000). Sunfish growth and recruitment also
may be reduced by extreme pH, which is a problem in many surface mine lakes (Gash
and Bass 1973). All of these density-independent factors can cause variation in sunfish
year-class strength.
Unharvested lakes typically contain dense populations of large, slow-growing fish
(Van Den Avyle and Hayward 1999). Usually these populations are considered stable
and have relatively low recruitment. I hypothesized that in the absence of exploitation in
the lakes selected for this study, bluegill populations have reached equilibrium and
recruitment is relatively constant between years. Environmental factors, however,
including lake morphometry and physical conditions such as littoral habitat, temperature,
water quality, and food abundance could be responsible for disrupting this equilibrium by
influencing the structure and recruitment processes of these sunfish populations.
Many factors can affect production of larvae and timing of spawning in
unexploited systems. Understanding the relative effects of adult size structure and abiotic
factors on these processes is critical to explain the variability in sunfish recruitment. The
goal of this study was to examine these interactions in several privately owned surface
coal mine lakes to determine what density-dependent or density-independent factors were
driving both top-down and bottom-up controls structuring sunfish populations in these
unexploited systems.
4
METHODS
STUDY SITE
The 1,133-ha property (Randolph County, Illinois, managed by the Illinois Army
National Guard) was a reclaimed coal mining area surrounded primarily by row crops,
which contained 15 surface-mine lakes (3 large lakes L1-L3 and 12 smaller lakes S1S12) and a 3.2-km reach of Plum Creek (Figure 1). Exotic grasses dominated, with some
wooded riparian areas surrounding the creek and portions of the lakes (Heatherly et al.
2005). The 15 relatively steep-sided surface-mine lakes differed in many aspects
including depth, surface area, habitat, and wooded riparian zone. All lakes contained
unharvested fish populations because they were located on private, fenced property.
ADULT FISH
To assess fish community composition and reproductive success, fish
assemblages and size structure were quantified for each of the 15 lakes using three-phase,
alternating current, boat-mounted electrofishing during fall 2002 and spring 2003. Fish
were sampled along the entire shoreline of each lake. Time was recorded to standardize
catch rates as catch per unit effort (number of fish caught per hour). All fish captured
were identified to species and counted. Total length (mm) was measured for every fish
collected and up to 50 bluegill and largemouth bass were kept from each lake for age and
growth analysis.
Size structure and body condition of bluegill and largemouth bass in each lake
were analyzed using proportional stock density (PSD) and relative weight (Wr)
(Anderson 1980; Gabelhouse 1984; Anderson and Neumann 1996). Stock size (TL) for
5
bluegill is 8 cm and quality size is 15 cm (Gabelhouse 1984). Stock size (TL) for
largemouth bass is 20 cm and quality size is 30 cm (Gabelhouse 1984). A PSD range of
20-60 for bluegill and a range of 40-70 for largemouth bass is the goal of a balanced fish
community in a small impoundment (Anderson 1980).
PSD =
Number ≥ quality length
×100
Number ≥ stock length
Balance is a concept that suggests that a significant proportion of adults in a population
are large sized relative to average populations. Relative weight (Wr) was used to assess
fish condition. The equation for Wr is,
Wr =
W
× 100
Ws
log10 (Ws ) = a '+b × log10 ( L)
where W is the weight of fish being measured and Ws is the standard weight for a fish of
that length. The length-specific standard weight is predicted by a weight-length
regression for a specific species where a' is the intercept, b is the slope of log 10 (weight)
- log 10 (length) regression equation and L is the total length of the fish (Anderson and
Neumann 1996). The standard weight (Ws) represents the 75th percentile weight at a
given length of all populations of a specific species (Anderson and Neumann 1996).
Relative weight targets for fish of a balanced population are 95 to 105 (Anderson and
Neumann 1996). Individuals that have relative weights in or above this range are
considered to be in excellent condition (Anderson and Neumann 1996).
Seven of the 15 lakes (S3, S4, S5, S6, S8, S9, and S11) were then selected for this
study based on the adult bluegill PSD to test for differences in sunfish larval production
and timing due to adult size. These lakes were grouped into three categories of adult
6
sunfish size structure: large (S3 and S8; PSD 55-46), intermediate (S9, S5, and S11; PSD
22-18), and small (S4 and S6; PSD 10-3). These groupings were based primarily on
bluegill PSDs, because bluegill were the numerically dominant (65-97%) sunfish species
in the seven study lakes.
LAKE BATHYMETRY AND SPAWNING HABITAT
Bathymetric depth contours were quantified in each of the lakes to assess habitat
available for adult fish and spawning. During fall 2003, bathymetric surveys were
conducted on the seven selected study lakes using a boat-mounted Knudsen 320bp series
portable echosounder. A dual (28 and 200 kHz) frequency transducer was used to obtain
readings at two-second intervals. The high-frequency signal provided a true depth
reading, while the low-frequency signal estimated sediment depth. For each
echosounding, latitude and longitude was recorded with a Trimble Global Positioning
System (GPS) unit. To ensure adequate coverage of each lake, the entire shoreline was
first traced and then equally spaced perpendicular transects were surveyed. Bathymetric
maps were created in Arcview GIS 3.2 to quantify average depth (from echosounder
points), maximum depth, total area, shoreline development, total volume, and percent
littoral volume. Littoral volume was quantified by first estimating the photic zone depth
in each of the lakes using a Li-Cor light meter and then calculating the volume of water
from the shoreline to that depth. Percent littoral volume was then calculated by dividing
the littoral volume by the volume of the photic zone in each of the lakes.
7
LARVAL FISH
Collection
Lepomis spp. larvae were sampled weekly in each of the seven study lakes during
spawning from early May through August to assess total sunfish production. Two timed
larval tows (0-0.5m depth) were conducted with a single, 0.5-m diameter, 500-µm mesh
ichthyoplankton net in the pelagic zone along the long axis of each lake. Volume was
quantified for each tow with a flow meter mounted in the mouth of the net. All samples
were rinsed into the cod end and preserved with 95% ethanol.
Water quality was also quantified weekly to provide detailed information on the
limnological conditions of each lake throughout the spawning season. Within each lake,
temperature (ºC), dissolved oxygen (mg/L), conductivity (µs), pH, and light irradiance
readings (umol m-2 s-1) (using a Li-Cor light meter) were quantified at 1-m depth intervals
at a GPS (Global Positioning System) referenced site. Other parameters measured
included air temperature (ºC), secchi depth (cm), and chlorophyll a concentrations
(ug/L). Mean chlorophyll a concentrations for the summer were calculated from
concentrations quantified using the spectrophotometric method of ethanol extraction (Éva
Pápista, Éva Ács Béla Böddi. 2002).
Processing
To estimate total production of Lepomis spp. larvae throughout the spawning
season and timing of spawning in each study lake, all larvae of the genus Lepomis in each
sample were identified and counted using a dissection scope (Auer 1982). If the number
of larvae per sample exceeded 1,000, samples were split using a Folsom wheel until the
number of individuals was less than 1,000. Larval sunfish densities were quantified as
8
number per cubic meter of water sampled and the 2 tows were averaged for each week
sampled. Total production for each lake was indexed by summing all of the weekly
average densities for the 12 sampling events. Peak density was represented in each lake
by the sample which contained the highest density of larvae collected throughout the
sampling period.
JUVENILE SUNFISH
In October 2003, approximately 100 juvenile Lepomis spp. (< 90 mm TL) were
seined in each lake to assess effects of timing of spawning on the survival of larvae to the
juvenile stage and to quantify juvenile growth. A sub-sample of 10 bluegill per 1-cm size
class (TL) from each lake was used for the age and growth analysis. Total length (mm)
was measured and otoliths were removed from these fish and mounted on glass
microscope slides using thermoplastic cement. To expose daily increments in large
otoliths, they were polished using 2,000-grit wetsandpaper (see Taubert and Coble 1977).
Daily rings were counted twice by an individual reader using a compound microscope to
estimate swim-up date, if possible. A second reader verified age by reading a sub-sample
of the otoliths. If daily ring counts of readers differed by 10% or less they were
averaged. If daily increment counts were greater than 10% between the two individual
readings by the single reader or with the second reader, otoliths were either discarded or
an agreement was reached (Santucci and Wahl 2003). Hatch date was determined for
each bluegill by adding seven days to the age derived from otoliths because ring
deposition begins 7 days post hatch (Childers 1967; Bain and Helfrich 1983). Growth
9
(mm/d) was then determined for each juvenile sunfish by dividing the individual’s total
length by the daily ring counts (plus seven days).
Swim-up dates were back-calculated for all of the juvenile bluegill (< 80 mm TL)
by inserting their individual lengths into the growth regression equation calculated from
the otolith derived ages of juveniles aged from each lake. Swim-up dates were used to
assess what time the juveniles collected appeared at the larval stage in the water column.
An index of survival (IS) was calculated for all juveniles sampled in the fall by dividing
the proportion of juveniles from each back-calculated swim-up week (from the growth
regression equations) by the proportion of larvae collected during that week (Garvey et
al. 2002). An index value near 1 indicates an equal representation of larvae sampled in
the spring and the juveniles collected in the fall (Garvey et al. 2002). However, values
greater than 1 indicate larval survival to the juvenile stage greater than expected while
values less than 1 indicate poorer than expected survival to the juvenile stage (Garvey et
al. 2002).
DATA ANALYSIS
To test for potential relationships between adult bluegill and largemouth densities
and relative proportions of these two species, linear least squares regression analysis was
used through the General Linear Model (GLM) (SAS Institute 2001). To test the null
hypothesis that larval sunfish densities in the seven study lakes were unrelated to adult
bluegill size, both analysis of variance (ANOVA) and regression analysis were used. The
effect of adult size structure (independent variable) on total larval production (dependent
variable) was examined by analyzing relationships between the three different adult
10
sunfish size structure categories (large S3 and S8, intermediate S5, S9, and Sll, and small
S4 and S6) and total larval sunfish production (density/week) throughout the spawning
season using a repeated measures analysis of variance (RM-ANOVA). This analysis was
also used to examine possible differences in timing of spawning by testing for an
interaction between week and size structure. Larval densities were log10 transformed to
achieve normality and homogeneity of variance in the data set. Linear regression was
used to analyze if sunfish larval production (dependent variable) was related to percent
littoral habitat, chlorophyll a concentrations, and other habitat parameters (independent
variables) through the General Linear Model (GLM) (SAS Institute 2001).
To test for differences in frequencies of small (15-30 mm), medium (30-50 mm),
and large (50-80 mm) juvenile bluegill in the fall among the seven study lakes (grouped
by adult size structure category), a chi-square test was used. Linear regression was used
to analyze growth by regressing all total lengths (mm) (dependent variables) and ages
(days) (independent variables) of juvenile bluegill from each of the study lakes. Analysis
of covariance (ANCOVA) was used to test for significant differences among the seven
study lakes in the slopes of the lake-specific juvenile growth regressions (dependentlength, independent-lake, and covariate-age). To test for effects of adult and larval
densities or habitat parameters on juvenile bluegill growth, least squares regression was
used. Differences in survival among lakes were examined using analysis of variance
(ANOVA). The spawning season was divided by time into the three categories of early,
middle, and late to analyze differences in survival through time for the three different
adult size classes using a two-way analysis of variance (ANOVA). Survival values were
11
log10 transformed to meet assumptions of normality and homogeneity of variance in the
data set.
12
RESULTS
ADULT FISH ASSEMBLAGES AND SIZE STRUCTURE
Largemouth bass or bluegill were always > 59% (mean = 80%; N = 15 lakes)
of the total fish catch. Abundances (number of fish per hour electrofished) of adult
bluegill and largemouth bass were unrelated (P = 0.78) in all of the 15 lakes.
However, the proportions of these two species in the total catch were negatively
related (P < 0.001; R2 = 0.79; proportion bluegill = 0.76-0.81 proportion largemouth
bass).
Adult size structures for both largemouth bass and bluegill varied among all
15 lakes, with PSDs ranging from 3 to 67 for largemouth bass and 3 to 55 for bluegill
(Table 1). Size structure indices were unrelated between largemouth bass and
bluegill adults (P = 0.17). However, largemouth bass size structure was negatively
related to largemouth bass abundance (R2 = 0.56; P < 0.001). Adult bluegill size
structure was unrelated to abundance of adult bluegill (P = 0.95) and largemouth bass
(P = 0.60). Body condition (mean Wr) for bluegill was high in all lakes and ranged
from 89 to 102. It was unrelated to bluegill density (P = 0.97) (Table 1).
LAKE BATHYMETRY AND HABITAT CONDITIONS
The seven surveyed lakes varied in many different limnological aspects
including size, shape, and depth (Appendix A). The seven lakes ranged in surface
area from 2.47 to 8.67 ha (Table 2). Maximum depths ranged from 3.22 m to 12.94
m and mean depths ranged from 3.20 m to 5.07 m (Table 2). Shoreline development
indexes were low for all seven lakes ranging from 1.39 to 2.95 (Table 2). Photic zone
13
depths, which were used to estimate the amount of littoral habitat in each of the lakes,
ranged from 1.6 m in S4 to 2.73 m in S11 (Table 2). Percent littoral volume
estimated using the photic zone depths ranged from a low of 9% in S4 to a high of
40% in S5 (mean + 1 SD; 0.25 + 0.09) and was unrelated to lake size (P = 0.53). All
of the study lakes were relatively steep sided with limited littoral habitat, with the
exception of S5, which had a maximum depth of only 3.22 m. Chlorophyll a
concentrations during the spawning season ranged from 28.5 (ug/L) to 105.3 (ug/L)
(Table 2). If aquatic vegetation was present it mostly consisted of Eurasian water
milfoil (Myriophyllum spicatum), pondweed (Potamogeton spp.), or water primrose
(Ludwigia spp.).
LARVAL SUNFISH
Larval sunfish densities varied among the seven lakes. Larval sunfish
appeared in samples on May 13, 2003 and were not collected after August 28, 2003.
Lepomis spp. larvae were by far the dominant species captured in the ichthyoplankton
tows (76% to 99% of total catch). Lepomis spp. larvae appeared in the first week’s
samples at very low densities (0.02 to 0.13 larvae/m3) in all the lakes except S9 and
S11. Large numbers of Lepomis spp. larvae were captured in the pelagic zone when
temperatures reached approximately 25 ºC. The highest mean density of larval
sunfish was 101.24 larvae/m3, which occurred in S8 on 31 July 2003. Mean larval
sunfish densities peaked in the other six lakes during June and ranged from 29.68 to
45.67 larvae/m3 (Table 3). Densities summed across 12 weeks (i.e., crude
production) ranged from a high of 358.21 larvae/m3 in S8 to a low of 52.61 larvae/m3
14
in S6 (Table 3). Very low numbers of Lepomis spp. larvae were captured on the last
sampling event in lakes S8 and S4 and it was assumed that spawning had concluded
at the end of August.
JUVENILE BLUEGILL
Similar to the adult fish assemblages, bluegill were the dominant
(approximately 90%) sunfish species captured while seining for juveniles in all of the
study lakes. Daily growth rings were counted on otoliths of 146 juvenile bluegill
ranging in size from 19.7 to 51.1 mm TL. Replicate daily ring counts quantified by
the primary reader differed by 5% + 3% (mean + 1 SD), while counts performed by a
second reader on a sub-sample of 20 otoliths varied by 6% + 3% (mean + 1 SD) from
those of the primary reader. Because of overlapping rings in older individuals, swimup date was only successfully determined for bluegill less than approximately 130
days old. Fish older than this were either classified as age 0 (spawned the same year)
or age 1 (spawned the year before). Ages of older age-0 fish (N = 665) were backcalculated from growth-age regression equations. About 99% of the juvenile bluegill
captured while seining were age-0 fish, with the largest individuals of that age being
approximately 80 mm in length.
The relative proportions of small (15-30 mm), medium (30-50 mm), and large
(50-80 mm) juvenile bluegill differed among lakes with different adult size structures
(N = 811, X2 = 101.9, df = 4, P < 0.001). Medium-size juvenile bluegill comprised
the highest proportion of individuals in all seven study lakes. The greatest proportion
of large juveniles occurred in lakes with intermediate adults (29.2%) and the fewest
15
occurred in lakes with large adults (4.2%) (Figure 2 and Appendix B). Lakes with
large adults had the greatest percentage of small juveniles (35.5%) and lakes with
small adults had the lowest proportion (18.3%) (Figure 2 and Appendix B).
Daily ring counts and total lengths of all the juveniles aged were positively
related (R2 = 0.716, P < 0.001). Growth rates (slopes) differed among the seven study
lakes (ANCOVA: age, df = 6, 132; F = 3.21; P = 0.006) ranging from 0.242 mm/day
in Sll to 0.422 mm/day in S9 (Figure 3).
ADULT SIZE VS. LARVAL PRODUCTION AND TIMING OF SPAWNING
Total larval sunfish production ranged widely among the seven study lakes
and was positively related to adult bluegill PSD [larval production = 4.74(PSD) +
28.74; N = 7; R2 = 0.70; P = 0.02; Figure 4]. Peak larval sunfish densities among the
lakes were also positively related to adult bluegill PSD [peak larval density =
1.01(PSD) + 23; N = 7; R2 = 0.63; P = 0.03; Figure 4]. Therefore, lakes with large
adults produced more Lepomis spp. larvae and had higher peak densities than lakes
with smaller adults.
When the lakes were grouped into three different adult size classes, larval
production also differed (RM-ANOVA: df = 2, 44; F = 6.0; P = 0.005; Figure 5).
There was also a significant difference in larval densities across weeks (RMANOVA: df = 11, 44; F = 11.35; P < 0.001). Lepomis spp. larvae occurred earlier in
lakes with large adult bluegill (S3 and S8; Figure 5). Spawning also occurred in a
greater number of bouts over a longer period of time in lakes with larger adults than
lakes with smaller adults (Figure 5).
16
HABITAT CONDITIONS VS. LARVAL PRODUCTION
Even with a large gradient in the amount of littoral habitat available to adult
fish for spawning among lakes, larval sunfish production was unrelated to percent
littoral habitat (P = 0.87). There was also no relation between the other habitat
parameters (in Table 2) and larval sunfish production with the exception of summer
chlorophyll a concentrations. Total larval sunfish production was positively related
to summer chlorophyll a concentrations in the seven study lakes [ln(larval
production) = 0.96ln(chlorophyll a) + 1.21; N = 7; R2 = 0.57; P = 0.04].
JUVENILE GROWTH AND SURVIVAL
The growth of juvenile bluegill differed among lakes (ANCOVA: age, df =
6,132; F = 3.21; P = 0.006), but was unrelated to larval sunfish densities (P= 0.89).
Juvenile growth was unrelated to habitat conditions (in Table 2) in these systems with
the exception of mean depth. The growth of juvenile bluegill was higher in deeper
lakes [juvenile bluegill growth = 0.063(mean depth (m)) + 0.088; N = 7; R2 = 0.63; P
= 0.03; Figure 6] compared to shallow lakes. The growth of juvenile bluegill was not
correlated with the density of largemouth bass (P = 0.72). However, juvenile bluegill
growth was negatively related to adult bluegill densities in the seven study lakes
[juvenile bluegill growth = -0.001(adult bluegill density (N/h)) + 0.444; N = 7; R2 =
0.57; P = 0.048; Figure 7].
Approximately 90% of the juvenile back-calculated swim-up dates occurred
during dates in the spring when larval fish were collected; therefore survival values
could be calculated for a majority of the juveniles collected in the fall. In lake S11, a
17
majority (67%) of the juvenile bluegill had back-calculated swim-up dates that
occurred before larval sampling commenced. Larval survival to the juvenile stage
significantly differed among lakes (ANOVA: df = 6; F = 2.80; P = 0.015). Analysis
of survival indexes also revealed an interaction between adult size structure category
and season (ANOVA: df = 4; F = 5.11; P < 0.001; Figure 8). Larval survival was
only affected by one factor in the seven study lakes. Larval survival was negatively
related to larval sunfish densities [log10 larval survival = -0.557(log10 larval densities
(#/m3)) + 0.972; R2 = 0.30; P < 0.001]. Therefore, larval survival through the fall of
2003 was much higher in lakes with low densities of larval sunfish than lakes with
high densities of larval sunfish.
18
DISCUSSION
Density-dependent and density-independent processes are both important in
population ecology (Diana 2004). Indeed, a combination of both density-dependent
(i.e., size and abundance) and density-independent factors (i.e., chlorophyll a and
mean depth) influenced bluegill reproduction and structured bluegill populations in
these systems, with density-dependence being the predominant process.
ADULT BLUEGILL SIZE EFFECTS
Many small impoundments exhibit density-dependent size structure
relationships between adult largemouth bass and adult bluegill. For example, the
proportion of large bluegills is often linked to the abundance of largemouth bass, with
higher quality (i.e., larger, plumper adults) populations of bluegill occurring when
small largemouth bass are dense (Anderson 1976; Guy and Willis 1990; Belk and
Hales 1993). Low largemouth bass and high bluegill abundances in small
impoundments can lead to slow growth and low proportions of large bluegills
(Novinger and Legler 1978; Wiener and Hanneman 1982). In the surface mine lakes
I studied, this relationship was not apparent, with size structure of adult bluegill being
unrelated to adult largemouth densities and adult bluegill densities. Because they
were largely unharvested, the fish populations in these lakes were likely near
equilibrium. A combination of top-down and bottom up factors were likely the
primary causes for high variation in adult size structures among the lakes.
Production (fecundity) is closely linked to adult size in most fishes, with an
exponential relationship occurring between fecundity and fish mass (Roff 1983;
19
Diana 2004). Adult bluegill size structure could explain most of the variation in
larval production in these systems, with both total production and peak densities
being higher in lakes with high proportions of larger adults than lakes with smallsized adults. Similar patterns have been documented in past studies in similar bodies
of water (Goodgame and Miranda 1993; Garvey et al. 2002). Even though adult size
often dictates the reproductive potential of a certain fish species, with increased
gonad development in larger fish, this may not always be the case for bluegill
populations. Large individuals may be simply more successful in contributing to
future cohorts by outcompeting small conspecifics for nesting sites and females
(Jennings and Phillip 1992; Ehlinger 1997; Garvey et al. 2002). With this
combination of both higher reproductive capability and increased success in
competition for nesting sites and females, higher larval production was seen in lakes
with high densities of large adults than lakes with high densities of small adults.
For several fish species differences in timing of spawning in relation to adult
size has been documented, with larger adults spawning earlier than smaller adults
(Miranda and Muncy 1987a; Baylis et al. 1993). Bluegill exhibit protracted spawning
(Cargnelli and Gross 1996; Garvey et al. 2002), which could lead to differences in
recruitment success based on the timing of spawning. Spawning occurred earlier, in a
greater number of bouts over a longer period of time, producing higher larval
densities in lakes when large adults were abundant compared to lakes with low
numbers of large adults. Likely, small individuals generally had insufficient energy
reserves to spawn early in the season and had to feed several weeks in the spring to
mature gonads before spawning (Goodgame and Miranda 1993; Justus and Fox
20
1994). This pattern in sunfish reproduction has also been documented in other studies
in which lakes with larger adults in better reproductive condition spawned earlier and
over a longer period of time than smaller conspecifics (Miranda and Muncy 1987ab;
Goodgame and Miranda 1993; Aday et al. 2002).
HABITAT EFFECTS
With these systems having limited shallow areas, I predicted that littoral
habitat would be a limiting factor for larval production. However, even with the large
gradient in littoral habitat, larval sunfish production was unrelated to the amount of
littoral habitat. Increasing littoral habitat might reduce male competition but not
affect production (Ehlinger 1997). The number of colonies could increase but the
number of nests per colony could decline (Ehlinger 1997). Littoral habitat was likely
sufficient for these bluegill populations. In contrast, lake primary productivity (as
measured by chlorophyll a analysis) appeared to promote larval production.
Zooplankton abundance is often linked to lake primary productivity in lentic systems,
and high productivity likely facilitated growth and survival of larval fish in these
lakes. Adult condition may also have been positively affected by high primary
productivity.
GROWTH AND SURVIVAL
Growth and survival of offspring can be greatly influenced by adults and may
feed back to affect future patterns of production (Roff 1984; Baylis et al. 1993; Belk
1995). Juvenile growth was highly variable among lakes. In these lakes, juvenile
21
growth and survival were closely associated with adult bluegill densities and mean
lake depth. Juvenile bluegill had slower growth rates in lakes with higher densities of
adult bluegill, likely because of density-dependent competition for food (e.g.,
zooplankton). This pattern of adult bluegill negatively affecting larval growth, which
is an example of intra-cohort competition, has been documented in a study by Rettig
and Mittelbach (2002), in which adults greatly reduced the abundance of large
zooplankton, thus reducing larval growth in lakes with higher densities of adult
bluegill. In the seven study lakes, juvenile bluegill growth increased with increasing
mean depth perhaps due to a reduction in the direct competition for food and space
between the adult, juvenile, and larval stages.
Larval survival was also highly variable in these systems and was mainly
affected by density-dependent processes and timing of spawning. This was evident
because larval survival to the juvenile stage was negatively related to increasing
larval densities. Low survival in systems with high larval densities could have been
linked to many different factors including predation, food availability, and
competition. Larval survival also varied with hatch date. Variation in the survival of
larvae to the juvenile stage as a result of differences in timing of spawning has been
argued for bluegill populations (Cargnelli and Gross 1996; Garvey et al. 2002;
Santucci and Wahl 2003). In these studies, contradictory results arose on whether it is
advantageous to spawn early or late in the season to increase survival. In my view,
timing was not as crucial to survival as the number of larvae produced by the adults.
It is evident that lakes with large adults had relatively low survival across the entire
spawning season and they were able to overcome low survival by producing large
22
numbers of larvae. However, survival was greatest late in the season for lakes with
small adults, probably due to the fact that they must delay reproduction due to limited
energy reserves early in the spawning season. Those larvae produced late in the
spawning season in these systems likely avoided predation and high competition for
resources allowing them to have high survival to the juvenile stage.
CONCLUSIONS AND IMPLICATIONS
Density-dependent factors were likely responsible for structuring the bluegill
populations in these systems. Adults in lakes with high densities of large adults
spawned earlier, in a greater number of bouts, over a longer period of time than lakes
with small adults. This resulted in high densities of larvae, but poor larval growth
and survival, probably due to density-dependent processes. Surviving juveniles
captured in the fall were relatively small in size due to slow growth during the larval
stage. However, the few surviving individuals will likely grow rapidly in the second
growing season due to a release from density-dependent processes resulting in large
adults. Lakes from this study which contained high densities of small adult bluegill
tell a different story. In these lakes, adults spawned later in the season, in a fewer
number of bouts, over a shorter period of time than lakes with abundant large adults.
The abundant small adults in these lakes produced much lower densities of larvae
than lakes with large adults. Low densities of larvae in these systems resulted in high
first summer growth and survival, producing a high number of juvenile bluegill that
were large in size. High densities of juveniles represented in the following spring in
23
lakes with small adults will likely lead to poor growth due to density-dependent
factors, resulting in individuals that mature early and reach much smaller adult sizes.
This study showed many similarities to a study by Baylis et al. (1993), in
which they examined early life histories of smallmouth bass. Similar to their study, I
showed that differences in adult size and timing of spawning among populations can
lead to differences in the development of future cohorts. However, they claimed that
smallmouth bass exhibit an alternating life history which was responsible for changes
in the structure of future cohorts. Although differences in adult size and timing of
spawning among bluegill populations in my study occurred, I believe future cohorts
in these populations are structured by a single life history which has reached
equilibrium rather than by alternating life history strategies. This continuing cycle or
equilibrium which occurs in these systems may be disrupted by factors including
drastic changes in habitat conditions or exploitation by fishing.
It is evident from this study, with the absence of fishing pressure, adult size
and timing of spawning in bluegill populations are very important in determining
future life histories of individuals within a system and structuring future year-classes.
Density-dependent processes were mostly responsible for structuring the adult
bluegill in these lakes by driving top-down and bottom-up effects on different life
stages. With this in mind, it is important when managing bluegill populations to have
a good understanding of how the recruitment processes are affected by densitydependent factors.
24
Table 1. Catch per unit effort (CPUE), proportional stock density (PSD), and mean
relative weight (Wr) results for bluegill and largemouth bass in 15 surface-mine lakes
located near Sparta, IL during fall 2002 and spring 2003. PSD N and Wr N represent
the number of individuals used for those calculations. The seven bolded lakes were
selected to span the adult bluegill size structure.
Species
Lake
CPUE (N/h)
PSD
PSD N
Mean Wr
Wr N
Bluegill
L1
258
13
152
85
35
L2
75
20
75
90
41
L3
458
5
152
92
44
S1
424
6
102
92
47
S2
N/A
N/A
N/A
N/A
N/A
S3
133
46
132
89
49
S4
103
10
55
89
46
S5
222
22
152
97
40
S6
191
3
89
97
33
S7
9
50
2
105
2
S8
192
55
97
102
42
S9
65
20
28
97
16
S10
108
9
72
116
41
S11
326
18
158
90
43
S12
85
37
30
89
30
L1
74
50
74
96
29
L2
142
14
141
89
36
L3
57
63
57
101
29
S1
87
33
21
99
10
S2
32
70
30
94
23
S3
65
23
65
96
35
S4
21
67
11
90
9
S5
27
36
23
93
17
S6
30
50
20
95
10
S7
155
0
33
105
25
S8
232
10
116
98
34
S9
399
3
173
96
28
S10
23
85
15
97
13
S11
214
14
150
93
29
S12
14
67
5
89
3
Largemouth
bass
25
Table 2. Bathymetric dimensions, shoreline development indices, chlorophyll a
concentrations, and littoral habitat data for the seven study lakes located near Sparta,
IL sampled during summer/fall 2003.
Lake
Photic
Surface Max Mean
Shoreline
zone Littoral
Area Depth Depth Volume Development Depth Volume Proportion
(ha)
(m)
(m)
Index
(m3)
(m3)
Littoral
(m)
Chl a
(ug/L)
S8
2.47
8.17
3.60
100260
1.52
2.1
9347
0.21
70.2
S3
3.06
7.09
3.20
103500
2.95
2.6
18419
0.30
30.8
S5
2.52
3.22
1.95
50589
2.38
2.0
16092
0.40
34.4
S9
2.85
12.94
5.07
159899
1.40
2.7
14657
0.24
105.3
S11
8.67
12.69
3.79
387968
1.55
2.7
48065
0.25
31.7
S4
2.81
9.15
4.51
151493
1.93
1.6
3636
0.09
28.5
S6
3.61
11.37
3.76
152708
1.88
2.3
14711
0.23
29.1
26
Table 3. Summary of larval sunfish data for the seven study lakes located near
Sparta, IL sampled during the summer of 2003. Total production was quantified by
summing all the weekly densities for each lake. Peak density in each lake was the
highest density which occurred during the twelve sampling events. Mean densities
represent the mean of all twelve sampling events for each lake.
Lake
Large
Intermediate
Small
S8
S3
S5
S9
S11
S4
S6
358.21
162.80
87.01
198.70
87.52
78.78
52.61
Peak Densities (#/m )
101.24
43.36
40.06
45.67
37.48
38.85
26.68
3
29.85
13.57
7.25
16.56
7.29
6.57
4.38
Total Production (#/m3)
3
Mean Densities (#/m )
27
Figure 1. Aerial photo of 1,133-hectare reclaimed surface coal mining area near
Sparta, IL where all research was conducted from fall 2002 through fall 2003. The
yellow line is the property boundary surrounding all 15 lakes represented in blue.
The three larger lakes are labeled L1-L3 and the twelve smaller lakes are labeled S1S12. The seven lakes intensively studied for this study are labeled with lake names
inside the yellow boxes.
28
Figure 2. Percent frequencies of small (15-30 mm), medium (30-50 mm), and large
(50-80 mm) juvenile (age 0) bluegill collected in October 2003 in the seven study
lakes near Sparta, IL. Relative proportions of these three size ranges of juveniles
differed among the lakes with different adult size structures.
29
Figure 3. Daily growth regressions for juvenile bluegill collected in October 2003 in
the seven study lakes located near Sparta, IL.
30
Figure 4. Relationships between adult bluegill size structures (PSDs) and (A) total
larval sunfish production and (B) peak larval sunfish densities in lakes near Sparta, IL
2003. Total production for each lake was calculated by summing all of the weekly
larval densities calculated for the twelve sampling events and was positively related
to increasing PSD. Peak density was considered the time when the average weekly
larval density in each of the lakes was the highest of all twelve sampling events and
was also positively related to increasing PSD.
31
110
Large
Intermediate
Small
100
Mean Larval Sunfish Densities (#/m3)
90
80
70
60
50
40
30
20
10
0
13-May
25-May
6-Jun
18-Jun
30-Jun
12-Jul
Date
24-Jul
5-Aug
17-Aug
29-Aug
Figure 5. Weekly mean larval sunfish densities with associated standard error bars
for the three different adult size structure categories in the seven study lakes located
near Sparta, IL during the summer of 2003.
32
Figure 6. The relationship between mean lake depth (m) and regressed juvenile
bluegill growth (mm/day) for the seven study lakes near Sparta, IL during the fall of
2003.
33
Figure 7. The relationship between adult bluegill density (number per hour
electrofished) and regressed juvenile bluegill growth (mm/day) for the seven study
lakes near Sparta, IL during the fall of 2003.
34
Figure 8. Mean log transformed survival values for three seasons (early, middle,
late) with associated standard error bars calculated for the juveniles collected in the
fall of 2003 for the three different adult size structure categories.
35
LITERATURE CITED
Aday, D. D., C. M. Kush, D. H. Wahl, and D. P. Philipp. 2002. The influence of
stunted body size on the reproductive ecology of bluegill Lepomis
macrochirus. Ecology of Freshwater Fish 11:190-195.
Anderson, R. O. 1976. Management of small warmwater impoundments. Fisheries
1(6):5-7, 26-28.
Anderson, R. O. 1980. Proportional stock density (PSD) and relative weight (Wr):
interpretive indices for fish populations and communities. Pages 27-33 in S.
Gloss and B. Shupp, editors. Practical fisheries management: more with less
in the 1980’s. American Fisheries Society New York Chapter.
Anderson, R. O., and R. M. Neumann. 1996. Length, weight, and associated
structural indices. Pages 447-482 in B. R. Murphy and D. W. Willis, editors.
Fisheries techniques, 2nd edition. American Fisheries Society, Bethesda,
Maryland.
Auer, N. A. 1982. Identification of larval fishes of the Great Lakes basin with
emphasis on the Lake Michigan drainage. Great Lakes Fishery Commission,
Special Publication 82-3, Ann Arbor, Michigan.
Baylis, J. R., D. D., Wiegmann, and H. H. Hoff. 1993. Alternating life histories of
smallmouth bass. Transactions of the American Fisheries Society 122:500510.
Bell, R. 1956. Aquatic and marginal vegetation of strip mine waters in southern
Illinois. Transactions of the Illinois Academy of Science 48:85-91.
Belk, M. C., and L. S. Hales, Jr. 1993. Predation-induced differences in growth and
reproduction of bluegills (Lepomis macrochirus). Copeia 1993:1034-1044.
Belk, M. C. 1995. Variation in growth and age at maturity in bluegill sunfish:
genetic or environmental effects? Journal of Fish Biology 47:237-247.
Brain, M. B., and L. A. Helfrich. 1983. Role of parental care in survival of larval
bluegills. Transactions of the American Fisheries Society 112:47-52.
Breder, C. M., Jr. 1936. The reproductive habits of North American sunfishes
(family Centrarchidae). Zoologica 21:1-47.
36
Cargnelli, L. M., and M. R. Gross. 1996. The temporal dimension in fish
recruitment: birth date, body size, and size-dependent survival in a sunfish
(bluegill: Lepomis macrochirus). Canadian Journal of Fisheries and Aquatic
Sciences 53: 360-367.
Childers, W. F. 1967. Hybridization of four species of sunfishes (Centrarchidae).
Illinois Natural History Survey Bulletin 29:159-214.
Claramunt, R. M., and D. H. Wahl. 2000. The effects of abiotic and biotic factors in
determining larval fish growth rates: a comparison across species and
reservoirs. Transactions of the American Fisheries Society 129: 835-851.
Cooper, E. L., C. C. Wagner, and G. E. Krantz. 1971. Bluegills dominate production
in mixed population of fishes. Ecology 52: 280-290.
Diana, J. S. 2004. Biology and ecology of fishes. Biological Sciences Press,
University of Michigan.
Drake, M. T., J. E. Claussen, D. P. Philipp, and D. L. Pereira. 1997. A comparison
of bluegill reproductive strategies and growth among lakes with different
fishing intensities. North American Journal of Fisheries Management 17:
496-507.
Ehlinger, T. J. 1997. Male reproductive competition and sex-specific growth
patterns in bluegill. North American Journal of Fisheries Management
17:508-515.
Éva Pápista, Éva Ács Béla Böddi. 2002. Chlorophyll-a determination with ethanol –
a critical test. Hydrobiologia 485:191-198.
Gabelhouse, D.W., Jr. 1984. A length-categorization system to assess fish stocks.
North American Journal of Fisheries Management 4:273-285.
Garvey, J. E., and R. A. Stein. 1998. Competition between larval fishes in
reservoirs: the role of relative timing of appearance. Transactions of the
American Fisheries Society 127: 1021-1039.
Garvey, J. E., T. P. Herra, and W. C. Leggett. 2002. Protracted reproduction in
sunfish: the temporal dimension in fish recruitment revisited. Ecological
Applications 12:194-205.
Gash, S. L., and J. C. Bass. 1973. Age, growth and population structures of fishes
from acid and alkaline strip-mine lakes in southeast Kansas. Transactions of
the Kansas Academy of Science 76: 39-50.
37
Goodgame, L. S., and L. E. Miranda. 1993. Early growth and survival of age-0
largemouth bass in relation to parental size and swim-up time. Transactions
of the American Fisheries Society 122:131-138.
Guy, C. S., and D. W. Willis. 1990. Structural relationships of largemouth bass and
bluegill populations in South Dakota ponds. North American Journal of
Fisheries Management 10:338-343.
Hayes, D. B., W. W. Taylor, and P. A. Soranno. 1999. Natural lakes and large
impoundments. Pages 589-617 in C. C. Kohler and W. A. Hubert, editors.
Inland fisheries management in North America, 2nd edition. American
Fisheries Society, Bethesda, Maryland.
Heatherly, T., II, M. R. Whiles, D. Knuth, and J. E. Garvey. 2005. Diversity and
community structure of littoral zone macroinvertebrates in southern Illinois
reclaimed surface mine lakes. American Midland Naturalist 154:67-77.
Jennings, M. J., and D. P. Phillip. 1992. Female choice and male competition in
longear sunfish, Lepomis megalotis. Behavioral Ecology 3:84-94.
Jennings, M. J. 1997. Centrarchid reproductive behavior: implications for
management. North American Journal of Fisheries Management 17:493-495.
Jennings, M. J., J. E. Claussen, and D. P. Philipp. 1997. Effect of population size
structure on reproductive investment of male bluegill. North American
Journal of Fisheries Management 17:516-524.
Justus, J., and M. J. Fox. 1994. The cost of early maturation on growth, body
condition, and somatic lipid content in a lake pumpkinseed (Lepomis
gibbosus) population. Ecology of Freshwater Fish 3:9-17.
Latta, W. C., and J. W. Merna. 1977. Some factors influencing size of the year class
of bluegills (Lepomis macrochirus) in ponds. Michigan Academician 9:483502.
Lemly, A. D., and J. F. Dimmick. 1982. Growth of young-of-year and yearling
centrarchids in relation to zooplankton in the littoral zone of lakes. Copeia
2:305-321.
Miller, T. J., L. B. Crowder, J. A. Rice, and E. A. Marschall. 1988. Larval size and
recruitment mechanisms in fishes: toward a conceptual framework. Canadian
Journal of Fisheries and Aquatic Sciences 45:1657-1670.
Miranda, L. E., and R. J. Muncy. 1987a. Recruitment of young-of-year largemouth
bass in relation to size structure of parental stock. North American Journal of
Fisheries Management 7:131-137.
38
Miranda, L. E., and R. J. Muncy. 1987b. Spawning sequence of largemouth bass,
bluegill, and gizzard shad. Proc. Annu. Conf. Southeast. Assoc. Fish and
Wildlife Agencies 41:197-204.
Novinger, G. D., and R. E. Legler. 1978. Bluegill population structure and
dynamics. Pages 37-49 in G. D. Novinger and J.G. Dillard, editors. New
approaches to the management of small impoundments. American Fisheries
Society, North Central Division, Special Publication 5, Bethesda, Maryland.
Paukert, C. P., D. W. Willis, and D. W. Gablehouse Jr. 2002. Effect and acceptance
of bluegill length limits in Nebraska natural lakes. North American Journal of
Fisheries Management 22:1306-1313.
Rettig, J. E., and G. G. Mittelbach. 2002. Interactions between adult and larval
bluegill sunfish: positive and negative effects. Oecologia 130:222-230.
Roff, D. A. 1983. An allocation model of growth and reproduction in fish. Canadian
Journal of Fisheries and Aquatic Sciences 40:1395-1404.
Roff, D. A. 1984. The evolution of life history parameters in teleosts. Canadian
Journal of Fisheries and Aquatic Sciences 41:989-1000.
Rold, R. E., T. S. McComish, and D. E. Van Meter. 1996. A comparison of cedar
trees and fabricated polypropylene modules as fish attractors in a strip mine
impoundment. North American Journal of Fisheries Management 16:223227.
Santucci, V. J. Jr. and D. H. Wahl. 2003. The effects of growth, predation, and firstwinter mortality on recruitment of bluegill cohorts. Transactions of the
American Fisheries Society 132:346-360.
SAS Institute. 2001. SAS/STAT user’s guide. SAS institute, Cary, North Carolina.
Taubert, B. D., and D. W. Coble. 1977. Daily rings in otoliths of three species of
Lepomis and Tilapia mossambica. Journal of the Fisheries Research Board of
Canada 34:332-340.
Tomcko, C. M., and R. B. Pierce. 2001. The relationship of bluegill growth, lake
morphometry, and water quality in Minnesota. Transactions of the American
Fisheries Society 130:317-321.
Van Den Avyle, M. J., and R. S. Hayward. 1999. Dynamics of exploited fish
populations. Pages 127-163 in C. C. Kohler and W. A. Hubert, editors. Inland
fisheries management in North America, 2nd edition. American Fisheries
Society, Bethesda, Maryland.
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Wetzel, R.G. 2001. Limnology. Academic Press, London.
Wiener, J. G., and W. R. Hanneman. 1982. Growth and condition of bluegills in
Wisconsin lakes: effects of population density and lake pH. Transactions of
the American Fisheries Society 11:761-767.
40
APPENDICES
APPENDIX A
Figure A1. Depth profile map for lake S3, located near Sparta, IL using data points
collected while echosounding.
41
Figure A2. Depth profile map for lake S4, located near Sparta, IL using data points
collected while echosounding.
42
Figure A3. Depth profile map for lake S5, located near Sparta, IL using data points
collected while echosounding.
43
Figure A4. Depth profile map for lake S6, located near Sparta, IL using data points
collected while echosounding.
44
Figure A5. Depth profile map for lake S8, located near Sparta, IL using data points
collected while echosounding.
45
Figure A6. Depth profile map for lake S9, located near Sparta, IL using data points
collected while echosounding.
46
Figure A7. Depth profile map for lake S11, located near Sparta, IL using data points
collected while echosounding.
47
APPENDIX B
Figure B1. Length frequency distributions of juvenile bluegill (age 0) collected from
the seven study lakes located near Sparta, IL in October 2003.
48
VITA
Graduate School
Southern Illinois University
David S. Knuth
Date of Birth: November 11, 1979
11831 State Route 17, West Plains, MO 65775
Southern Illinois University
Bachelor of Science, Zoology, May 2002
Thesis Title:
Effects of Abiotic and Biotic Factors on Sunfish Reproduction and Growth in
Seven Unexploited Surface Coal Mine Lakes
Major Professor: James E. Garvey
Publications:
Heatherly, T., II, M.R. Whiles, D. Knuth, and J.E. Garvey. 2005. Diversity
and community structure of littoral zone macroinvertebrates in southern Illinois
reclaimed surface mine lakes. American Midland Naturalist 154:67-77.
49