THE EFFECT OF POOL GEOMORPHOLOGY ON FEEDING MORPHOLOGY OF ALPODINOTUS
GRUNNIENS AND LEPOMIS MACROCHIRUS IN THE OHIO RIVER, USA
Adam GerughtyCandidate For Masters of Environmental Studies
Dr. Tamara Sluss
Lotic Systems
• Characteristics:– Running water– Connected system– Open system•These characteristics make rivers difficult to study.
—Expensive—Hard to setup experiments—Time consuming—Each river around the world is different—Hard to create concepts for all rivers
Basic River Concepts• In attempt to describe rivers ecosystems many concepts have been
created.• River Continuum Concept (RCC)
– As the stream order increases the main source of production changes causing each stream order to have a different variety of organisms. (Vannote et al. 1980)
•Flood Pulse Concept (FPC)−Pulsing river discharge has a greater impact on food webs and
supports allochthonous materials from the floodplain and not just from production in the riparian zone (Junk et al. 1989)•Inshore Retention Concept (IRC)
–IRC explains how the biota and production levels change based on the river water retention, meaning the water velocity or discharge controls the biotic diversity and production levels. (Schiemer et al. 2001)
Introduction to the Ohio River
• Ohio River flow was created when Monongahela and Allegheny rivers converged in Pennsylvania
• Ohio River is about 1,579 river kilometers long and connects with the Mississippi River at Cairo, Illinois
• Ohio River drainage basin is about 517,998 square kilometers
(Ray 1974)
(Ray 1974)
Geological Formation of the Ohio
Ohio River Subdivision Valley Floodplain
Upper Ohio (alluviated valley)
High valley walls Wide Channel
Vast floodplain
Glaciated Valley Narrow Channel with steep banks
Narrow limited floodplain
Constricted Valley Deep valley wallsNarrow channel
Floodplain almost nonexistent
Alluviated Valley Extensive bottomlands Vast floodplain
(Ray 1974)
Navigational Dams of the Ohio• The Ohio River contains 20 navigational dams which have
channelized it and artificially control the flood stages (Ray, 1974).
• Maintain minimum water levels for barge traffic (US Army Corps of Engineers Pittsburgh District 2012)
• Water pools behind the dam, each pool has upstream riverine characteristic, high water velocity, and a downstream lacustrine like portion just above the dam (Wetzel 2001).
riverinelacustrineDam
(US Army Corps of Engineers)
Aplodinotus grunniens
• Main Characteristics– Habitat: Open warm waters with a muddy benthic
zone– Food: Young individuals feed primarily on
copepods and cladocerans, while adults feed on crayfish, fish, and mollusks
– Hunting behaviors: Rely on sight and touch to feed
(Priegel 1967)
Lepomis macrochirus
• Main Characteristics– Habitat: Prefer warm waters, can be found among
the littoral zone along lakes and rivers– Food: Young individuals feed on copepods and
cladocerans while adults feed on large insects or the occasional frog or fish
– Hunting behaviors: Rely on sight to find insects near the surface
(Snow et al. 1960)
Research Objectives
• Compare mouth morphology between navigational dam sites for Aplodinotus grunniens and Lepomis macrochirus
• Asses any similarities between sites• Conjecture what might be causing differences
if any
Methods: Specimen Collection
• Specimens for this project were obtained from Cincinnati Natural History Museum preserve ichthyology collection
• The specimens were preserved in a solution of 95% ethanol in a container had that had a specific ID number, information on location, date of the specimens was obtained, method of collection and a lot number which were recorded.
• Pictures were captured by using a Nikon D90 digital camera
• A. grunniens (n=155) & L. macrochirus (n=45)
(Adam Gerughty)
2 cm
2 cm
(Adam Gerughty)
Data Collection
• Each picture was then uploaded into imaging software, Spot Advance version 4.7 created by Diagnostic Inc
• The pictures were calibrated• Ten morphological measurements were
recorded
Maximum Standard Length
Fork Length
Maximum Total Length
(Adam Gerughty)
2 cm
Body DepthEye Diameter
Head Depth
Head Length
Snout Length
Jaw Length
(Adam Gerughty)
2 cm
Gape Width
(Adam Gerughty)
2 cm
Methods: Statistical Analysis• 20 different mouth morphology standardizations were
created• Principle Component Analyses (PCA) was used to
determine any differences between navigational sites using PC-ORD.
• Bonferroni-correct probabilities were used to determine the statistical significance in the mouth morphology standardization data (Systat 10.2).
• Tukey HSD Multiple comparison probabilities were preformed to asses the statistical significance difference between navigational pool sites. (Systat 10.2)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
1.000
2.000
3.000
4.000
5.000
6.000
7.000
Mean Mass for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (g
)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
1.000
2.000
3.000
4.000
5.000
6.000
Mean Maximum Total Length for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
0.500
1.000
1.500
2.000
2.500
3.000
3.500
4.000
4.500
5.000
Mean Maximum Standard Length for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
1.000
2.000
3.000
4.000
5.000
6.000
Mean Fork Length for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
Mean Head Depth for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.450
0.500
Mean Snout Length for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.450
0.500
Mean Gape Width of the Mouth for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
A. grunniens L. macrochirus 0.200
0.210
0.220
0.230
0.240
0.250
0.260
0.270
0.280
Mean Jaw Length for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
0.050
0.100
0.150
0.200
0.250
0.300
0.350
0.400
0.450
0.500
Mean Eye Diameter for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
1.800
2.000
Mean Depth of the Fish Body for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
A. grunniens L. macrochirus 0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
Mean Head Length for Aplodinotus grunniens and Lepomis macrochirus
Species Name
Mea
n (c
m)
Results: Descriptive Stats
Results: Lepomis macrochirus PCA
PCA Eigenvalue Percent of Variance
Cumulative Percent of Variance Eigenvalue
----- ----------------- --------------- ----------- ---------------
1 7.887 39.434 39.434 3.598
2 5.101 25.504 64.938 2.598
3 2.894 14.472 79.41 2.098
4 1.886 9.43 88.84 1.764
5 0.749 3.744 92.584 1.514
6 0.553 2.764 95.348 1.314
7 0.46 2.3 97.648 1.148
8 0.229 1.147 98.795 1.005
9 0.128 0.638 99.432 0.88
10 0.058 0.29 99.723 0.769
Results: Lepomis macrochirus PCAStandardization
PCA 1 PCA 2 PCA 3 Jaw length to mass 0.421 0.2011 0.7745Jaw length to maximum standard length 0.94 0.2213 -0.095Jaw length to fork length 0.9487 0.2412 -0.11Jaw length to maximum total length 0.9484 0.246 -0.129Jaw length to body depth 0.9463 0.1883 0.1045Jaw length to head length 0.2188 0.1929 0.4038Jaw length to eye diameter 0.7323 0.2943 -0.503Jaw length to snout length 0.7522 -0.078 -0.405Jaw length to head depth 0.9025 0.1722 0.0726Jaw length to gape width of the mouth 0.9455 -0.309 -0.066Gape width of the mouth to mass 0.0811 0.2727 0.8659Gape width of the mouth to maximum standard length -0.181 0.9029 -0.073
Gape width of the mouth to fork length -0.184 0.9424 -0.129Gape width of the mouth to maximum total length -0.196 0.9438 -0.143Gape width of the mouth to body depth 0.0331 0.8274 0.3108Gape width of the mouth to head length 0.0467 0.2511 0.4133Gape width of the mouth to eye diameter -0.226 0.6621 -0.569Gape width of the mouth to snout length -0.481 0.4101 -0.453Gape width of the mouth to head depth 0.117 0.7033 0.2506Gape width of the mouth to jaw length -0.928 0.291 0.073
Results: Lepomis macrochirus PCA Analysis
-8 -6 -4 -2 0 2 4 6 8
-4
-3
-2
-1
0
1
2
3
4
Lepomis macrochirus Mouth Standardizations: PCA 1 vs. PCA 2
Pike Island poolWillow Island poolGreenup poolMarkland poolNewburgh poolUniontown pool
PCA 1 (dimensionless)
PCA
2 (d
imen
sion
less
) Alluviated valley
Glaciated valley
Alluviated valley
Results: Lepomis macrochirus PCA Analysis
-8 -6 -4 -2 0 2 4 6 8
-6
-4
-2
0
2
4
6
Lepomis macrochirus Mouth Standardizations: PCA 1 vs. PCA 3
Pike Island poolWillow Island poolGreenup poolMarkland poolNewburgh poolUniontown pool
PCA 1 (dimensional less)
PCA
3 (d
imen
siona
l les
s) Alluviated valley
Glaciated valley
Alluviated valley
Results: Aplodinotus grunniens PCA
PCA Eigenvalue Percent of VarianceCumulative Percent of Variance Eigenvalue
1 7.72 38.602 38.602 3.598
2 4.629 23.144 61.746 2.598
3 2.003 10.014 71.76 2.098
4 1.855 9.275 81.035 1.764
5 1.783 8.917 89.952 1.514
6 1.065 5.325 95.277 1.314
7 0.429 2.147 97.424 1.148
8 0.291 1.455 98.88 1.005
9 0.076 0.379 99.258 0.88
10 0.042 0.212 99.471 0.769
Results: Aplodinotus grunniens PCA AnalysisStandardizations Eigenvector
1 2 3
Jaw length to mass 0.5975 -0.1438 -0.3402
Jaw length to maximum standard length 0.9277 -0.3258 0.0133
Jaw length to fork length 0.93 -0.3199 0.0083
Jaw length to maximum total length 0.9282 -0.3227 0.0434
Jaw length to body depth 0.208 -0.2252 0.5849
Jaw length to head length 0.872 -0.2841 0.1284
Jaw length to eye diameter 0.2274 -0.4245 -0.5948
Jaw length to snout length 0.5732 -0.0835 0.3611
Jaw length to head depth 0.8395 -0.3574 -0.0434
Jaw length to gape width of the mouth 0.9725 0.1508 -0.0363
Gape width of the mouth to mass 0.2546 -0.2056 -0.3511Gape width of the mouth to maximum standard length -0.169 -0.908 0.0568
Gape width of the mouth to fork length -0.1892 -0.9057 0.0417
Gape width of the mouth to maximum total length -0.2398 -0.8935 0.1132
Gape width of the mouth to body depth 0.0576 -0.2594 0.586
Gape width of the mouth to head length -0.47 -0.7086 0.1584
Gape width of the mouth to eye diameter -0.2172 -0.3898 -0.6074
Gape width of the mouth to snout length -0.6066 -0.2552 0.35
Gape width of the mouth to head depth -0.4669 -0.7143 -0.1741
Gape width of the mouth to jaw length -0.9474 -0.2107 -0.0877
Results: Aplodinotus grunniens PCA Analysis
-8 -6 -4 -2 0 2 4 6 8 10
-10
-8
-6
-4
-2
0
2
4
6
Aplodinotus grunniens Mouth Standardizations: PCA 1 vs. PCA 2
Pike Island poolWillow Island poolBelleview poolR.C. Byrd poolGreenup poolMarkland poolMcApline poolCannelton poolNewburgh poolUniontown pool
PCA 1 (dimensionless)
PCA
2 ( d
imen
sion
less
)
Alluviated valley
Glaciated valley
Alluviated valley
Constricted valley
Results: Aplodinotus grunniens PCA Analysis
-8 -6 -4 -2 0 2 4 6 8 10
-12
-10
-8
-6
-4
-2
0
2
4
6
8
Aplodinotus grunniens Mouth Standardizations: PCA 1 vs. PCA 3
Pike Island poolWilliow Island poolBelleview poolR.C. Byrd poolGreenup poolMarkland poolMcApline poolCannelton poolNewburgh poolUniontown pool
PCA 1 (dimensionless)
PCA
3 (d
imen
sionl
ess)
Alluviated valley
Glaciated valley
Alluviated valley
Constricted valley
Uniontown pool
Newburgh pool
Cannelton pool
McApline pool
Markland pool
Greenup pool R.C. Byrd pool Belleview pool
Williow Island pool
Pike Island pool
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0.080
0.090
Navigation Pool Mean for Jaw Length to Maximum Standard Length
Navigational Pool Name
Mea
n (d
imen
sionl
ess)
Uniontown pool
Newburgh pool
Cannelton pool
McApline pool
Markland pool
Greenup pool R.C. Byrd pool Belleview pool
Willow Island pool
Pike Island pool
0
0.005
0.01
0.015
0.02
0.025
0.03
Navigation Pool Standard Deviation for Jaw Length to Maximum Standard Length
Navigational Pool Name
Stan
dard
Dev
iatio
n (d
imen
sionl
ess)
Uniontown pool
Newburgh pool
Cannelton pool
McApline pool Markland pool Greenup pool R.C. Byrd pool Belleview pool Williow Island pool
Pike Island pool
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0.080
Navigation Pool Mean for Jaw Length to Fork Length
Navigational Pool Name
Mea
n (d
imen
sionl
ess)
Uniontown pool
Newburgh pool
Cannelton pool
McApline pool
Markland pool
Greenup pool R.C. Byrd pool
Belleview pool
Willow Island pool
Pike Island pool
0
0.005
0.01
0.015
0.02
0.025
Navigation Pool Standard Deviation for Jaw Length to Fork Length
Navigational Pool Name
Stan
dard
Dev
iatio
n (d
imen
sionl
ess)
Uniontown pool
Newburgh
pool
Cannelt
on pool
McAplin
e pool
Marklan
d pool
Greenup pool
R.C. Byrd
pool
Bellevi
ew pool
Williow Isl
and pool
Pike Isl
and pool
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
Navigation Pool Mean for Jaw Length to Maximum Total Length
Navigational Pool Name
Mea
n (d
imen
sionl
ess)
Uniontown pool
Newburgh
pool
Cannelt
on pool
McAplin
e pool
Marklan
d pool
Greenup pool
R.C. Byrd
pool
Bellevi
ew pool
Willow Isl
and pool
Pike Isl
and pool
0
0.005
0.01
0.015
0.02
0.025
Navigation Pool Standard Deviation for Jaw Length to Maximum Total Length
Navigational Pool Name
Stan
dard
Dev
iatio
n (d
imen
sionl
ess)
Uniontown pool
Newburgh
pool
Cannelt
on pool
McAplin
e pool
Marklan
d pool
Greenup pool
R.C. Byrd
pool
Bellevi
ew pool
Williow Isl
and pool
Pike Isl
and pool
0.000
0.050
0.100
0.150
0.200
0.250
Navigation Pool Mean for Jaw Length to Head Length
Navigational Pool Name
Mea
n (d
imen
sionl
ess)
Uniontown pool
Newburgh pool
Cannelton pool
McApline pool Markland pool
Greenup pool R.C. Byrd pool Belleview pool Willow Island pool
Pike Island pool
0
0.01
0.02
0.03
0.04
0.05
0.06
Navigation Pool Standard Deviation for Jaw Length to Head Length
Navigational Pool Name
Stan
dard
Dev
iatio
n (d
imen
sionl
ess)
Uniontown pool
Newburgh
pool
Cannelt
on pool
McAplin
e pool
Marklan
d pool
Greenup pool
R.C. Byrd
pool
Bellevi
ew pool
Williow Isl
and pool
Pike Isl
and pool
0.0000.0500.1000.1500.2000.2500.3000.350
Navigation Pool Mean for Jaw Length to Head Depth
Navigational Pool Name
Mea
n (d
imen
sionl
ess)
Uniontown pool
Newburgh pool
Cannelton pool
McApline pool Markland pool
Greenup pool R.C. Byrd pool Belleview pool Willow Island pool
Pike Island pool
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Navigation Pool Standard Deviation for Jaw Length to Head Depth
Navigational Pool Name
Stan
dard
Dev
iatio
n (d
imen
sionl
ess)
Uniontown pool
Newburgh
pool
Cannelt
on pool
McAplin
e pool
Marklan
d pool
Greenup pool
R.C. Byrd
pool
Bellevi
ew pool
Williow Isl
and pool
Pike Isl
and pool
0.0000.1000.2000.3000.4000.5000.6000.7000.8000.900
Navigation Pool Mean for Jaw Length to Gape Width
Navigational Pool Name
Mea
n (d
imen
sionl
ess)
Uniontown pool
Newburgh pool
Cannelton pool
McApline pool
Markland pool
Greenup pool R.C. Byrd pool
Belleview pool
Willow Island pool
Pike Island pool
0
0.05
0.1
0.15
0.2
0.25
0.3
Navigation Pool Standard Deviation for Jaw Length to Gape Width of the Mouth
Navigational Pool Name
Stan
dard
Dev
iatio
n (d
imen
sionl
ess)
Discussion: Lepomis macrochirus• Lepomis macrochirus showed no morphological
differences between navigational dam sites. • The sample size was low, additional Lepomis macrochirus
would need to be measured until an accurate conclusion could be formulated.
• One possible reason why there are no morphological differences is because L. macrochirus relies on the littoral zone of the river for surface insects. (Snow et al. 1960)
• The littoral zone might have similar characteristics between the alluviated valley and glaciated valley.
• Another possibility is that the L. macrochirus is not competing with other species.
Discussion: Lepomis macrochirus• When Lepomis cyanellus and Lepomis macrochirus
cohabitate, L. cyanellus exhibits a higher survivorship, growth rate, and greater amount of food contain in the stomach compare to L. macrochirus (Werner and Hall 1977).
• Competition in the littoral zone could be low in both valleys resulting in similar morphology between sites.
• If competition was high in either one of the sites, there would be a difference in morphology.
• If interspecies competition was high in both sites, one would expect there be similar morphology.
Discussion: Aplodinotus grunniens jaw length
• Results have shown that there is measurable difference in the A. grunniens population.
• Individuals habiting the glaciated valley on average are probably eating smaller prey compared to individuals habiting the alluvial valleys, where the jaw length standardization mean is greater indicating that these individuals are eating larger prey.
• Individuals in the McApline navigational pool are probably feeding on cladocerans, copepods, small fish and small mollusks, while individuals in the alluvial valleys are feeding on bigger fish, mollusks, and crayfish (Wallus and Simon 2006).
• This would also indicate the glaciated valley and the alluvial valley have different size prey.
Discussion: Habitat Differences
• Alluvial valleys and glaciated valleys have very different characteristics
• A. grunniens existing in the alluvial valley are relying on the annual flooding cycle to utilize an area that has an abundant source of food and nutrients (Junk et. al 1989).
• Rely on insects and even plant matter for their diet. • Insects seem to be a good source of nutrients during
development (Daiber 1952). • The floodplain would be rich source of terrestrial
insects during flood season.
Discussion: Habitat Differences• Individuals in Uniontown navigational pool, R.C Byrd navigational pool,
and Newburgh navigational pool on average have larger jaw lengths.• They are developing correctly coupled with large terrestrial insects. • A. grunniens living McApline Pool are not receiving enough insects to
develop correctly or since the floodplain is constricted they are limited to eating smaller insects.
• RCC was not considered as an alternative to the FPC because the stream order was the same throughout the river.
• In previous studies where stable isotopes were examined, the flood pulse had little influence over dissolved organic matter in the river and most nutrients came from production in the river.
• The flood plain and backwaters were an important factor for fish, especially juveniles, to use as a safe refuge and an alternate food source (Thorp et al. 1998).
Discussion: Competition effects• There is more diversity in the jaw lengths in the alluviated
valleys than in the glaciated valley due to competition.• Competition has increased in the glaciated due to the
constricted flood plain.• The water velocities in the limited floodplain are not low
enough and food is being washed downstream.• There would also be limited space.• Competition in the alluviated valleys would be minimal.• The floodplain water velocities are low allowing for more
diverse array of food and space.• The food chain lengths would be longer allowing for more
selection of prey and species could feed on traditional niches (Roach et. al, 2009; Werner and Hall, 1976)
Discussion: Affect of Water Velocity• There have been experiments that showed changes in water
velocity have an effect on biota.• Mesocosms were used to examine the effect of water velocity
on zooplankton community density and population growth. • Rotifer populations would grew faster in high turbulence tanks,
while microcrustaceans faired better in lower turbulence tanks.
• This could indicate where certain zooplankton would likely be found along the Ohio River, further away from a dam one would most likely find rotifers, while microcrustaceans would occur in water near the dam (Sluss et al. 2008).
Conclusion: Future Studies• Stable isotopes and gut content analysis would help to
better understand what A. grunniens and L. macrochirus feed upon.
• An increase in sample size, studied sites, and species would help to statistically verify differences between sites.
• Genetic studies could also be conducted to assist in the verification of differences between studied sites.
• Separating individuals to the correct age classes would also help confirmed differences between navigational pool sites.
• The findings from this study and future studies along the Ohio River could be adapted to all large rivers
Acknowledgements• This study of not have been possible without the contributions of Dr.
Herman Mays and the Cincinnati Museum of Natural History loan of their ichthyology collection. I would also like to thank Thomas Moore College for allowing me to have access to their ichthyology collection. Special thanks to Dr. Tara Trammell of the University of Louisville for helping with data analysis through PC-ORD. I am grateful to have Dr. Tamara Sluss as my advisor for her constant support and guidance throughout this whole study. This study was supported by Dr. Kazi Javed, department head of the Master's in Environmental Studies program and Kentucky State University. This study was supported by Kentucky Water Resource Research Institute grant. I would like to thank Charles Weibel and Kentucky State University Aquaculture and Aquatic Sciences for providing matches from the grant.
References• Anderson, R. O., and R. M. Neumann. (1996) Length, weight, and associated structural indices.
Fisheries techniques, 2nd edition, American Fisheries Society, Bethesda, Maryland, 447–482p• Butler R. (1965) Freshwater Drum, Aplodinotus grunniens, in the Navigational Impoundments of
the Upper Mississippi River. Transactions of the American Fisheries Society, 94, 339-349.• Daiber F. (1952) The Food and Feeding Relationships of the Freshwater Drum, Aplodinotus
Grunniens Rafinesque in Western Lake Erie. The Ohio Journal of Science, 52, 35-46.• Galbraith M. (1967) Size-selective Predation on Daphnia by Rainbow Trout and Yellow Perch.
Transactions of the American Fisheries Society, 96, 1-10.• Junk W., Bayley P., and Sparks R. (1989) The Flood Pulse Concept in River-Floodplain System.
Canadian Special Publication of Fisheries and Aquatic Sciences, 106, 110-127. • Labropoulos M. and Eleftheriou A. (1997) The foraging ecology of two pairs of congeneric
demersal fish species: importance of morphological characteristics in prey selection. Journal of Fish Biology, 50, 324-340
• Lukoschek V. and McCormick M. (2001) Ontogeny of diet changes in a tropical benthic carnivorous fish, Parupeneus barberinus (Mullidae): relationship between foraging behavior, habitat use, jaw size, and prey selection. Marine Biology, 138, 1099-1113.
• Priegel G. (1967) The Freshwater Drum Its Life History, Ecology, and Management. Department of Natural Resources Division of Conservation, 236, 3-15.
• Ray L. (1974) Geomorphology and Quaternary Geology of the Glaciated Ohio River Valley-A Reconnaissance Study. Geological Survey Professional Paper, 826, 1- 75.
• Roach. K., Thorp J., and Delong M. (2009) Influence of lateral gradients of hydrologic connectivity on trophic positions of fishes in the Upper Mississippi River. Freshwater Biology, 54, 607-620.
References• Sabatés A. and Saiz E. (2000) Intra- and interspecific variability in prey size and niche breadth of
myctophiform fish larvae. Marine Ecology Progress Series, 201, 261-271• Schiemer, F., Keckeis, H., Reckendorter, W., and Winker, G. (2001) The "inshore retention concept" and its
significance for large rivers. Large Rivers. 12, 509- 516.• Schluter D. (2012) Measure Fish. Dolph Schluter Lab,
https://www.zoology.ubc.ca/~schluter/wordpress/stickleback/measure/, accessed 2012.• Sluss T., Cobb G., and Thorp J. (2008) Impact of turbulence on riverine zooplankton: mesocosm
experiment. Freshwater Biology, 53, 1999-2012.• Snow H., Ensign A., and Klingbiel J. (1960) The Bluegill Its Life History, Ecology, and Management .
Wisconsin Conservation Department, 230, 3-14. • Spotte S. (2007) Bluegills: Biology and Behavior. American Fisheries Society, Bethesda, Maryland, 1- 214p.• Thorp J., Black R., and Haag K. (1994) Zooplankton Assemblages in the Ohio River: Seasonal, Tributary, and
Navigation Dam Effects. Canadian Journal of Fisheries and Aquatic Sciences, 51, 1634-1643.• Thorp J., Delong M., Greenwood K., and Casper A. (1998) Isotopic analysis of three web theories in
constricted and floodplain regions of a large river. Oecologia, 117, 551-563.• Thorp J. and Mantovani. (2005) Zooplankton of turbid and hydrologically dynamic prairie rivers.
Freshwater Biology, 50, 1474-1491.
References• US Army Corps of Engineers Pittsburgh District. (2012) Navigation.
http://www.lrp.usace.army.mil/nav/nav.htm. accessed 2012.• Vannote, R., Minshall G., Cummins, K., Sedell, J., and Cushing, C. (1980) The River
Continuum Concept. Canadian Journal of Fisheries and Aquatic Science, 37,130-137.• Wallus R. and Simon T. (2006) Reproductive Biology and Early Life History of Fishes in the
Ohio River Drainage. vol. 5, CRC Press, Boca Raton, Fl, 1- 360.• Wehr J. and Thorp J. (1997) Effects of navigation dams, tributaries, and littoral zones on
phytoplankton communities in the Ohio River. Canadian Journal of Fisheries and Aquatic Science, 54, 378-395.
• Werner E. and Hall D. (1974) Optimal Foraging and the Size Selection of Prey by the Bluegill Sunfish (Lepomis Macrochirus). Ecology, 55, 1042-1052.
• Werne E. and Hall D. (1976) Niche Shifts in Sunfishes: Experimental Evidence and Significance. Science, 191, 404-406.
• Werner R. and Hall D. (1977) Competition and Habitat Shift in two Sunfishes (Centrarchidae). Ecology, 58, 869-876.
• Wetzel R. (2001) Limnology, Third Edition: Lake and River Ecosystem. Academic Press, Waltham, Massachusetts, 1-1006p.