Hybridization between species has the potential to exert pleiotropic effects on metabolism. Reduced fitness in hybrids may arise through incompatibilities between nuclear- and mitochondrial-encoded subunits of the enzyme complexes of oxidative phosphorylation. In my thesis, I examined metabolic properties and hypoxia tolerance of bluegill (Lepomis macrochirus), pumpkinseed (L. gibbosus), and their unidirectional F1 hybrids (male bluegill x female pumpkinseed). Electron transport system (ETS) complex activities were examined in isolated mitochondria of bluegill, pumpkinseed and hybrids. The specific activities (units per mg mitochondrial protein) of complexes I, II, and V were indistinguishable between groups; however, both complex III and IV showed indications of depressed activities in hybrid mitochondria. The nature of sequence differences in complex IV catalytic subunits (CO1, CO2, CO3) were minor, however the mtDNA-encoded subunit of complex III (cytochrome b) showed 8 differences between bluegill and pumpkinseed, several of which could have structural consequences to the multimeric enzyme and contribute to the depressed complex III catalytic activity in hybrids. I next examined hypoxia tolerance in bluegill, pumpkinseed and hybrids to see if metabolic disruption in hybrids would lead to a reduced ability to cope with this stress. Though no difference in critical oxygen concentration (Pcrit) was noted, the time to loss of equilibrium (LOE) in 0.8 mg O2 /ml suggests that hybrids and bluegills have a lower hypoxia tolerance than pumpkinseeds. Hybrids showed a unique independence between size and LOE time. Analysis of tissue metabolite levels during normoxia, after LOE, and after a short-term hypoxia exposure suggest that differences in hypoxia tolerance are not due to differences in starting metabolite levels or differential metabolite use during hypoxia exposure. / Thesis (Master, Biology) -- Queen's University, 2013-08-30 15:08:45.779

Benthic macroinvertebrates, pumpkinseed sunfish (𝘓𝘦𝘱𝘰𝘮𝘪𝘴 𝘨𝘪𝘣𝘣𝘰𝘴𝘶𝘴) and brown bullhead (𝘈𝘮𝘦𝘳𝘪𝘶𝘴 𝘯𝘦𝘣𝘶𝘭𝘰𝘴𝘶𝘴) were sampled at three sites in western Hamilton Harbour and Cootes Paradise in early June 1995. The diversity, abundance, similarity and variability of the substrate benthic community and the gut contents of the fish were analyzed. The gut contents of both species of fish reflected the diversity, similarity and variability of the site at which they were caught. Mean gut fullness, analysized using prey abundance and volume, shows no significant difference between sites, suggesting that the fish were eating similar amounts of prey at all three sites. Both pumpkinseed sunfish and brown bullhead fed selectively on certain size classes and benthic taxa, including several taxonomic groups previously unreported for these species. Differences in benthic community structure at the three sites and the resultant differences in fish diet have important implications for the remediation of Hamilton Harbour. As water quality improves and the macrophyte cover increases, benthic diversity and abundance will increase. These improvements will increase the area of the littoral zone and the quality of the rearing and feeding environments for the recovering warmwater fisheries in Hamilton Harbour. / Thesis / Master of Science (MS)

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Mississippi has an abundance of ponds which provides a number of opportunities for anglers. Several enhancement strategies are used to improve fish production in ponds, including fertilizing and supplemental feeding. These strategies may ignore the potential ecological impacts that may unexpectedly arise, such as prolific plant growth. This study consists of two phases; first, a mesocosm experiment investigating fertilizer application rates (mg P/L) in relation to potential sunfish growth, and second, a replicated pond experiment consisting of four treatments to simulate commonly used enhancement strategies. Mesocosm experiment showed a peak of sunfish growth at the 0.6 mg P/L level and served as a high fertilizer threshold level in pond experiment. Ponds were surveyed to assess treatment effects on each trophic level. The costs associated with each pond management strategy were documented. Results from this research help refine management recommendations to maximize results while minimizing costs to landowners and ecosystems.

No description available.

Trade offs between mating and predator avoidance advantages were studied in the western mosquitofish (Gambusia affinis: Poeciliidae). When tested with green sunfish (Lepomis cyanellus) predators, larger male G. affinis were found to have a higher number of escapes compared to smaller males. Smaller males were captured more often than larger males in groups of six and in both complex and simple habitat types. Large males, on average, were found to attempt more matings and spend a larger proportion of time near the female than smaller males. When trials with predators were compared to trials without predators, large males decreased mating attempts and time spent near the female although, small males increased time spent near females. Size of the predator did not affect these behaviors. Fry were reared under varying levels of predator exposure (visual, olfactory, both, or neither) and predation response was measured for each group at maturity. Results were not significant and were confounded by G. affinis size.

This thesis explores the feeding habits of sunfish and bluegill in Texas lakes. Data gathered for this study is aimed to aid conservation of these pan fish by making a contribution toward a greater life history understanding of each species.

Laboratory studies conducted at 5, 15, 25, and 35 C measured changes in gilling rates and oxygen consumption of green sunfish in response to exposure to bentonite clay suspensions. The tests indicate that gilling rates are not affected by bentonite clay suspensions below 2125 FTU at 5 C, 1012 FTU at 15 C, and 898 FTU at 25 C. At turbidity levels exceeding 1012 FTU at 15 C and 898 at 25 C, gilling rates increased 50-70%. Tests were inconclusive at 35 C. Oxygen consumption rates were found to be unaffected by turbid suspensions below 3500 FTU at all four temperatures. Evidence suggests that increased gilling rates under highly turbid conditions are a means of compensating for reduced respiratory efficiency and a strategy for maintaining a constant oxygen uptake. Evidence indicates that the cost of increased gilling rates is probably met by a reduction in activity.

Hydrilla (Hydrilla verticillata) is an invasive aquatic plant that grows quickly across shallow freshwater habitats. It is a problem for recreational users of lakes and landowners. Grass carp (Ctenopharynogodon idella) is an effective biological control agent that preferentially consumes and can control the spread of hydrilla. However, grass carp also will consume other vegetation, which influences aquatic communities via direct and indirect interactions that can change food and habitat availability and use by various species. Aquatic plants influence habitat and types of prey used by sunfish (Centrarchidae), which must also avoid their own predators. Prey use among sunfish species depends on density and taxonomic identity of both prey and vegetation. This was a one-year analysis of stomach contents from three common species of invertivorous sunfish: bluegill (Lepomis macrochirus), longear sunfish (Lepomis megalotis), and redear sunfish (Lepomis microlophus). Thirteen sampling stations were randomly selected using ArcGIS software. Percentage of water surface covered by vegetation was recorded at each station. A five-minute electrofishing sample was performed within the littoral zone early morning in late September. The stomach contents of all targeted sunfish (N=489) showed high percentages of diet overlap pre- (0.77-0.92) and post- (0.83-0.88) introduction of grass carp. Multivariate analysis showed total explained variation (15.5%) in sunfish diet composition was (P < 0.05) correlated significantly with sunfish species (6.67%), percent surface vegetation coverage (3.97%), and sampling periods pre- versus post-introduction of grass carp (2.13%). Prey-specific abundance showed that all sunfishes displayed a generalized feeding strategy in both sampling periods. Diets of each sunfish species showed differences in abundance (by volume) and occurrence (among individual fish) of prey items between sampling periods. Levin?s standardized index of diet breadth for all sunfish species decreased from pre- (0.12) to post-introduction (0.05). Results imply that vegetation control by grass carp influenced the diets and feeding strategies of three cohabitating sunfish species. These findings may help fisheries biologists to plan future management actions that influence assemblages of aquatic plants and macroinvertebrates, herbivorous fish, invertivorous prey-fish, and piscivorous game fish, to promote a healthy and balanced ecosystem for Lake Conroe stakeholders.