Meeting Abstract
Recent years have shown a rise in mean global temperatures and a shift in the geographical distribution of ectothermic animals. Fish have evolved physiologically to live within a specific range of environmental variation and existence outside of that range can be stressful or fatal. This study investigates physiological processes limiting thermal tolerance, specifically how changes in water temperature affect the swimming muscle mechanics and energetics in largemouth bass (Micropterus salmoides) and bluegill sunfish (Lepomis macrochirus). We focus on the impact of temperature change at the muscle level in these two species and the capacity to adapt to rapid changes in the environment. Fish were housed at different temperatures (16°C and 20°C) and then tested in a recirculating flow tank 2BL/sec at the opposite temperature. Mass corrected oxygen consumption (MO2) differed with temperature, with the fish swam at 20°C group having a higher metabolic rate for both species. ANOVA showed that MO2 was dependent on both species and temperature. Active metabolic rate is 1.2 (in 20°C) and 1.3 (in 16°C) fold higher in largemouth bass than in bluegill sunfish. The Q10 calculated at 2 BL/s was 1.43 for bluegill sunfish and 1.57 for largemouth bass which is less than the normal Q10 reported for Perciformes of 1.98. At higher temperatures, both species have increased metabolic rates, which will leave fewer resources available for growth and reproduction. Additionally, at higher temperatures oxygen concentrations also tend to be lower, thus increasing the possibility of stress and oxygen being a physiological limiting factor. Freshwater habitats are changing faster than marine habitats and understanding energy requirements of these species will help us improve conservation efforts.
