Survey of Nitrogen Isotopes of Lepomis macrochirus (Blue Gill) from Kentucky Lake Reservoir and Ledbetter Creek, Kentucky

Previous research has shown stable isotope ratios of nitrogen in fish and other animals may vary depending on their food source. Ecologists have had some success in determining feeding and trophic relationships within an ecosystem using stable isotopic ratios. In this study, nitrogen stable isotopic ratios were measured in populations of Lepomis macrochirus (Blue Gill) in Kentucky Lake Reservoir and in a small tributary, Ledbetter Creek, in western Kentucky. The nitrogen isotopic ratios between these populations were statistically different. Even though fish are able to migrate freely between the two environments, the isotopic results suggest that the Lepomis macrochirus in Ledbetter Creek were spending enough time feeding in that environment to alter their isotopic signature. These results may lead to a better understanding of how Lepomis macrochirus utilize both stream and reservoir environments.