Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

Edward O. Moll


In Illinois the River cooter, Pseudemys concinna, is an enigmatic endangered species. Even throughout its range, ecological studies on the River cooter are rare. During 1994 and 1995 I quantified the: growth rates and trends, population size and structure and dietary habits of a population from floodplain lake in Gallatin county, Illinois. Population estimation (Schnabel method) predicted 136 individuals at a density of 4.6 turtles/ha with a biomass of 3.6 Kg/ha. The sex ratio is slightly male biased (1:1.14). From back-calculated growth data, the von Bertalanffy growth model (Fabens' method) estimates males with a higher growth rate (k) and lower asymptotic length (a) (k = 0.00062, a = 219.8) than females (k = 0.00023, a = 307.6). Male growth slowed between 5 - 10 years and females between 15 - 23 years. Estimated daily growth regressed to plastral length revealed that growth of both sexes declined as size increased. Diets were predominantly filamentous algae of the genera Cladophora and Oedogonium (98%).