Population structure and reproductive aspects of the freshwater turtle, Phrynops geoffroanus, inhabiting an urban river in southeastern Brazil

The population structure and reproductive aspects of P. geoffroanus (Chelid ae) in an urban river at Ribeirao Preto city, Sao Paulo state, southeastern Brazil, was studied by monthly captures and census from May 1997 to Octobe r 1998. A total of 247 turtles was sampled, 53 of them juveniles. Sex ratio was variable but never significantly different from 1 : 1. Captured turtle s varied throughout the months but census indicated higher activity of turt les in spring, positively correlated to high air temperatures and negativel y with rainfall. X-ray analysis of females revealed clutch sizes ranging be tween 8-20 and suggested that nesting occurred from February to August. Egg and clutch sizes were strongly correlated to female body size.