We conducted a 13-year study of a stream community of eight turtle species in a west-central Florida spring-run. A major shift towards smaller species is apparent when this study is compared to another made at the same locality six decades earlier. Over the duration of our study, sizes of Pseudemys concinna and P. floridana populations appeared to increase, though not to the levels of six decades previously. Average adult size for both species also increased significantly; these changes may reflect enhanced levels of protection. Growth rates of P. concinna and P. floridana vary throughout life and appear to be strongly seasonal. In light of constant water temperature and abundant food, we suggest that basking behaviors may limit growth, and the availability of basking sites may be critical to the health of the population. Data on sexual dimorphism in P. concinna and P. floridana are also presented.