PHYSICAL EXAMINATION OF CENTRAL AMERICAN RIVER TURTLE, Dermatemys mawii, IN CAPTIVITY IN TABASCO, MEXICO

The Central American river turtle, Dermatemys is a critically endangered species and wild populations have drastically decreased. Therefore, groups of turtles are bred in captivity in order to improve reproduction for sustainable use and for programs aiming for their release in their natural habitat. However, captive wild turtles seem to be in poor condition. For this reason, the objectives of this study were to assess the physical condition of 90 river turtles in captivity on three farms in the state of Tabasco, Mexico, to determine water quality variables in the ponds where the turtles are kept, and to identify the methods with which turtles are managed. Personnel in charge of their care were interviewed, and a group of 30 turtles was examined on each farm. External appearance was assessed in detail and the physical condition was determined for each group as a frequency variable. Body measurements of turtles at each site were compared with those at the other sites using a Kruskal-Wallis analysis. In each group, the ratio weight/size was analyzed with an ANOVA (p <= 0.05). The prevalence of external physical conditions was contrasted among the farms. Water quality variables were compared with reference values. Turtles of the three farms exhibited frequent lesions on the carapace and plastron as well as signs of dehydration. Water quality of the ponds was poor: low levels of transparency (<0.5 m), excessive concentrations of ammonia nitrogen (>0.05 mg L-1), high values of BOD5 (>20 mg L-1) and total suspended solids (>30 mg L-1), and high quantities of coliform bacteria (>1000 MPN 100 mL(-1)). Analysis of the results suggests that physical lesions are related to inadequately managed conditions such as excessive turtle population density and lack of pond water treatment.