TURTLE ASSEMBLAGE IN A HIGHLY ALTERED SPRING SYSTEM: COMAL SPRINGS, TEXAS

Comal Springs in New Braunfels, Texas, is the largest freshwater spring west of the Mississippi. The spring is within the Edwards Plateau Savanna Ecoregion of the Southeastern United States Turtle Priority Area. Comal Springs is an environmentally sensitive spring run situated in an urbanized area visited by >1,000,000 people each year and thus may be impacted by recreational use. We assessed baseline population levels for the turtle assemblage residing in Comal Springs. We captured 4,238 turtles from February 2012 to February 2015 across 12 separate sampling sessions. Captures and individually marked turtles (in parentheses) included 2,322 (1,715) Sternotherus odoratus, 1,558 (793) Pseudemys texana, 329 (141) Trachemys scripta, and 29 (19) Chelydra serpentina serpentina. We report population densities of 1,690/ha (S. odoratus), 230/ha (P. texana), 43/ha (T. scripta), and 5/ha (C. s. serpentina). We estimated biomass for each species and sex, resulting in a total biomass estimate of 5,309.6 kg or 632.1 kg/ha. Sex ratios for P. texana and T. scripta were 1:1, whereas the sex ratio for S. odoratus was 2.26:1, male biased. Our results suggest that a robust turtle assemblage inhabits Comal Springs, similar in richness to the more well-studied freshwater spring habitats in Florida. Future studies or management actions can use our data as a benchmark as the results of few turtle surveys in Texas have been published.