Habitat Use by the Texas River Cooter (Pseudemys Texana) in Spring Lake, Hays County, Texas

Abstract

Little information is available in the literature reporting underwater habitat use by freshwater turtles. Most investigators have focused on terrestrial and water surface habitat associations. Therefore, a major component of the habitat remains an unknown for these animals. Underwater habitat use by the Texas river cooter (Pseudemys texana) was studied in Spring Lake, Hays County, Texas. The lake is composed of a lotic springfed portion (main lake) and a lentic slough. The spring-fed portion has a constant temperature (22 + 2°C) and a vigorous flow (average annual flow = 166.0 cfs). Hourlong dives were conducted in the main lake approximately twice a week for a year in order to detect variations in seasonal habitat use. Data recorded for each observed individual included its sex, behavior, habitat, and depth within the water column. Data were analyzed using a three factor ANOVA. Factors all had p-values less than 0.01, indicating differences in the number of turtles per dive across months, between depths, between habitats, and between sexes. The number of P. texana observed was higher in the winter and spring, with the greatest numbers occurring January through March. Turtles were found more often in shallow water (less than 1 m) during summer and fall, with an increase in the use of the 1-3 m and > 3 m depths during the winter and spring months. Differences in habitat correlated with differences in depth. There were also differences between the sexes, with males recorded more often than females, and an increase in the males from January to May. Further dive surveys, including mid-day and night, need to be conducted on P. texana in order to have a better understanding of the three dimensional habitat that the turtles are utilizing. Future studies on the dive profiles of the other turtles in Spring Lake will also give better insight into the community ecology that is found there.