Abstract
Microhabitat selection, physiology, and body size all at-fed thermal biology of ectotherms. In this study, I determined the influence of these variables on the thermal biology of a large aquatic ectotherm, Macroclemys temminckii. I tested the hypothesis that M. temminckii selected microhabitats from those available using radio telemetry and by comparing occupied microhabitats to available microhabitats. Results indicated M. temminckii selected relatively warm and structurally complex microhabitats close to shore. Body size and physiology also affected thermal biology of M. temminckii. Using miniature temperature data loggers, I procured continuous records of ambient and body temperatures for four turtles. I found, in the field, M. temminckii heated faster than they cooled but equilibrated to ambient temperature when inactive. Cooling trials performed in the laboratory indicated larger turtles equilibrated more slowly to ambient temperatures than smaller turtles. These results indicated physiology and size of aquatic ectotherms affected body temperature transiently and prolonged periods when turtles' body temperatures remained different from ambient temperature. However, inactive turtles eventually equilibrated to ambient temperatures. I concluded that selection of appropriate microhabitats was the only method for aquatic turtles to control body temperature for longer time periods, and physiology and body size interacted to influence the amount of time body temperature dithered from ambient temperature.
Nelson, Ryan Edward (1999). Habitat selection and thermal biology of a large aquatic ectotherm, the alligator snapping turtle (Macroclemys temminckii). Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1999 -THESIS -N46.