THERMAL SELECTION AND TEMPERATURE PREFERENCE OF THE AQUATIC SALAMANDER, AMPHIUMA TRIDACTYLUM

Abstract.–The thermal biology of obligatory aquatic salamanders (e.g., Amphiumidae) is largely unknown. We therefore investigated thermal selection and temperature preference in the fully aquatic salamander, Amphiuma tridactylum. In a laboratory thermal gradient, A. tridactylum selected a mean water temperature of 26.3 ° C (SE = 0.29, n = 15, range = 24.3 to 27.9). We also investigated potential influences of body size on thermal selection and found no significant relationship between thermal selection and snout-vent length or body mass. The preferred selected temperature is higher than the preferred temperatures reported for other obligatory aquatic salamanders, a difference that may reflect A. tridactylum’s southern distribution in the U.S. We collected water and air temperatures at a site representative of A. tridactylum habitat to estimate when preferred temperature may be seasonally available in the field. Maximum water temperatures exceeded 25 ° C and thus would support activity of A. tridactylum near its preferred temperature during May to August. Key Words.—Amphibian; Amphiuma; temperature; thermoregulation; preferred body temperatur