Meeting Abstract

139.5  Monday, Jan. 7  Seasonal variation in osmotic and metabolic status of diamondback terrapins HARDEN, L.A.*; WILLIARD, A.S.; Univ. of North Carolina, Wilmington lah4492@uncw.edu

Estuarine ectothermic vertebrates are faced with highly variable, tidally-influenced conditions, and many aspects of their biology reflect their ability to withstand and respond to the challenges posed by this environment. Diamondback terrapins Malaclemys terrapin experience broad fluctuations in temperature and water availability during the summer, and sub-zero temperatures and low oxygen availability while buried in the mud during the winter. The physiological adjustments necessary to maintain water and salt balance and the metabolic adjustments that accompany seasonal changes in activity and behavior have not been well-characterized for terrapins under field conditions. To investigate seasonal changes in terrapin osmotic and metabolic physiology, we obtained repeat blood samples from 10 radio-tagged female terrapins maintained in a semi-natural open-air salt marsh enclosure that encompassed their typical habitat and allowed them to experience natural shifts in temperature, salinity, and photoperiod. From September 2011 to May 2012 we measured monthly plasma concentrations of inorganic and organic osmolyte concentrations (Na+, K+, Cl-, uric acid, urea, glucose, total Ca2+, Mg2+), osmolality, and lactate. Monthly changes in blood parameters were analyzed using repeated measures ANOVA and Tukey’s post-hoc analysis with sample collection date, terrapin size, and environmental variables (e.g. rainfall, salinity, behavior, tide, and mud, water, and air temperatures) included as model covariates. This study will provide unprecedented insight into the physiological strategies of terrapins exposed to natural environmental fluctuations throughout the year and provide baseline blood composition data for diamondback terrapins.