Meeting Abstract

54.8  Tuesday, Jan. 6  Longitudinal Measurements of Caloric Intake and Body Condition in Atlantic Bottlenose Dolphins (T. truncatus) Across Three Thermal Environments DUNKIN, R.C.*; DAVIDSON, E.; ROBERTS, K.; HURLEY, W.; WILLIAMS, T.M.; U.C. Santa Cruz; U.C. Santa Cruz; Dolphin Conservation Center; Dolphin Conservation Center; U.C. Santa Cruz dunkin@biology.ucsc.edu

Water temperature has long been considered important in driving seasonal variation in body condition and caloric intake in cetaceans but this hypothesis has not been tested. In this study, body condition (body mass and blubber thickness) and daily caloric intake were examined longitudinally in Atlantic bottlenose dolphins housed in three thermal regimes: uniform warm (UW) (25.5 +/- 1.2 °C) (n=10), variable cold (VC) (16.8 +/- 2.0 °C) (n=10), and uniform moderate (UM) (19.8 +/- 0.2 °C) (n=2). UW animals had significantly lower mean body mass (p<0.0001, F=89.34) and blubber thickness (p<0.0001, F=39.25) compared to VC animals and there was no correlation between body mass (p=0.16, r²=0.23) or blubber thickness (p=0.22, r²=0.14) with water temperature. In contrast, VC animals had higher body mass and blubber thickness compared to UW animals and these factors were negatively correlated with water temperature (p=0.01, r²=0.5; p=0.004, r²=0.73 respectively). Mean daily caloric intake was not significantly different between UW and VC groups but was 35% lower in the UM group. Despite apparent water temperature-driven trends in body condition, animals in all thermal regimes had similar mean percent annual variability in body mass (UW=10.5, VC=11.28, UM=11.6%) and blubber thickness (UW=30.0, VC=30.4, UM=18.0%), suggesting water temperature may not be the primary driver of seasonal changes in body condition in these animals. Further investigation of animals in the uniform moderate group found that testosterone concentration was significantly correlated with body mass, indicating the potential importance of endocrine cues in driving seasonal body condition changes.