Meeting Abstract
P1.94 Jan. 4 Ontogeny of reproductive thermoregulation in bottlenose dolphins Tursiops truncatus PABST, D.A.*; MCLELLAN, W.A.; ROMMEL, S.A.; SCOTT, M.; IRVINE, A.B.; SWEENEY, J.C.; STONE, R.; FRIEDLAENDER, A.S., Meagher E.M., Hohn A.A., Wells R.S.; UNC Wilmington; UNC Wilmington; UNC Wilmington; IATTC, CA; DBRI, Sarasota, FL; Dolphin Quest, CA; Dolphin Quest, CA; Duke Univ., NC; UNC Wilmington; NOAA, Beaufort, NC; Mote Mar. Lab, Sarasota, FL pabsta@uncw.edu
Male bottlenose dolphins possess a countercurrent heat exchanger (CCHE) that functions to regulate the temperature of their abdominal testes. We investigated CCHE development, by measuring deep body temperatures of wild dolphins from Sarasota Bay, FL. During health-monitoring events, dolphins were temporarily encircled, restrained, and given a veterinary exam. The CCHE flanks the colon; in captive dolphins temperatures measured within this region are cooler than those measured either cranially or caudally. We used a colonic probe to measure temperatures simultaneously at multiple positions. Over 11 years, we collected temperatures of 49 known-age males; 19 were multiply sampled. For most individuals, testis size (measured via ultrasound) and serum testosterone levels were also measured. Young males (2-9 yr) displayed uniformly high (37.1-37.3oC) temperatures along the length of their colons. In older males (10-43 yr) colonic temperatures were dependent upon position; temperatures measured at the CCHE (36.5�0.4oC) were on average 0.5oC, and maximally 1.7oC, cooler than those measured outside this region. Temperatures at the CCHE were lowest in males with testis length >20 cm, and serum testosterone levels >25 ng/mL. Longitudinal records from males that became sexually mature during the study also showed that temperatures at the CCHE decreased as testis size and testosterone levels increased. These results illustrate the importance of long-term field studies to enhancing our understanding of marine mammal biology. NOAA Permits 655,945,522-1569.
