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Research Interests
Dr. Worthy’s research interests relate to understanding the physiological ecology of marine mammals through the study of their energetics, growth, and nutrition. His research program integrates laboratory and field based investigations in an attempt to elucidate the capabilities of different species to withstand normal seasonal variation in their environment. He is also interested in integrating lab and field information to more appropriately define suitable criteria for the husbandry of animals in captivity. His program includes ongoing investigations into the life history and physiological ecology of manatees, cetaceans, and pinnipeds at study sites around the world. The main thrust of the research program centers around determining the energy requirements of marine mammals and how the availability and quality of food impacts their survival and growth. The Worthy lab is currently involved in studies investigating the thermoregulatory capabilities, water balance, feeding ecology, and free-ranging energetics of several important species of marine mammals using techniques such as indirect calorimetry, proximate composition analysis of prey, doubly-labeled water energetics, carbon/nitrogen isotope analysis, and fatty acid signature analysis, amongst others.
Selected Publications
Ortiz, R.M. and G.A.J. Worthy. 2006. Body composition and water turnover rates of bottle-fed West Indian manatee (Trichechus manatus) calves. Aquatic Mammals 32:41-45.
McFadden, K.M., G.A.J. Worthy, and T. Lacher. 2006. Photogrammetric estimates of size and mass in Hawaiian monk seals (Monachus schauinslandi). Aquatic Mammals 32:31-40.
Smith, H.S. and G.A.J. Worthy. 2006. Stratification and intra- and inter-specific differences in fatty acid composition in common dolphin (Delphinus sp.) blubber. Comparative Biochemistry and Physiology, Part B 143: 486-499.
Reich, K. and G.A.J. Worthy. 2006. An isotopic assessment of the feeding habits of free-ranging manatees. Marine Ecology Progress Series 322:303-309.
Fertl, D., A.J. Schiro, G.T. Regan, C.A. Beck, N. Adimey, L. Price-May, A. Amos, G.A.J. Worthy, and R. Crossland. 2005. Manatee occurrence in the northern Gulf of Mexico, west of Florida. Gulf and Caribbean Research 17:69-94.
Samuel, A.M. and G.A.J. Worthy. 2004. Variability in fatty acid composition of bottlenose dolphin (Tursiops truncatus) blubber as a function of body site, season, and reproductive status. Canadian Journal of Zoology 82:1933-1942.
Courbis, S.S. and G.A.J. Worthy. 2003. Opportunistic rather than incidental carnivory by Florida manatees (Trichechus manatus latirostris)? Aquatic Mammals 29:104-107.
Turner, J.P. and G.A.J. Worthy. 2003. Skull morphometry of bottlenose dolphins (Tursiops truncatus) from the Gulf of Mexico. Journal of Mammalogy 84:665-672.
Clark, L.S., D.F. Cowan, G.A.J. Worthy, and E.M. Haubold. 2002. An anatomical and pathological examination of the first recorded stranding of a Fraser’s dolphin (Lagenodelphis hosei) in the Northwestern Gulf of Mexico. Gulf of Mexico Science 2002:38-43.
Kurle, C.M. and G.A.J. Worthy. 2001. Stable isotope assessment of temporal and geographic differences in the feeding ecology of northern fur seals (Callorhinus ursinus) and their prey. Oecologia 126:254-265.
Worthy, G.A.J., T.A. Miculka, and S.D. Wright. 2000. Manatee response to cold: How cold is too cold? U.S. Fish and Wildlife Service. Florida Manatees and Warm Water: Proceedings of the Warm Water Workshop, Jupiter, FL. August 24-25, 1999.
Ortiz, R.M., D.S. MacKenzie, and G.A.J. Worthy. 2000. Thyroid hormone concentrations in captive and free-ranging West Indian manatees (Trichechus manatus). Journal of Experimental Biology 203: 3631-3637.
Ortiz, R.M. and G.A.J. Worthy. 2000. Effects of capture on adrenal steroid and vasopressin concentrations in free-ranging bottlenose dolphins (Tursiops truncatus). Comparative Biochemistry and Physiology Part A 125: 317-324.
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