Ecology & Evolutionary Biology
Earth & Marine Sciences A308
Phone: 831.459.5358
Fax: 831.459.5353
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CHARLES LEO ORTIZ Professor Emeritus of EE Biology B.A., California State University, Northridge Ph.D., University of California, Los Angeles ORTIZ LAB

Physical Sciences Building 415 University of California Santa Cruz, CA 95064 phone 831.459.2247 fax 831.459.5353 ortiz@biology.ucsc.edu office hours

Physiology of Marine Mammals

Seals, whales, and other marine mammals have fascinated man throughout history, but it is only recently that science has begun to examine the evolutionary, behavioral, and physiological details of their life histories. Each winter, a large population of elephant seals breeds at Año Nuevo near Santa Cruz. This event provides a unique opportunity for studying these animals from a broad biological perspective, ranging from behavior to population genetics. Our work on fasting comprises but one part of a highly integrated and cooperative research enterprise that includes Drs. B. J. LeBoeuf, D. P. Costa and T.T. Williams plus a large number of post-doctoral researchers, graduate students, and undergraduates.

For more than a decade, our research has focused on the physiology of the northern elephant seal, Mirounga angustirostris, during its annual return to land to conduct the terrestrially obligate functions of reproduction and molting. During these periods on land, which may exceed three months per year, animals fast entirely and have no access to fresh water. A major goal of our research is to understand the physiological mechanisms that underlie these remarkable fasts, not only as they relate to the life history of these, the largest of the pinnipeds, but also as they provide a unique opportunity to study mammalian physiological homeostasis under extreme but natural conditions. Early studies included measuring water and energy metabolism during long-term starvation, amino acid conservation, fat metabolism, changes in milk composition during lactation, and the development of nursing and weaned pups. The success of these earlier studies encouraged us to expand our research, which now includes looking for other ways these animals conserve water, how they hormonally regulate metabolism and reproduction, and how they handle nitrogen and other waste metabolites. We are firmly convinced that the multi-disciplinary approach we have taken in studying the biology of elephant seals will provide a more detailed understanding not only of the Pinnipedia but of marine mammals in general.

Selected Publications

Ortiz, R.M., Wade, C.E., Costa, D.P., and Ortiz, C.L. 2002. Renal effects of fresh water-induced hypo-osmolality in a marine adapted seal. Journal of Comparative Physiology B 172:297-307.

Ortiz, R.M., Wade, C.E., Costa, D.P. and Ortiz, C.L. 2002. Renal responses to plasma volume expansion and hyperosmolality in fasting seal pups. American Journal of Physiology (Comp. Reg. Integrative Physiol.) 282: R805-R817.

Gallo, J.P., Suarez, Gracida, G., Cabrrea-Santiago, H., Coria-Galindo, E., Egido-Villareal, J., and Ortiz, C.L. Status of Beavers (Castor canadensis) in Rio Bavispe, Sonora, Mexico. 2002. The Southwest Naturalist 17(3)500-504.

Ortiz, R.M., Noren, D.P., Litz, B. and Ortiz, C.L. 2001. A new perspective on adiposity in a naturally obese mammal. American Journal of Physiology (Endocrinol. Metab.) 281:E1347-E1351.

Ortiz, R.M., Wade, C.E., and Ortiz, C.L. 2000. Prolonged fasting increases the response of the renin-angiotensis-aldosterone system, but not the vasopressin levels, in postweaned northern elephant seal pups. General and Comparative Endocrinology 119:217-223.

Fernandez-Juricic, E., Campagna, C., Enriquez, V. and Ortiz, C.L. 1999. Vocal communication and individual varition in breeding South American seal lions. Behaviour. 136:495-517.

Kohin, S., Williams, T.M. and Ortiz, C.L. 1999. Effects of hypoxia and hypercapnia on aerobic metabolic processes in northern elephant seal pups. Respiration Physiology. 117:59-72.

King, D.P., Sanders, J.L., Nomura, C.T., Stoddard, R.A., Evans, S.W. and Ortiz, C.L. 1998. Ontogeny of humoral immunity in northern elephant seal (Mirounga angustirostris) neonates. Comp. Biochem. and Physiology, Part b 121:363:68.

Werner, R., Ana Luisa Figueroa-Carranza, A.L., Lavigne, D.M. and C. Leo Ortiz, C.L. 1996. Composition and energy content of milk from southern sea lions (Otaria flavescens). Marine Mammal Science 12(2):313-317

Ortiz, R., Adams, S., Costa, D.P. and Ortiz, C.L. 1996. Plasma vasopressin levels and water conservation in fasting, postweaned Northern elephant seal pups (Mirounga angustirostris). Marine Mammal Science 12(1):99-106.