EDUCATION

1995 Ph.D. in Biology,  University of California, Santa Cruz, CA

1992  M.S. in Marine Sciences, University of California, Santa Cruz, CA

1987 B.S. in Applied Biology, Georgia Institute of Technology
 

EMPLOYMENT

Professor, Sonoma State University, 2008 - present.

Associate Professor, Sonoma State University, 2003-2008.

Assistant Professor. Sonoma State University, 2000-2003.

Assistant Research Ocean Scientist, University of California, Santa Cruz, 2001-2004.

Assistant Research Biologist. University of California, Santa Cruz, 1997-2001.

Postdoctoral Researcher. University of California, Santa Cruz, 1995-1997.

Research Interests: Comparative Physiology of Vertebrates; Physiological Ecology; Bioenergetics; Behavioral Ecology; Biology of Marine Mammals.

Research Program: My research is focused on the physiological and behavioral ecology of pinnipeds, seals and sea lions. My approach is to integrate physiology and behavior with the aim of addressing ecological theory. I am investigating physiological factors that impact the reproductive and foraging strategies used by marine predators. Much of my current research is focused on the physiology and behavior of northern elephant seals. These investigations include both field and laboratory studies. My field research focuses on studies of fasting physiology and reproduction when seals are hauled out on land to breed and diving physiology and foraging when animals are at sea.  My graduate students are exploring a wide variety of research areas including fasting physiology, foraging behavior and life history strategies. My lab has a strong collaborative relationship with the Institute of Marine Sciences at the University of California, Santa Cruz.

 

Recent Work

Fasting Physiology

This work is sponsored by NSF in collaboration with Dorian Houser and Cory Champagne from the National Marine Mammal Foundation and others. We investigate the metabolic adaptations that allow animals to go for weeks and months without food and water while undergoing costly activities like breeding. These studies use cutting edge metabolic tracer technologies and 'omics approaches to better understand the regulation of metabolism under the constraints of extreme fasting and include investigations of the endocrine regulation of fasting.

We've found that, unlike other animals, elephant seals maintain high rates of glucose production while fasting, mainly by recycling glucose carbon through the Cori Cycle in association with high rates of pyruvate and TCA cycle activity. These features allow elephant seals to provide fuel for glucose dependent tissues while maintaining high rates of fat oxidation without significant accumulation of ketoacids or use of protein from vital organs. These unusual features allow elephant seals to exhibit some of the highest sustained metabolic rates during fasting found in nature.

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Conservation Physiology

This work is sponsored by the Office of Naval Research in collaboration with Dorian Houser and Cory Champagne from the National Marine Mammal Foundation and others. We are investigating the endocrine stress responses of marine mammals and how they vary with foraging success, fasting and life-history stage. We are examining the interaction of stress responses with the reproductive and immune systems to better understand how stress has demographic impacts. Our ultimate goal is to better understand how organisms respond to climate variability and anthropogenic stressors and how these responses integrate with the stress associated with breeding. These investigations include the regulation of natality and breeding behavior by reproductive hormones and impacts of breeding on the immune system.

Foraging Ecology

This work is sponsored by NSF and many others. In collaboration with Dan Costa's lab at UCSC, my lab participates in the Tagging of Pacific Predators (TOPP) project. My interest is in the foraging strategies used by elephant seals and other marine predators and how these strategies vary with intrinsic state variables (like mass or age) and ocean climate. These studies also integrate with our conservation physiology research which seeks to understand how foraging effort and success influences reproductive effort, stress and health. These studies have also included work on the foraging behavior of several Antarctic pinnipeds and their responses to the rapidly changing climate.

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Oxidative Stress and Metabolic Syndrome

This work is sponsored by NIH in collaboration with Rudy Ortiz from UC, Merced. We are investigating the oxidative stress defenses of elephant seals that allow them to survive extended breath-holds and fasting without oxidative damage. We are also studying the adaptations that allow elephant seals to maintain diabetic-like features including insulin insensitivity without harmful effects. Our goal is to not only understand the physiological adaptations of the seals but also to inform our understanding of oxidative stress and metabolic pathologies in humans.

Diving Physiology and Development

This work is sponsored by NSF and NIH and seeks to understand the physiological adaptations that allow marine vertebrates to hold their breath for extended periods while exercising. These investigations include the development of diving physiology in elephant seals and its impact on the foraging strategies used by juveniles.

 

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