Research

Our laboratory is interested in the adaptations of marine organisms to life in the marine environment, especially the movements, foraging ecology and energetics of pinnipeds and seabirds. Our research contributes to two major international initiatives: Tagging of Pacific Pelagics and Southern Ocean GLOBEC.

Research Areas

Animal movement and behavior

We study the diving, foraging, and searching behavior of pinnipeds, seabirds, and tuna, in order to determine areas and characteristics of the marine environment that are important for prey acquisition, and ultimately, the reproductive success of these animals. We investigate individual and population-level variability of diving and movement behavior of male and female California sea lions in the California Current system and Galapagos Islands, as well as develop methods for measuring prey consumption of free-ranging sea lions. We also look at how individual variation and intrinsic factors (sex and age) affect foraging behavior and movement patterns of elephant seals and albatrosses, and their association with differing oceanographic features.

In a number of species, we examine in-depth the relationship between animal behavior and habitat use: specifically, what oceanographic features are used to a high degree by animals exhibiting foraging behaviors. This research is being conducted in northern and southern elephant seals, California sea lions, southern sea lions, Laysan and black-footed albatrosses, sooty and pink-footed shearwaters, and Atlantic bluefin tuna. Collectively, these data will be used to investigate multi-species assemblages in the ocean environment, the role of seamounts in aggregating large marine predators, and the identification of oceanic “hot spots.”

 

Animals as ocean sensors

Our lab conducts research on elephant seals and sea lions in order to investigate the implementation of these large marine predators as ocean sensors. By equipping these animals with time depth recorders, satellite tracking devices, temperature, light, and conductivity sensors, we can use these animals as platforms from which to gather in-depth oceanographic data otherwise difficult to collect. These data are being collected from northern elephant seals departing from Año Nuevo State Reserve, California sea lions foraging in the California Current system, and southern elephant seals breeding in the South Shetland Islands, Antarctica. Data collected from these animals will be useful in building oceanographic models in the Pacific, as well as providing a much clearer picture of how a large top marine predator like the elephant seal uses the ocean environment to find food.

 

Physiological ecology

Our lab explores the mechanisms animals employ to carry out their functions under actual environmental conditions. By investigating the interaction between physiology, behavior, and reproductive ecology of free-ranging marine mammals and birds we can elucidate the environmental factors influencing their distribution and abundance. Energetic expenditure is a central theme in these investigations; we are particularly interested in how animals acquire and allocate energy toward various activities. Currently, we are examining diving physiology and oxygen consumption in both California sea lions and northern elephant seals, fasting physiology of elephant seals, age-related maternal investment in Antarctic fur seals, and foraging energetics and resource allocation in four species of albatrosses.

 

Population consequences of disturbance

Under the United States Marine Mammal Protection Act, U.S. companies and citizens are forbidden to “take” a marine mammal. Take is defined as “to harass, hunt, capture, or kill, or attempt to harass, hunt, capture, or kill any marine mammal” (16 U.S.C. 1362). Such a definition means that all regulation of marine mammals occurs on an animal-by-animal basis, although the spirit of the law is to maintain marine mammal populations in perpetuity. So, what are the population consequences if an animal is disturbed, meaning the animal exhibits some change in physiology or behavior as a response to human interactions? When an interaction with humans does not cause direct mortality or loss of offspring, what happens to a population when some individuals are repeatedly disturbed over a long period of time? What happens when the entire population is disturbed a little? We have begun to address these questions by quantifying the transfer functions between potential human interactions and the probability individuals will be exposed to that interaction, the probability and intensity to which individuals will respond to interactions, how those physiological and behavioral responses will in the long run affect an animal’s health, and how changes in health affect survival and reproduction. This type of analysis requires data on physiology, behavior, reproduction, and survival. We have been utilizing data collected on northern elephant seals, California sea lions, bottlenose dolphins, gray whales, humpback whales, and blue whales.

 

Research Programs

Tagging of Pacific Pelagics

The Tagging of Pacific Pelagics (TOPP) research project explores the Pacific, using a carefully selected group of animals from its ecosystems to gather data about their world. As apilot program of the Census of Marine Life (COML), an international endeavor to determine what lives, has lived and will live in the world’s ocean, TOPP scientists are tagging individuals from 21 species of marine predators in the Eastern Pacific to obtain an “organism’s eye” view of their world. Jointly run by Stanford’s Hopkins Marine Lab, the University of California, Santa Cruz’s Long Marine Laboratory, NOAA’s Pacific Fisheries Ecosystems Lab, and the Monterey Bay Aquarium, TOPP also includes team members from several countries.

TOPP tests the effectiveness of using animals to gather biological and environmental data, tracking the individuals’ movements while recording valuable oceanographic and ecosystem data from their immediate surroundings. TOPP tags have collected and returned massive quantities of this data, helping scientists build a rich picture of key travel corridors and “ocean hot spots,” or gathering zones where animals feed and breed.

 

Southern Ocean GLOBEC

The goal of Southern Ocean GLOBEC is to elucidate shelf circulation processes and their effect on sea ice formation, Antarctic krill distributions and the factors that affect krill survivorship and availability to higher trophic levels. Our role in Southern Ocean GLOBEC is to relate the behavior of crabeater seals to the distribution and abundance of krill and to examine those factors, which contribute to krill being the optimal prey item.

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