As long-lived animals, marine mammals must be capable of accommodating broad variations in food resources over large spatial and temporal scales. While this is true of all marine mammals, variation in the physical and biological environmental is particularly profound in the Southern Ocean. A basic understanding of the foraging behavior and habitat utilization of pelagic predators requires ... knowledge of this spatial and temporal variation, coupled with information of how they respond to these changes. Current understanding of these associations is primarily limited to population level studies where animal abundance has been correlated with oceanography. Although these studies are informative, they cannot provide insights into the strategies employed by individual animals nor can they provide insights into the spatial or temporal course of these interactions. Recent technological advances in instrumentation make it possible to extend an understanding beyond the simple linkage of prey and predator distributions with environmental features. The key to understanding the processes that lead to high predator abundance is the identification of the specific foraging behaviors associated with different features of the water column. This study will accomplish these objectives by combining accurate positional data, measures of diving and foraging behavior, animal-derived water-column temperature and salinity data, and available oceanographic data. This project will examine the foraging behavior and habitat utilization of two species of contrasting foraging ecology, the southern elephant seal, Mirounga leonina, and the crabeater seal, Lobodon carcinophagus in the Western Antarctic Peninsula, a region of strong environmental gradients. Although these two species are phylogenetically related, they utilize substantially different but adjacent habitat types. Southern elephant seals are predominantly pelagic, moving throughout the southern ocean, venturing occasionally into the seasonal pack ice whereas crabeater seals range throughout the seasonal pack ice, venturing occasionally into open water. The relationship of specific foraging behaviors and animal movement patterns to oceanographic and bathymetric features develop and test models of the importance of these features in defining habitat use will be determined along with a comparison of how individuals of each species respond to annual variability in the marine environment. The physical oceanography of the Southern Ocean is inherently complex as are the biological processes that are intrinsically linked to oceanographic processes. Significant resources are currently being directed toward developing mathematical models of physical oceanographic processes with the goals of better understanding the role that the Southern Ocean plays in global climate processes, predicting the responses of ocean and global scale processes to climate change, and understanding the linkages between physical and biological oceanographic processes. These efforts have been limited by the scarcity of oceanographic data in the region, especially at high latitudes in the winter months. This study will provide new and significant oceanographic data on temperature and salinity profiles in to further the understanding of the dynamics of the upper water column of west Antarctic Peninsula continental shelf waters. Outreach activities include website development and an association with a marine education program at the Monterrey Bay Aquarium Research Institute.
Because of extreme isolation of the Antarctic continent since the Early Oligocene, one expects a unique invertebrate benthic fauna with a high degree of endemism. Yet some invertebrate taxa that constitute important ecological components of sedimentary benthic communities include more than 40 percent non-endemic species (e.g., benthic polychaetes). To account for non-endemic species, intermittent ... genetic exchange must occur between Antarctic and other (e.g. South American) populations. The most likely mechanism for such gene flow, at least for in-faunal and mobile macrobenthos, is dispersal of planktonic larvae across the sub- Antarctic and Antarctic polar fronts. To test for larval dispersal as a mechanism of maintaining genetic continuity across polar fronts, the scientists propose to (1) take plankton samples along transects across Drake passage during both the austral summer and winter seasons while concurrently collecting the appropriate hydrographic data. Such data will help elucidate the hydrographic mechanisms that allow dispersal across Drake Passage. Using a molecular phylogenetic approach, they will (2) compare seemingly identical adult forms from Antarctic and South America continents to identify genetic breaks, historical gene flow, and control for the presence of cryptic species. (3) Similar molecular tools will be used to relate planktonic larvae to their adult forms. Through this procedure, they propose to link the larval forms respectively to their Antarctic or South America origins. The proposed work builds on previous research that provides the basis for this effort to develop a synthetic understanding of historical gene flow and present day dispersal mechanism in South American/Drake Passage/Antarctic Peninsular region. Furthermore, this work represents one of the first attempts to examine recent gene flow in Antarctic benthic invertebrates. Graduate students and a postdoctoral fellow will be trained during this research.