Weddell Seal Population Dynamics in Erebus Bay, Antarctica
The Demographic Consequences of Environmental Variability and Individual Heterogeneity in Life-history Tactics of a Long-lived Antarctic Marine Predator
A breeding population of Weddell seals, a prominent Antarctic high-level predator associated with fast ice, has been intensively studied in Erebus Bay at the southern extent of the Ross Sea since 1968. The long-term database, which includes data for more than 24,747 marked individuals, contains detailed population information that provides an excellent opportunity to study linkages between environmental conditions and demographic processes in the Antarctic. The Erebus Bay population of Weddell seals in Antarctica's Ross Sea is the most southerly breeding population of mammal in the world. The population's location is of special interest as the Ross Sea is one of the most productive areas of the Southern Ocean, and one of the few pristine marine environments remaining on the planet. The current project uses analysis and synthesis of long-term data for Weddell seals with multi-decadal data on temporal variation in climate, marine, and sea-ice conditions in the Ross Sea to evaluate a variety of hypotheses regarding effects of environmental variation on life-history evolution and population dynamics. Additional details regarding how physical drivers influence ecosystem dynamics from the bottom-up are being obtained by conducting field studies of how seal body mass, a surrogate for annual variation in marine food resources, varies among years and individuals. The study’s broad objectives are to evaluate (1) the factors that influence the lifespans and reproductive output of different individuals and (2) how temporal variation in the marine environment affects this long-lived mammal’s population dynamics. The study uses a combination of mark-recapture analysis of vital rates and population modeling to evaluate hypotheses regarding how fitness is affected by temporal environmental variation and collects longitudinal and cross-sectional data on body mass dynamics for mother-pup pairs to evaluate hypotheses relating environmental variation to changes in body mass and variation in body mass to effects on population dynamics. Jay Rotella, Robert Garrott, and Don Siniff are co-PI's on the study, which is funded by the National Science Foundation through the U.S. Antarctic Program. We have an award from the National Science Foundation to continue the work from August 1, 2017 through July of 2022.