The Interactions of Environmental Variability, Life History Traits, and Demography in an Apex Antarctic Predator

Montana State University, Bozeman MT

Investigators

Abstract

The complex effects of environmental variation cascade through trophic levels and are integrated by top predators. Thus, studies of predator population dynamics should be useful for integrating and understanding linkages between physical and biological ecosystem components. A breeding population of Weddell seals, a prominent Antarctic apex predator associated with fast ice, has been intensively studied in Erebus Bay at the southern extent of the Ross Sea since 1968. The proposed research couples synthesis and modeling 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. The research, in part, will rigorously 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 will be 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 will (1) use a combination of mark-recapture analysis of vital rates and matrix population modeling to evaluate hypotheses regarding how fitness is affected by temporal environmental variation and (2) collect longitudinal and cross-sectional data on body mass dynamics for mother-pup pairs to evaluate relationships between environmental variation, body mass, and population dynamics. Intellectual Merit - Theory predicts that life histories should evolve to minimize effects of environmental variation on fitness by favoring traits that buffer important vital rates from temporal variation. The proposed research will test this prediction using methods that consider covariation among vital rates and the possibilities of density-dependence and an open-population structure. The proposed work on body-mass dynamics will increase our understanding of linkages between physical and biological processes, and allow more informed prediction of the impacts of future climate change on marine mammal populations. Broader Impacts -.This study is uniquely positioned to provide data on how a marine mammal has been, and will be, affected by environmental variation, including massive icebergs, which are expected to be more prevalent with a warming climate. Continuation of the database will aid diverse research teams, and be valuable for interpreting the influence of developing commercial fisheries in the Ross Sea,. This aspect of the research will contribute to the mission of the Convention for the Conservation of Antarctic Marine Living Resources. The study also will provide professional training to young researchers, and the data and methods will be used in lecture and laboratory exercises in several graduate and undergraduate courses. Researchers will communicate from the field with K-12 students at ~50 schools throughout the U.S. and follow-up with in-school visits at a subset of schools. Opportunities to experience field research will be made available to interested citizen scientists, teachers, students, and artists.