Weddell Seal Population Dynamics in Erebus Bay, Antarctica
The Consequences Of Maternal Effects And Environmental Conditions On Offspring Success
In An Antarctic 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 information on the populations and individual animals that provide excellent opportunities 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 study population is ideal for increasing understanding of population dynamics of long-lived species because population members have strong site fidelity, are readily approached and tagged during the pup-rearing period, and have been intensively studied for 40 years.
Recent analyses have found that differences in maternal identity, age, body reserves, and reproductive experience are directly linked to variation in offspring phenotype through maternal effects. Thus, pups vary widely with respect to birth dates, body mass, and the amount of time they spend in the water before weaning. Further variation results because young born in different years can experience very different environmental conditions. Our current study has the broad objective of evaluating the importance of diverse sources of variation in pup characteristics to demographic performance. The study will (1) record birth dates, body mass metrics, and time spent in the water for multiple birth cohorts of pups born to known-age mothers; (2) conduct mark-recapture studies to monitor fates of the pups through the age of first reproduction; and (3) use mark-recapture analyses to evaluate hypotheses about how variation in birth dates, pup mass, time spent in the water by pups, and environmental conditions relate to variation in early-life survival and recruitment for those pups. The proposed study will also continue the long-term monitoring of the population and maintain the long-term database.
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. Our current award from the National Science Foundation is for the period August 1, 2017 through July of 2022.