Seals

Exploring the Vulnerability of Southern Ocean Seals to Climate Change

Previous research has documented the former existence of a large southern elephant seal (Mirounga leonina) breeding colony on the Victoria Land Coast of Antarctica, where conditions are too icy for them today. Radiocarbon dating of well-preserved mummified seal remains suggests that the colony was present from ~8000 to ~400 years ago. Analysis of ancient DNA from these samples shows that seals rapidly colonized the area once the habitat was released during a relatively warm period, but that there was a precipitous population decline beginning about 1000 years ago, coincident with a period of cooling and a return to icy conditions.

In collaboration with Rus Hoelzel, Paul Koch, Brenda Hall, and Dan Costa, we are collecting more data from this time period for southern elephant seals, as well as Weddell (Leptonychotes weddellii), crabeater (Lobodon carcinophagus), and leopard (Hydryrga leptonyx) seals, which differ in their habitat requirements for ice. By combining next-generation sequencing of ancient DNA, stable isotopes, radiocarbon dating, and paleoclimatic data for these four species we are gaining a better understanding of their sensitivity and responses – in terms of both demography and foraging ecology – to major shifts in the Holocene climate over the last several thousand years.

Seal mummy, photo by Kristan Hutchison