Kimberly Goetz at McMurdo Station, Antarctica--Two groups of researchers led by Dan Costa (at UC Santa Cruz) and Jennifer Burns (at the University of Alaska) are traveling down to Antarctica to study Weddell seals in one of the most uninhabited places on Earth.  Very little is known about Weddell seals and their ocean environment because it is very difficult and expensive to conduct studies in this harsh environment.  We will use advanced tagging technology to study both the winter behavior and the environment of the Weddell seal over the next three years.

During the winter, the weather in Antarctica is inhospitable – months of solid darkness, an unimaginable quantity of ice that physically doubles the size of the continent, and temperatures that often plummet 100 below zero.  Despite such conditions, climate change is occurring more rapidly here than most places on our planet.  However, our ability to detect, measure, and interpret climate change in Antarctica’s Ross Sea is especially difficult, and often impossible, due to limitations in accessing the ocean below the sea ice.

Given the lack of data on both Weddell seal ecology and the oceanography of the Ross Sea during winter, Weddell seals outfitted with Conductivity Temperature Depth - Satellite Relayed Data Loggers (CTD-SRDL) tags and acting as autonomous oceanographic samplers are well poised to provide just this sort of critical data.  Weddell seals diving during winter months can sample conditions under pack ice, dive deeply enough to collect data from the whole water column, and cover a large geographic area. The first aim of this research project is to collect new information on seal diving and movement patterns and to develop models of Weddell seal habitat use that incorporate information on physical habitat features thought to influence prey availability. The second major goal is to merge the temperature-salinity depth data acquired from tags on Weddell seals with physical oceanographic data to provide a better understanding of the physical oceanography of the Ross Sea as a basis for understanding climate change effects.

In order to monitor overwinter dive behaviors and oceanography, in each year of the study 22 adult Weddell seals will be captured in late January and early February after they have molted.  In October / November, previously deployed satellite tags will be recovered if possible. Tag recovery will be facilitated by deploying VHF tags on the seals and also using recent positions from the ARGOS satellite transmissions with aerial searches for VHF signals in the subsequent spring.

Fieldwork will be carried out in two locations, McMurdo Sound and Terra Nova Bay, to broaden coverage of the Ross Sea habitat within the Southern Ocean.  Since tags will be deployed in late January and February after the animals have dispersed from the breeding colonies and molted, the exact locations will vary with sea ice conditions and animal behavior.

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