Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Increasing Sea Ice in Baffin Bay and Adjacent Waters Threatens Top Marine Predators
Mads Peter Heide-Joergensen1, Kristin L Laidre2
1Greenland Institute of Natural Resources, c/o National Marine Mammal Laboratory, AFSC-NOAA, 7600 Sand Point Way NE, Seattle, WA, 98115, USA, Phone 206-526-6680, Fax 206-526-6615, MadsPeter.Heide-Joergensen@noaa.gov
2School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98195, USA, Phone 206-526-6866, Fax 206-526-6615, Kristin.Laidre@noaa.gov
Global climate change is expected to have severe impacts on Arctic ecosystems, yet predictions of ecosystem effects are complicated by region-specific patterns and non-uniform trends. Twenty-four open water overwintering areas (or “microhabitats”) were identified for 8 indicator sea bird and marine mammal species in the eastern Canadian high Arctic and West Greenland. Localized trends in the available fraction of open water were examined in each region, based on approximate sea ice concentrations within the ice pack from microwave SSMR/SSMI passive brightness temperatures gridded at a 25 sq km resolution between March 1978-2001. Decreasing trends in the fraction of open water in focal areas were identified in northern and central Baffin Bay and coastal West Greenland, following well with regional cooling and increased sea ice in the West Greenland ecosystem. Trends in localized habitats were unclear in Hudson Bay and Foxe Basin regions. The species-specific biological importance of each microhabitat was elucidated based on occurrence, distribution and abundance of sea birds and marine mammals, and potential population and life history consequences of sea ice trends were identified. Decreasing open water is predicted to differentially impact foraging efficiency, oxygen and prey availability of those predators that rely on these areas during the winter. Of the indicator species, the narwhal (Monodon monoceros) is among the most vulnerable due to high winter site fidelity in Baffin Bay, where the entire population (>50,000 individuals) occupies dense pack ice up for 6 months of the year with less than 3% open water. Decreasing trends in the area of open water were found on the two primary narwhal wintering grounds (25,000 km2), significantly so in northern Baffin Bay (-0.04% per year, SE 0.02). In combination with this trend, interannual variability in the fraction of open water was observed to be significantly increasing at +0.03% per year (SE 0.006). The limited number of leads and cracks available to narwhals during the winter period, in combination with decreasing trends in open water and increasing trends in annual variability, leaves little doubt that their high site fidelity makes them exceedingly vulnerable to changes in Arctic sea ice conditions.
Abstract Categories: Biological Feedbacks
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