Wednesday :: Apr 30, 2008

Thin Ice


by Turkana

Science Daily:

The loss of sea ice due to climate change could spell disaster for polar bears and other Arctic marine mammals. Sea ice is the common habitat feature uniting these unique and diverse Arctic inhabitants. Sea ice serves as a platform for resting and reproduction, influences the distribution of food sources, and provides a refuge from predators. The loss of sea ice poses a particularly severe threat to Arctic species, such as the hooded seal, whose natural history is closely tied to, and depends on, sea ice.

The Arctic undergoes dramatic seasonal transformation. Arctic marine mammals appear to be well adapted to the extremes and variability of this environment, having survived past periods of extended warming and cooling.

"However, the rate and scale of current climate change are expected to distinguish current circumstances from those of the past several millennia. These new conditions present unique challenges to the well-being of Arctic marine mammals," says Sue Moore (NOAA/Alaska Fisheries Science Center).

The April Special Issue of Ecological Applications examines such potential effects, puts them in historical context, and describes possible conservation measures to mitigate them. The assessment reflects the latest thinking of experts representing multiple scientific disciplines.

Climate change will pose a variety of threats to marine mammals. For some, such as polar bears, it is likely to reduce the availability of their prey, requiring them to seek alternate food. Authors Bodil Bluhm and Rolf Gradinger (University of Alaska, Fairbanks) note that while some Arctic marine mammal species may be capable of adjusting to changing food availability, others may be handicapped by their very specific food requirements and hunting techniques. Species such as the walrus and polar bear fall under this category, while the beluga whale and bearded seal are among those who are more opportunistic in their eating habits and therefore potentially less vulnerable, at least in this regard.

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