[Sea Ice as a Factor in Seabird Distribution and Ecology in the Beaufort, Chukchi, and Bering Seas]
by
George J. Divoky[1]
U.S. Fish and Wildlife Service
Fairbanks, Alaska
Abstract
Arctic sea ice has a variety of effects on seabirds. Although the decrease in surface area available for feeding and roosting is probably the major restrictive effect, also important are productivity of water covered by ice and the reduced prey abundance in nearshore areas due to ice scour. The most important benefit that sea ice provides to seabirds is the plankton bloom that occurs in the ice in the spring. In the Beaufort and Chukchi seas this bloom supports an under-ice fauna that is an important food source for seabirds.
Sea ice is a major factor in the distribution and ecology of many of the birds treated in this symposium. Sea ice is defined here as ice formed by the freezing of seawater and includes both free floating pack ice and the more stable shorefast ice. Since icebergs are composed of ice of land origin, they are not discussed.
Before discussing the specific relationship of birds and sea ice in the Beaufort, Chukchi, and Bering seas, I list the general effects that arctic ice can have on seabirds. For purposes of discussion these effects can be divided into negative effects, or disadvantages, and positive effects, or advantages.