Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
Biological Implications of Arctic Change
Jacqueline M. Grebmeier1
1Ecology and Evolutionary Biology, The University of Tennessee, 10515 Research Dr., Suite 100, Bldg A, Knoxville, TN, 37932, USA, Phone 865-974-2592, Fax 865-974-7896, jgrebmei@utk.edu
Studies in the northern Bering and Chukchi Seas over the last two decades provide many indications of ecosystem change. The tight pelagic-benthic coupling observed between seasonal water column carbon production processes and underlying short- and long-term benthic carbon transformation processes provide a “footprint” in the sediments of persistent ecosystem events and subsequent time-series changes. Pelagic-benthic coupling can be studied via underlying sediment processes on various time scales. Sediment metabolism can be an indicator of weekly-to-seasonal carbon depositional processes, while benthic faunal populations can act as multi-year, long-term integrators of a variety of marine processes. This detection of biological changes in the marine environment coincide with recent observations of Arctic environmental changes, including a seasonal reduction in the extent and duration of sea ice, increased seawater temperature, and changing hydrographic conditions. Thus, high latitude ecosystems appear particularly sensitive to climate change, and the shallow, productive nature of the Bering Strait region in the North American Arctic may provide a sentinel indicator of global change effects.
For example, recent studies show that the northern Bering Sea is shifting towards an earlier spring transition between ice-covered and ice-free conditions. Coincident changes in the timing, extent, composition and location of annual production, both primary and secondary trophic levels, can lead to dramatic ramifications for higher-trophic level fauna utilized by indigenous populations in the Arctic, such as benthic feeding walrus, bearded seals, gray whales, and diving seaducks. Within the Bering Strait Long-term Observatory project, time series sites have been continued south of St. Lawrence Island, in the middle of Chirikov Basin south of Bering Strait, and just north of Bering Strait in the southern Chukchi Sea. An overall decline in both sediment oxygen uptake (an indicator of carbon supply to the sediments) and overall benthic standing stock from the 1980’s to the present has occurred in this region, with subsequent ramifications to higher trophic organisms that use benthic prey. Declining bivalve populations south of St. Lawrence Island indicate a decline in the bivalve prey source for the diving spectacled eider, with indications that a change in hydrographic forcing and nutrient supply is limiting primary production in the region. Recent studies of gray whale feeding areas and time series measurements at select stations in the Chirikov Basin north of St. Lawrence Island also indicate a decline in the benthic amphipod prey biomass in the region over the last decade, with indications that gray whales are dispersing north of Bering Strait into the Chukchi Sea, and also feeding in new areas along their migration path to obtain food.
Thus, biological systems are detecting ecosystem change on the shallow shelves of the northern Bering and Chukchi Seas, which are intimately connected to systems further to the north. Current studies as part of the Western Arctic Shelf-Basin Interactions (SBI) global change project are investigating the production, transformation and fate of carbon at the shelf-slope interface in the northern Chukchi and Beaufort Seas, downstream of these productive shallow western Arctic shelves, as a prelude to understanding the impacts of a potential warming of the Arctic. As SEARCH moves into the implementation phase, it seems logical that international time series shelf-slope transects be maintained at key locations throughout the Arctic to detect change in this critical ecosystem.
Abstract Categories: Changes in the Sea
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