2002 ARCSS All-Hands Workshop

Using GIS to Assess Ice-Cover Impacts on a Productive Benthic System in the Northern Bering Sea

Jaclyn L. Clement¹, Jacqueline M. Grebmeier², Lee W. Cooper^3
1Ecology and Evolutionary Biology, University of Tennessee, 10515 Research Dr., Suite 100, Knoxville, TN, 37932, USA, Phone 865.974.6160, Fax 865.974.7896, jlc@utk.edu
²Ecology and Evolutionary Biology, University of Tennessee, 10515 Research Dr., Suite 100, Knoxville, TN, 37932, USA, Phone 865.974.2592, Fax 865.974.7896, jgrebmei@utk.edu
³Ecology and Evolutionary Biology, University of Tennessee, 10515 Research Dr., Suite 100, Knoxville, TN, 37932, USA, Phone 865.974.2990, Fax 865.974.7896, lcooper1@utk.edu

During April 1999 and March-April 2001, late winter biological, sediment, and hydrographic measurements were made at 28 stations in an area of historically high benthic biomass in the northern Bering Sea. Benthic macroinvertebrates are an important food source for diving seaducks (e.g., the threatened Spectacled Eider) and marine mammals in this region. This presentation will quantify the influence of seasonal ice cover on water column production and benthic processes during the two late winter cruises, using satellite ice coverage data and GIS mapping tools within the context of a longer, decadal ecosystem study in the region. The years of 1999 and 2001 were very different in terms of ice extent and concentration. From mid-January to the end of April 1999 the ice concentration was at least nine-tenths for the entire study region. This uniformity of ice during the winter of 1999 may explain the lack of any correlation between ice coverage and any water column or benthic parameters, during our subsequent April sampling. In contrast, the ice concentration and extent during 2001 was greatly reduced over the Bering Sea. A spatially and temporally integrated measure of ice concentration prior to late winter sampling was significantly correlated with water column chlorophyll-a measured during the cruise (Spearman's rho= -0.415, p=0.35). Integrated chl-a concentrations ranged from 3.1 to 52.2 (mg m^-2), low by comparison to maximum spring production events (e.g. during May 1994 integrated chl-a ranged from 21.1 to over 2000 mg m^-2). These data indicate a relationship between low winter ice coverage and temporal acceleration of water column production, which would be a likely scenario with global change. During 1999 benthic biomass (g C m^-2) was significantly correlated with late winter measurements of sediment chlorophyll-a (Spearman's rho=0.504, p=0.01). These data support the conclusion that late spring production events and subsequent advection of carbon within the study area are important for deposition and use of carbon in this region over an annual cycle.

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