Local, landscape, and regional influences on biotic indicators in Great Lakes coastal zones.
Niemi, Gerald *,1, Johnson, Lucinda 1, Danz, Nicholas1, Brazner, John1, Brady, Val1, Kelly, John 2, 1 University of Minnesota, Duluth, MN2 U.S. Environmental Protection Agency, Duluth, MN
ABSTRACT- The goal of our research collaboration is to develop ecological indicators that estimate condition and suggest plausible causes of ecosystem degradation in the US Great Lakes coastal zone. We subdivided the 6,500 km of coast into 762 segment sheds from the St. Lawrence River to the border of Minnesota and Canada. Each segment shed represents a combination of a watershed and the accompanying shoreline. For each segment shed, we calculated 207 potential stressor variables (e.g., agriculture, pollution, land cover, atmospheric deposition, population density, and shoreline characterstics)from 19 different data sources in a geographic information system. These stress variables represent multidimensional stress gradients across the coastal zone. Coastal wetlands that represent critical hydrogeomorphic types along the coastline were randomly selected from a total of 750 wetlands. The selected wetlands were sampled in 2002-2003 for populations of amphibians, birds, diatoms, fish, invertebrates, and vegetation. These populations have been examined relative to four increasing spatial scales: wetland type, Great Lake, ecological province, and the entire US Great Lakes basin. The stress gradients derived from public data bases have been verified with field data for many of the stress gradients (e.g., nutrients). Our results indicate variable responses by taxa to these spatial scales. Many bird, fish, and invertebrate species responded to local conditions, while amphibians, diatoms, and other fish species were more influenced by landscape and regional scales. Bird community attributes have shown many significant relationships with with all major stress axes. The practical application of ecological indicators requires an understanding of the relevant spatial scale upon which organisms respond to stress.
Key words: indicators, stress, communities, multivariate
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