PARENT SESSION
Symposium 20: Defining and Applying Environmental Indicators in Coastal Ecosystems
Organized by: R Howe and G Niemi
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Chatham Ballroom B.
Sampling design for linking stress with response in the Great Lakes coastal ecosystem.
Niemi, Gerald1, Danz, Nicholas*,1, Regal, Ronald1, 2, Hollenhorst, Tom1, Brady, Valerie1, Johnson, Lucinda 1, Brown, Terry1, Host, George1, 1 University of Minnesota Duluth, Duluth, MN2
ABSTRACT- The goal of our work is to develop indicators that both estimate ecological condition and suggest plausible causes of ecosystem degradation. Thus, the indicators developed must be based on their responsiveness to anthropogenic stress. To evaluate the association of potential indicators with stress, it is necessary that the sample be distributed across the stress gradients of interest. Although there are many examples of sampling designs for the goal of estimating mean condition such as in monitoring programs, a sampling framework has been lacking for relating stress to ecological response. Our project consists of five individual subcomponents to investigate different types of biological responses (e.g. birds, diatoms) with different sampling methodologies and sample size requirements. Previous work in the Great Lakes coastal region has identified many influential anthropogenic stresses. The major challenges for our sampling design were to distribute the sample across many stress gradients and to allow for integration of indicators from individual project subcomponents by maximizing site overlap. We used a GIS to compile over 200 data layers representing six types of anthropogenic stress: agriculture, atmospheric deposition, land cover, human populations, point source pollution, and shoreline modification. We divided the coastal region into 762 units using geomorphological criteria, and calculated stresses for each unit. We used principal components analysis to remove redundancy within the stress categories and cluster analysis was used with pc scores as input to create groups of coastal units having similar stress profiles. Random selection of sites from the clusters provided an unbiased sample of sites that spanned the range of stress conditions in the region and provided a high degree of overlap for project subcomponents. Sampling of the sites is being completed in 2002 and 2003.
Key words: sample design , ecological indicators, anthropogenic stress