Multi-species indicators of ecological condition in the coastal zone of the Laurentian Great Lakes

Background/Question/Methods

Assessing the health of a complex environment like the Laurentian Great Lakes of North America presents enormous challenges. Yet in order to formulate effective policies and to prioritize allocation of conservation resources, policy-makers need information about the condition of the lakes at multiple spatial and temporal scales.  During the past decade we and colleagues have sampled birds, amphibians, fish, invertebrates, vegetation, algae, water quality, and habitat structure in Great Lakes coastal wetlands and near-shore environments. Our goal was to quantify variation in populations and communities across gradients of environmental stress. Samples were stratified according to a composite measure of anthropogenic impacts (“SumRel”) based on land cover and a suite of publicly available watershed variables. Biotic responses have subsequently been incorporated into quantitative indicators of environmental condition that can be used by managers and policy-makers.

Results/Conclusions

In this paper we compare four analytical methods to calibrate relationships between biotic response variables and the environmental stressor gradient (SumRel). Taxonomic groups varied in their sensitivity to the stressor gradient; diatom, fish and bird abundance and taxonomic composition showed strong responses to the gradient, while invertebrates showed weaker response. A comparison of indicator values among sites suggests that multi-taxa suites of indicators provide informative and biologically interpretable assessments of ecological condition in the Great Lakes coastal environment.