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Integrating Coastal Systems into Lake-wide and Basin-wide Assessment Designs for the Great Lakes
Kelly, J. 1, P. Yurista 1 J. Scharold 1, M. Sierszen 1, S. Miller 1, J. Morrice 1, G. Peterson 1, M. Knuth 1, G. Niemi 2, N. Danz 2 T. Hollenhorst 2
1 EPA/ORD/NHEERL/Mid-Continet Ecology Division, Duluth MN
2 Univ of MN-Duluth, Natural Resource Research Institute, Duluth MN
A goal is to develop scientific approaches for coastal assessments that integrate with comprehensive lake-wide assessment on the one hand and couple with watershed/basin-wide health on the other. In this context, our research has provided significant results in two major theme areas.
- Ecological definition and inclusion of nearshore in lake-wide assessments. Studies of food webs (stable isotope analyses) have identified different ecological zones by depth, from the coast to offshore. In Lake Superior, a depth-based sampling designs confirms that excluding nearshore biota from lake-wide assessments would significantly underestimate lake-wide biomass, and misrepresent the lake’s ecosystem support capacity. Additional studies on semi-enclosed embayments suggest that stratifying the nearshore into open and semi-enclosed systems offers some design and interpretation advantages. Overall, studies have provided guidance on robust lake-wide assessment designs, which are now being piloted or adopted across the Great Lakes.
- Use of the nearshore condition itself as a sentinel to diagnose basin- and landscape-driven change that may ultimately transfer across the entire lake. Water chemistry measures establish landscape-derived signals in for coastal wetlands, embayments, and the open nearshore. In general, such signals are weakest in the nearshore. New indicators have been developed for coastal wetlands (Great Lakes Environmental Indicators – EPA collaboration). The nearshore is difficult because time-space variability is a major impediment to develop reliable diagnostic indicators. However, spatially-synoptic technologies have been successful in overcoming the signal to noise ratio inherent with stressor-response signals in heterogeneous, dynamic nearshore systems.