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Depth gradients in food web processes linking habitats in large lakes: Lake Superior as an exemplar ecosystem
Citation:
Sierszen, M., T. Hrabik, J. Stockwell, A. Cotter, J. Hoffman, AND D. Yule. Depth gradients in food web processes linking habitats in large lakes: Lake Superior as an exemplar ecosystem. FRESHWATER BIOLOGY. Blackwell Publishing, Malden, MA, 59(10):2122-2136, (2014).
Impact/Purpose:
This milestone under SSWR Project 1.1, Watershed Integrity and Sustainability, Task 1.1A will contribute to the design of large lake assessments. In it we use Lake Superior as a prototypical large lake and identify key ecological processes that support depth-organized biological resources. Those processes should be considered in efforts to protect, restore, and assess the condition of large lake ecosystems.
Description:
In large lakes around the world, water depth is often associated with shifts in ecological communities. Depth-based changes in the abundance and distribution of invertebrate and fish species suggest that there may be concomitant changes in patterns of resource allocation. Using Lake Superior of the Laurentian Great Lakes as a prototype, we found that the importance of benthic food web pathways to fish was highest in nearshore species, whereas the importance of planktonic pathways increased in offshore species. These patterns appear to be governed by two key processes: high benthic production in nearshore waters and the prevalence of diel vertical migration among offshore invertebrate and fish taxa, characteristics that are shared with the Great Lakes of Africa, Russia, and Japan. Substantial use of benthic resources was evident in nearly all fish taxa, and was indicated by depth patterns in their nitrogen stable isotope signatures. Support of whole-lake food webs through trophic linkages among pelagic, deep benthic, and littoral habitats appear to be integral to the functioning of large lakes. Those linkages can be disrupted though ecosystem disturbance, and should be considered in efforts to protect and restore large lakes.
