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Benthic versus Planktonic Foundations of Three Lake Superior Coastal Food Webs
Citation:
Sierszen, M E., J A. Morrice, M F. Moffett, AND C W. West. Benthic versus Planktonic Foundations of Three Lake Superior Coastal Food Webs. P. Chow-Fraser (ed.), JOURNAL OF GREAT LAKES RESEARCH. International Association for Great Lakes Research, , Canada, 30(1):31-43, (2004).
Impact/Purpose:
Investigations of the structure of aquatic food webs can provide information on system function, trophic dynamics and, potentially, responses to anthropogenic stressors.
Description:
The structure of aquatic food webs can provide information on system function, trophic dynamics and, potentially, responses to anthropogenic stressors. Stable isotope analyses in a Lake Superior coastal wetland (Allouez Bay, WI, USA) revealed that the food web was based upon carbon fixed by phytoplankton. We report analyses of two Lake Superior coastal wetland food webs not based upon plankton, indicating that Allouez Bay is not the prototype. In Lost Creek and West Fish Creek wetlands (WI, USA), upper trophic levels appear to be supported by epiphytic, rather than planktonic, food web pathways. Also, zooplankton in Lost Creek and West Fish Creek wetlands are enriched in 13 C relative to epiphytes, rather than 13 C-depleted as reported in most other systems. This appears to be a consequence of zooplankton feeding on detrital seston that is 13 C-enriched relative to phytoplankton. We suggest two possible causes for the observed differences in food web structure among these wetlands: hydrologic differences among the systems, and responses to nutrient enrichment among the dominant forms of primary producers, similar to those described in lakes. Nutrient concentrations and turbidity indicate trophic enrichment of plankton-based Allouez Bay relative to periphyton-based Lost Creek and West Fish Creek wetlands.