Benthos as the basis for arctic lake food webs |
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Authors: | Michael E Sierszen Michael E McDonald Douglas A Jensen |
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Institution: | (1) National Health and Environmental Effects Laboratory, Mid-Continent Ecology Division, U.S. Environmental Protection Agency, 6201 Congdon Blvd., Duluth, MN 55804, USA;(2) National Health and Environmental Research Laboratory, Ecological Monitoring and Assessment Program, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA;(3) Minnesota SeaGrant, 2305 E. Fifth St., Duluth, MN 55812, USA |
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Abstract: | Plankton have traditionally been viewed as the basis for limnetic food webs, with zooplankton acting as a gateway for energy passing between phytoplanktonic primary producers and fish. Often, benthic production has been considered to be important primarily in shallow systems or as a subsidy to planktonic food web pathways. Stable isotope food web analyses of two arctic lakes (NE14 and I minus) in the Toolik Lake region of Alaska indicate that benthos are the primary source of carbon for adults of all species of benthic and pelagic fish present. We found no effect of turbidity, which may suppress benthic algae by shading, on food web structure. Even though Secchi transparency varied from 10.2 m in NE14 to 0.55–2.6 m in I minus, food webs in both lakes were based upon benthos, had four trophic levels, and culminated with omnivorous lake trout. We suggest that the importance of benthos in the food webs of these lakes is due to their extreme oligotrophy, resulting in planktonic resources that are insufficient for the support of planktivorous consumers. |
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Keywords: | Food webs Oligotrophy Stable isotopes Trophic structure |
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