| Summary: | 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 is 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 1 minus) in the Toolik Lake region of Alaska indicate that benthos are the primary source of carbon for adults of all species of fish present, including benthic and pelagic species. We found no effect of turbidity, which may suppress benthic algae by shading, on food web structure. Even though Secche transparency varied from 10.2 m in NE14 to 0.55 - 2.6 m in 1 minus, food webs in both lakes were based upon benthos, had four trophic levels, and culminated with omnivorous lake trout. We suggest that a competitive advantage to periphyton over phytoplankton for nutrients in oligotrophic lakes has implications for the structure and energy source of entire food webs.
|
|---|