Effects of planktivorous and benthivorous fish on organisms and water chemistry in eutrophic lakes |
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Authors: | Gunnar Andersson Hans Berggren Gertrud Cronberg Curt Gelin |
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Institution: | (1) Institute of Limnology, University of Lund, S-220 03 Lund, Sweden |
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Abstract: | The effects of planktivorous and benthivorous fish on benthic fauna, zooplankton, phytoplankton and water chemistry were studied experimentally in two eutrophic Swedish lakes using cylindrical enclosures. In enclosures in both lakes, dense fish populations resulted in low numbers of benthic fauna and planktonic cladocerans, high concentration of chlorophyll, blooms of blue-green, algae, high pH and low transparency. In the soft-water Lake Trummen, total phosporus increased in the enclosure with fish, but in the hard-water Lake Bysjön total phosphorus decreased simultaneously with precipitation of calcium carbonate. Enclosures without fish had a higher abundance of benthic fauna and large planktonic cladocerans, lower phytoplankton biomass, lower pH and higher transparency.The changes in enclosures with fish can be described as eutrophication, and those in enclosures without fish as oligotrophication. The possibility of regulation of fish populations as a lake restoration method is discussed.This paper was presented at the XXth SIL Congress in Copenhagen in 1977. |
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Keywords: | Predation grazing eutrophication fish benthic fauna zooplankton phytoplankton blue-green algae lake restoration |
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