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Fish habitat requirements as the basis for rehabilitation of eutrophic lakes by oxygenation
Author(s) -
Müller R.,
Stadelmann P.
Publication year - 2004
Publication title -
fisheries management and ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 55
eISSN - 1365-2400
pISSN - 0969-997X
DOI - 10.1111/j.1365-2400.2004.00393.x
Subject(s) - hypolimnion , eutrophication , environmental science , hypoxia (environmental) , sediment , macrophyte , fish kill , epilimnion , ecology , organic matter , phosphorus , nutrient , algal bloom , oxygen , biology , phytoplankton , chemistry , paleontology , organic chemistry
Eutrophic lakes often suffer from hypolimnetic oxygen depletion during summer and autumn, and the accumulation of reduced substances in the hypolimnion. The space fish can occupy is therefore reduced, and the potential for fish kills caused by toxic algae and the upwelling of anoxic water increases. Fish, such as coregonids, require at least 4 mg O 2 L −1 to survive in the long‐term. This critical level has been postulated as one of the major goals for the rehabilitation of several eutrophic Swiss lakes. It was predicted that this oxygen criterion would reduce phosphorus release from the sediment and increase phosphorus retention, and re‐establish natural reproduction of coregonids. Rehabilitation measures applied to three eutrophic Swiss lakes were hypolimnetic oxygenation during summer stratification, and artificial mixing using compressed air to enhance circulation in winter. These lake‐internal measures carried out for more than 15 years showed the 4 mg O 2 L −1 criterion can be achieved most of the time. The measures have led to an expansion of habitat for oxygen‐dependent organisms to greater depths. However, other goals were not attained, such as increasing phosphorus retention by the sediment. In addition, natural reproduction of coregonids could not be re‐established. Excessive oxygen consumption by the sediment, arising from the decomposition of deposited organic matter produced during summer, caused death by suffocation of coregonid eggs developing on the sediment. Thus rehabilitation of eutrophic lakes by oxygenating the hypolimnion and artificial mixing will not be successful, unless it is accompanied by lowering the nutrient loading and thus primary production and oxygen consumption by the sediment. Nevertheless, positive effects of lake aeration were the expansion of living space for fish and benthic invertebrates, and the prevention of fish kills by upwelling anoxic hypolimnetic water.