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Changes in whitefish scales δ 13 C during eutrophication and reoligotrophication of subalpine lakes
Author(s) -
Gerdeaux Daniel,
Perga Marie-Elodie
Publication year - 2006
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2006.51.1_part_2.0772
Subject(s) - trophic level , eutrophication , coregonus lavaretus , trophic state index , ecology , pelagic zone , environmental science , montane ecology , phosphorus , coregonus , lake ecosystem , biology , fishery , ecosystem , nutrient , fish <actinopterygii> , chemistry , organic chemistry
We measured the isotope composition of whitefish (Coregonus lavaretus) scales from 50‐yr collections to determine the pattern of change of δ 13 C during the eutrophication and reoligotrophication of two subalpine lakes: Lakes Constance and Geneva. The isotope composition of scales from Lake Annecy, a subalpine lake that has been protected from eutrophication, was also determined, to provide a control value for modifications in the values of whitefish scale δ 13 C in the absence of any significant changes in the trophic status of the lake. In Lakes Constance and Geneva, changes in whitefish scales δ 13 C were closely correlated with those in the mean annual phosphorus concentrations and, to a lesser extent, also reflected the efficiency of winter mixing in Lake Geneva. In contrast, in Lake Annecy, whitefish δ 13 C exhibited only minor changes during the survey. Changes in whitefish scale δ 13 C with the trophic status of Lakes Geneva and Constance were not linked to either a shift in whitefish feeding behavior or to alterations in the length of the pelagic trophic chain. Hence, the pattern of variation of whitefish δ 13 C during the last decades mirrored the lakes' trophic history. The responses of the Lakes Geneva and Constance to changes in P tot were strictly synchronous and parallel, with a response during restoration that may have been the result of the antagonism between the effects of the falling phosphorus concentration and increasing temperature.