Evolution quantitative du plancton durant la phase d'eutrophisation accélérée du Lac Léman (Suisse — France)

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Summary

The eutrophication of Lake Geneva (Lac Léman) between 1959 and 1981 can be seen in the increase in stocks of N and P (respectively twofold and fourfold) in the surface layer (0–20 m). Phytoplankton biomass (chlorophyll a) peaked in 1976 and 1981, and zooplankton biomass (dry wt.) increased progressively from 1959 to 1971 (max: 4.5 g/m²), remaining high until 1981 (max: 3.8 g/m²), then decreasing during the last few years, with a mean value now close to those noted twenty years ago(2.5g/m²).