Abstract:

During the 1980s changes were observed in the Lake Kinneret ecosystem. Biomass and production of planktonic grazers declined. Copepod nauplii, Keratella spp. large body Diaphanosoma sp., Ceriodaphnia spp., Bosmina spp. and adult copepods became less abundant relative to small individuals. An increase of particulate P (PP) in lake water was observed, while particulate-N (PN) decreased. As a result, the TN/TP (wt/wt) and atomic ratio (AR) of PN/PP in the epilimnion (0-10 m) decreased from 42-63 (wt/wt) and 76-117 (AR) during the 1970s to below 29 (wt/wt) and 25-70 (AR) in the 1980s. Fish predation and the change of nutritional value of particulate food sources for zooplankton affected their community changes. The decline of zooplankton grazing capacity and the improved conditions of nutrients, together may have contributed to the increase of the algal biomass of Chlorophyta in the lake. Implications on other algal groups and lake management are considered.

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Date 1992/12/01

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