The Impact of Nitrogen and Phosphorus Dynamics on the Kinneret Phytoplankton: I: Cyanophytes-Peridinium Alternate

Abstract

During 1970-2001, several ecological changes were documented in the Lake Kinneret Ecosystem: Decline of total Nitrogen (TN) and increase of total Phosphorus (TP) loads with a corresponding decline of TN/TP ratio. The phytoplankton assemblages indicated consequence Increase of Cyanobacteria accompanied by elevation of the biomass of Chlorophyta and Diatoms. The Kinneret ecosystem functioning represented two superimposed events: the decline of TN enhanced Cyanobacteria and elevation of TP that was reflected by an increase of Chloropytes and Diatoms. Removal of Nitrogen was achieved but P load remained high enough to enhance Chlorophyta and Diatoms. Consequently, a top priority of future management perspective should be reduction of Phosphorus inputs.

Sustainable Utilization of the Lake Kinneret and Its Watershed Ecosystems: A Review

“…The discussion about dependence relations between phytoplankton and nutrients presented here emphasize the paradigm of an everlasting dilemma: Between phytoplankton composition and nutrient concentrations, who is the boss? (Figures 7 and 8) Algal community structure responds to the concentration of the nutrients or the contrary: does the nutrient concentrations is primary or secondary result of the algal density [6,11,[23][24][25][26][27][28][29][30][31][32][33]? Nitrogen input is defined as predictor of algal domination in Lake Kinneret: Peridinium or Cyanobacteria.…”

“…Monthly changes of epilimnetic TN stock were found to be related to the length of Residence Time (RT; the ratio between inflows rate and Lake Volume): higher TN stock accompanied longer RT [23,27,28]. Lake Volume increase and shorter RT are correlated with the epilimnetic load decline of TN an increase of epilimnetic TP loads during January-April and gradual decline later on until December was correlated with the Hydrological parameters: RT elongation during January-September, became shorter later; The decline of TN/TP Mass ratio is respective to RT prolongation: The higher the RT value is, the lower is the Epilimnetic TN/TP mass ratio [24,26,27] . The biomass of Peridinium contributes Phosphorus and the headwater input are carriers of Nitrogen.…”