Lake Kinneret: A seasonal mode1 for carbon flux through the planktonic biota

Abstract

Carbon standing stock distribution in the euphotic zone of Lake Kinneret and the immediate fate of primary‐produced carbon are very different during late winter–early spring (with the occurrence of the annual dinoflagellate bloom) than they are in late summer (when nanophytoplankton are the dominant primary producers). We used a linear programming model to construct balanced carbon flow charts for these two seasons based on measured primary productivity; on carbon standing stocks of algae, bacteria, flagellates, ciliates, cladocerans, rotifers, and fish; and on data on turnover times, respiration, and grazing rates obtained in 1989. The charts were compiled to fit as closely as possible all observed and inferred estimates of carbon fluxes while simultaneously ensuring that mass balance and key biological constraints were maintained for each of the 10 compartments representing the principal biota of the Kinneret food web. We used the model to examine the extent to which individual intercompartmental flux rates were free to vary while the mass‐balance and biological constraints were enforced. The model was also capable of generating different yet feasible flow‐chart scenarios; it thus proved useful in suggesting alternative hypotheses concerning the role of the microbial food web in the euphotic waters of’ Lake Kinneret.