Biomanipulation in shallow, eutrophic lakes: A numerical model with an application to Lake Bleiswijkse Zoom, The Netherlands.

Abstract

The prediction of temporal variations of biota following biomanipulation measures in lakes is of paramount importance in view of water quality management. The temporal variations of phytoplankton biomass as chlorophyll-a and transparency as Secchi depths measurements are studied in the Lake Bleiswijkse Zoom, The Netherlands with a comprehensive biological model. In the formulation of the biological model, phytoplankton as several species, zooplankton, detritus, planktivorous and benthivorous fish and piscivorous fish are considered to be the major contributing biota for the food web manipulation. The biological model enumerates the species compositions at a given time taking biological, physical and meteorological processes into account. Reduction of almost all planktivorous fish and 85% of benthivorous fish results in increase in transparency, decrease in algal biomass and decrease in resuspended inorganic matters leading to an environmental sound lake ecosystem. The model also provides useful insights into positive and negative interrelationships among biota in the ecosystem. In other words, from the biomanipulation point of view, poor understanding of interactions among biota and hence, uncertainties of their accurate predictions may lead to controversial evidences