Mathematical modeling of the evolution and current conditions of the Ladoga Lake ecosystem

This work presents a new ecosystem model of Ladoga Lake. This model contains a more detailed description of phytoplankton than in previous models constructed by the authors. In the new model, phytoplankton are presented as three ecological groups. It is allowed to reproduce more adequately, the process of Ladoga Lake eutrophication. The presented model allows calculation of the 3D spatial distribution of three groups of phytoplankton, dissolved organic matter, detritus, as well as nutrients, mineral phosphorus and dissolved oxygen. The model was used for reproducing year-round functioning of the basinʹs ecosystem, which corresponded to the condition of phosphorus loading, averaged over the period 1984–1991. The constructed model also was used in reproducing the lakeʹs ecosystem evolution since 1962, which is when antropogenic loading started to increase. The latter circumstance lead to the beginning of, and to the development of, the eutrophication process in the basin. The phosphorus loading changes and weather instability were taken into account during the evolution reproduction. The results of these computational experiments show that it is possible to use this model for forecasting the consequences of the phosphorus loading changes.