The effect of load reductions on algal biomass in the eastern Gulf of Finland estimated by the FINNALGA model

Eutrophication and algal blooms are major environmental problems in the Gulf of Finland. One possible way to approach the problem is mathematical modelling. If the most important processes are successfully modelled, it is possible to calculate the effects of human activity. The application of an ecological model to the eastern Gulf of Finland is presented here. The algal model used is coupled with a 3-dimensional hydrological one. The application year used was 1994 and the validation year 1995. The load reductions used are based on the recommendation of HELCOM or a more realistic assessment. Results received indicate, that clear effects can be observed even within a short period. According to our model the reduction of phosphorus load is important near river entrances, while for the open eastern Gulf of Finland nitrogen is more important.