Mesozooplankton of the gulf of finland and northern Baltic proper a review of monitoring data

A review of meso zooplankton population densities and biomasses in the Gulfof Finland and northernmost Baltic Proper is presented based on monitoring data collected over the period 1968–1990 from four coastal and six open sea stations. Acartia bifilosa, Eurytemora affinis (Copepoda), Bosmina longispina maritima (Cladocera) and Synchaeta baltica (Rotifera) were found to be the most important species in the area. Multidimensional scaling and cluster analyses revealed several distinct bic geographical areas separated by their mesozooplankton community structures in most of the seasons. Salinity gradients and coastal-open-sea-gradient explained most of the differences between the communities. However, these factors did not explain the distribution of individual species in all cases. The possible role of other factors affecting the mesozooplankton distribution and abundance, such as eutrophication, is discussed.