Seasonal variability of phytoplankton in the shallow waters of the southern Baltic Sea

Abstract

The Baltic Sea is characterized by a seasonal variation of phytoplankton structure. These organisms are particularly sensitive to changes in various environmental parameters. Cyclic, recurring annually fluctuation of species composition, abundance and biomass of phytoplankton is a consequence of these changes. Spatial and temporal variability of particular groups of phytoplankton is not the same in different areas of the Baltic Sea. The purpose of this work was to determine the spatial and temporal distribution of phytoplankton in three chosen areas of the coastal zone of the southern Baltic Sea (Ustka, Poddąbie and Rowy) in the period of November 2014 - September 2016. Mean values of abundance and biomass of phytoplankton for the surveyed areas were typical for this type of coastal waters. In each of the surveyed areas the same dominat species in terms of the abundance and biomass were observed. A growth of diatoms was recorded only in the area of Ustka, which could have been caused by the inflow of river waters. Seasonal surveys of phytoplankton indicated that in the case of the studies regarding this parameter – taxonomic composition, abundance and biomass in the same surveyed area were similar at the three research stations (e.g. 75-80%), depending on the season of the year. On this basis, it was concluded that, whether carrying out the monitoring of phytoplankton or planned investments, the sample collection frequency had a greater significance than the number of research stations.