Characterization of Brackish Coastal Waters of Different Trophic Levels by Means of Phytoplankton Biomass and Primary Production

Abstract

AbstractInvestigations on phytoplankton have been carried out in Baltic coastal waters, which are widely separated from the sea. Corresponding to their distance to the sea they differ in their trophic level. Annual phytoplankton production and a mean biovolume of 100‐200 g C · m−2 and 2‐10 mm−3 · 1−1 respectively were found for the mesotrophic level, of 200‐400 g C · m−2 and 10‐20 mm3 · 1−1 for the eutrophic level, and of 400‐600 g C · m−2 and over 20 mm3 · 1−1 for the polytrophic level.In the course of nearly two decades of investigation a slight increase of phytoplankton biovolume, but no increase of primary production was recorded. Some changes in species composition are to be recognized in Greifswalder Bodden, if old literature is compared with recent data. In the Darss‐Zingst boddens a shift from Cyanobacteria dominance towards Chlorophyceae dominance has appeared for at least 5 years. This was on account of the disappearance of Gomphosphaeria pusilla, which is thought to be an indicator species of the mesotrophic level.