The trophic state of the Vistula Lagoon: an assessment based on selected biotic and abiotic parameters according to the Water Framework Directive*

The aim of the study was to determine the trophic state of the Vistula Lagoon in 2007–2009. The analysis of various trophic state indices, abiotic parameters and different water classifications indicated the eutrophy and even advanced hypereutrophy of the lagoon waters. The composition, abundance and biomass of phytoplankton likewise reflect the eutrophic nature of this water body. For this lagoon, Reynold’s functional groups of phytoplankton were used as an indicator of eutrophication for the first time. The dominant phytoplankton organisms in the surface waters belong to 8 functional groups: S1, X1, F, J, K, H1, Lo, M. Some key concepts of the EU Water Framework Directive were implemented in this study.