CHANGES IN THE PHYTOPLANKTON COMMUNITY STRUCTURE AFTER A HUGE MUCILAGE EVENT IN THE MARMARA SEA

The mucilage formation which emegerd in the Marmara Sea in November 2020 continued increasingly in 2021. It existed all through the winter and spring of 2021 in the surface layer and water column of the Sea and caused an ecological and socio-economic destruction in the area including the pelagic and benthic regions. In this study, after a huge mucilage event in the Marmara Sea were examined the seasonal variations in composition and community structure of the phytoplankton, and assessed current situation of mucilage event, changes in frequency and intensity of mucilage-formed species. During the study period, phytoplankton community consisted of 72 taxa with a low diversity. Concerning phytoplankton community parameters showed similarity between stations and depths. On the other hand, phytoplankton community structure is most related to seasonality. During the present study, despite the presence of mucilage-causing species and their high relative proportions in phytoplankton composition of the sampling stations, no observed mucilage in surface water, and the density of these dominant species were relatively lower than those during the huge mucilage periods in 2020 and 2021. In the Marmara Sea, which is under climatic change and intense anthropogenic pressure, extreme algal increases observed more frequently and for longer periods in recent years and its consequences indicate a loss in the productivity, ecosystem functionality and ecological resilience of the Marmara Sea.