Factors, influencing on macroalgal communities in the Neva estuary (eastern Baltic Sea)

The Neva estuary is a shallow water body, characterized by low salinity (0-3.5⁰/₀₀) and high level of eutrophication. Sampling was conducted along the coast in 2002-2011 by scuba-diving method. Every summer we observed mass development of fast-growing filamentous macroalgae (up to 450 gDWm^-2) and the formation of decaying mats. During study period dredging works and land reclamation led to significant decline of total macroalgal biomass in 2008, but in next three years the biomass reached previous meanings. Natural factors, as a weather conditions and salinity also influenced on coastal communities. Changes of salinity determined distribution of marine species in the Neva estuary. At the same time weather conditions influenced on seasonal dynamic of macroalgae. Correlation analysis showed significant link between average seasonal biomass (depth 0.5 m) of macroalgae and average wind speed during sampling season (R=-0.94, p<;0.05). At the same time the link between midsummer biomass and temperature was founded. Our study showed, that species composition and biomass of macroalgal communities reflected complex of antropogenic and natural factors, which influenced on the Neva estuary.