Impact of the Construction of New Port Facilities on the Biomass and Species Composition of Phytoplankton in the Neva Estuary (Baltic Sea)

The construction of new port facilities and the creation of new lands is a natural consequence of the rapid growth in the population of ocean coastlines. Despite the fact that such human activity is becoming more and more widespread, its impact on various components of aquatic ecosystems, including phytoplankton, is still poorly understood. The aim of the study was to assess the effect of the large-scale construction of new port facilities on biomass and taxonomic composition of phytoplankton in the Neva Estuary (northeastern Baltic Sea). Studies have shown that digging and displacing large amounts of bottom sediments during these works led to a significant increase in suspended mineral matter and a decrease in water transparency in the estuary. This significantly reduced the species richness and biomass of phytoplankton. However, the analysis of beta diversity did not show significant changes in the phytoplankton community during the periods of port construction and the periods when no works were carried out. The changes mainly concerned rare species, while the occurrence and biomass of dominant and subdominant species changed to a lesser extent. Due to various adaptations, the phytoplankton species common in the estuary are apparently able to survive under prolonged shading and successfully compete with species that are unable to withstand the lack of light for a long time. To correctly take into account the effects of the construction of new port facilities on phytoplankton and, if possible, minimize it, additional studies of the ecology of certain phytoplankton species, their relationships, and physiological responses to various environmental factors are required.