Scholarly record

FEATURES OF THE ZOOPLANKTON DYNAMICS OF THE EASTERN PART OF THE FINNISH BAY (BALTIC SEA)

Natalia Silina, Elena Orlova, Natalia Lemeshko

Abstract

The eastern part of the Gulf of Finland of the Baltic Sea is the estuary of the Neva River. The study area has significant spatial variability in water salinity. The salinity regime is largely determined by the influx of fresh water from the Neva Bay and water exchange with sea waters from the western sections of the Gulf of Finland. Therefore, the eastern part of the bay is characterized by an increase in salinity from east to west. At the same time, salinity in the eastern part of the Gulf of Finland is characterized by rather essential short-period changes. Three regions were identified depending on the water salinity regime in the bay: a shallow-water desalinated area (I), transitional area from a fresh to a brackish-water (II), and a deep-sea brackish-water area (III). In a highly desalinated shallow-water area of the bay, zooplankton mainly consists of freshwater species. Representatives of the brackish-water complex prevail in other areas of the eastern part of the Gulf of Finland. Water salinity is a leading factor determining the species composition and spatial distribution of zooplankton in the bay. Features of the hydrological regime of the three selected regions of the eastern part of the Gulf of Finland determine the species composition of zooplankton. Estimates of changes in the structure and long-term dynamics of zooplankton in different regions of the eastern part of the Gulf of Finland are obtained on the basis of long-term studies.

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