LITTORAL ZONE RESEARCH IN THE NEVA ESTUARY (EASTERN GULF OF FINLAND): HISTORY AND PERSPECTIVES

Abstract

The history of littoral zone research in the Neva estuary, the largest estuary in the Baltic Sea, is described. Environmental problems, including effects of eutrophication and introductions of alien species, are discussed. A brief outline of future research is provided. The Neva estuary is the largest estuary in the Baltic Sea, located in the eastern Gulf of Finland. It has sustained a heavy impact from human activities, including discharges of treated and untreated wastewaters from point sources in St. Petersburg and intensive ship traffic. The Neva estuary consists of three main parts: Neva Bay (surface area 400 km 2 ), and the inner and outer estuaries (total surface area of the last two parts about 3200 km 2 ) (Pitkanen, 1991). Since the early 1980s freshwater Neva Bay has been separated from the brackish lower reaches of the estuary by a storm-surge barrier, which is still under construction (Fig. 1). The coastal zone of the estuary is intensively exploited for recreation (specifically in the Resort District of St. Petersburg), sport and commercial fishing, military purposes, and various industrial uses including nuclear power and shipping. The coastal zone also receives discharges of treated and untreated wastewaters, occurring mainly in the lower Neva River and in Neva Bay. Heavy nutrient loading (eutrophication), mainly from point sources in the Neva River and the upper estuary, is currently the most serious environmental problem for the Neva estuary and adjacent parts of the eastern Gulf of Finland (Alimov et al., 1996; Leppanen et al., 1997). The introduction of alien species is an emerging issue for the Neva estuary (Alimov et al., 1998; Orlova et al., 1999b; Panov et al.,