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ICES CM 2007/C:15

Dynamics of biodiversity in the eastern Gulf of (): the role of climatic and anthropogenic factors

Sergey Golubkov

Baltic Sea Regional Project (BSRP), Lead Laboratory on Biodiversity

ABSTRACT: Assessment of biological diversity of the Estuary (eastern ), which is one of the largest Baltic estuaries affected by very high human activity, has been conducted applying BSRP SGEH indicators. They include macrophytobenthos, macrozoobenthos, alien species, ichthyofauna, marine aviafauna, mammals as well as implementation of biodiversity protection measures in the area. Poor biodiversity status was estimated for the upper freshwater , and moderate biodiversity status – for lower brackish part of the estuary. Alien species and eutrophication are the most important threats to biodiversity of the Neva Estuary. At present, alien species contribute about 8 per cent of species richness and 60 - 90 per cent of biomass of the bottom communities. Climatic mediated fluctuations in near bottom oxygen conditions are the main natural factor responsible for the dynamics of benthic communities in the open waters of the estuary. These fluctuations also lead to decline of aboriginal and prosperity of invasive species. Filamentous algae blooms and macroalgal floating mats affect biodiversity dynamics in shallow coastal zone. Decline of bottom natural communities mostly dominated by leads to impairment of food conditions for fish and contributes greatly to sharp reduction of their populations, which in turn may be partly responsible for population decline of ringed seals. Large-scale digging and dumping of bottom sediments connected with constructions of new lands, ports and oil terminals are the main factor affected fish and submerged macrophyte communities in the Neva Bay. Most of fish spawning grounds in the shallow Neva Bay were lost during the last decades. Construction of 22 km long flood protection dam in the lower part of the Neva Bay led to expansion of reeds and prosperity of waterfowl. New protected areas are supposed to be established in the reed zones and on the of the eastern Gulf of Finland. Long-term forecasts and measures for conservation and improving biological diversity should take into account the periodicity of climate changes and planned development of the region. Sergey Golubkov, Zoological Institute RAS, Universitetskaya emb. 1, 199034, St. Petersburg, [tel: +7 812 328 0711, fax: +7 812 328 2941, e-mail: [email protected]].

Created with novaPDF Printer (www.novaPDF.com) 1. Introduction The eastern Gulf of Finland as well as the Gulf of Gdansk have been selected by the Baltic Sea Regional Project - BSRP (ICES, 2006; ICES, 2007) as a demonstration areas for the upcoming assessments of biological diversity in the Baltic Sea (HELCOM BSAP, 2006).The reasons for these selections are concerned with long-term research of different biodiversity patterns in these regions and importance of their goods and services which have been seriously affected by the diverse anthropogenic impacts. These impacts resulted mainly from large Baltic and large megapolis: Neva and St. Petersburg City in case of the eastern Gulf of Finland and River Vistula and Tri- city (Gdansk-Sopot-Gdynia) in case of the Gulf of Gdansk. The assessment of biological diversity of the eastern Gulf of Finland is based on historical and recent data published in scientific literature since the beginning of the last centaury and on a limited number of biodiversity indicators, proposed by the ICES/BSRP Study Group on Baltic Ecosystem Health (SGEH) as priority indicators (ICES, 2006; ICES, 2007). They include macrophytobenthos, macrozoobenthos, alien species, ichthyofauna, marine aviafauna, mammals as well as implementation of biodiversity protection measures in the area. The evaluation of biodiversity status has been done in five quality grades (high – score 5, good – score 4, moderate – score 3, poor – score 2 and bad – score 1, in accordance with recommendations of EU WFD (2000). Environmental quality and biological diversity existing in the eastern Gulf of Finland in the first half of 20th centaury has been chosen as reference conditions. Percent of reference value 0 to 10 % attributed to bad (score 1), 11 to 25 % to poor (score 2), 26 to 50 % to moderate (score 3), 51 to 75 % to good (score 4), and over 75 % considered as very good (score 5).

2. Identification and description of hydro-geo-morphological units Russian part of the eastern Gulf of Finland practically coincides with the boundaries of the Neva Estuary: the largest Baltic estuary with surface area 3600 km2 (Fig. 1). The Neva Estuary receives water from the Neva River, a major contributor of fresh water to the Baltic Sea. The catchment area of the Neva River exceeds 280 000 km2, and its water discharge averages 2490 m3 s-1, (78.6 km3 yr-1). The Neva Estuary consists of two parts: the upper freshwater - Neva Bay and lower brackish-water part of the estuary.

2.1. Neva Bay: the upper freshwater part of the Neva Estuary Surface area of the Neva Bay (Fig. 1) is about 400 km2, salinity – 0.07-0.02 ‰, with the exception of short-term intrusions of brackish water from the lower part of the estuary during surge

Created with novaPDF Printer (www.novaPDF.com) events when brackish waters from the lower part of the Neva Estuary come to the Neva Bay and mix there with fresh waters; the depth of the bay is 3.5 – 4 m. In the middle of 1980’s Neva Bay had been separated from lower part of the estuary by a storm-surge barrier (Dam), which is still under construction. The storm-surge barrier has several water leaking gates in its northern part and a broad ship gate in the southern part.

2.2. Lower brackish-water part of the Neva Estuary Salinity in the lower brackish part of the Neva Estuary (Fig. 1) ranges from 1.5-3 ‰ in the eastern part to 3-8 ‰ in the western part, depth from 12 – 14 m at the east to 40 – 50 m at the west. Several large bays are located in this part of the estuary, e.g., Luga Bay at the south and the Gulf of at the north, with desalinated water in their inner parts. There are a lot of islands in different parts of the estuary. The largest ones are Kotlin , which is located at the boundary between Neva Bay and the lower brackish part of the Neva Estuary, Beryozovyye islands at the north, Moschniy Island and Gogland Island in the middle-western part the estuary. The Neva River is among the most important sources of pollution for the Gulf of Finland, because it provides about 60-80 per cent of the nutrient loads to the Gulf (Kondratyev et al. 1997, Pitkanen et al. 1997). Considerable part of pollution comes from St. Petersburg, which is one of the largest megapolises in the world with 4.5 millions of citizens and well developed industry. This leads to intensive eutrophication of the eastern Gulf of Finland (Golubkov et al., 2003a, 2003b). The coastal zone of the estuary has been intensively used for recreation (especially in the Resort District of St. Petersburg situated along the northern coast of the Gulf), sport and commercial fishery, and different industries, including a nuclear power station, and shipping (Fig. 1). Intensity of ship traffic has increased greatly during the last decade. There is almost fivefold increase in oil transportation in the eastern Gulf of Finland since 1987. Two large oil terminals were constructed in its north-western part and cargo port in the Luga Bay in early 2000’s (Fig. 1). High anthropogenic impact comes from intensive dredging activity connecting with creations of new building lots and passenger terminal in the Neva Delta. Considerable amounts of bottom sediments and sand drag from the bottom in the eastern part of the Neva Bay, part of them suspends in the water decreasing its transparency and pass to the western part of the bay and even in the lower brackish part of the Neva Estuary.

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Fig. 1. Neva Estuary at the eastern Gulf of Finland.

3. Descriptive assessment of the status of biological diversity

3.1. Macrophytobenthos Indicator: Phytobenthos: area distribution of submerged vascular plants and macroalgae beds First evaluations of composition and distribution of macrophytobenthos in the Neva Estuary were conducted at the end of 19th centaury and in the first half of 20th centaury (Gobi, 1874, 1877; Rozanova, Golubeva, 1921; Derjugin, 1947). The investigations were continued in the second half of XX centaury mostly in connection with eutrophication processes in the estuary (e.g., Belavskaya, 1987; Korelyjkova, 1997; Golubkov et al., 2003b). Macrophytobenthos is a good indicator of environmental changes and anthropogenic impacts in the Neva Estuary, especially in a case of eutrophication. At the beginning of 20th centaury submerged vascular plant and macroalgae meadows were widely distributed in coastal zone of Neva Bay. Reeds were mostly distributed along the southern and north-eastern coasts (Rozanova, Golubeva, 1921; Derjugin, 1947). In 1980’s most of submerged plant meadows (probably 80-90 %) were lost. More then 20 species of submerged macrophytes, e.g., Isoetes lacustris, I. echinospora, Zannichelia palustris, disappeared (Zhakova, 2007). Submerged plant

Created with novaPDF Printer (www.novaPDF.com) meadows were replaced by reed beds, which widely expanded along the northern coast (Belavskaya, 1987). The reason for deterioration of submerged vegetation was intensive dredging activity in summer time connecting with creations of new building lots of St. Petersburg along the eastern cost of the Neva Bay and construction of the storm-surge protecting Dam in 1980’s. This activity decreased water transparency to 0.1 – 0.3 m in summer time. After cessation of dredging in 1990 and early 2000’s and increase of transparency to 1.0 – 1.5 m, which was only a little less, than at the beginning of 20th centaury (Zalesskiy, Volf, 1913), the sparse meadows of submerged vegetation reestablished in the littoral zone of the Neva Bay, but their area is small as compared with reeds which have considerably increased during last three decades. Some species, e.g., macroalgae Nitella gracilis, N. syncarpa, N. mucronata, which disappeared in 1980’s anew appeared in the littoral zone of the bay, two new species Сhara braunii and Сh. fragilis were found (Zhakova, 2007). Since summer 2006 intensive dredging activity in the Neva Bay renewed, that negatively effects the submerged vegetation in the Neva Bay and adjacent brackish part of the estuary. Taking into account great decrease (probably 80-90 %) of the area distribution of submerged vegetation - present status in Neva Bay may be designated as poor (score 2). In contrast to the Neva Bay, where reeds are the dominant type of water vegetation nowadays, submerged vascular plants and macroalgae are widely distributed in the littoral of the lower brackish part of the Neva Estuary. Dominant species of vascular plants in this part as well as in the Neva Bay are Potamogeton perfoliatus, Stuckenia (Potamogeton) pectinatus, Potamogeton gramineus (Zhakova, 2007). These species are widely distributed in the eastern brackish part of the estuary. Perennial macroalgae replace them in western part of the Neva Estuary where salinity is more favorable for marine species. 15 species of Phaeophyta and 6 species of Rhodophyta are found there (Kovalchuk, 2007). Unfortunately, progressive eutrophication is observed in the littoral and open waters of the eastern Gulf of Finland during last decade (Golubkov, 2003a, 2003b). As a result, depth distribution of macroalgae is restricted only by 3-5 m. 6 species of Phaeophyta and 1 species of Rhodophyta (Hildenbrandtia rubra) were included in the Red Book of Leningrad Region (2000) as endangered. Among them Fucus vesiculosus, this was common at the end of XIX centaury (Gobi, 1874). The role of brown and red algae in littoral vegetation of the islands in western part of the Neva Estuary decreased during the last four decades and was succeeded by green filamentous algae (Kukk, 1988; Kovalchuk, 2007). Taking into account this fact and that about 30 % of perennial macroalgae species of have become endangered present status of macrophytobenthos in the lower brackish part the Neva Estuary may be designated as moderate (score 3).

Created with novaPDF Printer (www.novaPDF.com) 3.2. Macrozoobenthos Indicator: Community structure including (extinct) threatened and/or declining species Composition and community structure of zoobenthos in the eastern Gulf of Finland is closely related to as natural as anthropogenic factors. The first investigation of zoobenthos in the Neva Bay showed the dominance of glacial relict crustacean Pallasea quadrispinosa and small mollusks Sphaerium corneum and S. solidum (Pisidiidae), another relict crustacean Mysis relicta was also common (Skorikov, 1910). Later in 1920-1930 this dominance succeeded by large freshwater mollusks Unionidae (Derjugin, 1947). Oligochaeta worms were rare in 1910’s but common in 1920- 1930’s. The further succession of zoobenthos was connected with progressive decline of glacial relicts (P. quadrispinosa occurs only occasionally nowadays) and increase of the dominance of Oligochaeta worms probably resulted from eutrophication processes in this part of the Neva Estuary. The influence of natural climatic mediated factors is evinced by periodic high increase in zoobenthic biomass with dominance of Pisidiidae in the eastern near Neva Delta part of the bay for the years of the high River Neva run-of (Maximov, 2004) and periodic dominance of large mollusks Unionidae in the other parts of the Neva Bay for the years of the low river run-of. Status of zoobenthic biodiversity in Neva Bay may be considered as moderate (score 3) due to considerable decrease in abundance of Pallasea quadrispinosa and increase of Oligochaeta worms. Similar changes have happened in the most eastern brackish part of the Neva Estuary where dominance of relict is succeeded by the dominance of Oligochaeta worms and chironomids due to a progressive eutrophication in this part of the eastern Gulf of Finland (Golubkov et al, 2003a). Nowadays two species of Oligochaeta, Potamothrix hammoniensis and Limnodrillus hoffmeisteri, and larvae of Chironomus plumosus (Insecta) dominated in bottom animal communities there. More complicated situation was observed in the deep-water western part of the estuary. Glacial relict crustaceans , Monoporeia affinis and femorata sharply dominated in bottom animal communities until the 1990’s. Since the middle 1990’s these communities were deteriorated several times by periodic intrusions of poor oxygen near bottom waters from western part of the Gulf of Finland (Maximov, 2003). As a result, vast areas in the western part of the estuary became free from the aboriginal benthic fauna and were populated in 2000’s by alien species: oligochaetes Tubificoides pseudogaster and Marenzelleria neglecta (Maximov, 2007). Negative changes in benthic animal communities were observed also in the littoral zone of the eastern Gulf of Finland, were several alien amphipods and non-indigenous mollusk Dreissena polymoprha sharply dominated since the end of 1990’s (Orlova et al., 2006). One of the reason for the population development of alien species in shallow littoral is deterioration of native animal communities as a result of filamentous algae blooms which are observe there nowadays (Berezina et al., 2007). At the

Created with novaPDF Printer (www.novaPDF.com) moment, alien species contribute 60-99% of the total benthic biomass of the brackish part of the Neva Estuary (Orlova et al., 2006) So the present status of native animal communities in the lower brackish part of the Neva Estuary may be designated as poor (score 2).

3.3. Alien species: non-indigenous species Indicators: rate of new invasions and impact on community structure The problem of invasions of non-indigenous species is one of the most actual environmental problems of the eastern Gulf of Finland (Panov et al., 2002) due to its location at the termination of -Baltic invasion corridor and high intensity of ship cargo and oil transportation in the region. Dominant freshwater and brackish-water non-indigenous species (NIS) have originated from the Ponto-Caspian region, from the coastal waters of North America, and from inland waters of eastern Asia. Very high rate of new invasions was observed from 1998 to 2004 and to the moment these species account for 5 % of all animal species inhabit the eastern Gulf of Finland (Orlova et al., 2006). Key alien species from the Ponto-Caspian region is zebra mussel Dreissena polymorpha occupying deep littoral in the brackish part of the Neva Estuary. Now D. polymorpha contribute up to 96% of total biomass at stony and stony sandy mixed bottoms (Orlova et al., 2006). Apart from the damage for hydro technical facilities its main negative impact on environment is a facilitation of filamentous algae blooms in the littoral of the brackish part of the Neva Estuary by means of clearance the water and recycling of nutrients (Golubkov et al., 2003b). Two key NIS in the benthos of deep western part of the Neva Estuary are polychaetes Marenzelleria neglecta from North America and oligochaetes Tubificoides pseudogaster from the North Sea, that established in the eastern Gulf of Finland during last decade and contribute at the moment up to 70-99% of the total benthic biomass in deep waters of the gulf (Orlova et al., 2006). They replaced the native glacial relict crustaceans, that were widely distributing there until the middle of 1990’s, at vast areas in the western part of the estuary (Maximov, 2007). Replacement native nectobenthic crustaceans by alien worms negatively effects the populations of Baltic , the most important commercial fish in lower part of the Neva Estuary, decreasing availability of food for this species. Establishment of dense population of M. neglecta also contributes to eutrophication of this part of the Gulf of Finland due to its ability to enhance nutrient fluxes from bottom sediments (Golubkov et al., 2004). Two alien amphipods Gmelinoides fasciatus and Pontogammarus robustoides together contribute up to 45 % of total biomass in shallow littoral of both the Neva Bay and lower brackish part of the Neva Estuary (Orlova et al., 2006). They are omnivores and affect strongly the other zoobenthic species and replaced the native amphipod Gummarus lacustris in 1990’s (Berezina, Panov, 2003).

Created with novaPDF Printer (www.novaPDF.com) Another important alien species establishing in the littoral zone of the Neva Bay is a fish Perccotus plenii affect directly and indirectly native fishes such as roach and various juveniles in this part of the eastern Gulf of Finland. Predatory cladoceran Cercopagis pengoi should be mentioned among the planktonic NIS. This species contribute up to 33% of the total zooplankton biomass in the second half of recent summers and considerably affects planktonic community in the eastern Gulf of Finland (Telesh, 2004). All mentioned species established in the eastern Gulf of Finland during the last two decades, and nowadays affect different aspect of biodiversity and function of its ecosystem. Most of them arrived with ship ballast waters, but some such as crustacean G. fasciatus as a result of secondary invasions from continental water bodies where they were deliberately introduced by human. The reasons for considerable increase of the rate of NIS introduction are the deterioration of native communities as a result of high eutrophication, climatic fluctuations and exclusive increase of ship traffic in the region. Biodiversity status in this aspect may be designated as a moderate (score 3) for Neva Bay and poor (score 2) for the lower brackish part of the Neva Estuary.

3.4. Fish Indicators: Coastal fish community structure, and status of commercial fish species 53 species of cyclostomes and fishes have been recorded for the Eastern Gulf of Finland (Kudersky, 1996), including the most valuable but rare species like sea sturgeon Acipenser sturio and common at beginning of 20th centaury but now rare salmon Salmo solar. Fish populations include three ecological groups: marine, freshwater and anadromous species, but only part of them has a commercial importance. The most important marine Baltic species, sprat and cod, periodically come to the Neva Estuary and contribute considerably to fish catch but do not spawn there. Coastal areas especially in the Neva Bay and also in the large Gulf of Vyborg and Luga Bay provide spawning and feeding habitats for many marine, diadromous and freshwater fish. The most commercially important marine species, the Baltic herring Clupea harengus membras, comes to the coastal zone of the Eastern Gulf of Finland for a short time to spawn. Also many of diadromous species including the most numerous and commercially valuable smelt Osmerus eperlanus occur in near shore areas and in inflowing waters during the short time of spawning. But some species, e.g., commercially valuable Salmo solar, Salmo trutta, river lamprey Lampetra fluviatilis, stay in rivers during several years until they reach the migration stage (Kudersky, 1996). The total catch of the marine species increased since 1929-1950 until the middle 1970’s when it exceeded 25,000 ton yr-1, and was high enough until the begging of 1990’s (Kudersky, 1996). Since that time it has decreased greatly and now it is less than 5,000 ton yr-1 (Kudersky et al, 2007). The

Created with novaPDF Printer (www.novaPDF.com) reasons for this decrease connected with considerable diminish of nectobenthic populations of glacial crustacean relicts, the most valuable food items, which is resulted from climatic fluctuations (Maximov, 2003), progressive eutrophication in the coastal and open waters (Golubkov et al., 2003), and replacement of native benthic species by alien worms (Golubkov et al., 2007). The dynamics of herring catch in the Eastern Gulf of Finland is similar to general dynamics of commercial catch of this species in the Baltic Sea. The difference is that in the whole Baltic it decreased by only about 1.5 times during the last two decades (Kudersky, Alekseev, 2005). Similar trends to dramatic decline of population were observed for diadromous and freshwater fish. But in opposite to marine species substantial factors to these group of species is a lost of spawning and feeding areas due to the intensive dredging activity connected with constrictions of several new ports in the Luga Bay and in the Gulf of Vyborg and new lands in the Neva Bay (Kudersky et al, 2007). Very intensive public fishery is also partly responsible for the population decline of diadromous and freshwater fish during the last decade (Popov, 2006). Opposite to some other Baltic coastal regions, where significant trend to increase of perch and roach catches were observed during the last decade (Adjers et al., 2006) definite decline of the populations of all species (except alien Perccotus plenii) are observed in the Eastern Gulf of Finland since 1970-1980’s. Several species, e.g. sea lamprey Petromyzon marinus and trout Salmo trutta are included in the Red Data Book of Nature of the Leningrad Region (2002) as endangered. Total catch of fish spawning in the Neva Bay has decreased 4 times as compared with the beginning 1980’s (Kudersky et al, 2007). Thus, taking into account great decline of commercial fish species status of fish populations in both units of the Eastern Gulf of Finland may be considered as poor (score 2).

3.5. Avifauna Indicator: Coastal bird species populations (key groups – sea ducks, divers, eiders, auks, cormorants) The avifauna of the eastern Gulf of Finland relatively well documented in the scientific literature. In 1920-1940’s it was investigated by Finish ornithologists (e.g., Рutkonen, 1936, 1942), then investigations were continued by Russian scientists (e.g., Malchevskiy, Pukinskiy, 1983; Khrabriy, 1991; Noskov et al., 1993; Bublichenko 2000; Afanasyeva et al. 2001). As a result, it was shown that to the moment coastal zone of the Eastern Gulf of Finland used by 234 bird species for nesting, foraging and rest during seasonal migrations (Khrabriy, 2007). That makes this part the Baltic Sea by one of the most important regions for conservation and protection of bird fauna. There is a great difference in long-term dynamics in avifauna in two hydro-geo-morphological units of the eastern Gulf of Finland. Lower western part of the Neva Estuary for a long time was a state border restricted area for public excess and most kinds of economical activity. Therefore,

Created with novaPDF Printer (www.novaPDF.com) observed changes are probably mostly related to natural dynamics. The abundance of some species has decreased. For instance, large merganser Mergus merganser and middle merganser Mergus serrator were numerous birds in the north-western part of the area until the end of 1970’s (Khrabriy, 1984), but their number decreased greatly during the last two decades and now they have become a rear nesting species (Khrabriy, 2007). On the other hand, population of the large cormorant Phalacrocorax carbo considerably increased in number in the lower western part of the Neva Estuary during last decades (Gaginskaya, 1995) and this species become as common as another cormorant Phalacrocorax aristotilis. Grebes Podiceps auritus and Podiceps cristatus are common species in this area, but loons Gavia arctica and Gavia stellata are endangered. Tufted duck Aythia fuligula is common, but greater scaup Aythia marila is rear (Khrabriy, 2007). Auks Alca torda and Cepphus grille are relatively rear. In general, the present status of coastal bird populations of the lower brackish part of the Neva Estuary may be considered as good (score 4), but their future is uncertain, due to a great intensification of oil transportation in the area, which increases the risk of oil spills in the region. This is especially anxious because shallow littoral near Kurgalskiy Peninsula in the south-western part of the Neva Estuary and near the islands in its central and northern parts is one of the most important resting places of waterfowl during seasonal migrations in the eastern Baltic (Noskov, 2002, Khrabriy, 2007). Gradual increase in public and industrial companies’ excess to the region negatively affects aviafauna of the region nowadays. This situation may be improved by establishment of national reserves especially at the islands situated in the lower part the estuary. Quite another biodiversity dynamics one may observe in the Neva Bay where it is greatly affected by anthropogenic factors. In former time the eastern part of the bay together with River Neva Delta was one of the important habitat and bird migration resting place in the eastern Baltic for numerous species of waterfowl (Malchevskiy, Pukinskiy, 1983; Khrabriy, 2007). Unfortunately, these important habitats are practically lost nowadays as a result of great widening of St. Petersburg City and its suburbs since the beginning of 1980’s. The number of the coastal birds has decreased dozens of times. This lost is partly compensated due to expansion of reeds in the eastern part of the Neva Bay as a consequence of the Dam construction. Some species such as gadwall duck Anas strepera appeared recently and became abundant there (Richkova, 2004). Abundant bird colonies also retained near and in the reads along southern and northern coast of the Neva Bay. Status of biodiversity of coastal birds in Neva Bay may be considered as moderate (score 3).

Created with novaPDF Printer (www.novaPDF.com) 3.6. Mammals Indicator: Seal species population Two seal species, Baltic subspecies of Gray seal Halichoerus grupus and Baltic ringed seal Phoca hispida botnica, were very abundant in the Baltic Sea at the beginning of the XX centaury, when their number were supposed to be about 200,000 (Verevkin, Sagitov, 2004). Progressive decrease of seal number was observed during the whole last centaury. The first data on the number of ringed seal in the eastern Gulf of Finland, 5,000 seals, were obtained in 1970 (Rezvov, 1975; Tormosov, 1977). It was estimated as 5,000 seals. In 1982-1985 their number decreased to 4,000 (Tormosov, Esipenko, 1990). Massive death of ringed seals was observed in 1991-1992: more then 150 corpses, mostly adult , were found at the coast and islands of the eastern Gulf of Finland. At present, its population has dramatically declined and recent surveys indicated about 300 ringed seal (Verevkin, Sagitov, 2004). This species lives in the eastern Gulf of Finland during the whole year: in winter they are most abundant in northern part of the Gulf: to the south and south-west from Bolshoy Beriozoviy Island, but in summer they migrate to the southern part of the Gulf. As in the other parts of the Baltic Sea the main reasons of population decline are eutrophication and pollution, fisheries’ by- catch and habitat destruction. As compared to the other regions of the Northern Baltic, where some progressive increase in seal numbers has been observing during the last decades (http://www.helcom.fi/environment2/biodiv/seals/), the ringed seal population in the eastern Gulf of Finland remains at a very low level. In contrast to ringed seals, gray seals occur in the eastern Gulf of Finland mostly in summer (Verevkin, Sagitov, 2004). They mostly occur in the south-western part of the estuary. About 100 gray seals were recorded in 1970’s; 200-300 seals in 1980’s (Red Book of Russian Federation, 2001). 400- 500 grey seals occurred in the western part of the Neva Estuary nowadays (Verevkin, Sagitov, 2004). Therefore, the number of these seals has a tendency to increase, but it is still very low in comparison with the beginning of the last centaury. So, in general, taking into account more then tenfold decrease of the number of ringed seals and some increase of occurrence of gray seals status of seal populations in Neva Estuary may be considered as poor (score 2).

3.7. Status of Baltic Sea Protected Areas Indicator: Percentage of the valuable biotic components covered by the MPA There are no special MPA in the eastern Gulf of Finland, but some terrestrial specific protected natural territories (PT) that have been already established at its coast or will be established in nearest future include the part of the marine area. Eleven of them are acting and four are at a planning stage. The largest and most important acting protected territories are partial regional complex sanctuaries

Created with novaPDF Printer (www.novaPDF.com) Beryozovyye Islands and Kurgalskiy. The first one locates in the northern western part of the Neva Estuary and includes 45,320 ha of marine area; the second one locates in southern part of the gulf and covers 38,400 ha of water surface (Red Data Book of Nature of the Leningrad Region, 1999). Both of them are very important for protection of marine bird populations, bird migration areas, Baltic seals and other components of marine biodiversity. Vyborgsky Sanctuary in the Gulf of Vyborg includes about 5,000 ha of water area. Large Ramsar Site Lebyazhye situates along the southern-eastern cost of the brackish part of the Neva Estuary. Its area is 6,400 ha. This site along with Vyborgsky Sanctuary preserves the coastal landscape and stop-overs of migratory birds and nesting sites of waterfowl and coastal birds. Very important PT, Ingermanlandsky Strict Natural Reserve, should be established at several islands scattered in the western part of the Neva Estuary at the end of 2007. It will also cover considerable marine area (16,980 ha) near the coast of the islands and together with sanctuaries Beryozovyye Islands and Kurgalskiy supposed to be very effective in conservation of marine and island wild-life. So the status of Baltic Sea Protected Areas in lower brackish part of the Neva Estuary may be considered as good (score 4). Much worse situation with protection of marine environment is the Neva Bay although this part of the eastern Gulf of Finland is also very important for wild-life conservation, e.g., coastal bird populations. Only two very small areas along the southern coast of the bay have status of natural monuments where economic activity is restricted. Two large PT are proposed to be established in north-western part of the bay and near Kotlin Island to preserve coastal bird populations and stop- overs of migratory birds. But at the moment the status of Baltic Sea Protected Areas in the Neva Bay is bad (score 1).

4. Results of the scoring exercise The results of biodiversity assessment in two hydro-geo-morphological units of the eastern Gulf of Finland are presented in Table 1.

Table 1. Estimated quality or health status of biodiversity indicators in the eastern Gulf of Finland

Scoring: Biodiversity indicators v. Reference conditions Area Scoring/ Phtob. Zoob. Aliens Fish Birds Mammals BSPA Status Neva Bay 2 3 3 2 3 - 1 14/poor Brakish part of 3 2 2 2 4 1 4 18/moderate the Neva Estuary

Created with novaPDF Printer (www.novaPDF.com) The following assessment of biodiversity status has been applied: Neva Bay (variable 1 to 3, average – 2) – poor. The main losses of biodiversity include disappearance of more than 75 % of submerged vascular plant meadows and disappearance of main spawning areas of fish in the eastern part of the bay. Alien species contribute up to 45 % of total biomass of zoobenthos in shallow littoral. At present, protected areas, which may promote to biodiversity conservation in this part of the eastern Gulf of Finland, are absent. Brackish part of the Neva Estuary (variable 1 to 4, average – 3) – moderate. The main losses of biodiversity include disappearance of more than 90 % of seal populations, fivefold decrease of commercial fish catch, and replacement of native dominant zoobenthic species by aliens in coastal and open waters. Good status may be considered only for marine birds due to a relatively good situation with protected areas in this part of the gulf, which mostly directed to conservation of bird biodiversity.

5. The role of climatic and anthropogenic factors in biodiversity dynamics Alien species and eutrophication are the most important threats to biodiversity in the brackish part the Neva Estuary nowadays. Climatic mediated fluctuations in near bottom oxygen conditions are the main natural factor responsible for the dynamics of benthic communities in this part of the estuary. Deterioration of environment leads to decline of aboriginal and prosperity of invasive species. Alien species contribute about 8 per cent of species richness and 60 - 90 per cent of biomass of the bottom animal communities. Filamentous algae blooms and macroalgal floating mats resulted from progressive eutrophication of the region negatively affect biodiversity dynamics in shallow coastal zone. Exclusive increase of ship traffic in the region also contributes to hasten of the rate of new invasions. Decline of bottom natural communities mostly dominated by crustacean leads to impairment of food conditions for fish and contributes greatly to sharp reduction of their populations, which in turn may be partly responsible for population decline of ringed seals. Large-scale digging and dumping of bottom sediments connected with constructions of new lands, ports and oil terminals is important group of anthropogenic factors responsible for negative dynamics of biodiversity in the Neva Bay and in shallow coastal zone of the brackish part of the Neva Estuary. This activity affects fish spawning grounds, submerged macrophyte communities and destroys important habitat and bird migration resting place. Most of fish spawning grounds in the shallow Neva Bay were lost during the last decades. On the other hand climatic mediated factors such as fluctuations in Neva River run-off are at least partly responsible for long-term dynamics of bottom animal communities and food conditions for fish in this part of the eastern Gulf of Finland. Therefore, long-term forecasts and measures for conservation and improving biological diversity should take into account the periodicity of climate changes and planned development of the region.

Created with novaPDF Printer (www.novaPDF.com) 6. Summary/Recommendations: advices and recommendations to decision makers for conservation and improving biological diversity

 Eastern Gulf of Finland is a complicated natural system, which biodiversity suffered from diverse anthropogenic impacts: high nutrient and contaminant loads, high fisheries, dredging and creation of new lands, high ship traffic. The boundary of the region coincides with the boundary of the Neva Estuary and consists of two natural sub-systems: upper freshwater Neva Bay and lower brackish water part of the estuary.

 Biodiversity status of these areas according to priority indicators proposed by ICES/BSRP Study group on Ecosystem Health (SGEH) assessed as “bad” for the Neva Bay and “moderate” for the brackish part of the Neva Estuary.

 To improve biological diversity of the eastern Gulf of Finland the intensity of anthropogenic impacts such as nutrient and contaminant loads, dredging and creation of new lands, construction of new ports should be reduced. Toughening of legislation to control of ballast waters and of deliberate acclimations of new species in the region is necessary. There is sufficient number of protected areas in the lower brackish part of the Neva Estuary but they mostly aimed to protect bird and land habitats. Status of true marine protected areas (MPA) should be distributed to marine parts of existing and proposed protected areas.

For selected areas some specific measures should be taken:

Neva Bay: restriction of dredging in the eastern part of the bay; restoring of spawning grounds for commercial fish species; further reduce of nutrient load from sewage plants of St. Petersburg and reduce the use of nutrients in agriculture at River Neva watershed; establishment of MPA along the northern and southern coasts of the bay and near Kotlin Island.

Brackish part of the Neva Estuary: further reduce of nutrient load from sewage plants of St. Petersburg and other cities in the region and reduce the use of nutrients in agriculture at River Neva watershed; further development of the measures for security of the oil transportation; restriction of construction of new port facilities in the vicinity of protected areas; improvement of the regulation of commercial fisheries in the region; development of preventive measures of overexploitation of the coastal zone by tourists, e.g., forbidden of pitching the tent, camp-fire, organization of scavenging, etc.

Created with novaPDF Printer (www.novaPDF.com) Acknowledgements I thank Eugeniusz Andrulewicz for helpful comments and amendments of the manuscript.

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