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Главная THE RESULTS OF LONG-TERM ECOLOGICAL MONITORING OF THE BARENTS SEA COASTAL AREA
THE RESULTS OF LONG-TERM ECOLOGICAL MONITORING OF THE BARENTS SEA COASTAL AREA Печать E-mail

SOKOLOV V.I., SHTRIK V.A., Russian Federal Research Institute of Fisheries and Oceanography, Russia

High prices for energy make exploitation of oil and gas on the continental shelf challenging even in rough northern conditions. Conversion of the resources of the Barents Sea coastal area into reserves is one of strategic concerns of Russia. However, the projects on exploitation of already explored reservoirs in the Barents and Pechora Seas, transportation and processing of oil and gas may have substantial effect on environmental situation in the region in general and on fisheries resources in particular. Coastal areas are especially vulnerable to negative effects of oil and gas complex, as potential oil spills would first of all affect coastal territories. Coastal areas are characterized by high level of biological diversity due to the large number and variability of environmental factors influencing coastal ecosystems. Coastal areas are also very important as fishery grounds. Coastal area provides the only habitat for some species (e.g. marine algae, sea urchins), while playing a key role in the life cycles of other species of commercial importance (e.g. the red king crab).

The Laboratory of Commercial Invertebrates and Algae of the Russian Federal Research Institute of Fisheries and Oceanography (VMRO) has started the project on the complex monitoring of bottom biocenoses of the Barents Sea coastal waters in 2002. Primary goals of the project included not only collection of the data on environmental quality of the area before exploitation of the reservoirs and transportation of oil and gas, but also monitoring the effects of other kinds of human activities, observations on natural interannual and seasonal dynamics of the abundance of certain species, as well as preparation of maps of the Kola Peninsula indicating sites of special fishery importance.

In 2002 Guba Teriberka was chosen as a polygon for the studies. On one hand, this bay is the place where nearshore fishing fleet is based and where fish food processing factories are located, and, on another hand, this area is considered as a potential place for building a terminal. In 2003 the study area was expanded and included the most part of the Kola Peninsula, from Guba Pechenga (Varanger-fjord) to the Varzuga River (White Sea basin). In 2004-2005 technical difficulties did not allow to continue the monitoring in all the polygons studied in 2004-2005, but key polygons have nevertheless been described. Therefore, we established ecological monitoring system of the coastal areas of the Barents and White Seas, which incorporates 16 polygons described by means of unified methods.

Besides biocenoses descriptions, we have conducted the assessment of stock abundance for commercial and semi-commercial species of bottom-living invertebrates and algae. We have also studied the patterns of seasonal distribution of migrating animals, first of all the red king crab and echinoids, and determined the areas that provide especially favorable habitats and nursery grounds for these species. Additionally, we collected specimens for the analyses of heavy metals and hydrocarbons content in the tissues of aquatic animals and bottom sediments.

Coastal area of the Kola Peninsula of the Barents Sea has been divided into sectors. Within each sector, a polygon containing one or two bays and the offshore areas has been selected. Thus, in 2002-2005 the following areas of the Barents Sea coast have been monitored: Guba Pechenga and Guba Ambarnaya (Varanger-fjord), Guba Titovka, Guba Vichany, Guba Ura, parts of the Kola Bay, Guba Dolgaya, Guba Zelenaya, Guba Teriberka, Guba Voronja, Guba Yarnishnaya, Guba Dalnezelenetskaya, Guba Tryashina, Guba Porchniha, Guba Krasnaya, Guba
 
Podpahta, the areas aroung Bolshoi Olenii Island and Seven Islands Arkhipelago, Guba Drozdovka, Guba Ivanovskaya and Svyatonossky Bay.
In commercially important species, size and gender structure of the population and condition of coastal aggregations has been studied. The following species have been considered commercial or semi-commercial: the red king crab (Paralithodes camtschaticus), mussels (Mytilus edulis, Modiolus modiolus) island scallop (Chlamis islandicus), urchins (Strongylocentrotus droebachiensis, S. pallidus, Echinus esculentus), Cucumaria frondosa, Arctica islandica. The specimens of the following species were collected for analyses of heavy metals and content in tissues: mussels, island scallop, red king crab and sea urchin (S. droebachiensis).

During the 4-year period of study, no substantial changes in distribution and average biomass of sessile benthic organisms have been recorded. Distribution and abundance of slow moving invertebrates, such as sea urchins, brittlestars and sea stars, changed in relation to the season when the studies where conducted. The most significant seasonal and annual changes were recorded for migrating animals: red king crab, shrimps (Pandalus montagui, Eualus gaimardi, Lebbeuspolaris, Spirontocaros spinus, S. phippsi, Sclerocrangon boreas, etc.), spider crabs (Hyas araneus), and hermit crabs (Pagunis pubescens, P. bemhardus). Average density of mature males in summer was the highest in the area of Seven Islands Archipelago and in 2003-2005 increased from 6.2 to 12.6 individuals per 1000 m2.

However, in Guba Teriberka area average abundance of this group has been observed to decrease constantly during the same period. In Varanger-fjord and Motovsky Bay average density was estimated as 3 to 5 individuals per 1000 m2, and the changes in abundance observed could be explained by the variability of seasons when the studies were conducted. Maximum densities of crabs were observed in June, while in July and August the abundance of mature males at the depths 0-40 m drastically decreased at all polygons.

Average abundance of mature females of the red king crab was higher in western areas. In early summer most females were found at the depths from 3 to 30 m in the middle portions of the bays. In August and September their abundance decreased in all the polygons, but still remained higher than the abundance of males. In 2004 average densities of mature females were lower in all the polygons compared to those in 2003. In 2005 this tendency was observed again in the eastern Murman area.

The highest average density of immature individuals of the red king crab was observed in the Varanger-fjord. Mass settlement of the larvae of the red king crab was recorded in the Varanger-fjord, the Motovsky Bay and Guba Drozdovka. In these areas the density of glaucothoe in some biocenoses reached 1000 individuals per m. Lower densities were observed in Guba Teriberka and Guba Zelenaya. Thus, the most important areas for the reproduction of this commercially valuable species are Varanger-fjord and Motovsky Bay, and Guba Teriberka and Guba Drozdovka to the east of Kola Bay.

Average density of sea urchins S. droebachiensis has been changing insignificantly during a 3-year study period. This species was found commonly in rocky biotopes and, less frequently, on muddy bottoms at the depths from 2 to 30 m in the biocenoses of Laminaria spp. and Lithotamnion spp. In the Voronka and Gorlo of the White Sea low abundance of this species was recorded. Maximum densities of S. droebachiensis were observed off Seven Islands Archipelago, in Guba Ura and Svyatonossky Bay Island scallop Chlamis islandicus was observed in all the polygons in the Barents Sea investigated.

It has also been found in the Gorlo of the White Sea. In all the polygons of the Barents Sea commercial-size scallops (with shell height of more than 60mm) were primarily found, while the percentage of small individuals was always low.

Densities and biomass of the horse mussel Modiolus modiolus has also been changing insignificantly during a 3-year study period. This species was observed to form dense beds in Varanger-fjord, Motovsky Bay, off the Bolshoi Olenii Island and Seven Islands Archipelago. The largest density and biomass of this species (up to 140 individuals per m2 and 12 kg per m, respectively) were recorded in Guba Vichany and Guba Ura.

One of the most important directions of our monitoring program was the collection of the data on hydrocarbons and heavy metals content in the tissues of aquatic animals and bottom sediments. Among toxic substances of human-induced origin, oil products represent one of the most harmful matters.

Our studies have demonstrated that even before the start of oil and gas field operations in some areas of the Kola Peninsula tissues of aquatic animals contain relatively large quantities of toxic substances. In mussels the overall hydrocarbons content ranged from 3.16 to 18.17 mg per kg, depending on the habitat area. High hydrocarbons content was found in mussels from Guba Teriberka (11.09 mg per kg), Svyatonossky Bay (12.50 mg per kg), polygons off Bolshoi Olenii Island (13.17 mg per kg) and Seven Islands Archipelago (18.17 mg per kg). C12-C22/C23-C34 ratio was around or even more than 50% in the mussels from Guba Pechenga (42.04%), Guba Ura (45.3%), Guba Teriberka (47.2%). The highest content of cancerogenic polyaromatic hydrocarbons was recorded in mussels in Kola Bay (55.92 ug per kg), Guba Pechenga and Guba Teriberka (24.3 ug per kg) and off Bolshoi Olenii Island (36.4 ug per kg). The highest chrisen content was found in mussels from the Kola Bay (48.52 ug per kg).

Similar studies on hydrocarbons and heavy metals content were performed on other model species. As long as mussels are one of important component red king crab diet on various stages of its ontogenesis, the accumulation of toxic substances in these mollusks may adversely affect the state of red king crab populations. Our studies have revealed similar trends in cadmium content in the muscles of the red king crab and the mussel. However, additional investigations are needed in order to support these data.

OIL AND GAS OF ARCTIC SHELF 2006 (PROCEEDINGS OF INTERNATIONAL CONFERENCE) 

 


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