ANISIMOVA N.A., BERENBOIM B.I., LUBIN P.A., MANUSHIN I.E. Polar Research Institute of Marine Fisheries and Oceanography

Intensified oil and gas development on the shelf of the Barents Sea, one of major sources of fish resources of the polar region of the Russian Federation, puts on the agenda a number of issues relating to protection of environment, conservation of biological resources and development of long-term plans of their sustainable exploitation.

One of the key tasks of today is ecological monitoring of the status of environment and biota, where comparative assessment of the natural variability of biota induced by climatic factors and caused by adverse impacts of various economic activities is one of the components. With this aim is mind, of main interest are both regional studies of benthos in areas of the most intensive anthropogenic impact and large-scale surveys making it possible to determine the most significant factors of marine ecosystem impact in general and the most vulnerable regions to these factors.

It is recognized, that benthos as an indicator of environment changes (both at the level of biocenosis and population and species level) has an essential advantage relative to other biological objects of monitoring (e.g. pelagic organisms and communities). It is steady over time, describes well local situations in space and can reflect historic changes in the ecosystem. Descriptions of benthic communities provide a very good integral assessment of environment quality taking into account cumulative effect of all anthropogenic impacts and covering an entire variety of combinations of abiotic factors.

Studies of benthos were always one of the important directions of research activities undertaken by PINRO. One of the most comprehensive studies in this field was a total benthos survey in the Barents Sea carried out by the Polar Research Institute in 1968-1970. Unquestionable virtue of this survey was that all materials were collected within a very short time and according to one and the same methodology. Information provided by that survey was an important part of an array of scientific data obtained in a row of long-term studies to monitor the impact of large-scale climatic fluctuations on both the bottom community of the Arctic region and on the ecosystem of the Barents Sea in general.

The comparison of collected data with results from the surveys conducted in 1926-1935 (Brotskaya. and Zenkevich, 1939) and with long-term observations along the standard oceanographic section "Kola meridian" revealed that anthropogenic factors in the Barents Sea, in particular the effects of demersal trawling, can be compared to impacts of climate fluctuations with regard to the level of influence on bottom inhabitants (Denisenko. 2001).

In 2003 PINRO recommenced studies of benthos. An impetus to this was an initiative to continue the series of studies for monitoring the status of bottom biota in the Barents Sea as one of the important elements of the ecological system in this region.

Another incentive to conduct large-scale studies of benthos was increased pressure of anthropogenic factors at all levels of the ecological system. If during the time interval between benthos surveys in 1926-35 and 1968-70 the fishing was an essential factor of anthropogenic influence on the Barents Sea ecosystem, a list of such factors essentially extended in subsequent years. Among the most significant factors we can mention expansion of bottom fisheries owing to inclusion of new fishing targets (Iceland scallop, northern shrimp, red king crab), increase of anthropogenic pollution, including radiation pollution, changes in structure of bottom communities as a result of deliberate (red king crab) or random (snow crab) introduction of new species. Furthermore, rapid growth of exploitation of oil and gas fields on the Barents Sea shelf in the last decade should be specially emphasized.

In the course of the next benthos survey it is envisaged to cover the same grid of stations as in 1968-1970 collect materials according to the methodology enabling to apply all modem methods for assessing the impacts at the level of biocenosis and population and species level and undertake more thorough studies in areas of the heaviest anthropogenic impact, including that resulting from exploitation of oil and gas fields.

This program was launched in 2003 by conducting a complex expedition organized by PINRO. A hydrographic navy vessel "Romuald Muklevich" conducted a survey of benthos in the Varangerfjord, Motovsky Bay and the area between 74°N and Murman coast, and from the Kola Meridian to 45°E. A total of 95 stations were completed, where 470 samples were collected by van Veen grabs and 76 hauls by Sigsby trawl were taken. Currently all materials are in the process of being analyzed at PINRO.

In 2004 within the frames of this program benthos survey will be undertaken to cover the south-eastern part of the Barents Sea, including the whole area of the Pechora Sea and eastern areas as far to the north as 74°N. The proposed area will include the Stockman gas field and all oil and gas-bearing structures in the Pechora Sea.

References
Brotskaya V.A. and L.A. Zenkevich. 1939. Quantitative estimation of bottom fauna in the Barents Sea. Trudy VNIRO, vol. 4, p.3-127. (In Russian)
Denisenko S. 2001. Lons-term chanses of zoobenthos biomass in the Barents Sea. Proc. Zool. Inst. Russ. Acad. Sci. p. 59-66.

ARCTIC SHELF OIL AND GAS CONFERENCE 2004