SHIROKOLOBOVA T.I., VENGER M.P.
Murmansk Marine Biological Institute RAS, Russia Murmansk State Technical University, Russia

Putting into operation of the planned objects of the Stockman gas- condensate field leads inevitably to the increase of the anthropogenic pressure on the marine coastal ecosystems.

The major load falls on the bays and gulfs areas as the construction and exploitation of the ports, supply bases, cargo terminals etc promote traditionally to the exceeding of Total Allowable Concentrations of pollutants in the aquatic environment.

The problem of investigation of natural ecosystems to overcome similar types of the loadings is raised sharply and the study of the state of hydrobiontes is one among the problems of primary importance. Indisputable priority in the oxidation, destruction and mineralization of the pollutants belongs to the bacterial communities. Capability to the quick adaptation in new conditions, a wide set of the enzyme systems allow them using and transforming different organic compounds. Location at the beginning of the chain of biological oxidation of contaminants, microbes destruct highly toxic organic compounds, decrease toxicity of heavy metals (Oleinik et al., 1996), oxidize till simple compounds oil hydrocarbons (Alekin et al., 1984).

Abundance and composition of bacterial population, participating in the self purification processes in the coastal zone of the Barents Sea have been for quite a long time the object for the investigations by MMBI microbiologists. Thus, it was shown on the large fact material that three peaks of abundance are typical for the seasonal dynamics of microorganisms in the Murmansk coastal zone bays: the first is in March when concentrations of bacterial cells reached its maximum, then in July and in September. Annual average values of total abundance and biomass for separate depths practically coincided.

Dominance of the cocci forms was revealed everywhere in the bacetrioplankton structure with the dimension fraction of cells in the range 0.2 - 2 mkm. According to the results obtained values fluctuations of structural characteristics were as follows: 200xl03 - 1300xl03 cells /ml, 76 - 497mg/m³ at the average values 554xl031cells/ml and 204.3mg/m³ for the abundance and biomass, correspondingly (Kuznetsov et al., 1996; Baitaz, Pesegov, 1991).

Distribution of large amounts of bacterial cells in the water column of the Barents Sea was of the mosaic character and corresponded to the accumulation zones of the quickly assimilated organics. Heterotrophs constituted single- tens of cells in 1 ml in the water masses of gulfs and bays in the western and in the eastern coastal parts in winter increasing till hundred cells/ml by summer. Bays and gulfs in the central coastal area subjected to the fresh-water run-off and anthropogenic impact characterized more significant values of saprophyte micro-flora: hundred and thousand cells in ml for winter and hundred of thousand cells in ml for summer (Teplinskaya, 1985; Pesegov, 1991).

Microbiological parameters of general and saprophyte bacterioplankton allowed referring to the gulfs and bays' areas of Central Murman to the mezotrophic type of water basin with approaching to the lower boundary of the eutotrphic waters (Baitaz, Baitaz, 1991; Mishustma et al., 1997).
The necessity to carry out expert estimations of the damage caused to the gulfs and bays areas by the human activity demands a complete impression on the current state of their biocenoses. In this connection the information obtained during the conducted by the MMBI scientists Kola bay monitoring which constituent part are microbiological investigations seems opportune. Existing incomplete data on the bacterioplankton on its area are limited by only summer period (Baitaz, Baitaz,1991, Peretrukhina, 2001), thus, the results of the structural characteristics of the bacterial population in the gulf by three winter hydrological seasons: 2001-2002., 2002-2003, and 2005-2006., obtained by the methods of epi-fluorescent microscopy and traditional sowing are of special interest. Membrane filter staining was carried out with fluorescamine, cultivation -on the dense media SPA, Gorbenko and agar Difko.

The survey data testify to the significant density of bacterial cells in the water column in the southern Kola bay. Their structural characteristics varied in large range: total abundance- in the range 26x10 - 3600x10 in ml, biomass 40 - 2733 mg/m , constituting in average 780x10 cells/ml, and 562.2 mg/m3. The near bottom layers turned out the poorest as for the microorganisms' contents, there the average abundance values were 2.15 times as low in respect to the surface waters. Averaged for the surface data from three stations near the eastern coast and from one station near the western station constituted by abundance and biomass 915x103 cells/ml and 691.3 mg/m3, correspondingly. Dominance of the cocci microorganisms served marker the presence in the sea environment of labial components of the organic matter is revealed in the morphostrucrure of the bacterial community (Baitaz, 1998). Their high percent from the total abundance preserved during three winter seasons might testify to the input of large contamination dozes of the organic origin.

Comparative investigation of the heterotrophic component of the bacterial population in the southern part of the bay showed the increase of its density along the east coast. A typical division into the zones connected first of all with the inequality of the input of the domestic sewerage into the bay is observed here in the distribution of the bacteria- destructors of the organic matter. Thus, fluctuations of heterotrophic bacteria abundance in the surface waters of the contaminated to the largest degree areas of the southern berths constituted 2 orders (min 1x103 - max 140x10 ), and in a relatively clean bay's areas (the Zeleny cape area), fluctuations were insignificant and bacteria contents did not exceed a thousand of colony formation units (Сое) in ml.

Ecological - trophic composition of microorganisms in the period when hydrological winter comes to its end revealed as the result of the three weekly surveys in the middle among the stations on the eastern coast of the bay showed the presence of significant amounts of the oligotrophic (2.3x103coe/ml) and eutotrophic (1.7x103) organisms. A stable preservation of the numerical values of one order for the upper and the lower depths at the existing salinity gradient which is 13-14% is a peculiarity of their distribution. It should be stated that the average values of heterotrophic bacteria on the Gorbenko medium for the area were 3.7x103 Coe/ml.

Analysis of the obtained results on the density of the bacterial population in the water column of the Kola Bay showed that the averaged for the three winter seasons data are comparable with the literature data. The existing differences are connected with the amplitude of fluctuation of total bacterioplankton. They constituted two orders for the bay and were maximally expressed in the surface layer. The ratio of the total number of micro- organisms to the number of heterotrophs was greater for the Murmansk coast (280) in comparison to that of the bay (210). This fact and the close to the values' indices of the number of the growing on SPA and on the agar Disco colonies point out to the eutrophication of the Kola bay waters.

Relatively high values of different ecologic - trophic microorganisms' groups in the investigated area during winter period testify to the active destruction processes of the organic matter.

The data on the investigations of the microorganisms' population structure in the Kola bay presented might be used as both: background for the carrying out expert estimations of a possible damage from the construction and exploitation of the coal and oil terminal in the southern part of the bay.

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