Murmansk Marine Biological Institute RAS, Russia,
Southern Science Center RAS, Russia,
Lukoil-Nizhnevoljsk-neft, Russia

"Lukoil" Ltd. set protection of biological resources and environment from the oil- gas exploitation activity as one of the priority tasks from the onset of its activity in the Caspian Sea. This resulted in acceptance of a "zero discharge" principal which served the basis of "Lukoil" Ltd. ecological security system in the Caspian Sea. Already in the mid- 90s of the last century "Lukoil" Ltd. established a wide network of the industrial monitoring covering the Northern Caspian area in the limits of the licensed areas of the company, and this lead to the accumulation of the unique material on the state of the Caspian Sea ecosystem. Nowadays the company is confronted the task of the adequate interpretation of the data available, creation of the models allowing forecasting the response of the Northern Caspian ecosystem taking into consideration variability of the nature factors to a possible environmental contamination, reveal the zones of ecological sensitivity.

Ecosystem approach to the description of marine basins is applied in MMBI for more than 15 years for the seas of the north-western sector of Arctic. On the basis of available in MMBI developments in the field of ecological mapping, establishment and interpretation of the data bases carried out together with NOAA (USA) on the Program «Large Marine Ecosystems» in the frames of a joint cooperation with "LUKOIL Nizhnevolzhsk-neft» Ltd. a generalized structural scheme of Northern Caspian including significant trophic objects of both: off-sea and coastal areas was established.

Three ecological zones distinguished significantly from each other are revealed in the Northern Caspian, they are: coastal, estuary and marine. These zones are located in the areas of either existing or supposed oil-gas excavation and on the basis of the trophic linkages they unite several complexes of the key biological species of the Northern Caspian ecosystem. Estimation of the boundaries is the most difficult problem as the sea level, fluvial run-off fluctuations, wind regime affect significantly the location of zones relative to each other. Coastal (fresh-water) zone is the smallest as far as the area is concerned, but it plays a significant role in the functioning of the whole ecosystem (the first place on the specific productivity). Estuary (brackish water), the largest by the area extent and plays the most significant role from the point of view of the participation of the key biological species (benthic forms, sturgeons, birds). Sea zone (sea down-slope) in the ecosystem ranging of the Northern Caspian area occupies a place of the transitional link between the brackish water part and the Middle Caspian (transit of the matter, energy, organisms: seal, fishes, comb-bearer mnemiopis) is distinguished by a lesser productivity in comparison to the two above mentioned zones.

On the basis of the carried out ecological division of the territory into separate areas a preliminary selection of the Northern Caspian zones of ecological vulnerability became possible. To solve this problem the integral method considering several methodical approaches was applied. It should be noted that to reveal the reaction of ecological systems on the external impacts different indices have been developed already for quite a long period of time. The integral indices, for instance AMBI (Marine Biotic Index) seem to be the most attractive. The approach based on NOAA method is directed mainly on the reveal of the sensitive zones in the coastal zone and is directed to a great degree to the consideration of the rare and socially significant biological
objects. For the estimation of the long-term effects the approaches connected with the development of mathematical models of the ecosystem, for instance, its trophodynamic components are used, which allows obtaining a quantitative integral estimate of the impact on the ecosystem upon the whole, local impacts on its separate components in conditions of the simultaneous impact of climatic factors and other types of the anthropogenic activity.

Biological objects (species, populations, ecological groupings) are the basis determining ecological sensitivity of the Northern Caspian area.
The established mathematical models of the response of the waterfowl abundance to oil contamination in the shallow-water part of the Northern Caspian may be given as an example of the application of the pointed above model apparatus to solve the problems connected with the estimations of risk from oil-gas excavation activity in the most sensitive coastal zone in the Northern Caspian. The calculation results have shown a heterogenous distribution of birds along the sea edge and in the zones located far from it. Mouth areas of the Volga, the Terek, and the Ural Rivers turned out to be the most vulnerable zones.. Depending on dynamics of the level of the Caspian Sea the birds might be concentrated either farther from the sea margin of the nesting area (in the period of a sharp fall of the sea level) or be in the vicinity of it (in the period of rise of the sea level). Comparative analysis showed differences in species distribution along the sea margin in the nesting area. Abundance of mute swan, grey-lag goose, mallard in the "kultuk" (deeply jagged shallow bay) zone and in the fore-delta decreased, spatial re-distribution of birds took place. Nowadays mallard and bald coot nest in the zones located at the significant distance from the sea. "The kultuk" (deeply jagged shallow bay) and fore-delta preserve their significance as the nesting areas only for the mute swan and grey-lag goose (model abundance estimation of these species along the sea margin of the nesting area is identical which is explained by similar requirements to biotope). This increases a probability of birds' mortality at the accidental oil spills. It is important to notice a seasonal character of variability of the degree of danger. During a reproductive period (spring- start of summer) the total birds' mortality will be insignificant as the majority of bird species nest farther from the sea margin of delta. In the autumnal period when young and adult birds are concentrated on shallow-water areas of the fore-delta and the northern Caspian probability of the mass birds' mortality increases.
Generalizing the discussed above there may be stated the following methodical approaches to solve the problems connected with the guarantee of ecological security of the Northern Caspian which are already partially fulfilled:

1. Establishment of the electronic data base of the initial hydrological-meteorological, hydrochemical and hydrobiological information for the Northern Caspian area.

2. Integrating the distribution maps of biotic and abiotic parameters applying GIS technologies.

3. Carrying out of the landscape-ecological division of the areas, definition of large nature-territorial complexes and zones.

4. Establishment of the transparent procedure for ranging of biological components for inclusion into the system of indices of ecological vulnerability estimation.

5. Typization of the major kinds of work on the shelf by the impact scale and the expected affect on biological components.

6. Suggestion of a transparent procedure to calculate the coefficient of ecological vulnerability considering the approaches discussed above and the Northern Caspian ecosystem peculiarities.

7. Construction of the separate (by different ecosystem's components) and integral schemes of the ecosystem's vulnerability uniting all kinds of work(impacts).

8. Suggestion of practical recommendations for the optimization of "Lukoil" Ltd. activity in the field of ecological security on the Northern Caspian.



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