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On Distribution of Comb-Jelly Mnemiopsis Leidyi (A. Aggsiz) in the Turkmenistan Waters of the Caspian Sea

F. M. Shakirova

Today the Caspian like other seas of the world undergoes a man’s impact caused by pollution of rivers and the sea by oil products, chlororganic pesticides, heavy metals as well as by active navigation, hydroconstruction linking earlier isolated water basins, interbasin water transfer, deliberate or accidental acclimatization shipments resulting in significant expansion of natural habitats of many species, intermixing of once geographically-isolated populations of the species and subspecies and sometimes in a fall-out of species from the fauna of reservoirs. As a result thereof under new conditions of inhabitancy non-native and exotic species appear. Those are the species of plants and animals being uncharacteristic of the region, though having acclimatized in it.

It’s a well-known fact that pollution of marine environment by exotic organisms represents a special sanitary and epidemiological and ecological danger since their introduction results in adaptation of many species outside of their natural habitat, thus damaging ecosystems of the reservoirs through ousting valuable local species and disrupting their food chains. At that point a potential threat to habitats and economy of the country appear since exotics provoke serious ecological problems and involve huge economical expenses.

Since the second half of the XX century the problem of invasive species has become important in the ecology of many seas of the world.

Thus, for example, invasion of the comb-jelly Mnemiopsis leidyi in the Azov-Black sea basin with ballast waters of the ships early in the 1980s caused a real ecological catastrophe.

Therefore its occurrence in the Caspian gained deep resonance among specialists from scientific circles as well as among those of other institutions and organizations involved.

First information on occurrence of Mnemiopsis leidyi in the Caspian Sea was obtained accidentally during the second half of September 1999 when data on biology and ecology of artemia of Karabogazgol was collected.

Oral reports of fishermen were on occurrence of “jelly-fish” in the Caspian in the region of the bay (ref. Chart). When questioned about their sizes, color and number, the fishermen answered those jelly-fish were of light color, medium size, not longer than 5 cm as well as that they were few.

During that period we could not deny the possibility of the comb-jellies penetrating in the Caspian, since due to participation in the international workshop on ballast waters held in September 1999 in the Black Sea on “Georgiy Ushakov” motor ship we had certain information on Mnemiopsis and presumed variance of its introduction in the Caspian not only with ballast waters but also through a transit Volga-Don channel.

Late November 1999 during international workshop in Astrakhan (Caspian Scientific Research Institute of Fishery) an information was obtained from the specialists of the institute on penetration of Mnemiopsis in the Caspian and a video film named “Thorough studies” having been shot in the locality close to that where our fishers found comb-jellies was shown. Learned from presentation material was information on the invasive species, its abundance, vertical distribution and other parameters. Since that time we have started our well-directed efforts in collecting data on distribution of the comb-jelly in water area of the sea as well as literary data on the invasive species. As we do not have a possibility to carry out subsea surveys and collect data on vertical distribution of the comb-jelly in the Caspian, we study its horizontal distribution throughout the water area of the sea. During summer, August 2000, when hydrobiological activities in the Caspian Sea in Avaz region close to Turkmenbashi city were implemented, the comb-jelly was found in the region of studies and was few apparently due to the fact that our studies were conducted following one week storm. Animals found were transparent, medium-sized, not longer than 3-5 cm.

During expedition in the Caspian on “M. Suleymanov” motor ship in October 2000 wide distribution and the highest number of Mnemiopsis along the western shore of the Caspian (See Fig) were observed. Found in the trawl and funnel nets for catch of kilka were comb-jellies of various ages and sizes, some part of which had transparent body and the other part was characterized by milky tint while the fish needed for analysis was not practically caught on the stations. When talking with the specialists of Azerbaijan having taken part in the expedition we found out, that with occurrence of comb-jelly in the Caspian within the last two years a decrease in the number of kilka and sometimes even its full absence in the places of minor concentration of Mnemiopsis was observed as compared to earlier pretty high number of fish in those places being known as kilka-abundant regions.

Literary sources (Comb-jelly …2000) point out high stability and low sensitivity of Mnemiopsis to various pollutants. The fact was proved by the invasive species having been found in the port of Baku, at berthing of “M. Suleymanov” motor ship, marine environment of which was polluted by gasoline and oil. Also found were the species of comb-jellies of different ages and sizes.

Thus, during 1999-2000 wide distribution of Mnemiopsis in waters of the Middle and South Caspian was observed. Having found suitable ecological and feeding conditions, the comb-jelly not only acclimatized practically the whole of the Caspian water area creating strong numerous population but also started influencing the ecosystem of the sea and its fish, in particular kilka. We foresaw this option and believed the populations of Caspian kilka will be the first vulnerable fish chain in the ecosystem of the sea. Proceeding from the abovesaid, the seriousness of the problem in the Caspian does not require any further proof. When taking into consideration that ichthyofauna of the Caspian Sea is poor enough from the point of view of its diversity and some part of its populations being destructed as a result of economic activities and fishery, with Mnemiopsis influence to be added to the list, the urge of prompt development of Action Plan on biological control over populations of the comb-jelly to either prevent or reduce the introduction to the minimum could not be undervalued.

Taking into consideration the importance of the problem for all littoral states unification of efforts of the specialists as well as organizations and institutions involved is required. The problem is to be solved under the umbrella of a single program such as “The problem of Mnemiopsis in the Caspian” plus KPU.

Also, while being aware of the regions with high level of eutrophication where biological diversity reduces rapidly enough and replacement of valuable species by those non-valuable and sometimes even by non-native organisms takes place and to succeed in solving the problem of invasive species the problem of reducing eutrophication of the reservoir should be dealt with in the first place.

To solve the problem with greater efficiency we should take into account and use international practice on decrease and elimination of negative consequences as a result of impact of the comb-jelly, especially since rich experience of the Azov-Black Sea and other basins is available.

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