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POTENTIAL RISK TO CASPIAN FROM IMMIGRANT JELLYFISH

This year substantial quantities of Mnemiopsis leidyi have been sighted in the Caspian. This plankton organism belonging to the invertebrate animal group Ctenophora (comb-jellies; Russian: grebnevik), attracted considerable attention when in the early eighties it suddenly appeared in the Black Sea. It was known as a resident of the east coast of North America, far away from Ponto-Caspian waters. It had most likely moved across the Atlantic as a stowaway in the ballast water of cargo ships.

In the Black Sea, it soon became the subject of much discussion among scientists and fishery people, since in the late 1980's it exploded into mass occurrences all around the sea. This explosion in population coincided with a dramatic drop in the populations of an anchovy species (Russian: khamsa; Turkish: hamsa) that was the basis of important fisheries in the coastal states.

The newcomer species feeds on other plankton including fish larvae. Apart from the immediate threat to the first life stages of herring-like pelagic fish such as anchovies and kilka, it also shares important food components with the adults of these fish and can therefore be an important competitor for food. It is immediately clear that the appearance of the new comb-jelly in the Caspian raises great interest and concern in those people trying to protect the original nature of the Caspian and others living on the exploitation of its fish resources.

How could this disturbing creature make it to the Caspian? Don't forget the Volga-Don Canal, which provides a similar route for stowaways to reach the Caspian from the Black Sea in the same way as from America to the Pontus.

What can be done? The first thing is to get a sufficiently detailed picture of the present distribution of Mnemiopsis in the Caspian and its further spread. To understand precisely what are the interactions between the intruder, its new environment and the resident organisms is of utmost importance. Experiences from other parts of the world show that not all introductions of foreign species are successful in the long run, although a few have conquered their new environment for ever, forcing the ecosystem into a new equilibrium.

To combat the intruder is a delicate undertaking, the more so as the Caspian is a large highly bio-diverse ecosystem. For example, the introduction of another foreign organism that would feed on the first intruder could even cause unexpected and unwanted side effects exceed the benefits achieved.

Many experts have become alarmed and are considering how best to cope with the new situation. The Caspian Environment Programme is currently collating the available information and consulting with a wide range of specialists, in preparation for hosting an international meeting in Baku early next year on this potentially severe risk to the Caspian ecosystem. The Caspian Centres for Bioresources Management, Astrakhan, Russian Federation, and Biodiversity Conservation, Atyrau, Kazakhstan are actively involved in the effort.

Any additional information on this fact will be welcomed and will contribute to the discussion. Information provided to the Programme Coordinating Unit in Baku, Azerbaijan will be passed on to the experts leading the investigations.

Contact persons:

Stuart Gunn,
the Caspian Environment Programme,
Programme Coordination Unit,
Room 108, Government Building,
40 Uzeir Gadjibekov Street,
Baku 370016 Azerbaijan,
E-mail: stuartgunn@caspian.in-baku.com
Phone: + (99412) 97 17 85, 93 80 03
Fax: + (99412) 97 17 86

Elina Farmanova,
the Caspian Environment Programme,
Programme Coordination Unit,
Room 108, Government Building,
40 Uzeir Gadjibekov Street,
Baku 370016 Azerbaijan,
E-mail: efarmanova@caspian.in-baku.com
Phone: + (99412) 97 17 85, 93 80 03
Fax: + (99412) 97 17 86