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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
© 2005 Caspian Sea Environment | #63, Golestan Alley, Valiasr Avenue, 1966733413, Tehran, I.R. Iran
Tel. No.: (+ 9821) 22059574; 22042285; 22042935 | Fax No.: (+ 9821) 22051850
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