Self-cloning crayfish threatens native species

Thursday, February 20, 2003 By Reuters

LONDON A mysterious self-cloning female crayfish, popular with German aquarium owners, could pose a threat to native European species if it were released into the wild, scientists said Wednesday.

The marbled crayfish, called Marmorkrebs, is probably related to a North American species, although scientists at Humboldt University in Berlin admit they do not know exactly where it originated.

But they are sure that it can reproduce without mating. Parthenogenesis, a form of
self-cloning, is found in creatures such as snails and water fleas but is unusual in crayfish.

The Marmorkrebs' ability to produce 20 or more clones of itself in six months could create a competitor to crayfish in the wild, according to Gerhard Scholtz, a
comparative zoologist at the university.

"It might pose a threat to European native crayfish," he said.

Marmorkrebs, which can be bought for about five euros (US$5) in
Germany, may also be able to transmit a deadly crayfish plague to other less robust
species, according to Scholtz, who published his findings in the science journal Nature.

"This crayfish, which is now widespread in Europe's aquaria, could become a menace to European freshwater ecosystems, as the release of even one specimen into the wild would be enough to found a population that might out-compete native crayfish," he said in the report.