Mnemiopsis

Mnemiopsis leidyi in the "New England Aquarium " by Boston

Mnemiopsis leidyi, German sea walnut, is a species of comb jellies ( Ctenophora ) from the order of lobata. Mnemiopsis leidyi is about 100 mm long. It feeds on zooplankton, fish larvae and eggs.

Dissemination

The species was originally distributed in subtropical waters on the Atlantic coast of North and South America. 1982 copies have been spotted in the Black Sea for the first time. Presumably they came through the ballast water of cargo ships there. Due to lack of enemies, the nature spread rapidly and thereby displaced native species. The income of the fishing fell to a tenth of what could be achieved before the penetration of the species. Your maximum population density in the Black Sea reached the kinds in 1989 with 240 copies per cubic meter of water. Only the introduction of Beroe ovata comb jelly, a feeding enemy could push back the population. Probably turn Mnemiopsis leidyi could also penetrate into the Caspian Sea through the ballast water of ships. On 17 October 2006, the kind of researchers from the Leibniz Institute of Marine Sciences was discovered in the Baltic Sea. A density of 30 copies per cubic meter of water was found. The population also rose sharply, reaching 90 copies per cubic meter. In their actual tropical home they live in water temperatures of about 25 degrees. In the Baltic and the North Sea they live with temperatures below 10 degrees, only less than 2 degrees, the comb jelly is no longer viable. Warmer winters could therefore populations grow even faster. Overall, in the North Sea becoming more common jellyfish on - including Mnemiopsis leidyi of predators: the glass - cloth jellyfish and the melon jellyfish. Researchers belonging to the Helmholtz Association Biologische Anstalt Helgoland ( BAH ) pointed out in this connection that the predators of the sea walnut, at least - could keep them at bay - as has already happened in the Black Sea.