Origin and destination of selected species

Description

North American comb jelly (Mnemiopsis leidyi) was brought accidentally to the Caspian in the ballast water of oil tankers. A voracious feeder on zooplankton and fish larvae, it first arrived in the Black Sea in the early 1980s where it changed the whole ecosystem and contributed to the collapse of more than two dozen major fishing grounds. From there the comb jelly also invaded the Azov, Marmara and Aegean Seas and most recently the Caspian.