How the comb-jelly (Mnemiopsis leidyi) is spreading through European seas (invasive species)
Description
The most threatening event for the Caspian ecosystem was the arrival of the North American comb jelly (Mnemiopsis leidyi). It was brought accidentally to the Caspian in the ballast water of oil tankers. Invasive and alien species can exploit ecological niches that are not currently occupied, and spread rapidly, out-competing indigenous species.