Invasive Species, Comb Jellyfish

"The comb jellyfish arrived on ships from the American Atlantic coast in 1982. It eats both zooplankton, the food of commercially important fish in the Black Sea, and the eggs and larvae of the same fish species. With no enemies in their new home, the jellies propagated at an alarming rate. By the mid-1990s, they accounted for 90% of the total biomass in the Black Sea - a biomass more than the total annual fish catch around the world...The invasion contributed to the near collapse of Black Sea commercial fisheries within a few years. The once quite prosperous seafood industry has lost about US$1 billion since the jellies were released. Anchovy fisheries in the Azov Sea, already under stress from pollution and overfishing, have completely collapsed."