In the mid - 1980 ’ s, a thumbnail - size mollusk called the zebra mussel was inadvertently introduced into the Great Lakes of North America in the ballast water of freighters from Europe.
aastate keskpaiku sattus Euroopa kaubalaevade ballastvetega Põhja - Ameerika Suurde järvistusse pöidlaküünesuurune limune tavaline rändkarp.