NEOZOANS IN EUROPEAN WATERS - EXEMPLIFYING THE WORLDWIDE PROCESS OF INVASION AND SPECIES MIXING

The loss of biodiversity - the tendency of the world's fauna to become more and more homogeneous is widely acknowledged as a problem. Biodiv ersity is threatened by neozoism and acculturation as much as the exti nction of species, but these dangers are less well known. Neozoism and acculturation have an effect on two levels; they lead 1) to an equali sation of the faunal regions and their originally different, specially adapted biocenoses, and 2) to a reduction of genetic diversity below the species level. These processes develop very rapidly in the Europea n waters, particularly in the lowland river systems. The present contr ibution gives a brief review on neozoans in European inland waters.