The threat of native molluscs by the New Zealand mud – snail (Potamopyrgus antipodarum (gray)

Potamopyrgus antipodarum has been introduced to brackish and fresh waters of Europe probably in the first half of XIXth century, when the regular clipper lines have connected from 1840 the British Isles with New Zealand. Because these snails can survive in water to 24.6% salinity only, the transportation of individuals on outer parts of ship is impossible (Strzelec, 1996).