No experimental evidence for vector-free, long-range, upstream dispersal of adult Asian clams [Corbicula fluminea (Müller, 1774)]

Abstract The Asian clam ( Corbicula fluminea ) is one of the rapidly spreading, very successful aquatic invasive species, which has become established widely in many parts world. Its spread assumed to be by both passive and active dispersal. However, importance pedal movement dispersal hardly known. Since there was no direct evidence this phenomenon, field observations were combined with laboratory experiments find out if clams move upstream actively, how affected quality substrate, density clams, water velocity. Field conducted at a small watercourse waterborne transport. Experiments done an indoor artificial stream system, where distances moved adult measured via digital image analysis. Substrate grain size, starting velocity significantly movement. Fine sediment slow flow facilitated spread, while clear pattern density-dependent Also, we found preference for either or downstream maximum distance lab predicts more than 0.15 km/y direction, our detected much faster (0.5–11 km/y) movement, might explained dispersal, such as human transport ecto- endozoochory. Overall, it seems that species cannot read long-distance migration.