Invasion of the freshwater snail Physella acuta (Draparnaud, 1805) in selected ponds of north Dinajpur, India.
Aim: The dispersal and geographical range expansion of globally invasive snail Physella acuta (Draparnaud, 1805) (Gastropoda: Physidae) were little being monitored following the first report from Kolkata, India. An account of the encounter of P. acuta in two ponds of North Dinajpur district of West Bengal, India is recorded here. Methodology: Multiple samples of freshwater snails were collected using aquatic nets from the invaded and non-invaded ponds for assessment and comparison. The shell lengths of the collected P. acuta were measured using a vernier calliper to represent size class variations of the population in the ponds. Results: Varying numbers of P. acuta were present in the shoreline and the hydrophytes of littoral zone of invaded ponds. The size class distribution of P. acuta indicated the establishment of a stable population in the invaded ponds where a significant difference (P < 0.05) was observed in the abundance of a native snail Racesina luteola (Lamarck, 1822) when compared with the abundance in the non-invaded ponds. Interpretation: Invasion of P. acuta in the ponds reflected its ability to overcome the predator-borne barriers and to coexist with the native snails. The geographic range of P. acuta seems to have extended, even though slower with reference to the first record in India.