Schelperosie bij zoetwatermollusken in de Heemtuin te Lelystad

Liviug specimeu of Stagnicola palustris with eroded shells were observed iu three iuterconnected small ponds in the Lelystad botanica! garden. This was the reason to collect the malacofauna of these ponds and to compare the degree of erosion with the malacofauna from another pond where S. palustris had been found before. In the ponds in the botanica! garden only three species of freshwater molluscs showed erosion pattems: S. palustris, Bithynia tentaculata and Radix balthica. No shell erosion was observed with the same species from the pond outside the garden. Growth of time-boring blue-green algae on the shells is proposed as the most probable cause of the erosion.