Impact of conspecifics on recruitment and behaviour of Dreissena polymorpha (Pallas, 1771)

Abstract

Behaviour of larvae, juveniles and adults of Dreissena polymorpha in the presence of the conspecifics was investigated in field and laboratory experiments. Mussel recruitment was studied in plastic chambers containing living conspecifics, their empty shells or calcareous, mussel-sized stones. The objects were glued to the chamber bottom and covered by nylon mesh. The experiment was carried out in the channel connecting the Port Zimowy harbour with the Vistula River (Toruñ, Poland). Total mussel densities in the above treatments were the same as in the empty chambers. However, the distribution of the new settlers depended on the quality of the glued objects, with the vicinity of living mussels and empty shells being preferred to stones. This suggests that mussels responded to conspecifics after settling on substrate. Migration of juvenile and adult mussels in the presence of the same stimuli was then studied in a laboratory experiment. Both groups preferred the vicinity of living conspecifics, but any kind of the firmly attached objects decreased the number of individuals leaving the substrate, compared to the flat surfaces.