IN-SITU SWIMMING BEHAVIOR OF THE AMPHIPOD COROPHIUM VOLUTATOR (PALLAS)

An important factor structuring and maintaining spatial heterogeneity is mobility. The intertidal, burrowing amphipod Corophium volutator, c an only move rapidly over large distances (10s of m-km) by swimming. A n investigation into the swimming behaviour of Corophium on the Ythan estuary, Aberdeenshire, using emergence, settlement and plankton traps indicated that on most high tides very few animals emerge, swim or se ttle, and that these individuals are mostly adult males. Such swimming is probably related to reproduction, and with such low frequency will have little impact on spatial heterogeneity. However, periodically du ring the progression from neap to spring tides high numbers of juvenil es swim on nocturnal high tides. This is reflected by higher, juvenile dominated, settlement after these periods. This swimming is probably related to dispersal and the survival of juveniles after dispersal wil l determine the subsequent patterns of heterogeneity at large (km), an d potentially also small (m-cm), scales. (C) 1998 Elsevier Science B.V .