In situ swimming behaviour of the amphipod Corophium volutator (Pallas)

Abstract

An important factor structuring and maintaining spatial heterogeneity is mobility. The intertidal, burrowing amphipod Corophium volutator, can only move rapidly over large distances (10s of m–km) by swimming. An 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 settle, 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 during the progression from neap to spring tides high numbers of juveniles 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 will determine the subsequent patterns of heterogeneity at large (km), and potentially also small (m–cm), scales.