Pumping activity ofArctica islandica(L) and some other common bivalves

Abstract

Thermistor flowmeters were used to investigate the pumping activity of Arctica islandica together with five other subtidal and three intertidal bivalves. The subtidal species, with the exception of Chlamys opercularis, show an intermittent pattern of pumping activity of several minutes’ periodicity which is independent of phasic shell adduction. In contrast the intertidal species and the subtidal Chlamys pump more or less continuously. The pumping behaviour of Arctica is modified under conditions of respiratory stress; the time spent pumping increases from 40–60 % to over 95% as the PO₂ of the ambient water is reduced from 160 mm Hg to 30–35 mm Hg. Continuous recordings were made of the PO₂ of the mantle cavity water of Arctica during normal pumping activity. The possible mechanism controlling pumping behaviour is discussed, together with the problems of determining bivalve respiration rates at defined levels of activity.