Feeding Physiology of Bivalves: Time-Dependence and Compensation for Changes in Food Availability

Abstract

In spite of considerable experimental and observational study over many years, controversies and uncertainties still exist concerning fundamental features of feeding behaviour in suspension-feeding bivalves (Bayne and Newell, 1983; Griffiths and Griffiths, 1987; Jorgensen, 1991). These include uncertainties over the mechanisms of particle capture (Jorgensen, 1983; Silvester and Sleigh, 1984; Shimeta and Jumars, 1991; Ward et al., 1991) and controversy over the role of physiological processes in determining feeding behaviour (Bayne et al., 1988; Jorgensen, 1991; Iglesias et al., 1992). This paper addresses the second of these topics and suggests that physiological and behavioural compensations for changes in the food environment are important elements for a full understanding of suspension-feeding. This is not to deny the significance of physical constraints on feeding, such as the viscocity of the medium, or frictional forces influencing water flows within the mantle cavity, but rather to argue that behavioural and physiological flexibility in aspects of particle capture, sorting, digestion and absorption are also important. Since physiological traits are inherently timedependent, it follows that feeding in bivalves should be viewed as a linked series of processes with different time-constants, coupled to relevant time-scales of change in the environmental availability of food.