MAXIMAL GLYCOLYTIC ENZYME ACTIVITIES IN MUSCLES OF BIVALVES OF THE GENUS Donax IN RELATION TO THEIR BEHAVIOUR AND ECOLOGY

Abstract

Maximal activities of glycolytic enzymes have been shown to relate to energy production and physiological function of muscles from a diverse range of marine invertebrates. There have, however, been few attempts to relate maximal enzyme activities to interspecific differences in behavior and energy production in muscles from closely related species of marine invertebrates. This chapter provides an overview of the maximal glycolytic enzyme activities in muscles of bivalves of the genus Donax in relation to their behavior and ecology. It also focuses on the thermal tolerance of marine invertebrates and several species of bivalves of the genus Donax . Donax vittatus is the most northerly distributed of European Donax species while Donax sordidus and Donax serra belong to the warm temperate fauna of southern Africa. The species characteristically occur in clean sandy beaches and have essentially similar life cycles, but they differ in behavioral adaptation to the tidal environment and in temperature tolerance. Maintenance of zonation in all the species depends on frequent movements of burrowing and recovery in response to wave action. The most intense burrowing activity is exhibited by the South African species that are found on very exposed surf washed beaches, and each show characteristic patterns of migration related to tidal action. In contrast, the European species, D. vittatus , tends to be found in relatively sheltered sandy bays. The chapter discusses whether there are differences in maximal glycolytic enzyme activities in muscles of the three species related to these interspecific differences in burrowing activity. Phosphofructokinase and pyruvate kinase activities in foot and adductor muscles of D. vittatus are typical of muscles that depend largely on anaerobic glycolysis for energy production, and are capable of short but rapid bursts of contraction.