Activity and Metabolism in the Mussel Mytilus edulis L. during Intertidal Hypoxia and Aerobic Recovery

Abstract

Coordinated calorimetric and respirometric measurements revealed differences in heat dissipation during exposure to air (tq̇air) and its partitioning into aerobic and anaerobic components in intertidally and subtidally acclimatized specimens of Mytilus edulis. Variations in air-gaping behavior were associated with these differences. There appeared to be a minimum (anaerobic) tq̇air and a constant overshoot in heat dissipation associated with recovery metabolism in aerated seawater; superimposed on this anaerobic rate in air was individual variability in air-gaping behavior, which produced a fivefold range of tq̇air. There was a positive relationship between the volume of air enclosed by individual mussels and maximum tq̇air. Those individuals which gaped less in air showed more shell valve movements during recovery. Exceptionally active mussels accumulated more strombine in their posterior adductor muscles and had a higher anaerobic contribution to muscular activity during recovery. Differences between intertidal and subtidal mussels in the time course of reoxygenation of the hemolymph on reimmersion were associated with differences in the time required to achieve maximum rates of aerobic heat dissipation. Differences between these groups of mussels in aquatic heat dissipation and oxygen consumption following recovery were related more to differences in ration than to aerial exposure per se.