THE EFFECT OF TIDAL EXPOSURE ON ASPECTS OF METABOLIC AND IMMUNOLOGICAL ACTIVITY IN THE HARD CLAM MERCENARIA-MERCENARIA (LINNAEUS)

1. Variations in the immunological state of the marine bivalve Mercenaria mercenaria were followed by measurement of haemolymph lysozyme activity, haemocyte concentrations and haemocyte locomotion. 2. Animals subjected to chronic tidal exposure were found to have higher hydrogen peroxide concentrations on re-immersion, reduced lysozyme activities, lower rates of granulocyte locomotion and a greater number of small granulocytes when compared with control animals. 3. Cyclical variations could be linked to tidally related changes in metabolic activity quantified by measurement of hydrogen peroxide concentrations.