ACCLIMATIZATION TO INTERTIDAL CONDITIONS MODIFIES THE PHYSIOLOGICAL-RESPONSE TO PROLONGED AIR EXPOSURE IN MYTILUS-EDULIS

Both the tolerance of air exposure and the metabolic means by which mu ssels, Mytilus edulis, face air exposure can be modified by intertidal acclimatization. Short-term intertidal acclimatization enhanced the t olerance of air exposure most in early summer. Prevention of air breat hing increased the mortality of wild and non-acclimatized cultured (i. e., control) mussels, but only slightly enhanced that of intertidally acclimatized mussels, suggesting their increased dependence upon anaer obic metabolism. In June, anaerobic end products accumulated in the ad ductor muscle of cultured but not of wild mussels. Intertidal acclimat ization shifted the pattern and rates of metabolite accumulation. Cont rol mussels accumulated succinate and alanine in the adductor muscle w hile intertidally acclimatized mussels accumulated strombine + alanopi ne, albeit at far lower levels. Pyruvate kinase (PK) from adductor mus cle of intertidally acclimatized mussels was gradually activated durin g prolonged air exposure, while that of control and wild mussels was m ore inhibited. In July and August, during prolonged air exposure, the PK from the most viable mussels generally was the most inhibited. Prev ention of air breathing did not markedly change the time course of PK inhibition during air exposure. Cultured mussels used in the present s tudy were obtained from growers in Quebec, and wild mussels were colle cted from the Baie des Chaleurs (Quebec, PQ) in 1988.