INTERACTIVE EFFECTS OF PENTACHLOROPHENOL (PCP) AND HYPOXIA ON THE ENERGY-METABOLISM OF THE MUSSEL, MYTILUS-EDULIS

Mussels were exposed to different hypoxic conditions (10 and 2 kPa) after the accumulation of various levels of pentachlorophenol (PCP) in the tissues. Total metabolic activity and the aerobic rate of energy metabolism were measured by calorespirometry, and end-products of anaerobiosis were quantified by HPLC. At the lowest concentration of PCP (50 mug/litre), the aerobic rate of metabolism was enhanced over a wide range of Po2, reflecting the degree of uncoupling of oxidative phosphorylation. After exposure to an intermediate PCP concentration (350 mug/litre), the aerobic rate at 20 and 10 kPa was further enhanced but then declined markedly at 2 kPa. At the highest concentration of PCP (700 mug/litre), the aerobic rate was enhanced only at 20 kPa, whereas at 10 and 2 kPa there was a significant depression of metabolic rate and a significant involvement of anaerobic metabolism. This was mainly due to the increased production of lactate rather than succinate. However, the activation of anaerobic metabolism did not compensate for the reduction in aerobic metabolism at 2 kPa.