The energy production of juvenileArenicola marina (Polychaeta) under anoxic and hypoxic conditions

The mode of anaerobic energy production of juvenileArenicola marina (0-generation) was investigated under experimental conditions and in the biotope. Under experimental anaerobic conditions, juvenileA. marina produce energy by the pathways known from the adults and other euryoxic invertebrates with succinate and the volatile fatty acids, acetate and propionate, as main end products. However, the juvenile lugworms are less resistent to anoxia than the adults. The reasons for this might be their small glycogen stores and their limited ability to reduce the metabolic rate. Nevertheless, on the tidal flats the juveniles settle particularly in the area next to the high tide line, which offers such extreme conditions that adult lugworms cannot live there. This different behaviour can be explained by the dissimilar ability to use oxygen at very low partial pressures. Juveniles maintain an aerobic energy metabolism even at a P_{WO 2} of 15 Torr at which adults are forced to produce energy exclusively by the less effective anaerobic mode. In the field, no indications of an anaerobic energy metabolism were detected in juveniles even after an exposure of 8 hours.