Natural occurrence of anaerobiosis in molluscs from intertidal habitats.

The scope for anaerobiosis of Patella vulgata and Scrobicularia plana was investigated during experimental hypoxia. Furthermore these two species as well as Mytilus edulis and Crdium edule were taken from their habitat during low tide in order to assess whether the animals were anaerobic.When kept in nitrogen saturated water Patella vulgata and Scrobicularia plana showed an increase in the concentration of succinate,acetate and propionate. In addition the energy charge fell and the content of phosphorylarginine decreased.On exposure to low tide, within their habitat, only Mytilus edulis and Scrobicularia plana became anaerobic as judged from a 10 to 30 fold increase of succinate concentrations. Succinate was never elevated in Cardium edule and Patella vulgata.Succinate concentrations of Mytilus edulis and Scrobicularia plana were measured at intervals throughout the year and found to increase whenever the animals were emersed.