Respiration and anaerobiosis of free living nematodes from marine and limnic sediments

Abstract Ecological evidence for the existence of a characteristic nematode fauna inhabiting permanently anoxic sediments in marine and limnic environments is given. In marine sediments this fauna is highly diverse and separated by a sharp boundary from the association in oxydized layers, whereas in freshwater only a few species from anoxic habitats are known. The striking physiological differences between these 2 groups could be demonstrated by tolerance experiments. Respiration rates of benthic nematodes proved to be significantly lower compared with those from animals from better oxygenated environments. In addition different levels of oxygen consumption could be distinguished within the benthic species, correlated with trophic types, but maybe also with the stage of adaptation to anaerobic life. The trophic conditions under which anaerobiosis can be expected are discussed.