Anaerobic Life in a Tropical Crater Lake

Abstract

THERE are very few records of animals other than Protozoa found living in oxygen-free water for which there seems to be good evidence of prolonged and active anaerobic life^1,2. In many cases there is the possibility of periodic visits to oxygenated water and in others the oxygen demand is lowered by the reduction or even complete cessation of activity. Certain planktonic Crustacea especially Cyclops spp. and some insect larvæ and molluscs have, however, been found living actively in the oxygen-free water and mud at the bottom of temperate eutrophic lakes during summer stratification, and the evidence for anærobiosis lasting for a few months is convincing.