ON THE ECOLOGY OF COLURELLIDAE (ROTIFERA)

A material consisting of 45 colurellid rotifers from diverse waters in south and central Sweden was analyzed to reveal their relationships t o their substrate. Periphytic substrates were generally preferred Most species are obviously mobile and more or less euryecious, but a few s how a predilection for bog environments. Some colurellids are euryhali ne, but when inhabiting fresh water they prefer rivers and other envir onments with a high oxygen concentration, probably because of problems with osmoregulation.