THE USE OF OFFSHORE MEIOBENTHIC COMMUNITIES IN LABORATORY MICROCOSM EXPERIMENTS - RESPONSE TO HEAVY-METAL CONTAMINATION

A microcosm, originally developed for intertidal, estuarine meiobenthi c communities, has been used to determine the effects of the heavy met als copper, zinc, cadmium and lead on offshore meiobenthic nematode co mmunities. Significant differences were observed in community structur e between controls and all metals except cadmium. The dose response of the offshore meiofauna to experimental contamination was rather confu sing as copper and zinc low doses appeared to have much more drastic e ffects than the high doses. We speculate that at the highest copper an d zinc dose levels the metals acted as preservatives such that animals died but did not decompose. This indicates that metals will affect th e microbial component of the sediment as well as the meiobenthos in th is type of experimental design. The response to the contaminants of of fshore sediment biota differed from that previously observed in intert idal estuarine biota. This may be because fauna in the estuarine envir onment are subjected to greater levels of natural physicochemical stre ss and are therefore more generally tolerant. This suggests that envir onmental impact assessments should bioassay communities which naturall y inhabit the environment to be assessed. The methods used have potent ial in the development of a community level bioassay particularly sinc e it appears that the dominant nematode component of meiobenthic commu nities, from a wide range of habitats, can be easily maintained in sim ple microcosms. (C) 1997 Elsevier Science B.V.