THE SPECIFICITY OF MEIOBENTHIC COMMUNITY RESPONSES TO DIFFERENT POLLUTANTS - RESULTS FROM MICROCOSM EXPERIMENTS

In preliminary microcosm experiments we have been able to demonstrate a clear differential response of meiobenthic assemblages to zinc, copper and cadmium contamination. Sediment and natural meiobenthic communities were collected from two estuaries, the Lynher (mud with a high organic content) and Exe (sand with a low organic content). The sediments were dosed separately with zinc, copper and cadmium at three different dose levels. The meiobenthic community structure from both sites was unaffected by cadmium at any of the dose levels. The communities in the zinc and copper treatments were significantly different (ANOSIM p < 0.05) from each other and from the controls (and cadmium treatments). Although the differential response occurred in both sediment types, its intensity was greater in the sand than the mud. The Exe sand communities were much more strongly affected by the contaminants, even at the lowest dose, copper having a more severe effect than zinc. The Lynher mud meiobenthos was most strongly affected by the zinc treatment and there was a graded response to both zinc and copper with significant differences in the communities at different doses (ANOSIM p < 0.05). These differences between sediments could be due to the binding of metals onto organic material, thus reducing their availability to the fauna.