A case of recovery in benthic communities following a reduction in chemical pollution in a Mediterranean ecosystem.

The paper examines the effects of a reduction in pollution on benthic communities after the introduction of a tannery-effluent-treatment plant in the Gulf of Geras (Lesvos Island, Eastern Mediterranean, Aegean Sea, Greece). The univariate methods used were the diversity index, the evenness, the plots of the individuals among species, and the k-dominance curves, applied to data from five stations from 1983 to 1988. Classification, ordination, and the ANOSIM randomization test were also used to examine the similarity between years and stations. Results showed that multivariate methods are much more sensitive than univariate techniques. Descriptive plotting (k-dominance curves) was also proved to be valuable for evaluating the pollution effects. Dominance patterns of species are important, provided that there is a good knowledge of benthic assemblages in clean and undisturbed areas. In all cases, a large data set throughout time is needed to evaluate in the best way the effects of pollution on benthic communities. There was evidence of recovery in the benthic communities at sites near the tannery after the introduction of a biological-treatment plant.