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 pla nt in the Gulf of Geras (Lesvos Island, Eastern Mediterranean, Aegean Sea, Greece). The univariate methods used were the diversity index, th e evenness, the plots of the individuals among species, and the k-domi nance curves, applied to data from five stations from 1983 to 1988. Cl assification, ordination, and the ANOSIM randomization test were also used to examine the similarity between years and stations. Results sho wed that multivariate methods are much more sensitive than univariate techniques. Descriptive plotting (k-dominance curves) was also proved to he valuable for evaluating the pollution effects. Dominance pattern s of species are important, provided that there is a good knowledge of benthic assemblages in clean and undisturbed areas. In all cases, a l arge data set throughout time is needed to evaluate in the best way th e effects of pollution on benthic communities. There was evidence of r ecovery in the benthic communities at sites near the tannery after the introduction of a biological-treatment plant.