Community parameters and multivariate analysis as a means of assessing the effects of tannery effluents on macrobenthos.

Classification and ordination techniques were employed on the benthic communities of the gulf of Geras (Lesvos Island, Aegean Sea, Greece), as supplementary to conventional measures used (species composition, species diversity, abundance, community diversity and evenness) in order to assess the impact tannery effluents have on them. There is no evidence of contamination or disturbance of any sort, not even at stations near the tannery conductors as concluded from the above community parameters. Seasonal changes were apparent in species diversity and abundance, but they were of secondary importance to spatial changes, related to differences in sediment type. both multivariate techniques applied, led to the same distributional pattern. That is, the station in the open sea and the station near the tannery conductor are separated from the others. At a lower level of similarity, a subgroup of stations is formed by the stations located at the narrow channel, while another subgroup is formed by the stations located in the inner part of the gulf. Since there is no sign of major disturbances in the benthic communities, the above grouping must be attributed to differences in sediment type, degree of isolation, depth and wave action.