The impact of industrial pollution on macrobenthic fauna communities

Abstract

Mossa creek is a long, deep, tidal canal in Iran. The creek stretches almost 56 km along the northwestern edge of the Persian Gulf. The creek contains numerous sources of organic pollution including industrial sewage effluent. A survey of the creek was performed assessing organic pollution, water properties, and the macrobenthic community. The need to assess the environmental status of marine and coastal waters encouraged the design of specific biotic indices to evaluate the response of benthic communities to human-induced changes in water quality. In this study of the benthic community structure in two creeks surrounding an industrial sewage discharge, water and sediment samples were collected at eight sites in the warm season (September) and cold season (February). Environmental data on physical and chemical variables were also collected from each site and a multivariate analysis was carried out to determine the effect of environmental factors on the biodiversity distribution. The result indicated that: Shannon's-weaver index has significant correlate with dissolved oxygen (DO) and organic matter (OM). In addition, in station near of the swage pollution biodiversity index, water quality and DO decreased and organic matter increased. However, very heavy pollution was observed according to the biodiversity index value in both seasons. The results showed that in both seasons 1, 2, 3 and 5 stations (which are located near the sewage output) in pollutant confine, 4 station in moderate confine and 6, 7, 8 stations located in un pollutant class. Also the results of water quality determine base on Welch index indicated that 1, 2, 5 stations in both season, 362.95 ha (7%) and other stations in moderate pollution load, 4885.73 ha (93%) located in high and moderate pollution load, respectively. Also, the results indicated that stations around the sewage outlet had less macrobenthic species and higher organic matter. On the contrary, the station furthest from the petrochemical industries (station located in Ghanam creek) had higher species diversity and consequently a higher value for the Shannon-Weaver diversity index. The present study also showed that Polychaetes, a biotic index of pollution biotic, were more abundant. Although Polychaetes were also recorded at all the other stations, these stations had greater biodiversity with different numerically dominant species such as: Isopoda, Decapoda, Gastropoda, Copepoda, Bivalvia, Pennatulacea, and Crustaceastations. Consequently, it was established that macrobenthic biodiversity was related to dissolved oxygen and the percentage of organic matter in the sediment.

Key words: Biotic indices, pollution, macrobenthos.