The effect of marine fish cage culture on benthic communities using BOPA index in Ghazale Creek

Abstract

The present work has been carried out to investigate the probable effects of fish cage culture on benthic communities as a pollution and stress indicator and to evaluate the biotic health condition using BOPA index, in Ghazale Creek (Khowre-Mussa - Persian Gulf). Monthly sampling from 4 stations was carried out from June 2007 to March 2008 (during nine months). Stations were selected from under the cage to 400 m distant (as control site) in Ghazale Creek. Three samples were taken at each station for macrobenthos and one for sediment grain size and total organic matter (TOM), using a 0.0125 m2 van veen grab. Also physical-chemical parameters sampling from three stations was done (during nine months). Stations were under cage station, 50 m and 400 m far from cages in Ghazale Creek.The percentage of total organic matter (TOM) in sediment ranged from 6.11 to 23.26 and the range of silty-clay percentage was from 4.76 to 97.47. The dominant macrobenthos groups were Polychaets (60.62%), Mulluska (19.67%), Crustacea (16.49%). Macrobenthic abundance, biomass and diversity index values in the under cage station were less than that in the control station. Comparing the results of BOPA with the guidelines shows that all stations had bad environmental conditions. The under cage station was more polluted than the control station. The range of physical-chemical parameters in water were: DO ­(6.5-11.43) ppm,­ BOD ­(1.5-10.9) ppm, Salinity (43-45.6) ppt, NO2- (0.006-0.29) ppb, NO3- (3.98-32.2) ppm, Turbidity (14-70)­ NTU temperature (11.8-32.5) ° C.