Qualitative assessment of organic pollution from aquaculture activities on benthic organisms using ABC (Abundance Biomass Curves) in Ghazale creek (Persian Gulf)

The present study was carried out to find the probable effects of marine fish cage culture on benthic communities as pollutant and stress indicators. Also, the biotic health condition was assessed using ABC index, in Ghazale creek, Khore-Mussa area in northwest of the Persian Gulf. Monthly sampling from four stations was conducted from June 2007 to March 2008. Stations were selected according to distance from cages in Ghazale creek. The distances were immediately under the cages, 50, 150 and 400m from the cages. At each station, three samples for macrobenthos and one sample for sediment grain size analysis and total organic matter (TOM) were collected by Van Veen grab with 0.0225m2 area. The range of total organic matter percentage in sediments was (6.17-23.26) and the range of silt-clay percentage was (4.76-97.47). We found 12 macrobenthic orders and Polychaets (60.62%), Mullusca (19.67%), Crustacea (16.49%) were the dominant groups. Macrobenthic abundance, biomass and diversity index value under cage station were less than those 400m away from the cages. Capitella sp. as opportunist species was dominant under cage station. This genus is introduced as the pollution indicator in the area. The result of ABC index show that under the cages and distances 50 and 150m away from the cages have average pollution, while the 400m distance from the cage (control site) is unpolluted.