Study of Abundance and Diversity Change of Polychaete under Marine Fish Cage Culture in Ghazale Creek (Mussa Creek)

Since aquaculture activities are increasing and becoming more important, the evaluation of the effect of these activities on marine ecosystem seems to be necessary. The present study was carried out to investigate the changing abundance and diversity of Polychaetes under marine fish cage culture in Ghazale creek, in Khore-Mussa area in north west of Persian Gulf. Monthly sampling from 4 stations had been done from August to December 2007 (during five months). Stations were selected from under cages to 400 m distant (as control site) in Ghazale creek. At each station, 3 samples for Polychates studying and one sample for sediment grain size analysis and total organic matter (TOM) were collected by van veen grab with 0.0225 m2 area. The range of total organic matter (TOM) percentage in sediment was 6.11-23.26. The maximum and minimum TOM values were observed in the fares station (400 m distant) in August and November respectively. The range of silty-clay percentage was 4.76-97.47 and the minimum and the maximum values were observed in 50m and 150m distant station, in October and August respectively. The result of Polychaetes represented that Cirriformia sp. 18.93%, Cossura sp. 18.04%, Capitella sp. 17.42%, Nephthys sp. 5.85%, Sternaspis sp. 5.84% were dominance species between stations. The result of biotic indices showed higher diversity in 400 m distant station comparison with under cage station. Diversity and dominance index values were increased from under cage station (1.79H′ and 0.41λ) to 400 m distant station (2.11H′ and 0.16λ).