Community structure and biodiversity of intertidal sandy beach polychaetes in Chabahar Bay, Oman Gulf, Iran, related to the monsoon period

Community structure and biodiversity of polychaetes of the intertidal sandy beach at Chabahar Bay, the largest bay in the north-east of Oman Gulf, were studied for ten months in 2007. A total of 16 polychaete species belonging to 15 families were identified. The results showed that densities were influenced by the monsoon season so that maximum density (1370 ind m−2) was observed at pre monsoon while minimum density (117 ind m−2) was obtained during monsoon. Two species, Synelmis albini and Magelona cornuta, were the most abundant species. The highest and lowest values of diversity and richness indices were obtained at pre monsoon and during monsoon, respectively. Also, multivariate analysis separated monsoon season from pre and post monsoon clearly. Our results show that the monsoon can be the most important factor on community structure and biodiversity of polychaetes at Chabahar Bay and the intertidal of this bay is not a favourable environment for polychaete development.