Population dynamics, dispersal and reproductive cycle of the Nereis diversicolor, in the Noor Coast-The south of the Caspian Sea

Population dynamics and reproduction cycle of the Nereis diversicolor in 5,15 and 30 meter depths of the Noor Coast was studied seasonally during a year. Results revealed the density and biomass of Nereis diversicolor during various seasons increased with increasing depths and total organic mater and decreasing sand percentage of the substrate.The annual average density and biomass of this worm were observed 128.70±23.58 ind/m2 and 476.66±88.21 mg/m2. Reproductive season was in spring and the maximal egg diameter was obtained 139.4 micrometer.