Benthos density and its relationship with sediment condition in the north coast of Gorgan Bay, Golestan Province

The frequency and distribution of benthos species in the north coast of Gorgan Bay (proposed site for cage and pen culture) were studied. Sampling was carried out in three water depths 1, 2 and 3 meters and 10 stations in each depth using Van Veen sampler with 3 replications. Totally, 12 families were identified: Nereidae, Ampharitidae, Spionidae Amphipodae, Osteracodae, Mytilidae, Dreissenidae, Cardidae, Neritidae, Pyrgulidae, .Lithoglyphidae and Planorbidae of which Osteracodae and Ampharitidae with 26% and 1% had maximum and minimum abundance, respectively in all depths. The maximum and minimum abundance of benthos was 6025 per square meter in waters 3 meters deep and 52 per square meter in waters 1 meter deep. In addition, sediment texture and total organic matter (TOM) were analyzed which showed that 2 and 3 meter deep waters had the maximum percent of T.O.M (7.8%) in spring and autumn while the minimum T.O.M (2.5%) in 1 meter deep waters was observed in winter

Distribution, abundance and biomass of Polychaeta in the north coast of Gorgan Bay

The biomass, distribution and ecological index of Polychaeta in the north coast of Gorgan Bay was assessed during spring to winter 2004. Sampling of benthic organisms was also conducted seasonally. Polychaeta species such as Hypniola annenicova (Ampharetidae) and Streblosplo gynobranchiata (Spionidae) belonging to sessil polychaetes and Nereis diversicolor (Nereidae) belonging to mobile Polychaeta were distinguished. The maximum and minimum biomass was 4489.77±712.13 and 4150~c246.37mg/m^ (2) in summer and winter respectively which showed a uniform distribution in all depths. Results indicated no difference in diversity and evenness index in depths and seasons during the year. The highest prevalence and richness of Polychaeta diversity were observed in summer especially in waters one meter deep