In this study, the effects of sediment texture and T.O.M. (total organic matter) in sediments of Gomishan Wetland
on density and diversity of macroinvertebrates were studied. The sampling was carried out in spring (as waterlevel fall season) and summer (as water-level rise season). The wetland divided to four stations and the samples of
sediments and macroinvertebrates were collected from the coast area, near the sea area and water-rise area in each
station by Ekman Grab. 10 families were identified which the most abundance was belonged to Pyrgulidae. The
sediment texture was different in each location, but Loam was the common texture. Results showed that except of
south station, TOM increased from the north to the south of Gomishan Wetland. There were low correlations
between the amounts of T.O.M. and silt-clay of bottom sediment with the density and diversity of
macroinvertebrates, but the amount of TOM is effective on the distribution of Cardiidae. Totally, the density and
diversity of organisms follow complex actions.
