A survey of diversity and density of Gastropoda before and after summer Monsoon in the Iranian coasts of Oman sea

study on diversity and density of Gastropoda in sediments of Oman Sea (Hormoz strait – Quatr Bay)10 stations were selected. In this study Ferdous 1 vessel and a 0.1 m2 Van-Veen grab sampler was used for collecting sedimens in addition to the physical and chemical parameters such as temperature, salinity, dissolved oxygen and pH using the CTD module. Ethanol 95% and Rosebengal were used for fixing and staining. In this study 71 genera of 43 families of Gastropoda were identified. Among the identified groups, Nassaridae 27%, Retusidae 16%, Pyramidellidae 12%, Cyclostrematidae 8% and Scaphandridae 7% were dominant groups. Results show that diversity and density of Gastropoda in Oman Sea, affected by the southwest Indian Ocean monsoon winds. As far as the frequency of them will be increased and their diversity will be decreased after summer monsoon. But the density of Gastropoda did not show significant difference among before and after Monsoon.