Study of benthic foraminifera abundance in the sediments of southern Caspian Sea from Fereidoonkenar to Babolsar

In order to study benthic Foraminifera abundance in southern coast of Caspian Sea (Fereidoonkenar to Babolsar), sediment samples were gathered with Vanvin Grab from 12 stations (3 transects and each of them contains the depth 5, 10, 15 and 20 meters) in spring 2011. Environmental conditions of water near the bottom including: Temperature, dissolved oxygen and salinity were measured during sampling and analysis of grain size and counting of benthic forms were done in laboratory and their relationship with the Foraminifera communities was studied. Water temperature (20/2-22°C), dissolved oxygen (6.40–8.60mg/l) was measured and salinity with not too much difference was (10/6–11ppt). Structure of the bottom sediment mostly consisted of fine sand; very fine sand, silt and clay. These benthic Foraminifera were observed in all stations and they had the most abundance among the other meiobenthose and the cosmopolitan Foraminifera, Ammonia beccarii caspica was the dominant species and was present in all sampling stations. Density of benthic forms had a positive correlation with temperature, dissolved oxygen and salinity and had a significantly correlation with grain size, that their density were increased with adding silt and clay rate. The structure of the sediments, dissolved oxygen and temperature seemed to be the most important abiotic factors for controlling the abundance of benthic Foraminifera in the sampling stations.