Benthic Faunal Assemblages of the Holocene Sediments from the Southwest Black Sea Shelf

Abstract

Benthic faunal content (benthic foraminifera, mollusca and ostracoda) of sediment cores from the SW Black Sea shelf were examined. Based on the vertical distribution of abundance and diversity of the benthic fauna, three benthic assemblages were distinguished. These assemblages are BF1, BF2 and BF3, and reflect the changes in bottom water from the termination of the Neoeuxinian period to present. BF1 displays high abundance and diversity in the surroundings of the Bosporus channel, diminishing in the shelf sediments further away from the channel. In the Mid-Shelf and Outer Shelf, it displays low abundance and low diversity. BF1 which started to be deposited at about 6 ky BP reflects the source effect of the saline Mediterranean lower layer, diminishing in strength toward more distal areas. In the Outer Shelf, changing foraminiferal faunal content may suggest that relatively low salinity conditions in the bottom water were established after similar to 4 ky BP. BF2 consists of a mixed fauna (brackish and euryhaline Mediterranean species), suggesting transitional conditions with intrusion of Mediterranean water earlier than similar to 8 ky BP. BF3 corresponds to the Neoeuxinian lake phase of the Black Sea.