Recent benthic foraminifers from Tarut Bay, Arabian Gulf coast of Saudi Arabia

Abstract. Recent bottom sediments from Tarut Bay were studied for their foraminiferal content. 13 of the 43 taxa comprise more than 90 percent of the total living and dead foraminifers. The bay sediments are characterized by a Miliolina-dominated assemblage, Rotaliina constitutes the next abundant suborder, with the Textulariina as a minor part of the fauna. Both living and dead populations exhibit low diversity (S=l–5) due to adverse hydrographic conditions in Tarut Bay.

The foraminiferal species show significant variations between environments. The intertidal zone is dominated by Ammonia beccarii, Quinqueloculina spp., Elphidium, sp. aff. E. advena, Spirolina arietina and Peneroplis planatus. In the shallow subtidal zone (<3m), Ammonia beccarii becomes less important and other species of the intertidal zone show significant decreases in their concentrations. Trioculina spp. and Spiroloculina spp. become more abundant. The characteristic feature of the deeper subtidal zone (>3m) is the abundance of Eggerelloides scabra, which constitutes 18.5% of the total foraminifers. Quinqueloculina spp., is the only dominant intertidal taxa to be present as a dominant member of the deeper subtidal zone. Differences in hydrographic conditions and other ecological parameters are considered to be responsible for the species variation. The Quinqueloculina-abundant foraminiferal assemblage of Tarut Bay differs considerably from the foraminiferal assemblages of the southwest Gulf.