Biodiversity of foraminifera from Late Pleistocene to Holocene coral reefs, South Sinai, Egypt

Abstract

Tropical coral reefs are among the most diverse marine ecosystems. In order to better understand temporal and spatial variation in late Quaternary biodiversity, foraminiferal faunas of two fossil, raised reef terraces at the southern Sinai Peninsula were studied and compared to modern coral reef faunas. Eleven U-series dates of shell fragments of the giant clam Tridacna sp. indicates deposition largely during marine isotope stage 5 (MIS 5), 77–129 kyr BP, for the two raised terraces. In these terraces, Amphistegina (A. lessonii and A. lobifera) dominates the five fossil foraminiferal associations. The fossil reef-flat association 1 has common Gypsina plana, Homotrema rubra and Acervulina spp., and fossil reef-flat association 2 consists of Amphistegina spp. Of the three fossil fore-reef associations, one has abundant porcelaneous taxa including Sorites, Amphisorus, Peneroplis and Borelis, one has a mix of porcelaneous taxa and attached-arborescent taxa (Homotrema and Placopsilina) and one has abundant attached and arborescent taxa (Miniacina, Gypsina, Acervulina and Planogypsina). The modern fringing reef is dominated by porcelaneous foraminifera, and three modern associations are identified. These include a lagoonal association with abundant Peneroplis pertusus, a reef-flat association dominated by Sorites orbiculus and a fore-reef association with porcelaneous taxa plus common H. rubra, Amphistegina lessonii and A. lobifera. Based on our data and including additional published information on regional biodiversity it appears that during MIS 5 foraminiferal biodiversity was higher and community structure was different than within the modern reefs. These data and regional paleo-climate patterns indicate that oceanographic conditions in the Red Sea were probably closer to normal marine conditions during the last interglacial than they are today.