Impact of late Quaternary environmental changes on deep-sea benthic foraminiferal faunas of the Red Sea

Abstract

Fluctuations in abundance, diversity and species composition of benthic foraminifera from two sites of the northern and southern Red Sea indicate strong variability of deep-sea ecosystems during the last four glacial to interglacial cycles. In total, five and four different benthic foraminiferal assemblages have been identified in the northern core and southern core, respectively. Comparison with recent faunas from the Red Sea and adjacent oceans allowed the reconstruction of temporal changes in deep-water ventilation, salinity and food availability at the seafloor. Generally, the abundance of infaunal and miliolid taxa increase during glacial intervals indicating increased organic matter fluxes, oxygen decrease and salinity increase in deep waters during these times. These fluctuations are attributed to enhanced oxygen consumption rates and temporarily reduced deep-water formation in the northern Red Sea during glacial intervals. The recorded environmental changes are a reflection of both high- and low-latitude climate changes. The northern Red Sea is mainly influenced by glacio-eustatic sea level fluctuations that control deep-water formation rates and by mid-latitude climate changes of the Mediterranean region that control surface productivity. In contrast, deep-sea ecosystem variability of the southern Red Sea is additionally influenced by low-latitude climate changes attributed to the NE monsoon intensity that drives the inflow of nutrient-rich surface waters from the Gulf of Aden. These results demonstrate the high sensitivity of deep-sea ecosystems of the Red Sea to both global and regional climate changes.