Benthic foraminiferal fauna in the Ionian Sea

To reconstruct paleoceanographic changes in the eastern Mediterranean during the last 330,000 years, we studied benthic foraminifera in a piston core from the Ionian Sea. The fauna exhibits large fluctuations in foraminiferal number, diversity, and species composition. Interglacials are characterized by low foraminiferal number and diversity indicating oligotrophic conditions. Directly below or above interglacial sapropels, increased numbers of low-oxygen-tolerant species indicate a strong reduction of deep water circulation. Glacials are characterized by increased foraminiferal number and diversity and faunas that are dominated by shallow infaunal species indicating mesotrophic conditions. Around glacial sapropel S6 very high foraminiferal numbers and the dominance of shallow and deep infaunal species suggest enhanced organic matter fluxes. These faunal results provide information about changes in the African and North Atlantic climate systems (monsoon and westerlies) controlling the humidity and wind stress in the Mediterranean region.

为重建过去33万年东地中海的古海洋学（paleoceanographic）变化，我们对采自爱奥尼亚海（Ionian Sea）的一根活塞岩芯（piston core）中的底栖有孔虫（benthic foraminifera）开展了研究。该有孔虫动物群的丰度、多样性及物种组成均呈现显著波动。间冰期（Interglacials）以较低的有孔虫丰度与多样性为特征，指示寡营养（oligotrophic）环境。在间冰期腐泥层（sapropels）的正上方或正下方，耐低氧物种的丰度显著提升，指示深水环流大幅减弱。冰期（glacials）以较高的有孔虫丰度与多样性为特征，其动物群以浅内栖（shallow infaunal）物种占主导，指示中营养（mesotrophic）环境。在冰期腐泥层S6附近，有孔虫丰度极高，且以浅内栖与深内栖（deep infaunal）物种为主，表明当时的有机质通量显著增强。上述有孔虫动物群研究结果，为解析调控地中海区域湿度与风应力的非洲及北大西洋气候系统（季风（monsoon）与西风带（westerlies））的变化提供了关键依据。