Abstract The key to the utility of foraminifers as paleo-environmental indicators for coral reefs is the knowledge of modern assemblages in relation to environmental conditions. This study examined 44 surface-sediment samples from three small islands in Yongle Atoll, with the goal to investigate the relationship between foraminiferal distribution and environmental characterization. In samples, 192 foraminiferal species belonging to 74 genera were identified, among which the hyaline foraminifers totally dominated. Hierarchical Cluster Analysis resulted in the identification of three foraminiferal biofacies, representing different environmental settings and sedimentary regimes. (1) The Amphistegina (mainly Amphistegina lobifera) facies characterizes the upper fore-reef slope zone, which experiences strong wave action and currents from the open sea. (2) The Calcarina hispida–Neorotalia calcar facies represents the reef flat and lagoon slope zone, and patch reefs in the lagoon basin, which is the shallowest of all the biofacies, exposed to the strong solar radiation and strong hydrodynamic activity. (3) The Quinqueloculina crassa subcuneata–Elphidium advenum facies characterizes the lagoon basin, which is covered by fine sands and muds with abundant Halimeda fragments to water depths

中文翻译：

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南海西沙群岛永乐环礁近期有孔虫分布作为沉积指标

摘要 将有孔虫用作珊瑚礁古环境指标的关键是了解现代组合与环境条件的关系。本研究检查了来自永乐环礁三个小岛的 44 个地表沉积物样本，目的是调查有孔虫分布与环境特征之间的关系。样品中鉴定出有孔虫74属192种，其中透明有孔虫占绝对优势。层次聚类分析确定了三种有孔虫生物相，代表不同的环境背景和沉积制度。(1) Amphistegina (主要是 Amphistegina lobifera) 相表征了上前礁斜坡带，该带经历了来自公海的强烈波浪作用和洋流。(2) Calcarina hispida-Neorotalia calcar 相代表礁坪和泻湖斜坡带，泻湖盆地中的斑块礁，是所有生物相中最浅的，暴露于强烈的太阳辐射和强烈的水动力活动。(3) Quinqueloculina crassa subcuneata-Elphidium advenum 相是泻湖盆地的特征，该盆地被细沙和泥土覆盖，在水深处含有丰富的 Halimeda 碎片