Distribution of benthic foraminifera in surface sediments on the continental margin off North-West Africa

The benthic foraminiferal populations along three traverses across the Northwest African continental margin were analyzed on the base of ca. 60 surface sediment samples. Depth ranges of 213 species were established and the main trends of vertical distribution are compared with those known from adjacent regions. Main faunal breaks occure at 100/200 m and 1000/1500 m depth of water. Some species show latitudinal distribution boundaries and the same applies to population density (standing stock), reflecting the regional distribution of nutrients supply by river discharge and upwelling processes. – High proportions of Bolivina test at the lower slope indicate extended downslope transport.

本研究基于约60个表层沉积物样品，对西北非洲大陆边缘三条测线的底栖有孔虫种群开展了分析。本研究确定了213个物种的水深分布范围，并将其垂直分布的主要趋势与邻近区域已有的研究结果进行对比。主要动物群分界出现在水深100/200米和1000/1500米处。部分物种存在纬度分布界限，种群密度（现存量standing stock）亦是如此，这反映了河流径流与上升流过程所供给的营养盐的区域分布特征。此外，斜坡下部高比例的玻林虫（Bolivina）壳体指示了广泛的跨坡搬运作用。