Microfossils in surface sediments of brackish waters from the South African west coast@en

A faunistic survey covering 25 sites in estuaries, coastal lakes and ponds along the west coast of South Africa between the Cape of Good Hope in the south and the Olifants River in the north was carried out in May 2014. The study aimed to establish a dataset with ecological and distribution data of ostracods and foraminifers for later palaeoenvironmental reconstructions. Canonical correspondence analysis showed that the distribution of the 19 foraminifer and 32 ostracod taxa was controlled mainly by habitat structure, but that specific conductivity (salinity) was best and solely described by the second axis, highlighting the usefulness of the two microfossil groups for salinity reconstructions. Habitat structure was demonstrated by the foraminifer species Trochamminita irregularis' preference for stillwater areas of lakes. Sarscypridopsis aculeata and Sarscypridopsis glabrata were the dominant ostracod species in coastal ponds and lakes. However, their living distributions excluded each other, with S. aculeata preferring areas of lower salinity and S. glabrata dominating areas of higher salinity up to hyperhaline conditions in small, closed water bodies.2014年5月，研究团队于南非西海岸开展了一项动物区系调查，覆盖了自南部好望角（Cape of Good Hope）至北部奥利凡茨河（Olifants River）沿线的河口、沿海湖泊与池塘共计25个采样点位。本研究旨在构建一套包含介形类（ostracods）与有孔虫（foraminifers）生态及分布数据的数据集，以供后续古环境重建（palaeoenvironmental reconstructions）研究使用。典范对应分析（Canonical correspondence analysis）结果显示，19种有孔虫类群与32种介形类类群的分布主要受生境结构调控；而比电导率（specific conductivity，即盐度salinity）则可由第二轴最佳且唯一地拟合，凸显了这两类微化石类群在盐度重建中的应用价值。生境结构的影响可通过有孔虫物种不规则小旋砂虫（Trochamminita irregularis）对湖泊静水区的偏好得以印证。尖顶萨氏介（Sarscypridopsis aculeata）与光滑萨氏介（Sarscypridopsis glabrata）为沿海湖泊与池塘中的优势介形类物种，但二者的存活分布存在相互排斥现象：尖顶萨氏介偏好低盐度区域，光滑萨氏介则占据高盐度区域，甚至可在小型封闭水体中适应超盐度环境。