University of Bielefeld, Bielefeld, Germany.
Environ Toxicol Chem. 2011 Feb;30(2):427-38. doi: 10.1002/etc.387.
The direct and indirect effects of Cd on benthic communities were assessed in a freshwater microcosm study over a period of seven months (218 d). Cadmium was regarded as a model substance to evaluate the usefulness of small-scale laboratory microcosm with microscopic fauna. In particular, effects on the meiofauna community, an ecologically important but rather neglected benthic component, were investigated. In addition, some microfaunal parameters (protozoan abundance and microbial activity) were determined. The sediment was spiked with nominal Cd concentrations of 10, 100, and 1,000 mg/kg dry weight. Because of the strong binding of Cd to sediment particles, measured Cd pore-water concentrations never exceeded 129.5 ± 40.7 µg/L. At 1,000 mg/kg dry weight, the abundances of the two dominant meiofauna taxa, nematodes and oligochaetes, were significantly reduced throughout the present study. Regarding nematodes, species of bacterivorous taxa (Daptonema, Eumonhystera) decreased, whereas species of predacious and omnivorous taxa (Mononchus, Dorylaimus, and Ironus) increased in dominance in microcosms of the highest Cd concentration. Transient effects on microfauna were observed, especially in the first half of the present study, with a reduction in microbial activity and protozoan abundance. However, in microcosms receiving the highest Cd concentration, the abundance of the flagellate Euglena mutabilis increased significantly toward the end of the present study. The results of the present study support the use of small-scale microcosms with natural meiofauna communities as a suitable tool to assess the impact of pollutants in freshwater sediments.
在为期七个月（218 天）的淡水微宇宙研究中，评估了镉对底栖生物群落的直接和间接影响。镉被视为一种模型物质，用于评估具有微观动物群的小型实验室微宇宙的有用性。特别是，研究了对中型动物群（生态上重要但被忽视的底栖生物组成部分）的影响。此外，还确定了一些微动物参数（原生动物丰度和微生物活性）。沉积物中加入了名义上的 10、100 和 1000mg/kg 干重的镉。由于镉与沉积物颗粒强烈结合，测量的镉孔隙水中浓度从未超过 129.5±40.7µg/L。在 1000mg/kg 干重时，两种占优势的中型动物群（线虫和寡毛类）的丰度在整个研究过程中显著降低。就线虫而言，食细菌类群（Daptonema、Eumonhystera）的物种减少，而捕食和杂食类群（Mononchus、Dorylaimus 和 Ironus）的物种在最高镉浓度的微宇宙中占优势。在本研究的前半部分，特别是在本研究的前半部分，观察到了对微动物的短暂影响，微生物活性和原生动物丰度降低。然而，在接收最高镉浓度的微宇宙中，鞭毛虫 Euglena mutabilis 的丰度在本研究结束时显著增加。本研究的结果支持使用具有自然中型动物群的小型微宇宙作为评估淡水沉积物中污染物影响的合适工具。
