Multiple stressors and stream macroinvertebrate community dynamics: Interactions between fine sediment grain size and flow velocity
Multiple stressors and stream macroinvertebrate community dynamics: Interactions between fine sediment grain size and flow velocity
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DOI：
10.1016/j.scitotenv.2020.137070
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发表时间：
2020-05-15
影响因子：
9.8
通讯作者：
Piggott, Jeremy J.
中科院分区：
文献类型：
--
作者：
Blocher, Johanna R.;Ward, Matthew R.;Piggott, Jeremy J.
农业发展导致全世界淡水生态系统退化。影响农业集水区的溪流和河流的两个关键压力来源是沉积的细小沉积物(例如由于侵蚀)和流量减少(例如由于取水、大坝或气候变化)。以往的研究已发现细粒泥沙是河流中的“主应激源”，但不同粒度的泥沙与降低水流速度的联合作用却知之甚少。我们在60个室外水系中层同时操纵沉积的细粒泥沙(无添加泥沙；粉砂：0~0.125 mm；细沙：0.125~0250 mm；粗沙：1.2微米)和流速(快：26.5厘米/S；中等：13.9厘米/S；慢：0.0厘米/S)。我们确定了这些应激源对底栖、漂流和新兴河流大型无脊椎动物群落的单独和综合影响。细微沉积物和降低的流速对河流无脊椎动物群落都有普遍的不利影响。对于某些响应(摇虫科、桡足类、拟脊椎动物的丰度)，沉积物的负面影响在较小的两个粒度时更严重；然而，对于一些对沉积物敏感的常见类群或群落水平的无脊椎动物指标，无论粒度大小，影响都是负面的。尽管它们的综合影响主要是相加的，但在一些情况下，流速的降低会加剧泥沙的影响。我们的研究结果表明：(A)特别是对于泥沙敏感物种，所有细小的泥沙
Agricultural development has resulted in the degradation of freshwater ecosystems worldwide. Two key stressors impacting streams and rivers draining agricultural catchments are deposited fine sediment (e.g. due to erosion) and reduced flows (e.g. due to water abstraction, dams, or climate change). Past studies have identified fine sediment as a 'master stressor' in streams, but the effects of different sediment grain sizes in combination with reduced flow velocity are poorly understood.We manipulated deposited fine sediment (no added sediment; silt: 0-0.125 mm; fine sand: 0.125-0250 mm; coarse sand: 1 2 inm) and flow velocity (fast: 26.5 cm/s; medium: 13.9 cm/s; slow: 0.0 cm/s) simultaneously in 60 outdoor stream mesocosms. We determined the individual and combined effects of these stressors on the benthic, drifting, and emerging stream macroinvertebrate communities.Both fine sediment and reduced flow velocity had pervasive detrimental impacts on stream invertebrate communities. Negative effects of sediment were worse at the smaller two grain sizes for some responses (abundance of Chironomidae, Copepoda, Psilochorema spp.); however, for several sediment-sensitive common taxa or community-level invertebrate metrics, effects were negative regardless of grain size. Although their combined effects were mainly additive, sediment impacts were worsened by reduced flow velocities in several cases.Our findings imply that (a) especially for sediment-sensitive species, all fine sediment