Importance of advective mass transfer and sediment surface area for streambed microbial communities
Importance of advective mass transfer and sediment surface area for streambed microbial communities
复制标题
DOI：
10.1111/fwb.12856
复制
发表时间：
2017
影响因子：
2.7
通讯作者：
C. Mendoza‐Lera;Aline Frossard;Matthias Knie;Laura L. Federlein;M. Gessner;M. Mutz
中科院分区：
文献类型：
--
作者：
C. Mendoza‐Lera;Aline Frossard;Matthias Knie;Laura L. Federlein;M. Gessner;M. Mutz
流动和剪切应力的变化导致河床沉积物中颗粒尺寸的局部分选和斑块状分布。沉积物微生物群落可能会受到由此产生的异质性的影响，因为粒度决定（i）可用于微生物定植的沉积物表面积和（ii）水力传导率，因此溶质和氧化还原伙伴的平流传质。然而，这两个因素对沉积物微生物群落的相对影响尚不清楚。我们进行了实验，在12个室内水槽与三种类型的沉积物：砾石（2-8毫米），砂-砾石混合物（25和75%的质量）和砂（0.2-0.8毫米）在四个水槽。沉积物的平流质量转移（砾石>砂砾混合物=砂）和表面积（砾石<砂砾混合物<砂）不同。我们在每个水槽中加入了微生物接种物。经过40天的殖民化，我们收集了沉积物样品，通过测定细菌和藻类的丰度，呼吸速率和潜在的酶活性来确定沉积物微生物群落。在所有微生物变量中发现的一致模式表明，粒径通过平流传质明显影响沉积物微生物群落，尽管不能排除沉积物表面积的影响：（i）当以单位表面积表示时，砾石中的所有变量都最高，但沙子和砂砾混合物之间的差异很小，（ii）砾石和沙子或沙子中的所有变量都同样高-尽管砾石的表面积大大减少，但仍以体积为基础计算砾石混合物。总体而言，我们的研究结果表明，在流中的粒度分布应考虑在河床微生物群落的分析，特别是如果它有对流传质的影响。
Summary Variability of flow and shear stress cause local sorting and a patchy distribution of grain size in streambed sediments. Sediment microbial communities can be affected by the resulting heterogeneity because grain size determines (i) the sediment surface area available for microbial colonisation and (ii) the hydraulic conductivity and hence advective mass transfer of solutes and redox partners. However, the relative influence of the two factors on sediment microbial communities is not clear. We performed an experiment in 12 indoor flumes with three types of sediment: gravel (2–8 mm), a sand–gravel mixture (25 and 75% by mass) and sand (0.2–0.8 mm) in four flumes each. The sediments differed in both advective mass transfer (gravel > sand–gravel mixture = sand) and surface area (gravel < sand–gravel mixture < sand). We added a microbial inoculum to each flume. After 40 days of colonisation, we collected sediment samples to characterise the sediment microbial community by determining the abundance of bacteria and algae, respiration rates and potential enzyme activities. The consistent pattern found across all microbial variables showed that grain size clearly influences sediment microbial communities through advective mass transfer, although an influence of sediment surface area cannot be ruled out: (i) all variables were highest in gravel when expressed per surface area but differed little between sand and the sand–gravel mixture and (ii) all variables were similarly high in gravel and sand or the sand–gravel mixture on a volumetric basis, in spite of a greatly reduced surface area in gravel. Overall, our findings suggest that grain-size distribution in streams should be taken into account in analyses of streambed microbial communities, especially if it has an effect on advective mass transfer.