Université Lyon 1, UMR-CNRS 5023 Ecology of Natural and Anthropized Hydrosystem Laboratory, 43 Bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France; IRSTEA, UR MALY, F-69336 Lyon, France; Electricité de France, Savoie Technolac, 73373 Le Bourget du Lac, France.
Sci Total Environ. 2014 Jan 1;466-467:265-76. doi: 10.1016/j.scitotenv.2013.06.082. Epub 2013 Jul 31.
Streambed colmation by fine sediment, e.g. the deposition, accumulation and storage of fines in the substrate, is known to have severe effects on invertebrate assemblages in both the benthic and hyporheic zones but the changes in biological attributes of invertebrate assemblages related to colmation have never been considered simultaneously for these two zones. We studied the effects of colmation on the invertebrate assemblages of three rivers, testing a priori hypotheses on the biological attributes that should be more selected in communities subjected to different levels of colmation in both zones. Only the proportion of organisms with high fecundity increased and the proportion of small-sized organisms decreased along the colmation gradient in both zones simultaneously. As expected, a higher number of traits were significantly modified with colmation in the benthic vs. hyporheic assemblages. Most of the biological attributes impaired were different in the two zones. In the benthic zone, colmation mainly selected particular physiological or trophic characteristics of species and features related to their resistance or resilience capacities. In contrast, the morphological attributes of species were much more impaired by colmation in the hyporheic zone than in the benthic zone. In clogged benthic habitats, traits seemed to be more impaired by an increase in physico-chemical constraints (e.g. the reduction of oxygen availability) and a reduction of potential exchanges (including exchanges of food resources) due to a decline in stream bed conductivity. The morphological attributes of the hyporheic species were probably more influenced by changes in interstitial space characteristics. A potential indicator of the effects of colmation on river health may be based on the functional traits of benthic communities because they (i) satisfy the WFD recommendations, (ii) respond consistently along a colmation gradient and (iii) are comparable among assemblages even across ecoregions that differ in their taxonomic composition.
底床淤沙（例如，细颗粒物质在基质中的沉积、积累和储存）会对底栖和渗流区无脊椎动物群落产生严重影响，但淤沙对这两个区无脊椎动物群落生物属性的变化却从未同时考虑过。我们研究了淤沙对三条河流无脊椎动物群落的影响，检验了关于在这两个区中处于不同淤沙水平的群落中应更具选择的生物属性的先验假设。只有在两个区中，高繁殖力的生物比例随着淤沙梯度的增加而增加，小型生物的比例同时减少。与预期一致的是，与淤沙相比，在底栖和渗流区的无脊椎动物群落中有更多的特征发生了显著变化。在两个区中，受到影响的生物属性大多不同。在底栖区，淤沙主要选择了物种的特定生理或营养特征以及与它们的抵抗力或恢复力有关的特征。相比之下，在渗流区，物种的形态特征受到淤沙的影响比在底栖区大得多。在淤塞的底栖生境中，由于物理化学限制（例如，氧气供应减少）的增加以及由于河床电导率下降导致潜在交换（包括食物资源的交换）减少，特征似乎受到更大的损害。渗流区物种的形态特征可能更多地受到间隙空间特征变化的影响。底栖群落的功能特征可能成为淤沙对河流健康影响的潜在指标，因为它们（i）满足 WFD 的建议，（ii）在淤沙梯度上一致响应，（iii）即使在分类组成不同的生态区之间也具有可比性。
