Scale-dependent effects of fine sediments on temperate headwater invertebrates
Scale-dependent effects of fine sediments on temperate headwater invertebrates
复制标题
细沉积物对温带水源无脊椎动物的尺度依赖性影响
DOI：
--
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
S. Ormerod
中科院分区：
文献类型：
--
作者：
Stefano Larsen;I. Vaughan;S. Ormerod
1.人为活动可以在多个空间和时间范围内增加细颗粒泥沙对河流的供应。 确定的过程负责，并在流生物的任何影响变得明显的规模，是关键的管理需要，但适当规模的调查是令人惊讶的很少。
2.我们调查了乌斯克河（英国威尔士农村的一个温带山地流域）支流中两种空间分辨率（河段尺度和斑块尺度）的大型无脊椎动物和表层细沉积物。 土地利用，生境和地貌特征进行了现场测量或从现有的数据库（=河流审计）。我们的目标是确定：（i）河流沉积物如何随土地利用和相关地貌而变化;（ii）对大型无脊椎动物可能产生的后果;（iii）大型无脊椎动物与沉积物特征之间关系的任何尺度依赖性。
3.在河段尺度和斑块尺度上，细颗粒泥沙的河床覆盖与上游500 m处的侵蚀程度直接相关。 反过来，沉积和银行侵蚀呈负相关的集水区或河岸林地的范围。
4.在河段尺度上，大型无脊椎动物的组成随流域土地利用和河流化学而变化，随着粗糙放牧或林地被改良草地取代，丰富度下降。 有沉积沉积物没有反应，除了弱增加的相对丰度的寡毛类。
5.相比之下，在斑块尺度上，细颗粒沉积物伴随着无脊椎动物组成的显著变化，我们根据其表观沉积物耐受性对27个最常见的分类群进行了排序。 一般的估计方程表明，总的和蜉蝣目，鳞翅目和毛翅目丰富度显着下降20%和25%，在最泥沙影响的网站（30%的覆盖率）相比，无泥沙的网站。
6.我们得出结论，乌斯克系统上游的沉积物沉积主要反映了局部的河岸侵蚀，河岸林地可能通过河岸稳定来调节这一过程。 细泥沙释放有显着的生态效应，但这些都是检测到只有在补丁到补丁尺度。我们建议，调查本地化的沉积物释放流将受益于规模依赖或规模特定的采样，和一些影响可能无法检测到，除非仔细选择样品分辨率。
1. Anthropogenic activities can increase fine sediment supply to streams over multiple spatial and temporal extents. Identifying the processes responsible, and the scale at which any effects on stream organisms become evident, are key management needs, but appropriately scaled surveys are surprisingly few.
2. We surveyed macroinvertebrates and superficial fine sediments at two spatial resolutions (reach- and patch-scale) in tributaries of the River Usk, a temperate, montane catchment in rural Wales (U.K.). Land use, habitat and geomorphological character were measured on-site or derived from an existing database (=Fluvial Audit). We aimed to identify: (i) how in-stream sediments varied with land use and associated geomorphology; (ii) likely consequences for macroinvertebrates and (iii) any scale-dependence in relationships between macroinvertebrates and sediment character.
3. At both the reach- and patch-scales, bed cover by fine sediment was related directly to the extent of eroding banks 500 m upstream. In turn, sedimentation and bank erosion were negatively correlated with catchment or riparian woodland extent.
4. At the reach scale, macroinvertebrate composition varied with catchment land use and stream chemistry, with richness declining as rough grazing or woodland was replaced by improved grassland. There was no response to deposited sediment except for weak increase in the relative abundance of oligochaetes.
5. By contrast, at the patch scale, fine sediments were accompanied by pronounced changes in invertebrate composition, and we ranked the 27 most common taxa according to their apparent sediment tolerance. General estimating equations showed that total and Ephemeroptera, Plecoptera and Trichoptera richness decreased significantly by 20% and 25% at the most sediment impacted sites (30% cover) by comparison with sediment-free sites.
6. We conclude that sediment deposition in the upper Usk system mostly reflects local bank erosion, with riparian woodland likely to mediate this process through bank stability. Fine sediment release had marked ecological effects, but these were detectable only at patch-to-patch scales. We suggest that investigation of localized sediment release in streams will benefit from scale-dependent or scale-specific sampling, and some effects could go undetected unless sample resolution is selected carefully.