Kansas Cooperative Fish and Wildlife Research Unit, Division of Biology, Kansas State University Division of Biology, 209 Leasure Hall, Manhattan, KS 66506, USA.
U. S. Geological Survey, Kansas Cooperative Fish and Wildlife Research Unit, Kansas State University, Manhattan, KS 66506, USA.
Sci Total Environ. 2018 Apr 1;619-620:221-231. doi: 10.1016/j.scitotenv.2017.10.272. Epub 2017 Nov 14.
Conserving native biodiversity depends on restoring functional habitats in the face of human-induced disturbances. Low-head dams are a ubiquitous human impact that degrades aquatic ecosystems worldwide. To improve our understanding of how low-head dams impact habitat and associated biodiversity, our research examined complex interactions among three spheres of the total environment. i.e., how low-head dams (anthroposphere) affect aquatic habitat (hydrosphere), and native biodiversity (biosphere) in streams and rivers. Creation of lake-like habitats upstream of low-head dams is a well-documented major impact of dams. Alterations downstream of low head dams also have important consequences, but these downstream dam effects are more challenging to detect. In a multidisciplinary field study at five dammed and five undammed sites within the Neosho River basin, KS, we tested hypotheses about two types of habitat sampling (transect and mosaic) and two types of statistical analyses (analysis of covariance and path analysis). We used fish as our example of biodiversity alteration. Our research provided three insights that can aid environmental professionals who seek to conserve and restore fish biodiversity in aquatic ecosystems threatened by human modifications. First, a mosaic approach identified habitat alterations below low-head dams (e.g. increased proportion of riffles) that were not detected using the more commonly-used transect sampling approach. Second, the habitat mosaic approach illustrated how low-head dams reduced natural variation in stream habitat. Third, path analysis, a statistical approach that tests indirect effects, showed how dams, habitat, and fish biodiversity interact. Specifically, path analysis revealed that low-head dams increased the proportion of riffle habitat below dams, and, as a result, indirectly increased fish species richness. Furthermore, the pool habitat that was created above low-head dams dramatically decreased fish species richness. As we show here, mosaic habitat sampling and path analysis can help conservation practitioners improve science-based management plans for disturbed aquatic systems worldwide.
保护本地生物多样性取决于在面对人为干扰时恢复功能栖息地。低水头坝是一种普遍存在的人为影响，它会破坏全球的水生生态系统。为了更好地了解低水头坝如何影响栖息地和相关生物多样性，我们的研究考察了总环境的三个领域之间的复杂相互作用。即低水头坝（人类圈）如何影响水生栖息地（水圈），以及溪流和河流中的本地生物多样性（生物圈）。低水头坝上游形成类似湖泊的栖息地是大坝的一个有充分记录的主要影响。低水头坝下游的变化也会产生重要的后果，但这些下游大坝的影响更难察觉。在堪萨斯州 Neosho 河流域的五个有坝和五个无坝地点的多学科实地研究中，我们测试了关于两种类型的栖息地采样（横断和镶嵌）和两种类型的统计分析（协方差分析和路径分析）的假设。我们以鱼类作为生物多样性变化的例子。我们的研究提供了三个见解，可以帮助那些寻求保护和恢复受人类改造威胁的水生生态系统中的鱼类生物多样性的环境专业人员。首先，镶嵌采样方法确定了低水头坝下游的栖息地变化（例如增加了急流的比例），而这是使用更为常用的横断采样方法无法检测到的。其次，栖息地镶嵌采样方法说明了低水头坝如何减少了溪流栖息地的自然变化。第三，路径分析，一种测试间接效应的统计方法，展示了大坝、栖息地和鱼类生物多样性如何相互作用。具体来说，路径分析表明，低水头坝增加了大坝下游急流栖息地的比例，从而间接增加了鱼类物种丰富度。此外，低水头坝上游形成的池塘栖息地极大地减少了鱼类物种丰富度。正如我们在这里所展示的，镶嵌栖息地采样和路径分析可以帮助保护实践人员改善全球受干扰水生系统的基于科学的管理计划。
