Water Research Institute, National Research Council (CNR-IRSA), Brugherio, Italy; Dipartimento di Scienze Ecologiche e Biologiche (DEB), Università della Tuscia, Viterbo, Italy.
Water Research Institute, National Research Council (CNR-IRSA), Bari, Italy.
Sci Total Environ. 2019 Jul 10;673:489-501. doi: 10.1016/j.scitotenv.2019.04.124. Epub 2019 Apr 10.
The positive effect of mitigation measures on in-stream habitat conditions and the benthic community is recognised. In heavily modified rivers, though, the response of aquatic invertebrates to mitigation measures and habitat mosaic changes is scarcely documented. We used non-metric multidimensional scaling to explore the benthic community of leveed rivers in the agricultural lowlands of Northern Italy. The relevance of in-stream substrate microhabitat for the benthic community was assessed, together with the impact of mitigation measures. We proposed a straightforward approach to quantify similarity of microhabitat mosaic between sites testing its statistical significance based on Bayesian statistics. We hypothesised that changes of microhabitat mosaic would reflect the level of implementation of mitigation measures and benthic invertebrates would respond accordingly. Alpha, beta diversity and benthic metrics used to classify ecological status/potential were considered and their variation tested against different levels of measure implementation. Lastly, ecological potential classification was paralleled to both the level of measure implementation and habitat attributes. The microhabitats found at sites where measures were fully implemented differed from those observed elsewhere and they clearly mirrored morphological alteration and mitigation measures. Moreover, alongside morphological alteration, microhabitat diversity and mosaic were the main factors for benthic community structure. While benthic beta diversity strictly reflected microhabitat diversity, alpha diversity and ecological status metrics copied the mosaic gradient. Microhabitat attributes and most benthic metrics showed significant changes following measure implementation and they were accompanied by a gradual shift in ecological potential classes. We demonstrated the importance of in-stream substrate microhabitats as a bridge between mitigation measures and the benthic community. Particularly when ecological classification is under focus, microhabitat mosaic should be evaluated for achieving a better understanding of biological responses. The huge amount of data available worldwide could support a straightforward use of river mosaic information for river management.
缓解措施对河流生境条件和底栖生物群落的积极影响得到了认可。然而，在受严重干扰的河流中，水生无脊椎动物对缓解措施和生境镶嵌变化的响应却鲜有记录。我们使用非度量多维标度分析来探讨意大利北部农业低地堤坝河流的底栖生物群落。评估了河流内基质微生境对底栖生物群落的重要性，以及缓解措施的影响。我们提出了一种简单的方法来量化站点之间微生境镶嵌的相似性，并基于贝叶斯统计对其进行统计显著性检验。我们假设微生境镶嵌的变化将反映缓解措施的实施水平，底栖无脊椎动物将相应做出反应。我们考虑了用于分类生态状况/潜力的 alpha、beta 多样性和底栖指标，并针对不同的措施实施水平对其变化进行了测试。最后，生态潜力分类与措施实施水平和生境属性平行进行。在完全实施措施的地点发现的微生境与其他地方观察到的微生境不同，它们清楚地反映了形态改变和缓解措施。此外，除了形态改变外，微生境多样性和镶嵌是底栖生物群落结构的主要因素。虽然底栖 beta 多样性严格反映了微生境多样性，但 alpha 多样性和生态地位指标复制了镶嵌梯度。微生境属性和大多数底栖指标在实施措施后发生了显著变化，并伴随着生态潜力类别的逐渐转变。我们证明了河流内基质微生境作为缓解措施与底栖生物群落之间桥梁的重要性。特别是在生态分类受到关注的情况下，应该评估微生境镶嵌，以更好地理解生物响应。全世界可用的大量数据可以支持简单地使用河流镶嵌信息进行河流管理。
