Centro de Estudios Hidrográficos (CEDEX), Paseo Bajo de la Virgen del Puerto, 3, 28005 Madrid, Spain.
Centro de Estudios Hidrográficos (CEDEX), Paseo Bajo de la Virgen del Puerto, 3, 28005 Madrid, Spain.
Sci Total Environ. 2019 Dec 10;695:133774. doi: 10.1016/j.scitotenv.2019.133774. Epub 2019 Aug 6.
Flow regime alteration by dams has been recognized as a major impact factor for aquatic communities. Spain is currently the member state of the EU with the largest number of large reservoirs. With the broad objective of diminishing the ongoing river degradation trend through the management of environmental flows and the use of biomonitoring tools, we investigated the effects of dams on stream macroinvertebrates in several regulated rivers in Spain with contrasting environmental settings. Specifically, we studied longitudinal trends in macroinvertebrate communities to test: i) if currently used biomonitoring tools and multivariate community analyses can detect hydrological impact responses and biological recovery; ii) if an applicable quantification of the recovery gradient, in terms of distance downstream from dams, can be obtained for Iberian fluvial systems; iii) if macroinvertebrate community structure respond different to flow regulation, depending on the contrasting environmental river typologies; and iv) if the type and intensity of hydrological alteration modulates the observed community responses/recovery. Biotic indices and metrics displayed a decrease in 5 out of 6 systems immediately downstream of infrastructure. Complete recovery could not be clearly detected, but some recovery patterns started at a distance >11km. Multivariate community patterns and biomonitoring metrics showed the most pronounced hydrological alteration impacts and weaker recovery of the downstream macroinvertebrate communities within dammed Mediterranean streams (comparing to other rivers with continental or oceanic climate influence). Finally, both the intensity and type of hydrological alteration (highlighting the alteration of the floods and droughts components) were related to changes in common biomonitoring metrics. Our results could help in recognizing heavily modified water bodies (sensu European Water Framework Directive) downstream of dams or the delineation of fluvial zones or reserves. Furthermore, applied research areas dealing with environmental flows or the bioassessment of hydrological impacts could benefit from our main findings.
水流状态的改变是水生态系统的主要影响因素之一，而大坝对此有着重要影响。西班牙是欧盟成员国中拥有大型水库数量最多的国家。本研究以减少河流退化趋势为目标，通过管理环境流量和使用生物监测工具，对西班牙具有不同环境背景的几条受调控河流中的大型底栖无脊椎动物进行了研究。具体来说，我们研究了大型底栖无脊椎动物群落的纵向变化趋势，以检验：i）当前使用的生物监测工具和多变量群落分析是否能够检测到水文影响响应和生物恢复；ii）是否可以在伊比利亚河流系统中获得适用于量化的恢复梯度，即距大坝下游的距离；iii）大型底栖无脊椎动物群落结构是否会因河流环境类型的不同而对水流调节产生不同的响应；iv）水文变化的类型和强度是否会调节观察到的群落响应/恢复。生物指数和生物指标在 6 个系统中的 5 个系统中，在基础设施下游立即显示出下降。不能明确检测到完全恢复，但在距离大坝>11km 处开始出现一些恢复模式。多变量群落模式和生物监测指标显示，在受大坝影响的地中海河流中（与受大陆性或海洋性气候影响的其他河流相比），对下游大型底栖无脊椎动物群落的水文变化影响最为显著，且恢复能力较弱。最后，水文变化的强度和类型（突出洪水和干旱成分的变化）与常见生物监测指标的变化有关。我们的研究结果有助于识别大坝下游受严重影响的水体（参照欧洲水框架指令），或划定河流带或保护区。此外，与环境流量或水文影响生物评估相关的应用研究领域也可以从我们的主要研究结果中受益。
