Can salinity trigger cascade effects on streams? A mesocosm approach
Can salinity trigger cascade effects on streams? A mesocosm approach
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DOI：
10.1016/j.scitotenv.2015.03.039
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发表时间：
2016-01-01
影响因子：
9.8
通讯作者：
Kefford, Ben
中科院分区：
文献类型：
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作者：
Canedo-Argueelles, Miguel;Sala, Miguel;Kefford, Ben
人类活动大大增加了世界河流的含盐量，未来水资源短缺可能会加剧这种情况。虽然盐度对多种溪流无脊椎动物的致死效应已被证明，但亚致死效应（即生物条件的变化而不死亡）尚未得到深入了解。尚未研究的一个重要的亚致死效应是捕食效率的变化，这可能引发与控制藻类生物量的食草无脊椎动物丰度相关的级联效应。在这项研究中，我们结合使用的生物标志物与社区水平的数据在流围隔生态系统中，以评估潜在的级联效应，增加盐度的营养食物网。捕食和盐处理的水生无脊椎动物的丰度，丰富度和群落组成的影响。捕食者的存在具有明显的级联效应，它降低了草食性无脊椎动物的丰度和丰富度，导致较高的叶绿素a浓度。盐处理显着降低类群丰富度，但仅在砾石床。盐的添加，捕食者显着强调，所示的不同分析的生物标志物。一致的是，在捕食者的存在下，Tanytarsini注册较高的丰度和叶绿素a显示出较低的浓度时，盐的加入。然而，这些变化都不显著。因此，虽然盐的加入显着强调Dina lineata，我们的研究结果表明，需要更长的曝光时间，以充分捕捉级联效应（例如，叶绿素a减少，由于放松对食草无脊椎动物的捕食）。我们建议，潜在的级联效应的盐碱化需要进行评估时，解决水资源短缺（如气候变化和水需求增加造成的）对河流生态系统的影响，因为流量减少将导致更高的盐浓度。(C)2015爱思唯尔B.V.保留所有权利。
Human activities have greatly increased the salt concentration of the world's rivers, and this might be amplified by water scarcity in the future. While the lethal effects \of salinity have been documented for a wide variety of stream invertebrates, the sub-lethal effects (i.e. changes in biological condition without mortality) are not deeply understood yet. One important sub-lethal effect that has yet to be investigated is changes in predation efficiency, which could trigger cascade effects associated to the abundance of herbivorous invertebrates that control algae biomass. In this study we combined the use of biomarkers with community-level data in a stream mesocosm to evaluate the potential cascade effect of increased salinity on the trophic food web. Both predation and salt treatments had an effect on the aquatic invertebrate abundance, richness and community composition. The presence of predators had a clear cascade effect, it reduced herbivorous invertebrate abundance and richness leading to higher chlorophyll a concentrations. The salt treatment significantly reduced taxa richness, but only in the gravel bed. The predators were significantly stressed by salt addition, as shown by the different analyzed biomarkers. Concordantly, in the presence of predators, Tanytarsini registered higher abundances and chlorophyll a showed a lower concentration when salt was added. However, none of these changes was significant. Therefore, although salt addition significantly stressed Dina lineata, our results suggest that a longer exposure time is needed to fully capture cascading effects (e.g. a decrease in chlorophyll a due to a relaxation of predation on herbivorous invertebrates). We suggest that the potential cascade effects of salinization need to be evaluated when addressing the impacts of water scarcity (as caused by climate change and increasing water demand) on river ecosystems, since flow reductions will lead to higher salt concentrations. (C) 2015 Elsevier B.V. All rights reserved.