Climate change can result in multiple indirect alterations of the environment in riverine ecosystems, due to changes in precipitation and runoff. Flow velocity, concentrations of CO₂ and nutrients are thereby expected to change, and consequences of the combination of those effects for macrophytes, a key organism group, are still poorly understood. This was tested in a racetrack flume experiment on macrophyte species Berula erecta, an amphibious species growing fully submerged in the experiment. In a full-factorial design, plants were exposed to two different CO₂ concentrations, two nutrient concentrations (N, P and Si) and two flow velocities. Apart from individual dose–response tests, two climate change scenarios were tested: a wet scenario simulating heavy precipitation and runoff with high flow velocity, high CO₂ and high nutrient concentrations and a dry scenario simulating evapotranspiration with low flow velocity, high CO₂ and high nutrient concentrations. Growth rate, biomass, morphology, chlorophyll and nutrient content were measured. Berula erecta responded strongly to both scenarios. Biomass and relative growth rate increased, leaf BSi content decreased, and especially in the wet scenario macrophytes had shorter stems and formed stolons with new ramets: the plants invested in horizontal growth to avoid hydrodynamic stress. Moreover, the C/N ratio was higher, leading to lower quality of macrophyte tissue as food source, and chlorophyll concentration was lower in the high CO₂ treatment. It can be concluded that combined stressors caused by climate change strongly affect macrophytes, which may indirectly have consequences for other organisms of the aquatic ecosystem that depend on macrophytes.

中文翻译：

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气候变化对沉水植物的影响：CO 2，流速和养分浓度对直立贝拉虫的影响

由于降水和径流的变化，气候变化可导致河流生态系统中环境的多种间接变化。因此，预计流速，CO ₂和营养物的浓度会发生变化，而这些影响对关键生物群大型植物的影响的后果仍然知之甚少。这是在大型水生植物Berula erecta（一种在实验中完全淹没的两栖物种）的赛道水槽实验中测试的。在全要素设计中，将植物暴露于两种不同的CO ₂浓度，两种营养物浓度（氮，磷和硅）和两种流速。除了个别的剂量反应测试外，还测试了两个气候变化情景：模拟高流速，高CO ₂和高养分浓度下的强降水和径流的湿法模拟和模拟低流速，高CO ₂和高蒸发量下的蒸散的干法模拟。营养素含量高。测量生长速率，生物量，形态，叶绿素和营养成分。直对这两种情况都有强烈的反应。生物量和相对生长速率增加，叶片BSi含量降低，特别是在潮湿的情况下，大型植物的茎较短，并形成带有新分株的茎：为避免水动力胁迫，植物进行了水平生长。此外，C / N比较高，导致大型植物组织作为食物来源的质量较低，而高CO ₂处理的叶绿素浓度较低。可以得出结论，由气候变化引起的综合压力源强烈影响大型植物，这可能间接影响依赖大型植物的水生生态系统的其他生物。