It is expected that climate change will cause more frequent extreme events of heavy precipitation and drought, changing hydrological conditions in riverine ecosystems, such as flow velocity, evapotranspiration (drought) or runoff (heavy precipitation). This can lead to an increased input of terrestrial organic matter and elevated levels of dissolved organic carbon (DOC) and CO2 due to degradational processes in water. Consequences for submerged macrophytes, as essential organism group, are still poorly understood. The combined effects of changing flow velocity, DOC and CO2 have not been studied before, so this was tested in a racetrack flume experiment on the macrophyte Berula erecta using a trait-based approach. The plants were exposed to two different flow velocities, two DOC concentrations and two CO2 concentrations in a full factorial design. 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 DOC and CO2 concentrations and a dry scenario simulating evapotranspiration with low flow velocity, high DOC and high CO2 concentrations. Growth rate, biomass, morphology, chlorophyll and nutrient content (C, N, and P) were measured. B. erecta responded strongly to both scenarios. Biomass and the relative growth rate increased and stems were shorter, especially in the wet scenario, and vegetative reproduction (the number of stolons) decreased. In both scenarios, the N content was lower and P content higher than in conditions without climate change. It can be concluded that climate change effects, especially shading by DOC, strongly influence macrophytes: macrophyte abundance will probably be negatively affected by climate change, depending on the macrophyte species and abundance of epiphytic algae. This may have consequences for other components of the aquatic ecosystem.

中文翻译：

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沉水植物生长、形态、叶绿素含量和营养化学计量对流速增加和 CO2 和溶解有机碳浓度升高的响应

预计气候变化将导致更频繁的强降水和干旱极端事件，改变河流生态系统的水文条件，如流速、蒸散（干旱）或径流（强降水）。由于水中的降解过程，这可能导致陆地有机物质的输入增加以及溶解有机碳 (DOC) 和 CO2 的水平升高。沉水大型植物作为基本生物群的后果仍然知之甚少。以前从未研究过流速变化、DOC 和 CO2 的综合影响，因此在大型植物 Berula standa 的跑道水槽实验中使用基于性状的方法对此进行了测试。在全因子设计中，植物暴露于两种不同的流速、两种 DOC 浓度和两种 CO2 浓度。除了单独的剂量反应测试外，还测试了两种气候变化情景：模拟强降水和径流的湿情景和高流速、高 DOC 和 CO2 浓度的干情景和模拟蒸散的干情景、低流速、高 DOC 和高 CO2 浓度. 测量了生长速率、生物量、形态、叶绿素和养分含量（C、N 和 P）。直立树对这两种情况都有强烈的反应。生物量和相对增长率增加，茎变短，特别是在潮湿的情况下，营养繁殖（匍匐茎的数量）减少。在这两种情况下，与没有气候变化的条件相比，N 含量较低，P 含量较高。可以得出结论，气候变化效应，尤其是 DOC 的遮蔽，强烈影响大型植物：大型植物丰度可能会受到气候变化的负面影响，这取决于大型植物种类和附生藻类的丰度。这可能会对水生生态系统的其他组成部分产生影响。