Over the past four decades, mesocosm studies have been successfully used for a wide range of applications and have provided a lot of information on trophic interactions and biogeochemical cycling of aquatic ecosystem. However, the setup of such mesocosms (e.g., dimensions and duration of experiments) needs to be adapted to the relevant biological processes being investigated. Mixing of the water column is an important factor to be considered in mesocosm experiments because enclosing water in an artificial chamber always alters the mixing regime. Various approaches have been applied to generate mixing in experimental ecosystems, including pure mechanical mixing (e.g., using a disc), airlifts, bubbling with compressed air, and pumping. In this study, we tested different mixing techniques for outdoor mesocosms and their impact on plankton biomass and community composition. We compared mesocosms mixed with a disc, an airlift-system, and bubbling, and used a nonactively mixed mesocosm as a control. We investigated phytoplankton, ciliate, and zooplankton communities during a 19-d mesocosm experiment. Based on our results, we concluded that mechanical mixing with a disc was the most effective technique due to the undertow produced by lowering and lifting the disc. While no mixing technique affected seston biomass, zooplankton biomass was highest in the treatments mixed with the disc. The airlift treatments had the lowest relative share of small flagellates. However, no further differences in phytoplankton community composition occurred and no differences in zooplankton community composition existed between all actively mixed treatments.

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实验中宇宙的不同混合技术——混合会影响浮游生物的生物量和群落组成吗？

在过去的四十年里，中宇宙研究已成功用于广泛的应用，并提供了大量关于水生生态系统营养相互作用和生物地球化学循环的信息。然而，此类中观的设置（例如，实验的尺寸和持续时间）需要适应正在研究的相关生物过程。水柱的混合是中宇宙实验中要考虑的一个重要因素，因为将水封闭在人工室中总是会改变混合状态。已应用各种方法在实验生态系统中产生混合，包括纯机械混合（例如，使用圆盘）、气升、压缩空气鼓泡和泵送。在这项研究中，我们测试了室外中宇宙的不同混合技术及其对浮游生物生物量和群落组成的影响。我们比较了与圆盘、空运系统和鼓泡混合的中宇宙，并使用非主动混合的中宇宙作为对照。我们在 19 天的中宇宙实验期间调查了浮游植物、纤毛虫和浮游动物群落。根据我们的结果，我们得出结论，由于通过降低和提升圆盘产生的底流，使用圆盘进行机械混合是最有效的技术。虽然没有混合技术影响 seston 生物量，但浮游动物生物量在与圆盘混合的处理中最高。空运处理的小鞭毛虫的相对份额最低。然而，