For aquatic scientists mesocosm experiments are important tools for hypothesis testing as they offer a compromise between experimental control and realism. Here we present a new mesocosm infrastructure—SITES AquaNET—located in five lakes connected to field stations in Sweden that cover a ~760 km latitudinal gradient. SITES AquaNet overcomes major hindrances in aquatic experimental research through: (i) openness to the scientific community, (ii) the potential to implement coordinated experiments across sites and time, and (iii) high-frequency measurements (temperature, photosynthetic photon flux density, turbidity and dissolved oxygen, chlorophyll a and phycocyanin concentrations) with an autonomous sensor system. Moreover, the infrastructure provides operational guidance and sensor expertise from technical staff, and connections to a multi-layered monitoring programme (“SITES Water”) for each lake. This enables ecological observations from whole lake ecosystems to be compared with experimental studies aiming at disentangling major drivers and mechanisms underlying observed changes. Here we describe the technical properties of the infrastructure along with possibilities for experimental manipulations to tackle pressing issues in aquatic ecology and global change science. As a proof of concept, we also present a first mesocosm experiment across all five field sites with a cross-factorial design to evaluate responses of the sensor measurements to press/bottom-up (constant light reduction) and pulse/top-down (temporary fish predation) disturbances. This demonstrates the suitability of the infrastructure and autonomous sensor system to host modularized experiments and exemplifies the power and advantages of the approach to integrate a network of mecsocosm facilities with manageable costs across large geographic areas.

中文翻译：

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SITES AquaNet：用于跨湖泊高频传感器监测的中宇宙实验的开放基础设施

对于水生科学家来说，中宇宙实验是假设检验的重要工具，因为它们在实验控制和现实主义之间提供了折衷。在这里，我们展示了一个新的中宇宙基础设施——SITES AquaNET——位于与瑞典野外站相连的五个湖泊中，覆盖了约 760 公里的纬度梯度。SITES AquaNet 通过以下方式克服了水生实验研究中的主要障碍：(i) 对科学界的开放性，(ii) 跨地点和时间实施协调实验的潜力，以及 (iii) 高频测量（温度、光合光子通量密度、浊度和溶解氧、叶绿素 a 和藻蓝蛋白浓度）与自主传感器系统。此外，基础设施提供技术人员的操作指导和传感器专业知识，并连接到每个湖泊的多层监测程序（“SITES Water”）。这使得整个湖泊生态系统的生态观测结果能够与旨在解开观测到的变化背后的主要驱动因素和机制的实验研究进行比较。在这里，我们描述了基础设施的技术特性以及实验操作的可能性，以解决水生生态学和全球变化科学中的紧迫问题。作为概念证明，我们还展示了跨所有五个现场站点的第一个中宇宙实验，采用交叉因素设计来评估传感器测量对按压/自下而上（持续减光）和脉冲/自上而下（临时鱼类捕食）干扰。