Water temperature is a key environmental variable in stream ecosystems determining species distribution ranges, community composition, and ecological processes. In addition to global warming, direct anthropogenic impacts, for example through the influx of power plant cooling water or due to sun exposure after the removal of riparian vegetation, result in elevated water temperatures. However, temperature effects in stream ecosystems have mostly been tested in recirculating experimental systems, which can neither capture diurnal and seasonal variability in other environmental variables nor allow for entrainment of stream organisms. In contrast, open flow-through systems, which are constantly supplied with stream water, offer a more realistic setting for stream ecological experiments, yet are difficult to implement. Here, we outline a heating module for the purpose of differential temperature regulation in a flow-through mesocosm system by automatic control of warm water supply. We validated the functionality of the module in indoor trials as well as in an outdoor ExStream experimental mesocosm system. Furthermore, we tested the implications of different warm water temperatures for the survival of invertebrates drifting through the heating module to derive recommendations for the maximum warm water temperature for mixing with the natural water inflow. The module allows for controlled open flow-through experiments in the field and the key components are flexible and scalable. Therefore, the module can be easily integrated into existing experimental flow-through setups.

中文翻译：

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用于实验流通流介观系统的自动化模块化加热解决方案

水温是河流生态系统中的一个关键环境变量，决定着物种分布范围、群落组成和生态过程。除了全球变暖之外，直接的人为影响，例如发电厂冷却水的流入或河岸植被去除后的阳光照射，也会导致水温升高。然而，河流生态系统中的温度影响大多是在再循环实验系统中进行测试的，该系统既不能捕获其他环境变量的昼夜和季节变化，也不能夹带河流生物。相比之下，持续供应溪流水的开放流通系统为溪流生态实验提供了更现实的环境，但实施起来却很困难。在这里，我们概述了一种加热模块，其目的是通过自动控制温水供应来调节流通式中生态系统中的温差。我们在室内试验以及室外ExStream实验介观系统中验证了该模块的功能。此外，我们测试了不同温水温度对漂流通过加热模块的无脊椎动物生存的影响，以得出与自然水流混合的最高温水温度的建议。该模块允许在现场进行受控开放流通实验，并且关键组件灵活且可扩展。因此，该模块可以轻松集成到现有的实验流通装置中。