Biodiversity loss and climate warming are occurring in concert, with potentially profound impacts on ecosystem functioning. We currently know very little about the combined effects of these changes on the links between the community structure, dynamics and the resulting in situ CO2 concentrations in freshwater ecosystems. Here we aimed to determine both individual and combined effects of temperature and non-resource diversity (species inedible for a given consumer) on CO2 concentration. Our analysis further aimed to establish both direct effects on CO2 concentrations and potential indirect effects that occur via changes to the phytoplankton and zooplankton biomasses. Our results showed that there were no interactive effects of changes in temperature and diversity on CO2 concentration in the water. Instead, independent increases in either temperature or non-resource diversity resulted in a substantial reduction in CO2 concentrations, particularly at the highest non-resource diversity. The effects of non-resource diversity and warming on CO2 were indirect, resulting largely from the positive impacts on total biomass of primary producers. Our study is the first to experimentally partition the impacts of temperature and diversity on the consumer-resource dynamics and associated changes to CO2 concentrations. It provides new mechanistic insights into the role of diverse plankton communities for ecosystem functioning and their importance in regulating CO2 dynamics under ongoing climate warming.

中文翻译：

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多样性和温度间接降低了实验淡水群落中的二氧化碳浓度。

生物多样性的丧失和气候变暖正在同步发生，对生态系统的功能可能产生深远的影响。目前，我们对这些变化对群落结构，动力学和淡水生态系统中原位CO2浓度之间联系的综合影响知之甚少。在这里，我们旨在确定温度和非资源多样性（给定消费者不可食用的物种）对CO2浓度的个体和综合影响。我们的分析进一步旨在建立对CO2浓度的直接影响以及通过浮游植物和浮游生物量变化发生的潜在间接影响。我们的结果表明，温度和多样性变化对水中CO2浓度没有交互作用。代替，温度或非资源多样性的独立增加导致二氧化碳浓度的大幅下降，尤其是在非资源多样性最高的情况下。非资源多样性和变暖对二氧化碳的影响是间接的，这主要是由于对初级生产者的总生物量产生了积极影响。我们的研究是第一个通过实验划分温度和多样性对消费者资源动态以及相关CO2浓度变化的影响的方法。它为各种浮游生物群落对生态系统功能的作用以及它们在持续气候变暖下调节CO2动态的重要性提供了新的机制见解。非资源多样性和变暖对二氧化碳的影响是间接的，这主要是由于对初级生产者的总生物量产生了积极影响。我们的研究是第一个通过实验划分温度和多样性对消费者资源动态以及相关CO2浓度变化的影响的方法。它为各种浮游生物群落对生态系统功能的作用及其在持续气候变暖下调节CO2动态的重要性提供了新的机制见解。非资源多样性和变暖对二氧化碳的影响是间接的，这主要是由于对初级生产者的总生物量产生了积极影响。我们的研究是第一个通过实验划分温度和多样性对消费者资源动态以及相关CO2浓度变化的影响的方法。它为各种浮游生物群落对生态系统功能的作用以及它们在持续气候变暖下调节二氧化碳动态中的重要性提供了新的机制见解。