Positive relationships between biodiversity and ecosystem functioning (BEF) highlight the importance of conserving biodiversity to maintain key ecosystem functions and associated services. Although natural systems are rapidly losing biodiversity due to numerous human-caused stressors, our understanding of how multiple stressors influence BEF relationships comes largely from small, experimental studies. Here, using remote assemblages of coral reef fishes, we demonstrate strong, non-saturating relationships of biodiversity with two ecosystem functions: biomass and productivity. These positive relationships were robust both to an extreme heatwave that triggered coral bleaching and to invasive rats which disrupt nutrient subsidies from native seabirds. Despite having only minor effects on BEF relationships, both stressors still decreased ecosystem functioning via other pathways. The extreme heatwave reduced biodiversity, which, due to the strong BEF relationships, ultimately diminished both ecosystem functions. Conversely, the loss of cross-system nutrient subsidies directly decreased biomass. These results demonstrate multiple ways by which human-caused stressors can reduce ecosystem functioning, despite robust BEF relationships, in natural high-diversity assemblages.

中文翻译：

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尽管在珊瑚礁上有多种压力，生物多样性仍能提高生态系统功能。

生物多样性与生态系统功能（BEF）之间的积极关系突出了保护生物多样性以维持关键的生态系统功能和相关服务的重要性。尽管由于众多人为压力源，自然系统正在迅速丧失生物多样性，但我们对多种压力源如何影响BEF关系的理解主要来自小型的实验研究。在这里，我们通过使用遥远的珊瑚礁鱼类组合，证明了生物多样性与两个生态系统功能（生物量和生产力）的牢固，非饱和关系。这些积极的关系对于引发珊瑚白化的极端热浪和破坏天然海鸟养分补贴的侵袭性老鼠均具有鲁棒性。尽管对BEF关系只有很小的影响，两个压力源仍通过其他途径降低了生态系统的功能。极端的热浪减少了生物多样性，由于强烈的BEF关系，生物多样性最终削弱了这两种生态系统的功能。相反，跨系统营养补贴的损失直接减少了生物量。这些结果表明，在自然的高多样性组合中，人为的压力源可以通过多种方式减少生态系统的功能，尽管它们之间存在稳固的BEF关系。