Big Data Institute, University of Oxford, Oxford, UK.
Department of Biology, University of Oxford, Oxford, UK.
Ecol Lett. 2024 Aug;27(8):e14480. doi: 10.1111/ele.14480.
Nutrient enrichment and climate warming threaten freshwater systems. Metabolic theory and the paradox of enrichment predict that both stressors independently can lead to simpler food-webs having fewer nodes, shorter food-chains and lower connectance, but cancel each other's effects when simultaneously present. Yet, these theoretical predictions remain untested in complex natural systems. We inferred the food-web structure of 256 lakes and 373 streams from standardized fish community samplings in France. Contrary to theoretical predictions, we found that warming shortens fish food-chain length and that this effect was magnified in enriched streams and lakes. Additionally, lakes experiencing enrichment exhibit lower connectance in their fish food-webs. Our study suggests that warming and enrichment interact to magnify food-web simplification in nature, raising further concerns about the fate of freshwater systems as climate change effects will dramatically increase in the coming decades.
营养富集和气候变暖威胁着淡水系统。代谢理论和富集悖论预测，这两个压力源独立地可以导致更简单的食物网，具有更少的节点、更短的食物链和更低的连接度，但当同时存在时，它们的影响会相互抵消。然而，这些理论预测在复杂的自然系统中尚未得到验证。我们从法国标准化鱼类群落采样中推断了 256 个湖泊和 373 条溪流的食物网结构。与理论预测相反，我们发现变暖缩短了鱼类食物链的长度，而这种效应在富营养化的溪流和湖泊中更为明显。此外，经历富营养化的湖泊在鱼类食物网中表现出较低的连接度。我们的研究表明，变暖与富营养化相互作用，放大了自然界中食物网的简化，这进一步引起了人们对淡水系统命运的担忧，因为未来几十年气候变化的影响将大幅增加。
