Marin Valentin, Colas Fanny, Boulêtreau Stéphanie, Cucherousset Julien
Centre de Recherche sur la Biodiversité et l'Environnement (CRBE), Université de Toulouse, CNRS, IRD, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UT3), Toulouse, France.
Laboratoire d'Écologie des Hydrosystèmes Naturels et Anthropisés, UMR 5023 CNRS, Université Claude Bernard, Villeurbanne, France.
Glob Chang Biol. 2025 Aug;31(8):e70410. doi: 10.1111/gcb.70410.
Global change strongly alters biodiversity worldwide, but our ability to predict their consequences for ecosystem functioning remains limited. This lack of knowledge may be attributed to the limited empirical evidence of the simultaneous ecological impacts of global change across multiple ecological levels. Here, we conducted a full factorial experiment to measure the isolated and combined effects of two global change drivers to which freshwater ecosystems are severely exposed: (i) nutrient addition, which mainly affects the lower trophic levels and modifies ecosystems from the bottom of the food chain, and (ii) warming, which primarily affects large organisms at the top of the food chain. We quantified the effects of the two global change drivers at four different ecological levels: community composition (zooplankton and benthic invertebrates), size structure, trophic architecture, and ecosystem functioning. We found that the impacts of treatments varied significantly across different ecological levels. Specifically, community composition was predominantly affected by warming, whereas nutrient addition played a more important role than warming in ecosystem functioning (e.g., primary production and atmospheric CO uptake). More importantly, we found that food webs (described using size spectrum and stable isotope structure) represent an integrative ecological level for capturing the effects of the two global change drivers tested, integrating changes in both community structure and ecosystem functioning. These results provide valuable insights into the responses of aquatic ecosystems to global change and reveal the importance of considering multiple ecological levels to improve our understanding of the processes driving the responses of ecosystems to global change.
全球变化极大地改变了世界各地的生物多样性，但我们预测其对生态系统功能影响的能力仍然有限。这种知识的匮乏可能归因于全球变化在多个生态层面上同时产生的生态影响的实证证据有限。在此，我们进行了一项全因子实验，以测量淡水生态系统严重面临的两种全球变化驱动因素的单独和综合影响：（i）营养添加，主要影响较低营养级，并从食物链底部改变生态系统；（ii）变暖，主要影响食物链顶端的大型生物。我们在四个不同的生态层面量化了这两种全球变化驱动因素的影响：群落组成（浮游动物和底栖无脊椎动物）、大小结构、营养结构和生态系统功能。我们发现，不同处理的影响在不同生态层面上有显著差异。具体而言，群落组成主要受变暖影响，而营养添加在生态系统功能（如初级生产和大气二氧化碳吸收）方面比变暖发挥了更重要的作用。更重要的是，我们发现食物网（用大小谱和稳定同位素结构描述）代表了一个综合生态层面，用于捕捉所测试的两种全球变化驱动因素的影响，整合了群落结构和生态系统功能的变化。这些结果为水生生态系统对全球变化的响应提供了有价值的见解，并揭示了考虑多个生态层面对于增进我们对驱动生态系统对全球变化响应过程的理解的重要性。
