Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain; Ecology and Aquatic Ecotoxicology Laboratory. Research Center for Emerging and Zoonotic Diseases, Gorgas Memorial Institute of Health Studies, 0816-02593. Divisa, Veraguas province, Panama.
Department of Plant Biology and Ecology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Leioa, Spain; Ecology and Aquatic Ecotoxicology Laboratory. Research Center for Emerging and Zoonotic Diseases, Gorgas Memorial Institute of Health Studies, 0816-02593. Divisa, Veraguas province, Panama; National Research System of Panama, Panama.
Environ Pollut. 2023 Sep 1;332:121966. doi: 10.1016/j.envpol.2023.121966. Epub 2023 Jun 6.
Several human activities often result in increased nitrogen (N) and phosphorus (P) inputs to running waters through runoff. Although headwater streams are less frequently affected by these inputs than downstream reaches, the joint effects of moderate eutrophication and global warming can affect the functioning of these ecosystems, which represent two thirds of total river length and thus are of major global relevance. In a microcosm study representing streams from a temperate area (northern Spain), we assessed the combined effects of increased water temperature (10.0, 12.5, and 15.0 °C) and nutrient enrichment (control, high N, high P, and high N + P concentrations) on the key process of leaf litter decomposition (mediated by microorganisms and detritivores) and associated changes in different biological compartments (leaf litter, aquatic hyphomycetes and detritivores). While warming consistently enhanced decomposition rates and associated variables (leaf litter microbial conditioning, aquatic hyphomycete sporulation rate and taxon richness, and detritivore growth and nutrient contents), effects of eutrophication were weaker and more variable: P addition inhibited decomposition, addition of N + P promoted leaf litter conditioning, and detritivore stoichiometry was affected by the addition of both nutrients separately or together. In only a few cases (variables related to detritivore performance, but not microbial performance or leaf litter decomposition) we found interactions between warming and eutrophication, which contrasts with other experiments reporting synergistic effects. Our results suggest that both stressors can importantly alter the functioning of stream ecosystems even when occurring in isolation, although non-additive effects should not be neglected and might require exploring an array of ecosystem processes (not just leaf litter decomposition) in order to be detected.
人类的一些活动常常导致氮（N）和磷（P）通过径流输入到流水。尽管上游溪流受这些输入的影响比下游河段少，但中度富营养化和全球变暖的共同影响可能会影响这些生态系统的功能，这些生态系统占总河流长度的三分之二，因此具有重要的全球相关性。在一项代表温带地区（西班牙北部）溪流的微宇宙研究中，我们评估了增加水温（10.0、12.5 和 15.0°C）和营养物富集（对照、高 N、高 P 和高 N+P 浓度）对关键过程的综合影响落叶分解（由微生物和碎屑分解者介导）以及不同生物区室（落叶、水生真菌和碎屑分解者）的相关变化。虽然升温一致地提高了分解速率和相关变量（落叶微生物调理、水生真菌孢子形成率和分类丰富度以及碎屑分解者生长和营养含量），但富营养化的影响较弱且更具变异性：P 添加抑制分解，N+P 添加促进落叶调理，并且碎屑分解者的化学计量受到单独或一起添加两种养分的影响。只有在少数情况下（与碎屑分解者性能相关的变量，而不是微生物性能或落叶分解），我们发现升温和富营养化之间存在相互作用，这与其他报告协同效应的实验形成对比。我们的研究结果表明，即使单独发生，这两个压力源也可以重要地改变溪流生态系统的功能，尽管不应忽视非加性效应，并且可能需要探索一系列生态系统过程（不仅仅是落叶分解）以检测到。
