Shantz Andrew A, Lemoine Nathan P, Burkepile Deron E
Department of Biology, Florida International University, Miami, FL, 33199, USA.
Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA.
Ecol Lett. 2016 Jan;19(1):20-8. doi: 10.1111/ele.12538. Epub 2015 Nov 9.
Nutrient exchange mutualisms between phototrophs and heterotrophs, such as plants and mycorrhizal fungi or symbiotic algae and corals, underpin the functioning of many ecosystems. These relationships structure communities, promote biodiversity and help maintain food security. Nutrient loading may destabilise these mutualisms by altering the costs and benefits each partner incurs from interacting. Using meta-analyses, we show a near ubiquitous decoupling in mutualism performance across terrestrial and marine environments in which phototrophs benefit from enrichment at the expense of their heterotrophic partners. Importantly, heterotroph identity, their dependence on phototroph-derived C and the type of nutrient enrichment (e.g. nitrogen vs. phosphorus) mediated the responses of different mutualisms to enrichment. Nutrient-driven changes in mutualism performance may alter community organisation and ecosystem processes and increase costs of food production. Consequently, the decoupling of nutrient exchange mutualisms via alterations of the world's nitrogen and phosphorus cycles may represent an emerging threat of global change.
光合生物与异养生物之间的营养交换共生关系，如植物与菌根真菌或共生藻类与珊瑚之间的关系，是许多生态系统功能的基础。这些关系构建了群落结构，促进了生物多样性，并有助于维持粮食安全。营养物质负荷可能会通过改变每个伙伴在相互作用中产生的成本和收益，从而破坏这些共生关系。通过荟萃分析，我们发现，在陆地和海洋环境中，共生关系的表现几乎普遍出现解耦现象，即光合生物从富营养化中受益，却以其异养伙伴为代价。重要的是，异养生物的身份、它们对光合生物衍生碳的依赖程度以及营养物质富集的类型（如氮与磷）介导了不同共生关系对富集的反应。营养驱动的共生关系表现变化可能会改变群落组织和生态系统过程，并增加粮食生产成本。因此，通过改变全球氮和磷循环而导致营养交换共生关系的解耦，可能代表着全球变化带来的一种新威胁。
