Allgeier Jacob Edward, Wenger Seth J, Rosemond Amy D, Schindler Daniel E, Layman Craig A
School of Aquatic and Fisheries Science, University of Washington, Seattle, WA 98105;
Odum School of Ecology, University of Georgia, Athens, GA 30602; and.
Proc Natl Acad Sci U S A. 2015 May 19;112(20):E2640-7. doi: 10.1073/pnas.1420819112. Epub 2015 Apr 15.
Reconciling the degree to which ecological processes are generalizable among taxa and ecosystems, or contingent on the identity of interacting species, remains a critical challenge in ecology. Ecological stoichiometry (EST) and metabolic theory of ecology (MTE) are theoretical approaches used to evaluate how consumers mediate nutrient dynamics and energy flow through ecosystems. Recent theoretical work has explored the utility of these theories, but empirical tests in species-rich ecological communities remain scarce. Here we use an unprecedented dataset collected from fishes and dominant invertebrates (n = 900) in a diverse subtropical coastal marine community (50 families, 72 genera, 102 species; body mass range: 0.04-2,597 g) to test the utility of EST and MTE in predicting excretion rates of nitrogen (E(N)), phosphorus (E(P)), and their ratio (E(NP)). Body mass explained a large amount of the variation in EN and EP but not E(NP). Strong evidence in support of the MTE 3/4 allometric scaling coefficient was found for E(P), and for E(N) only after accounting for variation in excretion rates among taxa. In all cases, including taxonomy in models substantially improved model performance, highlighting the importance of species identity for this ecosystem function. Body nutrient content and trophic position explained little of the variation in E(N), E(P), or E(NP), indicating limited applicability of basic predictors of EST. These results highlight the overriding importance of MTE for predicting nutrient flow through organisms, but emphasize that these relationships still fall short of explaining the unique effects certain species can have on ecological processes.
调和生态过程在不同分类群和生态系统之间的可推广程度，或取决于相互作用物种的身份，仍然是生态学中的一项关键挑战。生态化学计量学（EST）和生态代谢理论（MTE）是用于评估消费者如何调节生态系统中养分动态和能量流动的理论方法。最近的理论工作探索了这些理论的效用，但在物种丰富的生态群落中的实证检验仍然很少。在这里，我们使用了一个前所未有的数据集，该数据集收集自一个多样化的亚热带沿海海洋群落中的鱼类和主要无脊椎动物（n = 900）（50个科，72个属，102个物种；体重范围：0.04 - 2597克），以测试EST和MTE在预测氮（E(N)）、磷（E(P)）及其比率（E(NP)）排泄率方面的效用。体重解释了E(N)和E(P)中大量的变异，但没有解释E(NP)的变异。对于E(P)，发现了有力证据支持MTE 3/4异速生长比例系数，对于E(N)，仅在考虑了不同分类群排泄率的变异之后才发现。在所有情况下，将分类学纳入模型显著提高了模型性能，突出了物种身份对这种生态系统功能的重要性。身体养分含量和营养级对E(N)、E(P)或E(NP)变异的解释很少，表明EST的基本预测因子适用性有限。这些结果突出了MTE在预测养分通过生物体流动方面的首要重要性，但强调这些关系仍不足以解释某些物种对生态过程可能产生的独特影响。
