Ardón Marcelo, Zeglin Lydia H, Utz Ryan M, Cooper Scott D, Dodds Walter K, Bixby Rebecca J, Burdett Ayesha S, Follstad Shah Jennifer, Griffiths Natalie A, Harms Tamara K, Johnson Sherri L, Jones Jeremy B, Kominoski John S, McDowell William H, Rosemond Amy D, Trentman Matt T, Van Horn David, Ward Amelia
Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, 27695, U.S.A.
Division of Biology, Kansas State University, Manhattan, KS, 66506, U.S.A.
Biol Rev Camb Philos Soc. 2020 Dec 17. doi: 10.1111/brv.12673.
Anthropogenic increases in nitrogen (N) and phosphorus (P) concentrations can strongly influence the structure and function of ecosystems. Even though lotic ecosystems receive cumulative inputs of nutrients applied to and deposited on land, no comprehensive assessment has quantified nutrient-enrichment effects within streams and rivers. We conducted a meta-analysis of published studies that experimentally increased concentrations of N and/or P in streams and rivers to examine how enrichment alters ecosystem structure (state: primary producer and consumer biomass and abundance) and function (rate: primary production, leaf breakdown rates, metabolism) at multiple trophic levels (primary producer, microbial heterotroph, primary and secondary consumers, and integrated ecosystem). Our synthesis included 184 studies, 885 experiments, and 3497 biotic responses to nutrient enrichment. We documented widespread increases in organismal biomass and abundance (mean response = +48%) and rates of ecosystem processes (+54%) to enrichment across multiple trophic levels, with no large differences in responses among trophic levels or between autotrophic or heterotrophic food-web pathways. Responses to nutrient enrichment varied with the nutrient added (N, P, or both) depending on rate versus state variable and experiment type, and were greater in flume and whole-stream experiments than in experiments using nutrient-diffusing substrata. Generally, nutrient-enrichment effects also increased with water temperature and light, and decreased under elevated ambient concentrations of inorganic N and/or P. Overall, increased concentrations of N and/or P altered multiple food-web pathways and trophic levels in lotic ecosystems. Our results indicate that preservation or restoration of biodiversity and ecosystem functions of streams and rivers requires management of nutrient inputs and consideration of multiple trophic pathways.
人为增加的氮（N）和磷（P）浓度会强烈影响生态系统的结构和功能。尽管流水生态系统会接收施用于土地和沉积在土地上的养分的累积输入，但尚无全面评估对溪流和河流中的养分富集效应进行量化。我们对已发表的研究进行了荟萃分析，这些研究通过实验提高了溪流和河流中N和/或P的浓度，以研究富集如何在多个营养级（初级生产者、微生物异养生物、初级和次级消费者以及综合生态系统）上改变生态系统结构（状态：初级生产者和消费者生物量及丰度）和功能（速率：初级生产、叶片分解速率、代谢）。我们的综合分析包括184项研究、885次实验以及3497个对养分富集的生物响应。我们记录了多个营养级上生物量和丰度（平均响应=+48%）以及生态系统过程速率（+54%）对富集的普遍增加，营养级之间或自养或异养食物网途径之间的响应没有很大差异。对养分富集的响应因添加的养分（N、P或两者）而异，这取决于速率与状态变量以及实验类型，并且在水槽和整条溪流实验中比在使用养分扩散基质的实验中更大。一般来说，养分富集效应也随水温、光照增加，而在无机N和/或P的环境浓度升高时降低。总体而言，N和/或P浓度的增加改变了流水生态系统中的多个食物网途径和营养级。我们的结果表明，保护或恢复溪流和河流的生物多样性及生态系统功能需要管理养分输入并考虑多个营养途径。
