Diverse global change processes are reshaping the biogeochemistry of stream ecosystems. Nutrient enrichment is a common stressor that can modify flows of biologically important elements such as carbon (C), nitrogen (N), and phosphorus (P) through stream foodwebs by altering the stoichiometric composition of stream organisms. However, enrichment effects on concentrations of other important essential and trace elements in stream taxa are less understood. We investigated shifts in macroinvertebrate ionomes in response to changes in coarse benthic organic matter (CBOM) stoichiometry following N and P enrichment of five detritus-based headwater streams. Concentrations of most elements (17/19) differed among three insect genera (Maccaffertium sp., Pycnopsyche spp., and Tallaperla spp.) prior to enrichment. Genus-specific changes in the body content of: P, magnesium, and sodium (Na) in Tallaperla; P, Na, and cadmium in Pycnopsyche; and P in Maccaffertium were also found across CBOM N:P gradients. These elements increased in Tallaperla but decreased in the other two taxa due to growth dilution at larger body sizes. Multivariate elemental differences were found across all taxa, and ionome-wide shifts with dietary N and P enrichment were also observed in Tallaperla and Pycnopsyche. Our results show that macroinvertebrates exhibit distinct differences in elemental composition beyond C, N, and P and that the ionomic composition of common stream taxa can vary with body size and N and P enrichment. Thus, bottom-up changes in N and P supplies could potentially influence the cycling of lesser studied biologically essential elements in aquatic environments by altering their relative proportions in animal tissues.

多样的全球变化过程正在重塑河流生态系统的生物地球化学。营养富集是一种常见的应激源，可以通过改变流态生物的化学计量组成来改变流态食物网中生物学上重要的元素（如碳（C），氮（N）和磷（P））的流动。但是，人们对河流分类单元中其他重要必需元素和微量元素的富集作用了解得很少。我们调查了五种碎屑源水的N和P富集后，响应于底栖有机质（CBOM）化学计量比变化的大型无脊椎动物离子组的变化。在三个昆虫属中（Maccaffertium sp。，Pycnopsyche spp。和Tallaperla spp。）。Tallaperla中P，镁和钠（Na）的体内含量的属特定变化；Pycnopsyche中的P，Na和镉；和P在Maccaffertium P梯度：还跨越CBOM N实测值。这些元素在塔拉帕拉（Tallaperla）中增加，但在其他两个类群中则由于在较大体型时生长稀释而减少。在所有分类单元中发现了多元的元素差异，并且在塔拉帕拉（Tallaperla）和疯子（Pycnopsyche）中也观察到了随着饮食中氮和磷的富集而发生的离子组范围变化。我们的结果表明，大型无脊椎动物在C，N和P之外的元素组成上表现出明显的差异，并且普通流类群的ionomic组成会随体型以及N和P的富集而变化。因此，氮和磷供应的自下而上的变化可能会通过改变动物组织中的相对比例来潜在地影响较少研究的生物必需元素在水生环境中的循环。