Department of Anthropology, National Museum of Natural History, Smithsonian Institution, 10th St. & Constitution Ave. NW, Washington, D.C., 20560, USA.
Department of Biology, University of New Mexico, 219 Yale Blvd NE, Albuquerque, New Mexico, 87131-0001, USA.
Ecology. 2021 Jan;102(1):e03198. doi: 10.1002/ecy.3198. Epub 2020 Nov 14.
The widespread importance of variable types of primary production, or energy channels, to consumer communities has become increasingly apparent. However, the mechanisms underlying this "multichannel" feeding remain poorly understood, especially for aquatic ecosystems that pose unique logistical constraints given the diversity of potential energy channels. Here, we use bulk tissue isotopic analysis along with carbon isotope (δ C) analysis of individual amino acids to characterize the relative contribution of pelagic and benthic energy sources to a kelp forest consumer community in northern Chile. We measured bulk tissue δ C and δ N for >120 samples; of these we analyzed δ C values of six essential amino acids (EAA) from nine primary producer groups (n = 41) and 11 representative nearshore consumer taxa (n = 56). Using EAA δ C data, we employed linear discriminant analysis (LDA) to assess how distinct EAA δ C values were between local pelagic (phytoplankton/particulate organic matter), and benthic (kelps, red algae, and green algae) endmembers. With this model, we were able to correctly classify nearly 90% of producer samples to their original groupings, a significant improvement on traditional bulk isotopic analysis. With this EAA isotopic library, we then generated probability distributions for the most important sources of production for each individual consumer and species using a bootstrap-resampling LDA approach. We found evidence for multichannel feeding within the community at the species level. Invertebrates tended to focus on either pelagic or benthic energy, deriving 13-67% of their EAA from pelagic sources. In contrast, mobile (fish) taxa at higher trophic levels used more equal proportions of each channel, ranging from 19% to 47% pelagically derived energy. Within a taxon, multichannel feeding was a result of specialization among individuals in energy channel usage, with 37 of 56 individual consumers estimated to derive >80% of their EAA from a single channel. Our study reveals how a cutting-edge isotopic technique can characterize the dynamics of energy flow in coastal food webs, a topic that has historically been difficult to address. More broadly, our work provides a mechanism as to how multichannel feeding may occur in nearshore communities, and we suggest this pattern be investigated in additional ecosystems.
初级生产的各种类型（或能量通道）对消费者群体的广泛重要性已变得越来越明显。然而，这种“多通道”喂养的机制仍未得到很好的理解，特别是对于水生生态系统而言，由于潜在能量通道的多样性，它们带来了独特的后勤限制。在这里，我们使用批量组织同位素分析以及个体氨基酸的碳同位素（δ C）分析，来描述智利北部的大型海藻林消费者群落中，来自浮游和底栖能源的相对贡献。我们对超过 120 个样本进行了批量组织 δ C 和 δ N 测量；其中，我们分析了来自 9 个初级生产者群体（n = 41）和 11 个代表性近岸消费者类群（n = 56）的 6 种必需氨基酸（EAA）的 δ C 值。我们使用 EAA δ C 数据，通过线性判别分析（LDA）评估了当地浮游生物（浮游植物/颗粒有机物质）和底栖（大型海藻、红藻和绿藻）端元之间的 EAA δ C 值的差异。通过该模型，我们可以将近 90%的生产者样本正确地分类到它们的原始分组中，这比传统的批量同位素分析有了显著的改进。有了这个 EAA 同位素库，我们通过bootstrap 重采样 LDA 方法，为每个消费者和物种生成了最主要的生产来源的概率分布。我们在物种水平上发现了群落中多通道喂养的证据。无脊椎动物倾向于专注于浮游或底栖能量，从浮游生物来源获得 13-67%的 EAA。相比之下，位于较高营养级别的移动（鱼类）类群使用每个通道的比例更均等，从 19%到 47%的能量来自浮游生物。在一个分类群中，多通道喂养是个体在能量通道使用方面专业化的结果，56 个个体消费者中有 37 个估计从单个通道获得其 EAA 的>80%。我们的研究揭示了一种前沿的同位素技术如何描述沿海食物网中能量流动的动态，这是一个历史上难以解决的问题。更广泛地说，我们的工作提供了一种机制，说明了多通道喂养如何在近岸社区中发生，我们建议在其他生态系统中研究这种模式。
