Brandl Simon J, Yan Helen F, Casey Jordan M, Schiettekatte Nina M D, Renzi Julianna J, Mercière Alexandre, Morat Fabien, Côté Isabelle M, Parravicini Valeriano
Department of Marine Science, The University of Texas at Austin, Marine Science Institute, Port Aransas, Texas, USA.
College of Science and Engineering, James Cook University, Townsville, Queensland, Australia.
Ecology. 2025 Mar;106(3):e70065. doi: 10.1002/ecy.70065.
Biogeochemical fluxes through ecological communities underpin the functioning of ecosystems worldwide. These fluxes are often heavily influenced by small-bodied consumers, such as insects, worms, mollusks, or small vertebrates, which transfer energy and nutrients from autotrophic sources to larger animals. Although coral reefs are one of the most productive ecosystems in the world, we know relatively little about how small consumers make energy available to larger predators and how their roles may vary across reefs. Here, we use community-scale collections of small, bottom-dwelling ("cryptobenthic") reef fishes along with size spectrum analyses, stable isotopes, and demographic modeling to examine their role in harnessing and transferring carbon in two distinct coral reef habitats. Using a comprehensive dataset from Mo'orea (French Polynesia), we demonstrate that, despite only being separated by a narrow reef crest, forereef and backreef habitats harbor distinct communities of cryptobenthic fishes that play vastly divergent roles in carbon transfer. Forereef communities in Mo'orea are depauperate, largely consisting of predatory and planktivorous species that have comparatively high standing biomass (both individually and collectively). In these communities, the combination of size spectra and isotope values suggests important contributions of pelagic subsidies, but the rate of biomass production and turnover (i.e., the rate at which biomass is replenished) is relatively low. In contrast, cryptobenthic fish communities in the backreef are characterized by high abundances of the smallest bodied species, forming a traditional bottom-heavy trophic pyramid that is fueled by benthic autotrophs. In these communities, benthic productivity fuels rapid production and turnover of fish biomass, while pelagic energy channels are notably less productive. Our integrative approach demonstrates the utility of combining multiple methods (e.g., isotopically informed demographic models) to trace energy fluxes through small consumer communities in complex ecosystems. Furthermore, our results highlight that coral reef productivity dynamics are highly habitat-dependent and the role of the smallest coral reef consumers may be most pronounced in shallow systems with limited connectivity to the open ocean.
通过生态群落的生物地球化学通量是全球生态系统功能的基础。这些通量常常受到小型消费者的严重影响，比如昆虫、蠕虫、软体动物或小型脊椎动物，它们将能量和营养从自养源传递给大型动物。尽管珊瑚礁是世界上生产力最高的生态系统之一，但我们对小型消费者如何为大型捕食者提供能量以及它们在不同珊瑚礁中的作用可能存在怎样的差异却知之甚少。在此，我们利用小型底栖（“隐栖性”）珊瑚礁鱼类的群落规模样本，结合大小谱分析、稳定同位素分析和种群动态建模，来研究它们在两个不同珊瑚礁栖息地中获取和转移碳的作用。利用来自法属波利尼西亚莫雷阿岛的综合数据集，我们证明，尽管前礁和后礁栖息地仅被一条狭窄的礁脊分隔，但它们拥有截然不同的隐栖性鱼类群落，这些群落在碳转移中发挥着极为不同的作用。莫雷阿岛的前礁群落物种匮乏，主要由具有相对较高现存生物量（个体和总体）的捕食性和浮游生物食性物种组成。在这些群落中，大小谱和同位素值的结合表明浮游生物补贴有重要贡献，但生物量生产和周转速率（即生物量补充的速率）相对较低。相比之下，后礁的隐栖性鱼类群落的特点是最小体型物种数量众多，形成了一个由底栖自养生物提供能量的传统下重上轻的营养金字塔。在这些群落中，底栖生产力推动了鱼类生物量的快速生产和周转，而浮游能量通道的生产力则明显较低。我们的综合方法证明了结合多种方法（如同位素信息的种群动态模型）来追踪复杂生态系统中小型消费者群落能量通量的实用性。此外，我们的结果突出表明，珊瑚礁生产力动态高度依赖栖息地，最小的珊瑚礁消费者的作用在与公海连通性有限的浅海系统中可能最为显著。
