Year-round dynamics and drivers of the Biological Carbon Pump in the Weddell Sea revealed by autonomous sampling

生物碳泵(BCP)调节着全球海洋中碳的供应、消耗和储存。对BCP的机械性理解需要持续的观察，将生物学、海洋学和地球化学与时间、水层和环境条件联系起来。缺少对南大洋边界控制点的全年观测，需要自主方法。基于海底系泊的自主采样器和传感器，Yippee将在韦德尔海的整个年度周期内建立对BCP的分类、功能和物理化学特征的机械见解。这个对全球气候具有核心重要性的“最后冰区”代表着一个天然实验室，以了解极地过程及其对气候变化的潜在反应。该系泊设备已在2021年3月至2022年3月期间成功部署。对EDNA和环境参数的初步分析证实了数据集的一致性。三个工作包将在水团、海冰覆盖和营养物质浓度的背景下描述完整的年度周期中的生物多样性和功能基因组学。关键资产是高分辨率的生物和环境采样；将光区的生物动力学与深水的地球化学通量联系起来。具体来说，Edna后生生物编码将阐明从细菌到后生动物等不同生态系统状态的标志性种群，以及它们的时间和生态连通性。这将揭示年度周期中尚未探索的过渡期和中心转折点：日光启动浮游植物生长的阈值、光合作用脉冲后的细菌活动、原生动物和浮游动物食草动物的演替，以及深海对下沉碎屑的反应的时间尺度。长时间的元基因组测序将揭示季节性生态系统状态的功能特征，并量化单个生物地球化学途径对环境梯度的贡献。这一证据允许将年度周期区分为自养和(化学)异养时期，以及关键的潜在途径。对高冰盖期间普遍存在的功能的重视，将在气候变化的影响之前为“真正的”威德尔海设定一个基准。第三，南极和北极季节状态的基因目录将建立关于功能季节性和群落集合的两极观点。这张史无前例的关于Keystone分类群、遗传多样性、生态网络和营养通量的高分辨率图片对南极BCP和极地生态系统的总体运作具有重要影响。Yippee与其他约10个战略规划项目和核心战略规划目标保持一致，包括建议的长期观察。所有数据和生物信息代码将立即共享。除了与合作的科学家联合发表论文外，成果还将通过互动网络应用程序和公共交流渠道与科学和社会一起传播。

The biological carbon pump (BCP) mediates carbon supply, consumption and storage in the world’s oceans. A mechanistic understanding of the BCP requires continuous observations that contextualize biology, oceanography and geochemistry across time, water layers and environmental conditions. Year-round observations of the BCP in the Southern Ocean are missing, and require autonomous approaches. Based on autonomous samplers and sensors on a seafloor mooring, YIPPEE will establish mechanistic insights into taxonomic, functional and physicochemical signatures of the BCP over a full annual cycle in the Weddell Sea. This “Last Ice Area” with central importance for the global climate represents a natural laboratory to understand polar processes and their potential response to climate change. The mooring has been successfully deployed between March 2021 and March 2022. Preliminary analyses of eDNA and environmental parameters confirm the consistency of the data set. Three work packages will portray biodiversity and functional genomics over a complete annual cycle in context of water masses, sea-ice cover and nutrient concentrations. The key asset is the high-resolution biological and environmental sampling; connecting biological dynamics in the photic zone with geochemical fluxes to deep waters. Specifically, eDNA metabarcoding will elucidate signature populations of distinct ecosystem states, from bacteria to metazoans, and their temporal and ecological connectivity. This will reveal unexplored transition periods and central turning points in the annual cycle: the threshold of daylight initiating phytoplankton growth, bacterial activities following the photosynthetic pulse, the succession of protist and zooplankton grazers, and the temporal scale of deep-sea responses to sinking detritus. Long-read metagenome sequencing will reveal functional signatures of seasonal ecosystem states, and quantify the contribution of individual biogeochemical pathways over environmental gradients. This evidence allows distinguishing the annual cycle into periods of autotrophy and (chemo)heterotrophy, and the key underlying pathways. Emphasis on functions prevalent during high-ice cover will set a benchmark of the “true” Weddell Sea before the impact of climate change. Third, gene catalogues for Antarctic vs Arctic seasonal states will establish bi-polar perspectives on functional seasonality and community assembly. This unprecedented, high-resolution picture of keystone taxa, genetic diversity, ecological networks and nutrient fluxes has important implications for the Antarctic BCP, and polar ecosystem functioning in general. YIPPEE aligns with ~10 other SPP projects and central SPP goals, including suggested long-term observations. All data and bioinformatic code will be immediately shared. In addition to joint papers with collaborating scientists, results will be disseminated with science and society via an interactive web-app and public communication channels.