Collaborative Research: Zooplankton in the Redoxcline of the Cariaco Basin: Impact on Biogeochemical Cycling

CARIACO（有色海洋中的碳保留）项目是一个时间序列项目，其中心目标是更好地了解控制海洋生物地球化学过程的季节到十年的时间尺度。CARIACO遗址位于委内瑞拉附近多产的大陆边缘的热带地区，盆地缺氧，该遗址与古气候调查密切相关。因此，CARIACO的另一个目标是将现代海洋学过程与沉积物记录中颗粒物质的产生、转化和保存联系起来。浮游动物的组成、行为和生理速率是生物泵的重要组成部分。最近来自Cariaco盆地和其他具有远洋氧化还原界面（亚氧和缺氧界面）的地区的发现表明，它们是生物地球化学循环的活跃区域，其中C可能直接从细菌产生转移到浮游动物。该项目的目标是利用离散深度网样本和垂直剖面激光线扫描相机系统，确定两个季节与氧化还原斜相关的浮游动物的垂直和水平分布。将通过实验确定垂直洄游动物和近水面、缺氧和缺氧深度的常驻物种的厌氧和有氧呼吸、代谢物、排泄和消化率，以确定浮游动物的代谢和消化产物的释放是否因其代谢和/或食物资源组成的差异而不同。放牧实验，结合脂质生物标志物和稳定同位素组成，将用于评估浮游动物的原位饮食和长期摄食史。粪便颗粒组成将与沉淀物捕集器中的颗粒进行比较。还将分析时间序列浮游动物样本，以获得浮游动物群落动态的时间信息，并对浮游动物对元素通量的贡献进行季节性估计。知识价值。海洋学的一个重大挑战是了解控制海洋系统中有机碳的转化和命运的过程。由于缺乏关于控制生物活动对环境强迫和气候变化的反应的因素的基本信息，阻碍了迎接这一挑战。特别是，海洋生物圈在全球碳循环中的作用仍然缺乏限制，部分原因是对碳输出的质量和数量的生物控制存在不确定性。该项目将有助于我们了解中浮游动物在生物地球化学循环中的作用，特别是与缺氧或亚氧层和强氧化还原梯度地区的过程如何被改变有关，并将有助于正确理解在卡里亚科盆地不同沉积物中记录的水柱过程与气候历史之间的联系。更广泛的影响。浮游动物时间序列将提供一个鲜为人知的区域的海洋生物多样性和生态相互作用模式的信息。加勒比合作组织方案对委内瑞拉的技术转让和人力资源开发产生了持续的影响。该项目将帮助培训委内瑞拉的人员，并将支持几名研究生。主要研究人员和学生将开发有关该项目的材料，并通过位于南加州大学的美国国家科学基金会海洋科学教育卓越中心（COSEE）进行传播。

The CARIACO (CArbon Retention In A Colored Ocean) Program is a time-series programs, with the central goal to better understand seasonal to decadal time-scales of processes governing ocean biogeochemistry. The CARIACO site is situated in the tropics on a productive continental margin off Venezuela, the basin is anoxic, and the site is strongly connected to paleoclimate investigations. Thus, CARIACO has the additional goal of relating modern oceanographic processes with the production, transformation, and preservation of particulate matter in the sediment record. Zooplankton composition, behavior, and physiological rates are important components of the biological pump. Recent findings from the Cariaco Basin and other regions with pelagic redoxclines (suboxic and anoxic interfaces) suggest that they are active regions of biogeochemical cycling, in which C may be directly transferred from bacterial production to zooplankton grazers. The goals of this project are to determine the vertical and horizontal distributions of zooplankton in relation to the redoxcline during two seasons using discrete-depth net samples and a vertical-profiling laser-line scan camera system. Anaerobic and aerobic respiration and metabolites, excretion, and egestion rates will be experimentally determined for vertical migrators and resident species nearsurface and at suboxic and anoxic depths to determine whether zooplankton differ in their release of metabolic and egested products, due to differences in their metabolism and/or composition of food resources. Grazing experiments, in combination with lipid biomarkers and stable isotopic compositions, will be used to assess in situ diet and long-term feeding history of zooplankton. Fecal pellet composition will be compared with pellets in sediment traps. Time-series zooplankton samples also will be analyzed to obtain temporal information on zooplankton community dynamics and allow a seasonal estimate of the zooplankton contribution to elemental fluxes. Intellectual Merit. One of the grand challenges of oceanography is to understand the processes that control the transformation and fate of organic carbon in marine systems. Meeting this challenge is hindered by a lack of basic information about factors that govern the response of biological activity to environmental forcing and climate change. In particular, the role of the marine biosphere in the global carbon cycle remains poorly constrained, in part due to uncertainties about biological controls on the quality and quantity of carbon export. This project will contribute to our knowledge of the role of mesozooplankton in biogeochemical cycles, especially in relation to how processes may be modified in regions with anoxic or suboxic layers and strong redox gradients, and will help to correctly understand the links between water column processes and climate history as recorded in the varved sediments of the Cariaco Basin. Broader Impacts. The zooplankton time-series will provide information on patterns of marine biodiversity and ecological interactions from a poorly known region. The CARIACO Program has an ongoing impact in technology transfer and human resource development in Venezuela. This project will help train personnel in Venezuela and will support several graduate students. The lead investigators and students will develop materials on the project for dissemination through the NSF-Center for Ocean Science Education Excellence (COSEE) located at USF.