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

Cariaco(有色海洋中的碳保持)计划是一个时间序列计划，其中心目标是更好地了解管理海洋生物地球化学过程的季节到十年的时间尺度。Cariaco遗址位于热带地区，位于委内瑞拉近海多产的大陆边缘，盆地缺氧，该遗址与古气候调查密切相关。因此，Cariaco还有一个额外的目标，那就是将现代海洋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。Cariaco盆地和其他具有远洋氧化还原跃层(亚氧和缺氧界面)的区域的最新发现表明，它们是生物地球化学循环的活跃区域，在这些区域中，C可能直接从细菌生产转移到浮游动物。该项目的目标是利用离散深度网样和垂直剖面激光扫描摄像系统，确定浮游动物在两个季节期间与氧化跃层有关的垂直和水平分布。将通过实验测定垂直候鸟和栖息物种在近地表、亚缺氧和缺氧深度的厌氧和好氧呼吸及代谢物、排泄物和排泄率，以确定浮游动物是否因其新陈代谢和/或食物资源组成的不同而在代谢和排泄产物的释放上有所不同。放牧实验，结合脂质生物标志物和稳定的同位素组成，将被用来评估浮游动物的就地摄食和长期摄食史。将粪便颗粒组成与沉积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，并能够对浮游动物对元素通量的贡献进行季节性估计。智力上的功绩。海洋学的重大挑战之一是了解控制海洋系统中有机碳转化和命运的过程。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，迎接这一挑战受到阻碍。特别是，海洋生物圈在全球碳循环中的作用仍然受到限制，部分原因是对碳出口的质量和数量的生物控制存在不确定性。这个项目将有助于我们了解浮游动物在生物地球化学循环中的作用，特别是关于在具有缺氧或亚缺氧层和强氧化还原梯度的区域如何改变过程的知识，并将有助于正确理解Cariaco盆地各种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关于一个鲜为人知的地区的海洋生物多样性和生态相互作用模式的信息。加勒比方案对委内瑞拉的技术转让和人力资源开发具有持续的影响。该项目将帮助培训委内瑞拉的人员，并将支持几名研究生。首席调查人员和学生将编写关于该项目的材料，通过位于美国联邦的NSF-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.