Collaborative Research: Quantifying trophic roles and food web ecology of salp blooms of the Chatham Rise

合作研究：量化查塔姆海隆樽海鞘的营养作用和食物网生态

• 批准号: 1756465
• 负责人: Karen Selph
• 金额: $ 12.81万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2022-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1756465&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantifying; trophic; roles

Salps are unique open-ocean animals that range in size from a few millimeters to greater than twenty centimeters, have a gelatinous (jelly-like) body, and can form long chains of many connected individuals. These oceanic organisms act as oceanic vacuum cleaners, having incredibly high feeding rates on phytoplankton and, unusual for consumers of their size, smaller bacteria-sized prey. This rapid feeding and the salps' tendency to form dense blooms, allows them move substantial amounts of prey carbon from the surface into the deep ocean, leading to carbon dioxide removal from the atmosphere. However, salps are often considered a trophic dead-end, rather than a link, in the food web due to the assumption that they themselves are not consumed, since their gelatinous bodies are less nutritious than co-occurring crustacean prey. Along with this, salp populations are hypothesized to be increasing due to climate change. This proposal addresses these questions: 1) Do salps compete primarily with crustaceans (as in the prevailing paradigm) or are they competitors of single-celled protists, which are the dominant grazers of small phytoplankton? 2) Do salp blooms increase the efficiency of food-web pathways from tiny phytoplankton to fisheries production in nutrient-poor ocean regions? This project will support the interdisciplinary education of a graduate student who will learn modeling and laboratory techniques in the fields of biological and chemical oceanography and stimulate international collaborations between scientists in the United States and New Zealand. Additionally, several Education and Outreach initiatives are planned, including development of a week-long immersive high school class in biological oceanography, and education modules that will serve the "scientists-in-the schools" program in Tallahassee, FL.It is commonly assumed that salps are a trophic sink. However, this idea was developed before the discovery that protists (rather than crustaceans) are the dominant grazers in the open ocean and was biased by the difficulty of recognizing gelatinous salps in fish guts. More recent studies show that salps are found in guts of a diverse group of fish and seabirds and are a readily available prey source when crustacean abundance is low. This proposal seeks to quantify food web flows through contrasting salp-dominated and salp-absent water parcels near the Chatham Rise off western New Zealand where salp blooms are a predictable phenomenon. The proposal will leverage previously obtained data on salp abundance, bulk grazing impact, and biogeochemical significance during Lagrangian experiments conducted by New Zealand-based collaborators. The proposal will determine 1) taxon- and size-specific phytoplankton growth rate measurements, 2) taxon- and size-specific protozoan and salp grazing rate measurements, 3) compound specific isotopic analysis of the amino acids of mesozooplankton to quantify the trophic position of salps, hyperiid amphipods, and other crustaceans, 4) sediment traps to quantify zooplankton carcass sinking rates, and 5) linear inverse ecosystem modeling syntheses. Secondary production and trophic flows from this well-constrained ecosystem model will be compared to crustacean-dominated and microbial loop-dominated ecosystems in similarly characterized regions (California Current, Costa Rica Dome, and Gulf of Mexico).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海鞘是一种独特的开放海洋动物，其大小从几毫米到超过20厘米不等，有一个凝胶状的身体，并且可以形成许多连接个体的长链。这些海洋生物就像海洋的真空吸尘器，对浮游植物有着难以置信的高摄食率，而且对于它们这种体型的消费者来说，更小的细菌大小的猎物是不寻常的。 这种快速的进食和海鞘形成密集花朵的倾向，使它们能够将大量的猎物碳从表面转移到深海，从而从大气中去除二氧化碳。 然而，海鞘通常被认为是一个营养的死胡同，而不是一个环节，在食物网中，由于假设他们自己不被消耗，因为他们的凝胶状身体比共同出现的甲壳类猎物营养少。 沿着，假设由于气候变化，海鞘的数量正在增加。 这一提议解决了这些问题：1）海鞘主要与甲壳类动物竞争（如在流行的范式中），还是它们与单细胞原生生物竞争，后者是小型浮游植物的主要食草动物？ 2)在营养贫乏的海洋地区，海藻水华是否增加了从微小浮游植物到渔业生产的食物网途径的效率？ 该项目将支持研究生的跨学科教育，研究生将学习生物和化学海洋学领域的建模和实验室技术，并促进美国和新西兰科学家之间的国际合作。 此外，几个教育和推广计划，包括为期一周的沉浸式高中生物海洋学课程的发展，和教育模块，将服务于“科学家在学校”计划在塔拉哈西，佛罗里达州。 然而，这一想法是在发现原生生物（而不是甲壳类动物）是开放海洋中占主导地位的食草动物之前发展起来的，并且由于难以识别鱼内脏中的凝胶状海鞘而存在偏见。 最近的研究表明，海鞘存在于各种鱼类和海鸟的内脏中，当甲壳类动物数量较少时，海鞘是一种现成的猎物来源。 该提案旨在量化食物网流量，通过对比盐为主和盐缺席的水包裹附近的查塔姆上升关闭新西兰西部的盐花是一个可预测的现象。 该提案将利用新西兰合作者在拉格朗日实验期间先前获得的关于salp丰度，散装放牧影响和地球化学意义的数据。 该提案将确定1）分类和大小特定的浮游植物生长率测量，2）分类和大小特定的原生动物和salp放牧率测量，3）中型浮游动物氨基酸的复合特定同位素分析，以量化salp，hyperiid端足类动物和其他甲壳类动物的营养位置，4）沉积物陷阱，以量化浮游动物尸体下沉率，（5）线性逆生态系统模型综合。 次级生产和营养流从这个良好的约束生态系统模型将比较甲壳类动物为主的和微生物循环为主的生态系统在类似的特征区域（加州电流，哥斯达黎加圆顶，墨西哥湾）。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

Size‐specific grazing and competitive interactions between large salps and protistan grazers

大型樽海鞘和原生食草动物之间的尺寸特异性放牧和竞争性相互作用

• DOI: 10.1002/lno.11770
• 发表时间: 2021
• 期刊: Limnology and Oceanography
• 影响因子: 4.5
• 作者: Stukel, Michael R.;Décima, Moira;Selph, Karen E.;Gutiérrez‐Rodríguez, Andres
• 通讯作者: Gutiérrez‐Rodríguez, Andres

Enumeration of marine microbial organisms by flow cytometry using near‐ UV excitation of Hoechst 34580‐stained DNA

使用 Hoechst 34580 染色 DNA 的近紫外激发，通过流式细胞术对海洋微生物进行计数

• DOI: 10.1002/lom3.10454
• 发表时间: 2021
• 期刊: Limnology and Oceanography: Methods
• 作者: Selph, Karen E.