RAPID - Assessing the response of the Seychelles-Chagos Thermocline Ridge ecosystem to an Indian Ocean Dipole event

RAPID - 评估塞舌尔-查戈斯温跃层海脊生态系统对印度洋偶极子事件的响应

• 批准号: 2019983
• 负责人: JOAQUIM GOES
• 金额: $ 19.18万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-01 至 2024-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2019983&HistoricalAwards=false
• 关键词: RAPID; Assessing; response; Seychelles; Chagos

Phytoplankton constitute the base of the marine food web. Their diversity, productivity and abundance have a huge influence on fisheries. For example, seasonal increases in phytoplankton biomass caused by the surge of deep ocean nutrient rich waters into the upper sunlit layers in the Equatorial Indian Ocean lead to an increase in tuna stocks. However, non-periodic increases of sea surface temperatures in the Seychelles-Chagos Thermocline Ridge region in the eastern Equatorial Indian Ocean, a phenomenon known as the Indian Ocean Dipole, weakens deep ocean water surge, which seems to alter phytoplankton community structure and to reduce phytoplankton’s productivity to the detriment of tuna stocks. Yet, the impact from such unpredictable events is not fully understood. This project investigates the impacts of an ongoing Indian Ocean Dipole, one of the most severe on record, on phytoplankton. The broader impacts of the project relate to its value to inform fisheries management plans in that area. Data derived from this study is valuable to understand and predict wider changes in the food web in a region that is coming under increasing pressures of global warming. All the data is made publicly available.The research team is working with South Korean collaborators to understand how changes in phytoplankton biomass and in deep chlorophyll maxima may be linked to changes in phytoplankton productivity and growth rates due nutrient and/or iron limitation as a result of the weakening of deep-water upwelling. The team is also investigating the impact of the dipole event on cell size of dominating phytoplankton populations. Finally, they are testing if the phytoplankton community rely primarily on recycled as opposed to new nitrogenous nutrients for photosynthesis and growth during dipole events. The hypotheses are tested through extensive biological, hydro-chemical and biogeochemical measurements that include: 1) microscopic, Flow Cytometry, FlowCAM and HPLC pigment based analysis of phytoplankton biomass, community composition and size structure and Fast Repetition Rate based measurements of phytoplankton photosynthetic competency along a cruise track and different depths in the water column, and 2) on-deck incubation based photosynthesis and nutrient uptake experiments. In situ measurements and sample collection is carried out as part of the Korea-US inDian Ocean Scientific (KUDOS) Research Program cruise (April-May 2020) on board the Korea Institute of Ocean Sciences and Technology Ship R/V Isabu, one of the only multi-disciplinary oceanographic cruises planned for the Seychelles-Chagos Thermocline Ridge region during the dipole event.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.

浮游植物构成了海洋食物网的基础。它们的多样性、生产力和丰富性对渔业有着巨大的影响。例如，由于深海营养丰富的水域涌入赤道印度洋上层日照层，导致浮游植物生物量的季节性增加，导致金枪鱼种群增加。然而，赤道印度洋东部的塞舌尔-查戈斯温跃脊区域海面温度的非周期性上升，即所谓的印度洋偶极子现象，削弱了深海水波，这似乎改变了浮游植物群落结构，降低了浮游植物的生产力，损害了金枪鱼种群。然而，人们还没有完全了解这种不可预测事件的影响。该项目调查正在进行的印度洋偶极子对浮游植物的影响，这是有记录以来最严重的偶极子之一。该项目的更广泛影响与其为该地区的渔业管理计划提供信息的价值有关。这项研究得出的数据对于理解和预测全球变暖压力越来越大的地区食物网的更广泛变化具有价值。所有数据都是公开的。研究小组正在与韩国合作者合作，了解浮游植物生物量和深层叶绿素最大值的变化如何与由于营养和/或铁限制而导致的浮游植物生产力和生长速度的变化有关，这是由于深水上升流减弱的结果。该团队还在调查偶极事件对主要浮游植物种群细胞大小的影响。最后，他们正在测试，在偶极事件期间，浮游植物群落是否主要依赖回收的、而不是新的氮素营养来进行光合作用和生长。这些假设通过广泛的生物、水化学和生物地球化学测量得到验证，这些测量包括：1)基于显微镜、流式细胞术、FlowCAM和高效液相色素的浮游植物生物量、群落组成和大小结构的分析，以及基于快速重复率的浮游植物光合作用能力的测量，以及2)基于甲板培养的光合作用和营养物质吸收实验。现场测量和样品采集是韩国-美国印度洋科学(KUDOS)研究计划邮轮(2020年4-5月)的一部分，由韩国海洋科学与技术研究所的R/V Isabu号船进行，这是偶极事件期间计划在塞舌尔-查戈斯温跃层脊地区进行的仅有的多学科海洋邮轮之一。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Reviews and syntheses: Present, past, and future of the oxygen minimum zone in the northern Indian Ocean

• DOI: 10.5194/bg-17-6051-2020
• 发表时间: 2020-12
• 期刊: Biogeosciences
• 影响因子: 4.9
• 作者: T. Rixen;G. Cowie;B. Gaye;J. Goes;Helga do Rosário Gomes;R. Hood;Z. Lachkar;Henrike Schmidt;J. Segschneider;Arvind Singh