Collaborative Research: Regional variation of phytoplankton diversity and biogeochemical functioning in the subtropical Indian Ocean

印度洋占全球海洋光合作用的近五分之一，可能是全球海洋养分和碳循环的关键组成部分。然而，印度洋可能是地球上研究最少的主要海洋。我们有限的了解表明物理和化学环境条件存在广泛的变化，但这种变化如何影响生物多样性、营养胁迫以及更广泛的浮游植物功能的区域差异尚不清楚。为了帮助解决这些差距，研究人员将通过加入一个已经获得资助的大型研究巡航来开展一项研究。它将覆盖有开放海域记录的最高温度的北部地区，预测（但未在现场测试）铁应力约10°S的地区，以及具有独特氮磷（或N:P）比率的南部亚热带环流。该项目的重点是量化和综合环境条件、浮游植物多样性和基因组含量以及营养生物地球化学之间的相互联系，以了解这些因素如何导致印度洋独特的生物地球化学区域。这项研究将在许多层面上产生更广泛的影响。首先，它将通过与太平洋水族馆（AOP）的新合作伙伴关系，提高公众对浮游植物在海洋功能，气候和人们生活中的作用的认识，该水族馆是全国第四大参加人数最多的水族馆。二是培养博士后1人，研究生1人，本科生1人。第三，这项研究将大大增加我们对海洋生物地球化学的基本知识，在许多情况下，这将是在印度洋进行的第一次此类测量。该项目将解决两个主要问题：印度洋中部的环境条件、浮游植物多样性、浮游植物生理学和生物地球化学是如何变化的？IO中部是否存在明显的生物地球化学制度？研究人员假设，环境条件，包括氮(N)和铁（Fe）的相对可用性，导致了三种不同的浮游植物群落和生物地球化学制度。他们将采用一系列先进的分析工具，包括高灵敏度的溶解和颗粒营养物（氮、磷和铁）测量，基因组学，生物分析来测试营养压力，以及特定分类群的细胞分类，然后测量营养含量和吸收。该项目的一个重点是量化和综合环境条件、浮游植物多样性和基因组含量以及营养生物地球化学之间的相互联系，以及这些因素如何导致印度洋独特的生物地球化学区域。这组广泛的观测结果最终可以与海洋模型和卫星数据联系起来，从而全面了解印度洋化学、生物多样性和浮游植物生物地球化学功能方面的区域差异。

The Indian Ocean accounts for nearly a fifth of global ocean photosynthesis and is likely a key component in global ocean nutrient and carbon cycles. However, the Indian Ocean may be the least studied major marine body on the planet. Our limited understanding suggests extensive variations in physical and chemical environmental conditions, but how this variation influences biodiversity, nutrient stress, and more broadly regional differences in the functioning of phytoplankton is unknown. To help address these gaps, the investigators will conduct a study by joining an already-funded major research cruise to this region. It will cover a northern region with some of the highest temperatures recorded in open ocean waters, an area around 10°S of predicted (but not tested in situ) iron stress, and a southern subtropical gyre with unique nitrogen to phosphorous(or N:P) ratios. The focus of this project is to quantify and synthesize the interconnectedness of environmental conditions, phytoplankton diversity and genome content, and nutrient biogeochemistry, with the goal of understanding how these may lead to unique biogeochemical regions in Indian Ocean. The research will have broader impacts on many levels. First, it will increase public awareness of the role of phytoplankton on ocean functioning, climate, and people's lives through a new partnership with the Aquarium of the Pacific (AOP), which is the fourth most-attended aquarium in the nation. Secondly, the project will train a postdoctoral scholar as well as a graduate and undergraduate students. Third, the research will dramatically increase our basic knowledge ocean biogeochemistry and in many cases will be the first measurements of their kind made in the Indian Ocean.This project will address two major questions: How do environmental conditions, phytoplankton diversity, phytoplankton physiology, and biogeochemistry vary across the central Indian Ocean? Are there distinct biogeochemical regimes in the central IO? The researchers hypothesize that environmental conditions, including the relative availability of nitrogen (N) and iron (Fe), lead to three distinct phytoplankton communities and biogeochemical regimes. They will employ a series of advanced analytical tools including high sensitivity measurements of dissolved and particulate nutrients (nitrogen, phosphorus, and iron), genomics, bioassays to test for nutrient stress, and cell-sorting of specific taxa followed by measures of nutrient content and uptake. A focus of this project is to quantify and synthesize the interconnectedness of environmental conditions, phytoplankton diversity and genome content, and nutrient biogeochemistry, and how these lead to unique biogeochemical regions in Indian Ocean. This extensive set of observations can ultimately be linked to ocean models and satellite data to provide a comprehensive view of regional differences in chemistry, biodiversity and phytoplankton biogeochemical functioning in the Indian Ocean.