Collaborative Research: Seasonal and decadal changes in temperature drive Prochlorococcus ecotype distribution patterns

合作研究：温度的季节性和年代际变化驱动原绿球藻生态型分布模式

• 批准号: 1031064
• 负责人: Zackary Johnson
• 金额: $ 60.09万
• 依托单位: Duke University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1031064&HistoricalAwards=false
• 关键词: Collaborative; Research; Seasonal; decadal; changes

Intellectual Merit: The two numerically-dominant ecotypes of the marine cyanobacterium Prochlorococcus partition the surface ocean niche latitudinally, with ecotype eMIT9312 dominant in the 30°N-30°S region and eMED4 dominant at higher latitudes. These ecotypes may account for 25-50% of primary production in open ocean ecosystems, but this percentage is dependent on which ecotype dominates. The relative abundance of the two ecotypes follows a log-linear relationship with temperature, with the transition from eMIT9312 to eMED4 occurring at ~18 °C. From these descriptive data, it has been hypothesized that temperature is the primary driver of relative abundance. Their contribution to net primary production, however, appears to be independent of temperature, suggesting temperature regulates ecotype dominance through photosynthesis-independent mechanisms. To test these hypotheses, the PIs are undertaking a series of field and lab studies to investigate the effect of temperature change on the distribution of these ecotypes. Two cruises in the North Pacific will trace the transitions from eMIT9312- to eMED4-dominated regions, with one cruise during the winter and the other during summer. They have hypothesized that the ratio of ecotype abundance will move latitudinally with the seasonal shift in temperature gradient: migration of the 18° C isotherm northward in the summer will be matched by a similar migration of the 1:1 ecotype transition point. Multiple crossings of the 18° C isotherm are proposed, and the summer cruise will also follow the isotherm to the Western US coast to gain insight on physical and geochemical influences. Environmental variables such as nutrient concentrations, light/mixing depths, and virus /grazing based mortality, which may impinge on the relationship between temperature and ecotype ratio, will be assessed through a series of multivariate analyses of the collected suite of physical, chemical and biological data. Seasonal comparisons will be complemented with on-deck incubations and lab competition assays (using existing and new isolates) that will establish, for the first time, how fitness coefficients of these ecotypes relate to temperature. As latitudinal shifts in temperature gradient and migration of ecotypes during seasonal warming likely share common features with high latitude warming as a consequence of climate change, the investigator's analyses will contribute important biological parameters (e.g., abundances, production rates, temperature change coefficients) for modeling biological and biogeochemical responses to climate change. This research will be integrated with that of committed collaborators, generating data sufficient for ecosystem-scale characterizations of the contributions of temperature (relative to other forcing factors) in constraining the range and seasonal migration of these numerically dominant marine phototrophs.Broader Impacts: This proposal encompasses several layers of outreach to the scientific community at large. Biological, chemical and physical data will be deposited in GenBank, NOAA's National Oceanographic Data Center, and the Biological and Chemical Oceanography Data Management Office (BCO-DMO). Results will inform climate and ecosystem-change models, and be used in classrooms as examples of how ocean ecosystems may change in response to climate variation. There are also clear connections to molecular ecology: how do potentially small changes in an organism's genome lead to fundamental differences in their ecology or resiliency to climate change? This project will expand ongoing efforts by establishing formal outreach collaborations for each cruise. These collaborations will be based on two specific goals: (1) a science journalism student will document and broadly communicate the goals and activities of the cruise and (2) a hands-on cruise opportunity for K-12 teachers will serve as an information gateway to other teachers. In addition, this project will support three graduate students (two at Tennessee - an EPSCOR university - and one at Duke) and several undergraduates, composing a significant body of their respective theses. Finally, PIs will continue their efforts to provide opportunities to historically under-represented groups in molecular ecology and ocean sciences.

智力优点：海洋蓝细菌的两种单独主导的生态型在地表海洋litudinitionally latudininationally中，EMIT9312在30°N-30°S区域中占主导地位，而EMED4则在较高的纬度地区占主导地位。这些生态型可能占开放海洋生态系统中初级生产的25-50％，但该百分比取决于哪种生态型的主导地位。两种生态型的相对丰度遵循与温度的对数线性关系，从EMIT9312到EMED4的过渡发生在〜18°C。从这些描述性数据中，已经假设温度是相对丰度的主要驱动力。然而，它们对净初级生产的贡献似乎与温度无关，表明温度通过与光合作用的无关机制来调节生态型的优势。为了检验这些假设，PI正在进行一系列领域和实验室研究，以研究温度变化对这些生态型分布的影响。北太平洋的两次巡游将追踪从EMIT9312-到EMED4主导的地区的过渡，在冬季进行一次巡游，在夏季进行一次巡游。他们假设，随着温度梯度的季节性变化，生态型丰度的比率将延伸：夏季18°C等温线的迁移将与1：1生态型过渡点的类似迁移相匹配。提出了18°C等温线的多次穿越，夏季巡游还将跟随等温线到美国西部海岸，以深入了解物理和地球化学影响。环境变量（例如营养浓度，光 /混合深度以及基于病毒 /放牧的死亡率）将通过一系列的物理，化学和生物学数据的套件的多变量分析来评估，这可能会影响温度和生态型比之间的关系。季节性比较将通过甲板孵化和实验室竞争测定法（使用现有和新分离株）完成，这将首次确定这些生态型与温度的适应性系数如何相关。随着季节性变暖期间温度梯度的纬度变化和生态型的迁移可能会随着气候变化而具有高纬度变暖的共同特征，研究者的分析将贡献重要的生物学参数（例如，抽象，生产速率，温度变化系数，温度变化系数），用于建模生物地球化学反应，以使气候变化对气候变化进行建模。这项研究将与坚定的合作者集成在一起，生成足以为温度（相对于其他强迫因素）的生态系统规模特征（相对于其他强迫因素）的贡献的数据，以控制这些数值主导的海洋光养育的范围和季节性迁移。生物学，化学和物理数据将存放在Genbank，NOAA的国家海洋数据中心以及生物和化学海洋学数据管理办公室（BCO-DMO）中。结果将为气候和生态系统变化模型提供信息，并在教室中用作海洋生态系统如何随着气候变化而变化的示例。与分子生态学有明显的联系：生物体基因组的潜在小变化如何导致其生态学或对气候变化的弹性的根本差异？该项目将通过为每次巡游建立正式的外展合作来扩大持续的努力。这些合作将基于两个具体的目标：（1）科学新闻学生将记录并广泛传达巡航的目标和活动，（2）K-12教师的动手巡航机会将作为通往其他老师的信息网关。此外，该项目将支持三名研究生（田纳西州的两名EPSCOR University，一名在杜克大学）和几名本科生，构成了各自的论文。最后，PI将继续努力为历史上代表性不足的分子生态学和海洋科学群体提供机会。