Collaborative Research: Ocean Acidification: Impacts on copepod populations mediated by changes in prey quality

研究表明，海洋酸化对单个生物体有生理影响，甚至对那些缺乏碳酸钙骨架结构的生物体也是如此。然而，这项研究没有充分解决营养水平对个人的影响是如何联系起来的。远洋桡足类是大多数海洋生物地球化学循环中的关键角色。它们对浮游植物和微型浮游动物的消耗是细菌和浮游植物生产转移到更高营养水平的主要机制。尽管桡足类的数量和生态重要性很高，但关于骨性关节炎的研究很少受到关注。很少有研究集中在二氧化碳浓度升高对桡足类动物的直接急性影响(如卵孵化、存活)，而在预测未来二氧化碳浓度时，几乎没有观察到显著的影响。然而，越来越多的人认识到，OA显著影响它们的浮游植物猎物，包括提高生长速度、增加细胞大小、改变营养物质的吸收和比率以及化学成分。由于桡足类动物的觅食、产卵和孵化成功都会随着猎物的这些特征而变化，因此，OA介导的浮游植物质量的变化可能是OA作用于桡足类种群并最终影响海洋食物网的一个重要的间接机制。这项研究将促进我们对桡足类种群如何受到OA的影响的理解，特别是通过OA诱导的浮游植物质量的变化。这项研究的核心目标是确定浮游植物生理和生化(如脂肪组成)的变化如何影响桡足类的产卵、孵化和无节幼体的个体发育。PI将包括一个子集的实验，以测试OA是否独立于猎物的变化而影响桡足类的生殖输出。为了实现这些研究目标，研究人员将在几种二氧化碳浓度下半连续培养硅藻、光亮硅藻和甲藻，在此期间，研究人员将表征它们的生理和生化变化。在不同的二氧化碳浓度下，大型、高脂肪海洋物种太平洋水蚤和体型较小、低脂肪的河口物种Acartia Clausi将被维持，并喂养这些经二氧化碳驯化的猎物，并对它们的放牧和繁殖能力进行量化。这项研究中使用的桡足类和浮游植物将从Salish海采集，该地区已经经历了不同时间尺度上的高pCO2/H+(1000ppm，PH7.5)时期。因此，这项研究解决了一个问题，即未来气候变化可能如何影响海洋生态系统，但也与目前沿海环境中经历的二氧化碳/H+变化有关。更广泛的影响：该项目的绩效指标致力于：1)促进接触代表性不足的群体，2)培训和指导，3)扩大对开放式获取的知识，以及4)为正在进行的多学科开放式获取研究开发基础设施。未被充分代表的群体将通过香农角海洋中心的国家认可的国家科学基金会资助的海洋科学多元文化倡议：本科生参与(MIMSUP：http://www.wwu.edu/mimsup/)，)和华盛顿大学太平洋西北地区路易斯·斯托克斯少数群体参与联盟(PNW LSAMP)计划获得服务。教育目标是通过一系列活动来实现的，包括K-12外展，本科生的研究经验，包括SPMC的夏季REU计划，以及广泛传播的课程材料的开发。该项目将支持和参与SPMC？S的公众宣传活动，提高广大公众对海洋问题的认识。这项研究将支持三名早期职业科学家、一名公共教育推广专家，并将培训一名博士后研究员和一名研究生。对SPMC现有的办公自动化研究设施的基础设施的改进将增加可用性，使其更容易用于课堂使用和学生研究。额外的仪器还将使该设施成为监测萨利什海二氧化碳分压的区域资源。

Research shows that ocean acidification (OA) has physiological consequences for individual organisms, even those lacking calcium carbonate skeletal structures. However, this research does not adequately address how OA effects to individuals are linked across trophic levels. Pelagic copepods are critical players in most marine biogeochemical cycles. Their consumption of phytoplankton and microzooplankton is the primary mechanism by which bacterial and phytoplankton production is transferred to higher trophic levels. Despite their high abundance and ecological importance, copepods have received little research attention concerning OA. The few studies focused on direct acute effects to copepods (e.g. egg hatching, survival) under elevated pCO2, and few significant effects have been observed at predicted future pCO2. However, there is increasing recognition that OA significantly affects their phytoplankton prey, including elevating growth rates, increasing cell sizes, altering nutrient uptake and ratios, and chemical composition. Because copepod grazing, egg production, and hatching success all can vary with these prey characteristics, OA mediated changes in phytoplankton quality may be an important indirect mechanism through which OA acts on copepod populations and, ultimately, marine food webs. This study that will advance our understanding of how copepod populations may be affected by OA, specifically through OA induced changes in phytoplankton quality. The core objective of this study is to determine how changes in phytoplankton physiology and biochemistry (e.g. lipid composition) affect copepod egg production, hatching, and ontogenetic development of nauplii. The PIs will include a subset of experiments to test whether OA affects copepod reproductive output independent of changes to prey. To achieve these research goals, the diatom, Ditylum brightwellii, and dinoflagellate, Prorocentrum micans, will be cultured semi-continuously under several pCO2 concentrations, during which time the investigators will characterize changes in their physiology and biochemistry. The copepods, Calanus pacificus, a large, high lipid-bearing marine species, and Acartia clausi, a smaller, low lipid-bearing estuarine species, will be maintained across varying pCO2 concentrations and fed these pCO2-acclimated prey, and their grazing and reproductive capability quantified. The copepods and phytoplankton used in this study will be collected from the Salish Sea, a region already experiencing periods of high pCO2/H+ (1000 ppm, pH 7.5) on varying timescales. Therefore, this research addresses a question of how future climate change may impact marine ecosystems, but also is relevant to pCO2/H+ variability presently experienced in coastal environments. Broader Impacts: The PIs of this project are committed to: 1) promoting access to under-represented groups, 2) training and mentoring, 3) broadening knowledge of OA and 4) developing infrastructure for ongoing, multidisciplinary OA research. Under-represented groups will be served through Shannon Point Marine Center's (SPMC) nationally recognized NSF-funded Multicultural Initiative in the Marine Sciences: Undergraduate Participation (MIMSUP: http://www.wwu.edu/mimsup/), and University of Washington's Pacific Northwest Louis Stokes Alliance for Minority Participation (PNW LSAMP) programs. Educational goals are addressed through an array of activities including K-12 outreach, research experiences for undergraduates, including SPMC's summer REU program, and development of widely disseminated curricular materials. The project will support and participate in SPMC?s public outreach initiative, increasing awareness of marine issues in the general public. This study will support three early career scientists, a public education outreach specialist, and will train a postdoctoral researcher and a graduate student. Infrastructure improvements to SPMC's existing OA research facility will increase usability, making it more accessible for classroom use and student research. The additional instrumentation will also allow the facility to become a regional resource for monitoring pCO2 in the Salish Sea.