Collaborative Research: PLANKTON SIZE SPECTRA AND TROPHIC LINKS IN A DYNAMIC OCEAN

海洋浮游生物构成了大多数海洋食物网的基础，这些食物网支持着有价值的渔业。这个高度多样化和复杂的群落由随洋流漂流的生物组成。 浮游生物仍然没有得到充分的研究：由于它们的大小跨越六个数量级，从不到一微米到几米，因此很难对其进行采样。然而，了解这些社区如何应对气候变化，以及这些应对措施最终如何影响宝贵的渔业，从而影响粮食安全至关重要。由于许多生态和生理过程是由相对大小决定的，因此大小谱理论（即，生物体大小与生物体丰度之间的关系，因为它驱动着生态系统的特性，如食物网），为预测气候变化对海洋生态系统的影响提供了一个宝贵的框架。需要更深入地了解对比环境条件下尺寸谱变异的范围和性质。在夏季和冬季，俄勒冈州和华盛顿附近的北方加州海流动态、高产，产生了各种海洋条件，包括与缺氧和海洋酸化有关的海洋条件。本研究对该地区的浮游生物群落进行采样，以研究温度、营养盐、溶解氧和pH条件梯度如何影响大小谱。更广泛的影响包括培训学生，建立科学资源，并推广到更广泛的社区。本科生和研究生正在接受海洋学、实地研究和新技术方面的培训。作为该项目的一部分开发的自动图像分析管道向海洋学界开放，图像数据可通过新的全球浮游生物图像库（一个开放获取的浮游生物图像库）获取。从这项研究中获得的尺寸谱数据直接与生态系统建模者共享。该项目的旗舰外展活动是与锡特卡艺术与生态中心合作，并主办一个海上艺术家项目。 一名专业艺术家通过竞争被选中参加研究巡航，并创作艺术产品，为海洋学研究和所研究的生物体提供独特的声音。这些艺术品正在被组装成一个巡回公共艺术展，计划在锡特卡中心、俄勒冈州的哈特菲尔德海洋科学中心、俄勒冈州的查尔斯顿海洋生物中心和位于服务不足的沿海社区的中心展出。最后，该项目的图像数据正在通过浮游生物门户网站共享，该网站是与公民科学联盟的Zooniverse合作开发的一个公共网站，邀请公民科学家参与浮游生物图像的分类。（特别是，温度，营养物质，氧气，pH值）与尺寸谱的变化相关，以揭示食物网的功能后果。浮游生物的大小谱正在通过在具有陡峭环境梯度的栖息地和两个对比鲜明的季节进行采样来比较环境条件。生物量跨越10个数量级的浮游生物取样使用两个互补的高分辨率成像系统：原位鱼类浮游生物成像系统（ISIIS）和激光原位散射和透射（LISST）粒子成像仪。高通量图像分析软件用于创建大小分布以及分类学分类。深度离散的中型浮游动物样本平行收集，以检查社区的碳变化，获得长度到碳的转换和校准图像数据。测试从图像数据计算的归一化生物质尺寸谱与预期图案的偏差。浮游生物收集也正在分析的饮食和胶状浮游动物的繁殖状况，和饮食和代表性的仔鱼的每日生长率。这两个群体在历史上一直未得到充分研究，但在生态系统功能中发挥着核心作用。这些数据被用来研究这些生物如何受到环境条件的影响，以及它们如何影响浮游生物的大小谱。这项研究是理解气候变化背景下海洋生态系统的基础。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Marine plankton form the base of most ocean food webs that support valuable fisheries. This highly diverse and complex community is composed of organisms that drift with ocean currents. Planktonic organisms remain understudied: they are difficult to sample given that their sizes span more than six orders of magnitude from less than one micron to meters. Yet, understanding how these communities respond to climate change, and ultimately how these responses affect valuable fisheries, and therefore food security, is critical. Because many ecological and physiological processes are dictated by relative size, the theory of size spectra (i.e., the relationship between size and organism abundance as it drives ecosystem properties such as food webs) provides a valuable framework for forecasting climate change impacts on marine ecosystems. A deeper understanding of the scope and nature of variability in size spectra under contrasting environmental conditions is needed. The dynamic, highly productive northern California Current off Oregon and Washington, during the summer and winter seasons, produces a patchwork of oceanographic conditions including those associated with hypoxia and ocean acidification. This study is sampling the plankton communities in this region to investigate how gradients of temperature, nutrients, dissolved oxygen, and pH conditions impact size spectra. The broader impacts include the training of students, building scientific resources, and outreach to broader communities. Undergraduate and graduate students are being trained in oceanography, field research and new technologies. The automated image analysis pipeline developed as part of the project is openly accessible to the oceanographic community and the image data are available through the novel Global Plankton Imagery Library, an open-access repository for plankton imagery. Size spectra data from this study are shared directly with ecosystem modelers. The project’s flagship outreach activity is the collaboration with the Sitka Center for Art and Ecology and the hosting of an Artist-At-Sea Program. A professional artist is competitively selected to join the research cruises and to create artistic products that give a unique voice to oceanographic research and the organisms under study. The artwork is being assembled into a traveling public Art Exhibit with planned displays at the Sitka Center, Oregon State University’s Hatfield Marine Science Center, University of Oregon’s Charleston Marine Life Center and centers located in underserved coastal communities. Finally, imagery data from the project are being shared via the Plankton Portal, a public website developed in partnership with the Citizen Science Alliance’s Zooniverse, that invites citizen scientists to participate in classifying plankton images.The coupling of in situ plankton imagery and morphometric data allows quantifying scales of variation in plankton size spectra as well as testing predictions of how changes in environmental conditions (notably, temperature, nutrients, oxygen, pH) correlate with shifts in size spectra to reveal functional consequences to the food web. Plankton size spectra are being compared across environmental conditions by sampling in a habitat with steep environmental gradients and during two contrasting seasons. Planktonic organisms spanning 10 orders of magnitude in biomass are sampled using two complementary high-resolution imaging systems: the In Situ Ichthyoplankton Imaging System (ISIIS) and the Laser In-Situ Scattering and Transmissometry (LISST) particle imager. High-throughput image analysis software is used to create size distributions together with taxonomic classification. Depth-discrete meso-zooplankton samples are collected in parallel to examine community shifts in carbon, obtain length-to-carbon conversions and calibrate image data. The normalized biomass size spectra computed from the image data are tested for deviations from expected patterns. The plankton collections are also being analyzed for diet and reproductive status of gelatinous zooplankton, and diet and daily growth rate of representative larval fishes. These two groups have been historically understudied yet play central roles in ecosystem function. The data are being used to examine how these organisms are impacted by environmental conditions, and how they affect plankton size spectra. This study is foundational to the understanding of marine ecosystems within the context of climate change.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.