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，这些食物网支持着宝贵的渔业。这个高度多样化和复杂的群落由随洋流漂移的有机体组成。浮游生物的研究仍然不足：它们的大小从不到一微米到几米，跨度超过六个数量级，很难对它们进行采样。然而，了解这些社区如何应对气候变化，以及最终这些应对措施如何影响宝贵的渔业，从而影响粮食安全，是至关重要的。由于许多生态和生理过程是由相对大小决定的，大小谱理论(即大小与生物丰度之间的关系)为预测气候变化对海洋生态系统的影响提供了一个有价值的框架。需要更深入地了解在不同环境条件下粒度谱变化的范围和性质。在夏季和冬季，俄勒冈州和华盛顿州附近的动态、高生产力的加利福尼亚州北部洋流产生了各种海洋条件，包括与缺氧和海洋酸化有关的条件。这项研究正在对该地区的浮游生物群落进行采样，以调查温度、营养物质、溶解氧和pH条件的梯度如何影响大小光谱。更广泛的影响包括对学生的培训、建立科学资源以及向更广泛的社区推广。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对海洋学界开放，图像数据可通过新型全球浮游生物图像图书馆获得，这是一个开放获取浮游生物图像的储存库。这项研究的尺寸谱数据直接与生态系统建模人员共享。该项目的旗舰推广活动是与锡特卡艺术和生态中心的合作，并主办了一个海上艺术家项目。一位专业艺术家被竞争性地挑选加入研究巡航，并创作出给海洋研究和正在研究的生物以独特声音的艺术产品。这些艺术品正在被组装成一个巡回公共艺术展，计划在西特卡中心、俄勒冈州立大学哈特菲尔德海洋科学中心、俄勒冈大学查尔斯顿海洋生物中心以及服务不足的沿海社区的中心展出。最后，该项目的图像数据将通过浮游生物门户网站共享，这是一个与公民科学联盟的Zooniverse合作开发的公共网站，邀请公民科学家参与浮游生物图像的分类。浮游生物图像和形态测量数据的结合使浮游生物大小光谱的变化尺度得以量化，并测试环境条件(尤其是温度、营养物质、氧气、pH)的变化如何与大小光谱的变化相关联的预测，以揭示食物链的功能后果。通过在具有陡峭环境梯度的栖息地和在两个不同的季节采样，比较了不同环境条件下的浮游生物大小光谱。使用两个互补的高分辨率成像系统对生物量超过10个数量级的浮游生物进行采样：原位浮游鱼类成像系统(ISIIS)和激光原位散射和透射仪(LISST)粒子成像仪。高通量图像分析软件用于创建大小分布和分类分类。并行收集深度离散的中游动物样本，以检查碳的群落变化，获得长度到碳的转化，并校准图像数据。根据图像数据计算的归一化生物量尺寸谱被测试与预期模式的偏差。还分析了浮游生物采集的胶状浮游动物的食物和繁殖状况，以及典型幼鱼的食物和每日生长率。这两个群体在历史上一直没有得到充分的研究，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光谱。这项研究是在气候变化背景下理解海洋生态系统的基础。这一奖项反映了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。

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.