LTER: Scales of Variability in Ecosystem Dynamics and Production on the Changing Northeast U.S. Shelf (NES II)

美国东北大陆架（NES）是西北大西洋的区域，覆盖在从北卡罗来纳州到缅因州的大陆架上。NES有着人类强烈利用的悠久历史，并提供一系列生态系统服务，包括航运、娱乐、保护和能源开发。NES还包括季节性动态和生产性生态系统，支持着著名的渔业，其完整性对美国东北部经济的健康至关重要。NES生态系统的生产力是由浮游生物推动的，浮游生物在复杂的食物网中相互作用，其结构取决于环境条件（如温度、光照和营养水平）。由于气候变化相关的变暖和人类的利用，这些条件正在迅速改变。例如，NES是迄今为止美国最大的沿海风力发电场开发项目。美国东北大陆架长期生态研究计划（nes - ltii）的第二阶段提高了我们预测人为影响将如何影响大陆架浮游生物食物网的动态及其支持更高营养水平（从鱼类到鲸鱼和人类）生产力的能力的能力。由于国家海洋学面临将影响许多人的长期挑战，该项目强调积极的教育组成部分，以帮助培训下一代海洋科学家，并开展外展活动，以增加公众对海洋科学和技术的了解。项目团队通过三个主要部分开展教育和外展工作：(1)对LTER研究的早期职业研究人员进行培训和指导；(2)由初高中教师和学生参与的LTER校园计划；(3)通过有针对性的活动、项目网站和社交媒体渠道进行公众宣传。NES已经记录了不同季节到几十年的生态系统变化模式，但对物理环境、浮游食物网和更高营养水平变化之间的关键机制仍然知之甚少。因此，预测能力是有限的，管理策略很大程度上是被动的。为了满足这些需求，NES II的目标是对食物网结构和功能如何响应环境条件、自然变异性和人类引起的变化的机制理解。NES II结合了提供区域尺度背景的观测，沿高梯度跨大陆架样带的过程巡航，大陆架内部位置的高频时间序列，耦合生物-物理食物网模型和目标种群模型。此外，研究小组正在调查社区结构和营养转移如何受到干扰的影响，这些干扰包括：(1)热浪日益普遍，(2)与墨西哥湾流日益不稳定有关的近海水入侵，以及(3)目前正在NES上建设的海上风力发电场。长期研究计划以首要的科学问题为指导：“气候变化如何影响远洋NES生态系统，特别是如何影响组成（如物种多样性和大小结构）和总体（如初级生产力和向更高营养水平转移的能量）变异性之间的关系？”研究人员正在评估NES生态系统拥有的生物多样性储存库的程度，该储存库对环境的急剧变化具有弹性，并将使生态系统保持总体生产力。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

The Northeast U.S. Shelf (NES) is the region of the Northwest Atlantic Ocean that overlies the continental shelf from North Carolina to Maine. The NES has a long history of intense human utilization and provides an array of ecosystem services including shipping, recreation, conservation, and energy development. The NES also comprises a seasonally dynamic and productive ecosystem, supporting renowned fisheries, whose integrity is critical to the health of the Northeast U.S. economy. The NES ecosystem’s productivity is fueled by planktonic organisms that interact with each other in complex food webs whose structure depends on environmental conditions (e.g., temperature, light, and nutrient levels). These conditions are rapidly changing because of climate-change-related warming and human utilization. For example, the NES is seeing the largest development of coastal wind farms in the U.S. to date. Phase II of the Northeast U.S. Shelf Long-Term Ecological Research program (NES-LTER II) advances our ability to predict how anthropogenic impacts will affect the dynamics of the shelf’s planktonic food webs and their ability to support the productivity of higher trophic levels, from fish to whales and humans. Because the NES is subject to long-term challenges that will impact many people, the project emphasizes an active education component for helping to train the next generation of marine scientists and outreach activities to increase public understanding of marine science and technology. The project team conducts education and outreach via three main components: (1) training and mentoring for early career researchers from undergraduates to postdoctoral researchers in LTER research; (2) an LTER Schoolyard program that engages middle and high school teachers and students; and (3) public outreach through targeted events, the project website, and social media channels.Patterns of ecosystem change over seasons to decades have been documented in the NES, but the key mechanisms linking changes in the physical environment, planktonic food webs, and higher trophic levels remain poorly understood. As a result, predictive capability is limited and management strategies are largely reactive. To address these needs, NES II is targeting a mechanistic understanding of how food web structure and function responds to environmental conditions, natural variability and human induced changes. NES II combines observations that provide regional-scale context, process cruises along a high gradient cross-shelf transect, high-frequency time series at an inner-shelf location, coupled biological-physical food web models, and targeted population models. In addition, the research team is investigating how community structure and trophic transfer are impacted by disturbances including (i) the increasing prevalence of heat waves, (ii) intrusions of offshore water associated with increasing instability in the Gulf Stream, and (iii) offshore wind farms now under construction on the NES. The long-term research plan is guided by the overarching science question: “How is climate change impacting the pelagic NES ecosystem and, in particular, affecting the relationship between compositional (e.g., species diversity and size structure) and aggregate (e.g., rates of primary production, and transfer of energy to higher trophic levels) variability?” The investigators are assessing the extent to which the NES ecosystem possesses a biodiversity reservoir that is resilient to dramatic changes in the environment and that will allow the ecosystem to maintain overall productivity.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.