LTER: NGA Phase II - Resilience and Connectivity Across Transitions in the Northern Gulf of Alaska Ecosystem

阿拉斯加州北部海湾(NGA)是一个高生产力的亚北极海洋生态系统，不同的沿海社区数百年来一直依赖它。今天，NGA生态系统继续在食物、文化和经济方面支持国家渔业、当地沿海社区和部落政府。NGA长期生态研究(LTER)网站旨在了解这种动态的生态系统。NGA LTER的总体概念框架是，强烈的环境变异性--无论是在时间上还是在空间上--通过物种适应和群落组织产生了一个具有高度弹性的生态系统。基于对Seward Line沿线25年的多学科观察和NGA LTER第一阶段的发现，第二阶段正在提高对该生物群的关键生物体、生态过程和对气候变化的反应的机械理解。第二阶段继续教育各级学生，并与当地社区接触，以了解他们对这一生态系统的问题和关切。不同的机构和组织与NGA LTER合作并利用它们，展示了这个LTER站点的重要性和为阿拉斯加湾地区收集的数据。基于第一阶段的长期数据集和发现，阿拉斯加州北部海湾LTER第二阶段的研究有三个主要目标。首先，研究人员正在继续收集和分析长期生态系统数据，以了解物种丰度和连通性，以及它们与事件规模和长期变化的关系。其次，该团队正在探索生物体的功能冗余，以此作为生态系统弹性的基础。尽管物种丰富度不高，但在整个食物网中，NGA拥有大量具有类似营养作用的“冗余”分类群；研究人员提出，这些分类群具有不同但互补的营养策略、生活史和生命周期计时，有助于功能冗余。冗余稳定较高营养水平的可变性，从而赋予系统复原力(即维持或恢复关键的生态系统特性以应对干扰)，而冗余在多大程度上稳定食物网在中上层海洋生态系统中尚未得到很好的探索。第三，该团队正在研究自然锋(即不同水团之间的过渡)和相关生态带(即生物群落结构的过渡)在NGA中的生态作用。NGA正在利用新技术，这些技术可以克服在生物相关的空间和时间尺度上研究前沿及其组成社区的历史局限性。研究人员假设，前锋对关键生态系统属性(例如，生产、出口、生物多样性)产生不成比例的影响，因此与整个生态系统的复原力有关。此外，前线可能会受到事件规模和长期环境变化的影响。这三个主题下的观察和实验与建模活动相结合，以了解在锋面转变时发生的相关物理和生物关系。这些特定于生物群的配方正在探索基于对NGA预测的气候情景的历史、当前和未来的生态状态。与其他LTER站点的合作进一步加强了对生态理论的理解。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。

The Northern Gulf of Alaska (NGA) is a highly productive subarctic marine ecosystem, and diverse coastal communities have relied upon it for hundreds and thousands of years. Today, the NGA ecosystem continues to support national fisheries, local coastal communities, and Tribal governments in terms of food, culture, and economy. The NGA Long Term Ecological Research (LTER) site aims to understand this dynamic ecosystem. The NGA LTER overarching conceptual framework is that intense environmental variability – both temporally and spatially – has yielded a highly resilient ecosystem through species adaptation and community organization. Building off 25 years of multidisciplinary observations along the Seward Line and findings from Phase I of the NGA LTER, Phase II is improving mechanistic understanding of this biome’s key organisms, ecological processes, and responses to climate change. Phase II continues to educate students at all levels and to engage with local communities to understand the questions and concerns that they have regarding this ecosystem. Various agencies and organizations partner with and leverage the NGA LTER, demonstrating the importance of this LTER site and the data collected for the Gulf of Alaska region.Building on long-term data sets and findings from Phase-I, Northern Gulf of Alaska LTER Phase-II research has three primary goals. First, the investigators are continuing collection and analysis of long-term ecosystem data to understand species abundance and connectivity, as well as their relationships to event-scale and long-term change. Second, the team is exploring functional redundancy of organisms as an underpinning of ecosystem resilience. Despite modest species richness, the NGA hosts numerous instances of “redundant” taxa with comparable trophic roles throughout the food web; the investigators propose that these taxa, with differing but complimentary nutritional strategies, life histories, and life-cycle timing, contribute to functional redundancy. Redundancy stabilizes variability at higher trophic levels, thereby conferring resilience to the system (i.e., maintenance or recovery of key ecosystem properties in response to disturbance), and the degree to which redundancy stabilizes food webs has not been well explored in pelagic marine ecosystems. Third, the team is investigating the ecological role of physical fronts (i.e., transitions between different water masses) and associated ecotones (i.e., transitions in biological community structure) in the NGA. NGA is making use of new technologies that can overcome historical limitations to the study of fronts and their constituent communities at biologically relevant spatial and temporal scales. The investigators hypothesize that fronts exert a disproportionate influence on key ecosystem properties (e.g., production, export, biological diversity) and are thus related to whole-ecosystem resilience. In addition, fronts are likely to be influenced by both event-scale and long-term environmental change. The observations and experimentation under each of these three themes are coupled to modeling activities to understand relevant physical and biological relationships that occur at frontal transitions. These biome-specific formulations are exploring historical, current, and future ecological states based on climate scenarios predicted for the NGA. Collaboration with other LTER sites is further enhancing understanding of ecological theory.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.