LTER: Seasonal Controls and Emergent Effects of Changing Land-ice-ocean Interactions on Arctic Coastal Ecosystems (BLE II)

该项目延续了波弗特泻湖生态系统长期生态研究(BLE LTER)计划。BLE LTER于2017年加入NSF的LTER站点网络，目前的工作是这项长期努力的第二阶段。该项目的重点是阿拉斯加最北部海岸线上近岸生态系统的物理、化学和生物特性之间的相互作用。这项研究解决了关于什么控制和维持北极沿海水域的食物网，以及气候变化如何改变这些食物网的基本问题。该项目还研究了气候变化对北极陆地-海洋界面附近温室气体排放的影响。波弗特海沿岸的河口支持着对阿拉斯加北极土著居民很重要的生物群的生产性和生物复杂性组合。这些组合本身就受到物理和化学条件的极端季节性变化的影响，但越来越多地受到季节性变化以及快速变暖的北极的其他气候变化影响的挑战。在阿拉斯加的乌特恰格维克(前巴罗)、死马和卡托维克进行的研究正在研究海岸线侵蚀、淡水流入、冰盖和海洋环流在季节性、年度和更长时间范围内的变化如何影响近岸的食物网，从细菌到顶级捕食者。这包括考虑在阿拉斯加波弗特海沿岸的阿拉斯加原住民的生活中发挥重要文化和生存作用的栖息和沿河鱼类和候鸟。虽然该项目在食物网方面的工作包括当地社区特别感兴趣的组成部分，但侧重于温室气体排放的组成部分具有更广泛的社会意义。随着北极变暖的永久冻土(常年冻土)融化，从陆地到海洋的有机碳输入正在增加，该项目正在研究这些输入的温室气体的分解和相关释放如何可能导致全球变暖。研究活动是与当地和更广泛的利益攸关方团体合作进行的。该项目还大力致力于教育，包括研究生和本科生培训，博士后指导，继续在卡克托维克开展受欢迎的校园活动，以及在乌特恰格维克建立新的K-12和社区大学(IḷIsaġVIK)方案。生态学研究表明，时间强迫对于我们理解控制食物网络结构的因素至关重要。更具体地说，越来越多的证据表明，季节性不同资源的不同可获得性对于确定营养联系和维持食物网的稳定性和弹性特别重要。BLE LTER正在使用阿拉斯加博福特海岸的泻湖作为实验单位来探索这一概念。北冰洋泻湖是很好的试验台，因为它们经历了季节周期的极端变化，而季节周期现在受到气候变化驱动的快速方向性变化的影响。我们的首要问题是：在季节性、年际、年代际和更长的时间范围内，泻湖和海水之间陆地输入、当地生产和交换的变化如何通过对碳和氮循环、微生物和后生动物群落组成以及营养联系的影响来相互作用来控制食物网络结构？在没有边缘湿地的情况下，北冰洋泻湖提供了一个研究这些相互作用的独特机会，而边缘湿地往往调节着其他泻湖系统中的陆地-海洋相互作用。此外，堰塞岛地貌对泻湖和开阔海洋之间的水交换具有很强的控制作用，在北极是高度动态的，因为海冰效应叠加在海流、海平面和海浪的影响上。因此，陆地和泻湖生态系统之间的输入之间的联系更加直接，泻湖和开阔海洋之间的水交换比典型的低纬度系统更加多变。该项目的研究地点在埃尔森泻湖(博福特西部)、辛普森泻湖和斯蒂芬森海湾(博福特中部)，以及卡克托维克和贾戈泻湖(博福特东部)。BLE LTER团队在覆冰、破冰和开阔水域期间进行季节性野外工作，并部署传感器，连续长期测量关键的生物地球化学和水文参数。该项目还包括流域和泻湖生态系统建模组成部分。在努力促进对基本生态原理的理解的同时，该项目提供了一个急需的机制，用于跟踪和了解1)自然气候周期如何影响北极沿海生态系统，以及2)气候变化影响，如永久冻土融化、降水制度变化和海冰消失如何改变沿海生态系统。该奖项反映了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。

This project continues the Beaufort Lagoon Ecosystems Long Term Ecological Research (BLE LTER) program. The BLE LTER was added to NSF’s network of LTER sites in 2017 and current work represents the second phase of this long-term effort. The project focuses on interactions between physical, chemical, and biological properties of nearshore ecosystems along Alaska’s northern-most coastline. The study addresses fundamental questions about what controls and sustains food webs in Arctic coastal waters and how climate change is altering these food webs. The project also examines the effects of climate change on greenhouse gas emissions near the Arctic land-sea interface. Estuaries along the Beaufort Sea coast support productive and biologically complex assemblages of biota that are important to the Indigenous residents of the Alaskan Arctic. These assemblages are inherently shaped by extreme seasonal variations in physical and chemical conditions yet are increasingly challenged by shifts in seasonality as well as other climate change impacts in the rapidly warming Arctic. Studies based out of Utqiagvik (formerly Barrow), Deadhorse, and Kaktovik, Alaska, are addressing how changes in shoreline erosion, freshwater inflows, ice cover, and ocean circulation over seasonal, annual, and longer timeframes influence near-shore food webs, from bacteria to top predators. This includes consideration of resident and anadromous fishes and migratory birds that serve important cultural and subsistence roles in the lives of Alaska Natives that live along the Alaskan Beaufort Sea coast. While the project’s work on food webs includes components that are of particular interest to local communities, components focusing on greenhouse gas emissions have broader societal relevance. Inputs of organic carbon from land to sea are increasing as permafrost (perennially frozen ground) thaws in the warming Arctic, and this project is studying how decomposition and associated release of greenhouse gasses from these inputs may contribute to global warming. Research activities are conducted in collaboration with local and broader stakeholder groups. This project is also strongly committed to education, including graduate and undergraduate student training, post-doctoral mentoring, continuation of popular schoolyard activities in Kaktovik, and establishment of new K-12 and community college (Iḷisaġvik) programs in Utqiagvik. Ecological studies suggest that temporal forcing is critical to our understanding of what controls food web structure. More specifically, there is mounting evidence that the differential availability of seasonally-distinct resources is particularly important for defining trophic linkages and maintaining stability and resilience of food webs. The BLE LTER is using lagoons along the Alaskan Beaufort Sea coast as experimental units to explore this concept. Arctic lagoons serve as excellent test beds because they experience extreme variability in seasonal cycles, which are now subject to rapid directional shifts driven by climate change. Our overarching question is: How do variations in terrestrial inputs, local production, and exchange between lagoon and ocean waters over seasonal, inter-annual, inter-decadal, and longer timeframes interact to control food web structure through effects on carbon and nitrogen cycling, microbial and metazoan community composition, and trophic linkages? Arctic lagoons provide a unique opportunity to study these interactions in the absence of fringing wetlands that often modulate land-ocean interactions in other lagoon systems. In addition, barrier island geomorphology, which exerts a strong control on water exchange between lagoons and the open ocean, is highly dynamic in the Arctic because sea-ice effects are superimposed on the effects of currents, sea level, and waves. Thus, connections between inputs from land and lagoon ecosystems are more direct, and water exchanges between lagoons and the open ocean are more variable than is typical of lower latitude systems. The project’s study sites are in Elson Lagoon (western Beaufort), Simpson Lagoon and Stefansson Sound (central Beaufort), and Kaktovik and Jago lagoons (eastern Beaufort). The BLE LTER team conducts seasonal field work during ice covered, ice break-up, and open water periods and deploys sensors for continuous long-term measurements of key biogeochemical and hydrographic parameters. The project also includes watershed and lagoon ecosystem modeling components. While working to advance understanding of fundamental ecological principles, this project provides a much-needed mechanism for tracking and understanding 1) how natural climate cycles influence coastal ecosystems in the Arctic, and 2) how climate change effects such as permafrost thaw, shifting precipitation regimes, and losses of sea ice alter coastal ecosystems.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.