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

该项目是博弗特泻湖生态系统长期生态研究（BLE LTER）计划的延续。BLE LTER于2017年被添加到NSF的LTER站点网络中，目前的工作代表了这项长期努力的第二阶段。该项目侧重于阿拉斯加最北端海岸线近岸生态系统的物理、化学和生物特性之间的相互作用。这项研究解决了一些基本问题，包括是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。该项目还研究了气候变化对北极陆海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地区的土著居民很重要的生产和生物复杂的生物群组合。这些组合本身受到物理和化学条件的极端季节性变化的影响，但在迅速变暖的北极，季节性变化以及其他气候变化影响正日益挑战这些组合。乌特恰维克（以前的巴罗）、死马和阿拉斯加卡克托维克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、年度和更长的时间框架内的变化如何影响近岸食物网，从细菌到顶级捕食者。这包括考虑居住在阿拉斯加波弗特海岸的阿拉斯加原住民的生活中扮演重要文化和生存角色的常驻和溯河鱼类和候鸟。虽然该项目关于食物网的工作包括当地社区特别感兴趣的部分，但关注温室气体排放的部分具有更广泛的社会相关性。随着不断变暖的北极永久冻土（永久冻土）的融化，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导致全球变暖。研究活动是与当地和更广泛的利益相关者团体合作进行的。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，继续在卡克托维克流行的校园活动，并在乌特基亚维克建立新的K-12和社区学院（Iḷisaġvik）项目。生态学研究表明，时间强迫对我们理解控制食物网结构的因素至关重要。更具体地说，越来越多的证据表明，不同季节资源的不同可用性对于确定营养联系和维持食物网的稳定性和复原力尤为重要。BLE LTER利用阿拉斯加波弗特海岸的泻湖作为实验单元来探索这一概念。北极泻湖是一个很好的试验平台，因为它们经历了季节周期的极端变化，现在受到气候变化驱动的快速方向变化的影响。我们的首要问题是：陆地输入、当地生产以及泻湖和海水之间在季节、年际、年代际和更长的时间框架内的交换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相互作用来控制食物网结构？在缺乏边缘湿地的情况下，北极泻湖为研究这些相互作用提供了一个独特的机会，而边缘湿地通常会调节其他泻湖系统中的陆地-海洋相互作用。此外，堰洲岛地貌对泻湖和公海之间的水交换有很强的控制作用，在北极是高度动态的，因为海冰的影响叠加在洋流、海平面和波浪的影响上。因此，陆地和泻湖生态系统输入之间的联系更为直接，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。该项目的研究地点是埃尔森泻湖（波弗特西部），辛普森泻湖和斯蒂芬森海湾（波弗特中部），以及卡克托维克和贾古泻湖（波弗特东部）。BLE LTER团队在冰覆盖、冰破裂和开放水域期间进行季节性野外工作，并部署传感器，对关键的生物地球化学和水文参数进行连续的长期测量。该项目还包括流域和泻湖生态系统建模组件。在努力推进对基本生态学原理的理解的同时，该项目为跟踪和理解1)自然气候循环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、降水制度转移和海冰损失）如何改变沿海生态系统提供了急需的机制。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。

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.