| Abstract: |
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 (Ilisagvik) 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.
|
