| 英文摘要: | This project will establish a new Long Term Ecological Research (LTER) site along the Alaskan Arctic coastline. Research based out of Utqiagvik (formerly Barrow), Deadhorse, and Kaktovik will address how changes in shoreline erosion and freshwater inflows to the coastal ocean over seasonal, annual, and longer timeframes influence near-shore food webs. Research will be conducted in collaboration with local stakeholder groups and the U.S. Fish and Wildlife Service. This research will advance our fundamental understanding of how input of materials from land and oceanographic conditions interact to influence coastal food webs. It will also allow us to track and understand: 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. Near-shore food webs along the Alaskan Arctic coastline support large populations of migratory fish and waterfowl that are essential to the culture of Iñupiat communities of northern Alaska. The research at this LTER site will create a framework for anticipating the impacts of future changes on the coastal ecosystem that are of great concern to these communities. Results from this LTER program will also be of interest to a broader science community that is working to understand potential connections between Arctic change and global carbon cycling. Finally, this LTER project includes a strong commitment to education through graduate and undergraduate student involvement, post-doctoral mentoring, continuation of a very successful Summer Science K-12 Program in Kaktovik, and establishment of a parallel K-12 program in Utqiagvik. In addition, this project will employ native high school seniors or recently graduated students living in Utqiagvik and Kaktovik as field research assistants.
Recent studies suggest that the ecological framework for understanding what controls food web structure needs to be expanded to include temporal forcing. More specifically, there is mounting evidence that differential availability of seasonally-distinct resources is critical for defining trophic linkages and maintaining stability and resilience of food webs. This new LTER program will use lagoons along the Alaskan Beaufort Sea coast as experimental units to test this concept, and broaden it to include temporal variations over longer timeframes. The Beaufort lagoons are ideal for testing this concept 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 on coastal geomorphology 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. Specific study sites will be located in Elson Lagoon (western Beaufort), Simpson Lagoon and Stefansson Sound (central Beaufort), and Kaktovik and Jago lagoons (eastern Beaufort). The LTER will include seasonal field work during ice covered, ice break-up, and open water periods and also include sensor deployments for continuous measurements of key biogeochemical and hydrographic parameters. |