Synopsis of proposal:
High latitude continental shelves exhibit some of the highest levels of primary productivity, fisheries production, and benthic faunal abundances found in the world.s oceans. These observations are tightly linked to pronounced seasonality in solar radiation, sea-ice dynamics, and unusually tight benthic-pelagic coupling. Recent climate models predict that global climate change will be more pronounced in Arctic regions, suggesting that ecosystems shaped in large part by seasonality in ice cover may function differently under warmer temperature regimes. Continental shelf benthos in polar regions derive nutrition from two main sources: phytoplankton and ice algae, each displaying distinct seasonal maxima. The amount of phytodetritus from the euphotic zone reaching the sea floor, and the benthic response to that organic flux, is dependent on primary productivity regime, timing of pulsed deposition, and algal source. Sediment communities in the Arctic can rapidly cycle newly-deposited phytoplankton; and there is some evidence that they also quickly process ice algae. How this remineralization is partitioned among different components of the benthic community (from bacteria to mobile megafauna) has been suggested to vary depending upon whether the system is oligotrophic or more mes-/eu- trophic. To understand the role of the benthos in biogeochemical cycling in the Arctic, therefore, it is important to: determine how variability in phytodetrital flux to the sea floor at two Arctic sites affects the distribution of labile food in the sediments, and how different size classes of benthic fauna respond to food supply. Most of the studies addressing these questions have been performed over a small fraction of the annual cycle, usually well into the summer season. This study is the first to investigate these processes over the entire annual cycle at sites different in purported productivity levels. This study will take advantage of a unique opportunity. There are currently several international research programs studying carbon cycling in the Arctic. The Canadian Arctic Shelf Exchange Study (CASES) and the Norwegian/EU-funded CABANERA (CArbon flux and ecosystem feedback in the northern BAreNts Sea in an ERA of Climate Change) project have agreed to provide berth space for this project during the 4 (CASES) and 3 (CABANERA) seasons of the respective studies. In the oligotrophic Beaufort Sea (CASES) and the mesotrophic Barents Sea (CABANERA), surface sediments will be sampled to determine the spatial and temporal variability in phytodetrital input to the benthos. HPLC analysis of sediment pigments will help determine the sources of the algal detrititus. Oxygen consumption by different components of the benthic community will be determined by whole-core incubations, microvial incubations (for meio- and micro- biota), and whole organism incubations (for epibenthic megafauna). Densities of epifaunal species will be determined using a drop-camera; and these estimates will help determine the importance of this component of the benthos to total sediment-community oxygen consumption. The value of collaborating with multiple researchers studying the same general questions from different perspectives cannot be overestimated. For example, colleagues on both cruises will be describing benthic community structure, suboxic and anaerobic respiration pathways in the sediments, and carbon flux values. Additionally, data on atmospheric, ice, and water column processes will be available under the multidisciplinary organization of these projects. One component of this project will provide a broader impact, beyond the scientific value of the research to be conducted. Arctic research itself is intriguing, and carries with it a sense of mystery. Research cruises present opportunities to demonstrate elements that are prominent in national and state science standards: the scientific method, and the integration of science and technology and its societal applications. In collaboration with a Sea Grant Education Specialist, a CD-ROM will be produced for K-12 educators that will contain photographs; data; graphs; supplemental information about scientific topics, fauna, and geography; and interviews with scientists, crew, and students. This CD-ROM will be distributed to teachers to help them update existing or create new lesson plans in a variety of disciplines.