Arctic | Lower Trophic Levels UNDERGRADUATE POSTER PRESENTATION Spatial variability in sediment characteristics and benthic respiration in an Arctic lagoon Presenter: Sarah Gianturco , srgianturco@wm.edu Amber Hardison , akhardison@vims.edu, Virginia Institute of Marine Science Brian Kim , bskim@vims.edu, Virginia Institute of Marine Science Arctic coastal environments are recognized as one of the most vulnerable ecosystems on Earth in response to global warming and represent an interface between marine, cryospheric, terrestrial, and atmospheric systems. Arctic-wide average surface temperatures have increased at four times the rate of global mean temperatures, resulting in increasing freshwater inflow, permafrost thaw, coastal erosion, and decreasing ice cover, which correspond to increased organic matter inputs to coastal systems. Along the gradient from land to sea, coastal lagoons act as an intermediary bioreactor that processes terrestrial inputs and lagoon production before export to the ocean. Within the lagoons, sediments play a key role in carbon cycling as the site of aerobic and anaerobic oxidation of organic matter. To better understand the role of coastal lagoons in Arctic carbon export, we analyzed sediment characteristics and measured sediment respiration at 10 stations in Elson Lagoon, Alaska. Samples were collected as part of the Beaufort Lagoon Ecosystem Long Term Ecological Research program and included 6 shallow (< 1m) nearshore stations and 4 deep (> 2m) mid-lagoon stations. At each station, a sediment core was sectioned (0-2, 2-5, 5-10 cm) and analyzed for grain size, porosity, and organic matter content. Another sediment core was used to measure benthic respiration rates by analyzing oxygen profiles from a Unisense microelectrode. Preliminary data shows sand-based sediments at shallow stations and primarily silt and clay at mid-lagoon stations. These differences in sediment characteristics likely drive different rates and processes of organic matter oxidation.
Alaska Marine Science Symposium 2023 147
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