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Rates and drivers of benthic respiration in an Arctic coastal lagoon
Gianturco, Sarah
Gianturco, Sarah
Abstract
Arctic-wide average temperatures have increased at four times the global rate, resulting in increasing freshwater flow, permafrost thaw, coastal erosion, and decreasing ice cover, which correspond to increased organic matter (OM) inputs to coastal systems. Coastal lagoons are located along the gradient from land to sea and they 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 respiration of OM. To better understand the role of coastal lagoons in Arctic carbon export, I analyzed sediment characteristics and respiration at 10 stations in Elson Lagoon, Alaska in August 2022. Samples were collected as part of the Beaufort Lagoon Ecosystem Long Term Ecological Research program, including 6 shallow (less than 1m) and 4 deep (greater than 2m) stations. At each station, 1 sediment core was sectioned by depth to analyze for grain size (GS), porosity, and OM content. A second sediment core was used to measure benthic respiration rates by analyzing oxygen microprofiles. In Elson Lagoon, respiration was directly related to each of the sediment characteristics measured. Spatial variability was observed between shallow (20 ± 3 μmol O2 m-2 h-1) and deep (59 ± 11 μmol O2 m-2 h-1) stations in respiration rate which aligned with my observation that deep stations were characterized by a lower average GS (662 ± 10 μm), and higher porosity (50 ± 3%) and OM (8.6 ± 0.2%) compared to shallow station GS (123 ± 20 μm), porosity (23 ± 2%), and OM (3.4 ± 0.5%). Understanding drivers of respiration in Elson Lagoon is important to understand how the ecosystem is functioning, especially with the changing Arctic environment.
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2023-01-01
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Geology