Biogeochemical Dynamics of a Glaciated High‐Latitude Wetland

• Published in: Journal of geophysical research. Biogeosciences 2022-06, Vol.127 (6), p.n/a
• Main Authors: Buser‐Young, Jessica Z., Peck, Erin K., Chace, Peter, Lapham, Laura L., Vizza, Carmella, Colwell, Frederick S.
• Format: Article
• Language: English
• Subjects: Accumulation; Aquatic ecosystems; Biodiversity; Biogeochemistry; Carbon; carbon burial; Carbon cycle; Climate change; Cold regions; Copper; Deglaciation; Deltas; Ecological function; Ecosystems; Gases; Gene sequencing; glacial outwash; Glaciers; Greenhouse effect; Greenhouse gases; Ice cover; Identification; Iron; Latitude; Manganese; Meltwater; Metabolism; methane; Microbial activity; Microbiomes; Microorganisms; Minerals; Northern Hemisphere; Organic matter; Outwash; Ponds; Rivers; rRNA 16S; Sediment; sediment microbiome; Sediment samples; Sediments; Water analysis; Water sampling; Watersheds; Wetlands
• ISSN: 2169-8953; 2169-8961
• DOI: 10.1029/2021JG006584

High‐latitude, coastal wetland biogeochemistry is dynamic in response to climate change, and yet we do not understand, and thus cannot fully predict, how crucial aspects of these systems will change in the future. Temperatures in the Northern Hemisphere have disproportionately increased 4°C in 30 years causing the rate of deglaciation to increase significantly in global high‐latitude river deltas. This will have a prolonged effect on local microbiome metabolism and biodiversity of the subsurface, influencing solid, liquid, and gaseous compounds in the system. Using sediment geochemical analyses, autonomous sampling techniques, and 16S rRNA gene sequencing, we have identified key processes that occur in the Copper River Delta, AK, a model system to study high‐latitude watersheds during rapid climate change. We calculated carbon accumulation rates upwards of 520 ± 60 g C m−2 yr−1 in outwash pond sediments nearest to the glaciers, which co‐occurred with pronounced suboxic peaks in Fe (III) and Mn (II). Sediment microbial communities across the outwash ponds are structured on the basis of total iron and manganese concentrations, proximity to glaciers, and organic matter content. Additionally, we revealed no methane accumulation in the ponds during ice‐cover, despite high organic matter content. High‐latitude wetland ecosystems are not only influenced by the changing climate, but also have the potential to impact carbon cycling considering high carbon burial rates. These findings show the importance of understanding changing biogeochemical processes in high‐latitude wetlands, as they have the potential to influence carbon cycling. Plain Language Summary Climate change is reshaping how ecosystems function. Average temperatures are rising most rapidly near Earth's poles, causing these cold regions to lose snow and ice. Water from melting glaciers carries minerals to wetlands where the activities of naturally occurring microorganisms may be altered. Our study focused on describing microbial communities and the chemistry in ponds on the Copper River Delta in Alaska, a glacially influenced coastal wetland, along a gradient between the glaciers and ocean. We sampled water and sediments from wetland ponds over several years and identified that ponds near the glaciers bury carbon in sediments faster than other recorded coastal wetlands. Our findings suggest that iron minerals from the glaciers and the microbes in the system may be associated with this carbon burial and