Tectonics and climate are shaping an Alaskan ecosystem

October 16, 2025

Tectonics and climate are shaping an Alaskan ecosystem

by Nathaniel Scharping,

edited by , reviewed by

Tectonics and climate are shaping an Alaskan ecosystem — (a) Aerial view of the Copper River Delta, south central Alaska, depicting the six sampling locations and their abbreviations. Wetland ponds imaged with a yellow point represent areas of 1.8聽m uplift, while wetland ponds imaged with a red point represent areas of 3.4聽m uplift during the 1964 megathrust earthquake. Glacial outlines (blue polygons) are derived from the Randolph Glacier Inventory version 7.0. The inset image gives global orientation of the Copper River Delta where green shaded regions represent subsidence, and pink shaded regions represent uplift. (b)聽Recent transition from marine to freshwater wetland ponds during the 1964 megathrust earthquake, approximately denoted by the yellow arrow. Sediments above this line were developed within freshwater conditions and are rich in organic matter and iron from macrophyte intrusion and glacial meltwater while sediments below this line are low in organic matter and were marine/brackish prior to the uplift event. Credit: *AGU Advances* (2025). DOI: 10.1029/2025av001821

Increased warming in high-latitude wetlands seems poised to increase the activity of methanogens, or methane-producing microbes. These ecosystems are complex places, however, making outcomes hard to predict.

In new biogeochemical research taking into account tectonic, climatic, and ecological factors affecting the Copper River Delta in Alaska, Buser-Young and team found that seismic uplift and glacial meltwater have each contributed to changes in microbial metabolism, with the surprising effect of potentially decreasing methane production. The work is in the journal AGU Advances.

The Copper River Delta in south central Alaska has a history of large seismic events. That includes, most recently, a 1964 earthquake that lifted portions of the delta to up to 3.4 meters above sea level, turning much of it from a marine environment to a freshwater one. In more recent decades, increasing amounts of iron-rich glacial runoff have also begun flowing through the delta, the result of climate change.

Combining geochemical studies of sediment cores from six wetland locations in the delta with metagenomic analyses of the microbes in the cores, the authors documented a distinct shift in microbial metabolism. Though genes for methanogenesis are still prevalent, and organic matter is available, they found that in an increasingly freshwater, iron-rich environment, the dominant means of energy production among the microbes shifted to involve iron cycling. Their findings are a demonstration of the ways large-scale geological and climatic shifts can affect small-scale processes such as the dynamics of microbial communities.

Looking ahead, the researchers say analyzing deeper sediment core samples could provide more information about how microbial dynamics have changed over time. In addition, they say, further culture-based experiments could improve understanding of the relationships between iron and organic matter within the carbon cycle.

More information: Jessica Z. Buser鈥怸oung et al, Megathrust Earthquake Legacy Linked to Changes in Widespread Potential for Methane and Iron Cycling in Glaciated Wetlands, AGU Advances (2025).

Journal information: AGU Advances

Provided by American Geophysical Union

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