A new study, conducted by Jaehyun Lee at the Korea Institute of Science and Technology in Seoul, has found some promising results. It finds previously unappreciated rapid shifts in microbial activity across coastal wetlands, particularly at the fringes of the Chesapeake Bay. Genevieve Noyce, a biogeochemist at the Smithsonian Environmental Research Center (SERC) in Edgewater, Maryland, co-authored the research. It shows that climate change, specifically increased temperatures and carbon dioxide levels, are likely impacting the biogeochemistry of wetlands.
The research was specifically looking at how these alterations affect methane emissions, an especially potent greenhouse gas. In the lab, the study team tested various soil conditions on 18 marshy plots in SERC’s brackish wetlands. Each plot allowed to vary different environmental parameters, i.e., vegetation type, temperature, ambient CO2 concentration.
Increasingly, as temperatures increase, wetland soil microbes who are methane-generating hunkers down, basically, owing to methane-oxidizing genes having a higher temperature optima. These microbes do best in warmer temps. As they take off, they can inadvertently outcompete and kill other microbial communities that assist in methane consumption. Compared with other ecosystems, microbial competition in the ocean has long been described and studied.
To do some of the experiments they wanted to do, the researchers fenced off the 18 plots to create controlled environments for their observations. Each 2-meter square plot gave scientists the opportunity to recreate different stressors that wetlands could face in a rapidly changing climate. The findings may provide insights into a concerning trend observed over the past decade: a notable increase in methane emissions from wetlands.
Noyce noted the complexity of these interactions, stating, “You can’t actually predict what’s going to happen until you understand all the little pieces.” This way of thinking captures the intricacy of wetland ecosystems. More importantly, it touches on the difficulties ahead in predicting how they will act as climate change develops.
This programmatic analysis showed that increased atmospheric CO2 can mitigate some of these warming impacts. It accomplishes the second by encouraging the conversion of toxic hydrogen sulfide to safe, non-toxic sulfate. This new discovery shows that warmer temperatures can awaken methane-producing microbes. The increase in CO2 can reverse this trend by enhancing certain biochemical processes.
“It’s clear that many of our current models of wetlands seem to be underestimating the emissions,” said Euan Nisbet, underscoring the need for more accurate predictions regarding greenhouse gas emissions from these vital ecosystems.
In her testimony, Noyce stressed how consequential the findings of the study were. He said it answers “one missing piece of the puzzle” about wetland methane emissions. The research not only sheds light on microbial dynamics but raises questions about how these ecosystems will respond to ongoing climate changes.
Wetlands have long been prized for their ability to sequester carbon and cycle nutrients through, making them vital for climate resiliency. As they adapt to rising temperatures and altered conditions, understanding their contribution to greenhouse gas emissions becomes increasingly essential.
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