Deep in the waterlogged peat of salt marshes, carbon is stored at much greater rates than in land ecosystems, serving as an offset to climate change due to carbon dioxide (CO2) build-up in the atmosphere.
However, a new study indicates that a common pollutant of coastal waters, nitrate, stimulates the decomposition of organic matter in salt marsh sediments that normally would have remained stable over long periods of time. This increase in decomposition, which releases CO2, could alter the capacity of salt marshes to sequester carbon over the long term. The study, led by scientists at the Marine Biological Laboratory (MBL), Woods Hole, and Northeastern University, is published in Global Change Biology.
“Traditionally, we have viewed salt marshes as resilient to nitrogen pollution, because the microbes there remove much of the nitrogen as gas through a process called denitrification,” writes first author Ashley Bulseco, a postdoctoral scientist at the MBL.
“But this research suggests that when nitrate is abundant, a change occurs in the microbial community in salt marsh sediments that increases the microbes’ capacity to degrade organic matter. This potentially reduces the ability of the marsh to store carbon,” Bulseco writes.
Read more at: Marine Biological Laboratory
Great Sippewissett Marsh in Falmouth, Mass. Salt marshes sequester carbon at rates more than an order of magnitude greater than their terrestrial counterparts. (Photo Credit: Daniel Buckley)