Sediment physicochemical and dissolved organic matter control microbial responses and nitrous oxide emissions across a coastal wetland transition from invasion to reclamation.
Cao S, Liu Y, Yang P, Hu X, Dong Y
Invasive Species
The same cordgrass takeovers reshaping salt marshes along the Atlantic and Gulf coasts are quietly turning these carbon-storing, storm-buffering wetlands into sources of a greenhouse gas 300 times more warming than CO2.
Coastal wetlands are being transformed: a tough invasive grass called smooth cordgrass moves in first, then people convert the land to fish farms. Researchers found that each step in this transformation changes the tiny organisms living in the mud — and those microbes end up releasing more nitrous oxide, a powerful greenhouse gas, into the atmosphere. The chemistry of the dissolved organic matter and the physical makeup of the sediment are the main factors controlling which microbes thrive and how much gas gets released.
Key Findings
The invasion-to-aquaculture conversion pathway significantly increases nitrous oxide emissions compared to native coastal vegetation.
Sediment physicochemical properties and dissolved organic matter composition are the primary drivers of microbial community composition and activity, more so than plant cover alone.
Each stage of transition (native marsh → Spartina invasion → aquaculture pond) produces a distinct microbial community with different nitrogen-cycling functions.
chevron_right Technical Summary
Converting coastal salt marshes — first invaded by an exotic grass, then turned into fish ponds — dramatically changes how nitrogen cycles through the sediment and increases emissions of nitrous oxide, a potent greenhouse gas. The type of organic matter and sediment chemistry, not just land use, drives which microbes control these emissions.
Abstract Preview
Natural coastal salt marshes are increasingly altered by invasion of the exotic plant Spartina alterniflora (SA) and subsequent reclamation into aquaculture ponds (AQ), forming a common transformat...
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Species Mentioned
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Sporobolus alterniflorus, or synonymously known as Spartina alterniflora, the smooth cordgrass, saltmarsh cordgrass, or salt-water cordgrass, is a perennial deciduous grass which is found in intertidal wetlands, especially estuarine salt marshes. It has been reclassified as Sporobolus alterniflor...