Vegetation of exotic fast-growing species Sonneratia apetala increases the potential of methylmercury production: Insights from carbon bioavailability, microbial metabolism and mercury methylators.
Chen X, Tan QG, Pan K, Xiao A, Cheng H
Invasive Species
Mangrove restoration projects along coastlines are increasingly using fast-growing exotic species for quick results, but this study shows those species can quietly turn coastal sediments into hotspots for a neurotoxin that moves up the food chain into fish.
Scientists compared two mangrove species growing in China's coastal wetlands and found that the fast-growing exotic one—despite having less total organic matter in its soil—produced far more methylmercury, a potent neurotoxin. The reason is that its fallen leaves break down more quickly, making the carbon in them easier for microbes to eat. Those well-fed microbes happen to be the same ones that convert mercury into its most dangerous form. This means choosing the 'wrong' plant for a restoration project can turn a wetland into a mercury factory.
Key Findings
Methylmercury levels were 2.1–2.6 times higher in sediments under the exotic Sonneratia apetala despite it having 1.2–4.2 times less total organic carbon than the native Kandelia obovata.
Exotic species sediments had a higher proportion of bioavailable carbon (34–50%) versus native species (28–36%), driving 1.4–3.3 times greater abundance of mercury-methylating microbe genes (hgcAB).
Metagenomics revealed the exotic species actively upregulated microbial metabolic pathways for labile carbon use and mercury methylation, implicating species-specific litter chemistry as the key ecological risk driver.
chevron_right Technical Summary
Planting an invasive fast-growing mangrove species in restoration projects dramatically increases toxic methylmercury in sediments—not because of total carbon, but because the plant's leaf litter breaks down more easily, fueling mercury-producing microbes.
Abstract Preview
Mangrove sediments are hotspots for neurotoxic methylmercury (MeHg) production, with litter-derived organic carbon strongly affecting mercury (Hg) methylation. However, the specific role of carbon ...
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Sonneratia is a genus of plants in the family Lythraceae. Formerly the Sonneratia were placed in a family called Sonneratiaceae which included both the Sonneratia and the Duabanga, but these two are now placed in their own monotypic subfamilies of the family Lythraceae. The genus was also named B...