Microplastic pollution threatens mangrove carbon sequestration capacity.

Area of Science:

• Environmental Science
• Microbiology
• Ecology

Background:

• Mangrove forests are crucial blue carbon ecosystems that sequester carbon but also cycle methane.
• Microplastic pollution is widespread in coastal environments, including mangroves.
• The impact of microplastics on methane cycling in mangroves is poorly understood.

Purpose of the Study:

• To investigate the relationship between microplastic pollution and methane production in Chinese mangrove soils.
• To identify the microbial communities affected by microplastics and their role in methane dynamics.
• To determine the anthropogenic drivers of microplastic accumulation and their consequences for mangrove ecosystem function.

Main Methods:

• Nationwide survey of microplastic concentrations in mangrove soils across China.
• Analysis of microbial community composition and gene expression related to methane cycling.
• Correlation analysis between microplastic levels, microbial networks, and industrial activity.

Main Results:

• Higher microplastic concentrations were found in surface soils (0-20 cm) compared to deeper soils (20-40 cm).
• Microplastic pollution was associated with increased abundance of methanogenic archaea, favoring methane production.
• Elevated microplastics in topsoil correlated with more complex microbial networks and a higher methanogens-to-methanotrophs gene ratio, linked to secondary industry output.

Conclusions:

• Microplastic pollution enhances methane production potential in mangrove soils by altering microbial communities.
• Anthropogenic activities, particularly secondary industry, are drivers of microplastic pollution in mangroves.
• Mitigating microplastic discharge is crucial for preserving the climate-regulating functions of mangrove ecosystems.