Microplastic Pollution Is Associated with Fragmentation and Environmental Sensitivity of Marine Planktonic Microbial...

Area of Science:

• Marine microbiology
• Environmental science
• Ecotoxicology

Background:

• Marine microplastic (MP) pollution is a growing concern, yet its impact on free-living microbial communities under natural conditions is not fully understood.
• Existing research often focuses on plastisphere biofilms, overlooking the broader effects on planktonic microbial ecosystems.

Purpose of the Study:

• To systematically evaluate how microbial community structure and function respond to varying microplastic concentrations in marine environments.
• To quantify changes in microbial sensitivity and ecological interactions using a comprehensive analysis framework.

Main Methods:

• Utilized the Response Modulation Analysis Framework (RMAF) integrating co-occurrence network analysis, random forest modeling, and SHAP/partial dependence methods.
• Analyzed Tara Oceans metagenomic data, assessing species diversity and seven functional gene categories across microplastic concentration gradients.
• Focused on free-living marine microbial communities (0.8-5 μm).

Main Results:

• High MP environments (>5,500 items·km-2) showed a decrease in nondominant taxa and increased dominance of abundant species.
• Functional profiles revealed higher abundance of genes involved in carbon, nitrogen, and sulfur cycling.
• Network analysis indicated reduced connectivity, increased fragmentation, weakened ecological interactions, and decreased system stability.

Conclusions:

• Microbial communities in high-MP environments exhibit increased sensitivity to environmental drivers, with response centralization and niche compression.
• Microplastics are associated with high microbial functional activity but may signal reduced ecosystem resilience.
• Findings highlight the significant ecological consequences of microplastic pollution on marine microbial ecosystems.