Spatiotemporal Distribution of Marine Viral Functions Associated with Microplastics

Microplastics (MPs) and marine viruses co-occur globally, yet the spatiotemporal distribution of MP-associated viral functional gene abundance remains poorly resolved. We synthesized 262 metagenomes to infer global MP pollution and tested associations between MPs and viral functional gene abundance against 24 physicochemical-biological variables. From 2000 to 2020, >20% of the North and southeastern Atlantic showed significant increases (p < 0.05) in viral functional gene abundance, whereas 61% of the northwestern Atlantic decreased. These shifts covaried with MP accumulation, nutrient regimes, and climate indices. In a northwestern Atlantic hotspot, neglecting MPs may lead to a ∼15% underestimation of viral functional gene abundance. In low-chlorophyll (Chl) regions (57.6% of the ocean), genes linked to carbon, nitrogen, and sulfur cycling were >30% more abundant in high- versus low-MP regions; MPs did not strongly affect the abundance of viral functional genes. Network analyses revealed cascading interactions among viral functional gene abundance, MPs, Fe, Chl, and environmental properties. Our results suggest that ignoring MPs may lead to the underestimation of viral functional potential and related biogeochemical processes, and that low-Chl regions─proposed priority protection areas─are particularly vulnerable to MPs pollution.