Anthropogenic impacts on the global groundwater viral ecosystem

Urbanization profoundly impacts ecological systems, yet its effects on groundwater viral communities, particularly bacteriophages, remain poorly understood. Groundwater sustains Earth's ecosystems and human societies through drinking water, agriculture, and natural habitats. Bacteriophages play a crucial role by modulating bacterial communities through predation and gene transfer, influencing microbial processes that maintain groundwater quality. We investigated the relationship between anthropogenic land use and viral diversity in groundwater ecosystems, hypothesizing that urbanization and agriculture reduce viral diversity while enhancing stress-resistance metabolic gene diversity. We analyzed 373 groundwater metagenomes across five global biomes, reconstructing 30,046 high-confidence uncultivated viral genomes using a custom pipeline and MetaPhlAn for bacterial diversity estimation. We annotated 7,495 auxiliary metabolic genes using DRAM-v, analyzed viral lifestyle using PhaTYP, and integrated high-resolution land cover and urbanization datasets with machine learning models. Our initial findings supported our hypotheses: urbanization correlated with reduced viral diversity in groundwater systems through host depletion and altered environmental conditions. Metabolic gene analysis revealed distinct patterns across land uses, with specific signatures in built-up, semi-arid, forest land covers, suggesting unique viral adaptations. We found consistent associations between urbanization and stress-resistance genes, indicating shifts in host functional potential. Further analysis showed approximately 65% of identified viruses were virulent, suggesting frequent lytic interactions. To address sample autocorrelation, subsequent analyses will incorporate spatial sampling techniques. These findings contribute to our understanding of viral ecology in groundwater ecosystems and could inform approaches to water management, agriculture, and pollution control in urbanized landscapes. Our results indicate that anthropogenic land use substantially influences groundwater viral communities, providing insights relevant for urban development and ecosystem management strategies.