Response of marine benthic viral communities to anthropogenic disturbances

Viruses are key regulators of microbial mortality, gene flow, and metabolic functioning in marine sediments, yet their responses to different forms of anthropogenic disturbance remain poorly understood. Here, we present the first comparative viral metagenomic analysis of benthic viral communities across two major but contrasting disturbance regimes: organic enrichment beneath salmon aquaculture farms and crude-oil contamination near offshore oil installations. Using 123 sediment metagenomes from Scotland and Norway, we assessed how virus diversity, taxonomic composition, and community structure vary between high- and low-impact sites within each disturbance type and across regions. Virus alpha-diversity increased consistently under high-impact conditions in all environments, suggesting enhanced microbial turnover or productivity in disturbed sediments. Viral taxonomic profiles revealed strong habitat specificity. Beta-diversity analyses showed that viral community composition differed clearly between disturbance regimes, although these patterns were expressed within the context of region-specific environmental settings and sedimentary processes that also influence benthic microbial dynamics. Only a very small core set of vOTUs occurred in all samples with peak abundances throughout all low-impact categories suggesting strong environmental filtering. Together, these findings reveal that benthic viral communities are highly sensitive to environmental perturbation and reflect the contrasting microbial and geochemical processes associated with organic enrichment and hydrocarbon contamination. Our results advance the understanding of viral ecology in industrially impacted marine sediments and highlight the potential of virus-based indicators in next-generation biomonitoring tools that capture the full complexity of benthic microbial dynamics in anthropogenically impacted coastal and offshore ecosystems.