The response of the bacterial community to long-term pollution in coastal sediment cores

Coastal sediments are vital yet vulnerable interfaces of pollutant transformation and microbial activity. However, the response of coastal bacterial community to accumulating environmental pollution over time remains poorly resolved. Our study unraveled four decades from 1980 to 2020 of pollution dynamics and bacterial adaptation in coastal ecosystems by analyzing sediment cores. The concentrations of most detected contaminants exhibited a temporal increase as a function of core age, particularly for the heavy metals. Concurrently, bacterial alpha-diversity increased over time, accompanied by significant structural reorganization of community. In total, 16 bacterial metabolic pathways were predicted, with the majority intensifying over time. Bacterial networks displayed marked declines in complexity and stability under increasing pollution, and partial post-2000 enhancement remained below 1980-1990 baseline. Heavy metals emerged as the dominant stressor, profoundly shaping community composition and functional profiles. Notably, K-strategists demonstrated superior adaptation to heavy metals over r-strategists, reflecting their resilience in environment with resource-limited and high-stress. Our findings link the accumulated contamination to reorganized diversity, altered functionality, and reconfigured co-occurrence patterns, underscoring the dynamic adaptive strategies of coastal bacterial community to chronic pollution.