Rethinking Mussel Watch in the Era of Exposome and One Health

For five decades, Mussel Watch has provided an unparalleled record of coastal contamination using bivalve sentinels. However, contemporary marine pollution is increasingly complex, involving chemical mixtures modulated by climate change and tightly linked to ecosystems and human health. Traditional pollutant-by-pollutant monitoring approaches, while essential for tracking regulatory contaminants, are poorly suited to capture mixture effects, emerging contaminants, and cumulative exposures, which characterize real-world environmental risks. This Perspective paper reassesses Mussel Watch through the lenses of the chemical exposome and One Health frameworks. We argue that the program could evolve from a primarily descriptive monitoring system into a mechanistic observatory capable of linking environmental exposures to biological responses and ecosystem-level processes. Achieving this transition requires integrating emerging tools-including non-traditional stable isotopes, high-resolution non-target screening, and omics-based biomarkers-to better characterize complex exposure patterns and their biological consequences. We propose a dual-track architecture in which long-term routine monitoring is maintained to preserve the historical record, while a complementary research track supports hypothesis-driven investigations into biogeochemical transformation, exposure pathways, mixture effects, and biological responses. By combining these approaches, Mussel Watch could strengthen its capacity to detect emerging risks, support mechanistic understanding, and enhance the policy relevance of coastal monitoring in a rapidly changing environment.