Gene‐to‐Population Level Responses to Multiple Stressors on the Rocky Shore

N towards values indicative of greater assimilation of sewage-derived material, while warming increased elemental C:N ratios, consistent with altered nutritional stress. Barnacle transcriptomic responses mirrored this dominance of pollution, broadly regulating gene expression linked to protein turnover, DNA repair and protein folding; combined warming and pollution further intensified proteostasis-related changes and produced predominantly reversal and antagonistic interaction types. Our results show that sewage pollution can overwhelm and reshape warming effects over time and across biological levels, linking group-level responses with parallel shifts in trophic biomarkers and gene regulation. Our scalable field approach provides a template for in situ marine multiple stressor experiments across wider spatiotemporal scales.