Data_SI.xlsx

Ocean acidification (OA) is an escalating global stressor, yet a comprehensive assessment of its impacts on crustaceans remains lacking. Here, we synthesize data from 111 studies encompassing 18 biological parameters across three life stages, while accounting for methodological heterogeneity. Our analysis revealed that crustaceans maintain a stable internal pH despite elevated internal <i>p</i>CO₂ and acidified seawater, a resilience attributed to advanced acid-base regulation, particularly in brackish species adapted to fluctuating pH levels. However, this buffering incurs metabolic costs, reflected in reduced protein content and depressed respiration, consistent with a metabolic “freeze response” that conserves energy while sustaining catabolism. Exoskeleton calcification is less sensitive to OA. Despite regulatory capacities, survival decreases, accompanied by declines in condition factor and hemocyte counts, with juveniles emerging as the most vulnerable stage. Food limitation further diminishes resilience, underscoring the importance of trophic context. Responses to synergistic stressors are variable but generally exacerbate mortality relative to OA alone. Outcomes are also strongly modulated by experimental design, including feeding regimes, exposure duration, and local pH variability. Overall, our findings reveal that crustaceans’ multifaceted responses to OA are shaped by intrinsic physiological traits, synergistic stressors, and experimental conditions, offering insights into their adaptive limits and energetic trade-offs.