How Acclimation Temperature Affects the Plasticity of Thermal Limits of North Atlantic Fishes

Climate change is exerting profound effects on marine ecosystems, prompting shifts in biodiversity, productivity, and function. Considerable insight into the distribution of ectothermic organisms, such as fishes, can be gleaned from an understanding of their thermal tolerances. However, understanding the influence of acclimation temperature on the thermal tolerance of marine species is crucial for predicting and managing climate-induced range shifts. In this study, we quantified the effect of acclimation temperature on the critical thermal minimum (CTMin) and critical thermal maximum (CTMax) of temperate to subtropical fishes. Our findings reveal species-specific increases in both CTMin and CTMax with higher acclimation temperatures. However, the subtropical species in our study had larger zones of intrinsic thermal tolerance compared to both tropical and temperate fish species. These results challenge conventional expectations based on the Climate Variability Hypothesis (CVH), indicating that subtropical species might be more adaptable to warming than previously thought.    Our study emphasizes the importance of considering acclimation temperature in predicting the response of fish species to climate change.