Embryonic development represents a vulnerable life stage in marine organisms, yet its role in shaping the invasion success of non-native species under climate change remains understudied. In this study, we assessed the upper thermal sensitivity of embryogenesis of the blue crab Callinectes sapidus , a globally invasive species, by quantifying their physiological responses across a temperature gradient relevant to projected climate warming scenarios. Using Electron Transport System (ETS) activity as a proxy for aerobic metabolism, we evaluated respiration, egg size, hatching time, and larval morphology in brooding eggs incubated at 22 °C, 24 °C, 26 °C, and 28 °C. Elevated temperatures induced increased ETS activity, indicating heightened metabolic stress, and were associated with reduced egg size and earlier hatching of malformed, non-viable larvae. Within the Oxygen- and Capacity-Limited Thermal Tolerance (OCLTT) framework, we identified a physiological pejus range (24–26 °C) beyond which embryonic performance declined. These results suggest that moderate warming may accelerate development and facilitate invasion, but extreme temperatures constrain aerobic capacity and compromise larval viability. Our results highlight embryogenesis as a potential bottleneck for blue crab recruitment under future warming, with implications for predicting the invasive potential of marine species.
Rodríguez-Ruiz et al. (2025) studied this question.