Assessing the upper thermal limit constraining the physiological performance of Callinectes sapidus embryogenesis under climate warming scenarios

Abstract

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 Call-inectes 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 de-clined. 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.