Coping with Variability: Physiological Performances and Plasticity of the Invasive Blue Crab Callinectes sapidus under Fluctuating and Constant Conditions

As the invasive blue crab Callinectes sapidus rapidly expands over European coastal habitats, its capacity to adapt to shifting environmental conditions may be essential to its success (Marchessaux et al., 2022). In this study, we compared constant laboratory conditions with fluctuating conditions which reproduce the natural diel and seasonal fluctuations typical of the euphotic zones in the Venice Lagoon (Ministero delle Infrastrutture e dei Trasporti, 2020), in order to assess their potential effects on metabolic performance. Most importantly, the research focused on temperature and dissolved oxygen, considered the main environmental driver of physiological and metabolic processes in marine ectotherms (Booth et al., 2021; Pörtner, 2010; Semsar-kazerouni and Verberk, 2018). Metabolic rates were measured through closed chamber respirometry, while a temperature-dependent mortality curve was used to assess cumulative heat tolerance. Potential feedforward mechanisms linked to environmental predictability were investigated by examining how oxygen consumption rates varied according to diel fluctuations. Our results identify statistical differences between fluctuating (natural) regimes and constant conditions in terms of metabolic responses and mortality, emphasizing the importance of environmental heterogeneity in shaping the environmental plasticity of the blue crab C. sapidus and providing insights to its ability to thrive under ongoing climate change. By focusing on naturally occurring fluctuations, the current study demonstrates how realistic fluctuations in the environment can influence metabolic processes and illustrates that constant laboratory settings could fail to accurately represent the physiological responses of organisms. Moreover, this particular approach allows us to evaluate how C. sapidus is able to respond to extreme events, providing insights into the resistance and resilience of this invasive species.