Thermal adaptation strategies in crustaceans: Potential threats to aquaculture in a warming climate

Global warming severely challenges aquatic ecosystems and aquaculture, threatening crustacean production through rising temperatures and extreme heat events. As ectotherms with limited thermoregulatory capacity, crustaceans are vulnerable to prolonged thermal stress. Yet, they exhibit remarkable thermal adaptability and behavioral thermoregulation across diverse thermal zones. This review synthesizes evidence that crustaceans employ a hierarchical suite of behavioral responses to heat stress: a primary response involving temperature perception via ion channels and neural signal transmission; a secondary response involving energy allocation, body protection, and enhanced neuromuscular coordination regulated by hormones, enzymes, and genes to maintain homeostasis; and a tertiary response involving behavioral adjustments impacting growth, survival, and reproduction. Crucially, as temperatures approach species-specific tolerance thresholds, crustaceans engage in thermal navigation to avoid detrimental extremes. This resilience is fundamentally rooted in the nervous system's plasticity, enabling adaptation within bounds. However, short-term acclimation often fails to shift intrinsic thermal preferences or adequately resolve the inevitable physiological trade-offs between survival, growth, and reproduction under sustained thermal stress, creating a conflict for aquaculture objectives. Over time, extreme temperatures act as potent selection pressures. While driving phenotypic plasticity, they risk population decline, particularly in stenothermic species contracting their ranges. Eurythermic species, with greater neural and behavioral plasticity, show superior resilience but risk diluting valuable commercial traits through increased genetic polymorphism. Understanding these adaptation mechanisms, including the identification of critical thermal thresholds and the neural basis of plasticity limits, provides crucial insights. Future research must prioritize investigating transgenerational inheritance of thermal responses and selecting breeding stock with enhanced neural plasticity or the capacity to maintain growth-reproduction equilibrium under warming, alongside identifying resilient eurythermic strains suitable for aquaculture. The review examines external thermoregulation mechanisms in sensation, molecular regulation, physiological responses, and ecological adaptations. It provides strategic insights for crustaceans and aquaculture species confronting escalating thermal stress.