Thermal environments drive the metabolomic response of an intertidal snail at microhabitat scale

Extreme high-temperature events pose severe physiological challenges to species, with conspecific individuals experiencing divergent thermal stress across heterogeneous microhabitats. Investigating metabolomic response patterns provides critical insights into how these organisms respond to extreme heat at the microhabitat scale. In the present study, we conducted in situ measurements of substrate and body temperatures to analyze the relative importance of substrate temperature to body temperature. Additionally, we determined the metabolomic responses of intertidal snails Littorina brevicula inhabiting exposed and shaded rock microhabitats during an extreme high-temperature event in summer. Results showed that microhabitat type and substrate temperature significantly affect the body temperatures of intertidal snails. Snails inhabiting different microhabitats exhibited distinct metabolomic response patterns. On exposed rock, snails showed a metabolomic response pattern of high-energy expenditure, strong defense, and robust repair, while snails on shaded rock preferred to maintain cellular homeostasis. Variations in temperature across different microhabitats can alter the functional priorities of the snails' metabolic networks and can lead to functional differentiation in the same metabolic pathways depending on the microhabitat. These findings underscore the importance of microhabitat thermal heterogeneity and enhance our understanding of metabolomic responses to thermal stress at the microhabitat level.