Acoustic stress: how biological and anthropogenic noise shape oxidative balance in a coastal crab.

Environmental sounds, both natural and anthropogenic, are increasingly recognized as relevant stressors for marine and coastal organisms. This study aimed to evaluate the impact of biologically (crustacean and fish) and anthropogenic (motorboat) sound stimuli from a coastal lagoon environment on oxidative stress biomarkers in the crab Cyrtograpsus angulatus, considering different sexes and developmental stages (adult males, adult females and juveniles). Lipid peroxidation (LPO), protein carbonylation (PO), and the activity of the antioxidant enzymes glutathione-S-transferase (GST) and catalase (CAT) were measured in the gills, hepatopancreas, muscle, hemolymph and brain. Sound exposure induced tissue-specific and stage-dependent oxidative responses. These results reveal a complex physiological response to different acoustic cues, suggesting a differential vulnerability to acoustic stress across developmental stages, sexes and specific tissues. Adult males were mainly affected by boat noise, while adult females and juveniles were more vulnerable to natural sounds. LPO increased in most tissues, indicating a potential stress biomarker. This study provides the first report of oxidative stress biomarkers in the brain of a crustacean species, contributing to a better understanding of the neurobiological impact of acoustic stimuli. These findings provide novel insight into how soundscapes shape the oxidative physiology of coastal crustaceans and highlight the need to consider acoustic pollution in the conservation of ecologically relevant habitats.