Dual stressors impair bioenergetics and antioxidant defenses in Etroplus suratensis

Marine biota is confronted with the simultaneous pressures of anthropogenic drivers, such as ocean warming and engineered nanoparticles, that pose a compounded threat to aquatic ecosystems and productivity. The present study investigated the combined impacts of ocean warming and zinc oxide nanoparticle (ZnO-NP) on the eco-physiological response of Etroplus suratensis. Essential bioenergetic parameters, comprising ingestion rate, absorption rate, respiration rate, ammonia excretion, and scope for growth (SfG), were evaluated in conjunction with oxidative stress biomarkers, including superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation (LPO). Results indicated significant reductions in food consumption and absorption efficiency under individual and combination treatments, highlighting diminished energy availability. Elevated temperatures surpassed the optimal habitat temperature threshold of studied fish, which provoked heightened metabolic expenditure and accentuated ammonia release, while nanoparticle exposure further jeopardized energy balance by disrupting digestive processes. Concurrent stressors induced pronounced impairments, marked by a reduced scope for growth and pushing to severe energetic trade-offs under adverse situations. Antioxidant biomarkers such as SOD, CAT, and GST exhibited pronounced augmentation, yet antioxidant defenses were insufficient to prevent LPO production. The Integrated Biomarker Response (IBR) index substantiated these findings, which reveal conspicuous elevations in stress conditions, particularly under combined nanoparticle and warming treatments. Collectively, the outcomes accentuate the pervasive repercussions of dual stressors, which provide unequivocal evidence of physiological jeopardy in E. suratensis. These findings underscore the need for integrative biomarker approaches to disentangle the ramifications of concurrent environmental perturbations and improve predictions for sustainable aquaculture under foreseeable climate and contaminant pressures.