Combined effects of silver nanoparticles and temperature on Palaemon pandaliformis : a toxicity and physiological biomarker-based approach

The increasing release of nanomaterials into aquatic environments has raised global concern regarding their ecological impacts, particularly under ongoing climate change. Among these materials, metallic nanoparticles are of special interest due to their widespread use and environmental persistence. Silver nanoparticles (AgNPs) are extensively applied in industrial and medical products and are frequently detected in aquatic systems, where their toxicity may be strongly influenced by abiotic factors such as temperature. In ecotoxicological studies, silver nitrate (AgNO₃) is commonly used as a positive control to represent dissolved ionic silver and to enable comparison with nanoparticulate forms. However, the combined effects of AgNP exposure and thermal variation on crustacean physiology remain poorly understood. Here, we demonstrate that temperature markedly enhances the toxicity and physiological stress induced by AgNPs in the shrimp Palaemon pandaliformis, using AgNO₃ exclusively as an ionic silver control. Acute 96-hour toxicity assays showed consistently lower LC₅₀ values for AgNO₃ than for AgNPs across all temperatures, confirming its higher intrinsic toxicity, while both silver forms exhibited pronounced toxicity amplification at elevated temperature (25 °C). Sublethal responses revealed significantly increased oxygen consumption under combined thermal and silver stress, indicating elevated metabolic demand, whereas ammonia excretion declined with increasing concentration and temperature, suggesting impairment of branchial excretory function. Overall, our findings demonstrate that warming not only intensifies mortality but also exacerbates metabolic and excretory dysfunction associated with metallic nanoparticle exposure, highlighting the critical role of temperature in nanotoxicological risk assessment and supporting P. pandaliformis as a sensitive bioindicator under climate change scenarios.