Landaeta_2026_Comp.Biochem.Physiol.A.Mol.Integr.Physiol_316_111997

Climate change is increasing average temperatures and thermal variability of aquatic environments globally, potentially exacerbating the toxicity of anthropogenic pollutants. Amphibians are particularly vulnerable to these stressors due to their complex life cycles, permeable skin, and ectothermic nature, which has contributed to the ongoing decline of their natural populations. However, the combined effects of pesticide exposure and increasing aquatic thermal variability-both driven by anthropogenic activity-on amphibian physiology remain understudied. This study evaluated the physiological, biochemical, and immunological responses of the African clawed frog (Xenopus laevis) to two thermal regimes: constant (23 degreesC; C) and variable (23 +/- 7 degreesC; V). Individuals were exposed to pesticide-free water (0 microg/L; NP) or to a concentration of 1 microg/L chlorpyrifos (P) for 14 days. Our results showed that pesticide exposure was the primary driver of impairment, significantly reducing locomotor activity, metabolic rate, antioxidant defenses, and butyrylcholinesterase enzyme activity. Furthermore, indices related to immune and oxidative stress responses were elevated under combined thermal variability and pesticide exposure. These findings highlight the importance of considering environmental thermal variability when assessing the effects of pesticides, as both rising and fluctuating temperatures can exacerbate the adverse effects of pesticides on frogs and toads.