Caha_2026_Environ.Toxicol.Pharmacol__105206

Wildlife is exposed to fluctuating environmental stressors, yet biomarker-based assessments are typically derived from single-year research. This study evaluated temporal dynamics of blood responses (cholinesterase [ChE], carboxylesterase [CES], glutathione S-transferase [GST], glutathione reductase [GR], reactive oxygen species [ROS], reduced glutathione [GSH]) in White Stork (Ciconia ciconia) nestlings from eastern Croatia over a six-year period (2020-2025): (I) interannual variation and temporal trends, (II) magnitude of change, and (III) temporal predictability. Interannual variation was observed across all biomarkers, with linear trends indicating increasing plasma ChE activity, but decreasing trends in detoxification and antioxidant biomarkers. Standardised slopes revealed that ROS increased, whereas antioxidant and detoxification enzymes decreased. ChE activity displayed non-concordant patterns between blood fractions. Temporal cross-validation demonstrated differences in predictability. Detoxification enzymes showed low prediction error, whereas antioxidant biomarkers exhibited high prediction error. The results indicate that multi-year and multi-biomarker monitoring frameworks may improve the interpretation of long-term environmental impacts on wildlife.