Changes in serum lactate and creatine kinase levels in free-living Geoffroy's (Phrynops geoffroanus) side-necked turtle captured using funnel traps.

Capture techniques are widely employed in wildlife monitoring programs, yet confinement and handling may induce transient physiological alterations that complicate interpretation of biochemical parameters. This study evaluated temporal changes in serum lactate and creatine kinase (CK) concentrations in free-living Phrynops geoffroanus captured using funnel traps in southern Brazil. Ten adult turtles (5 males, 5 females) were sampled at two time points: immediately after transport from capture sites (T0) and 24 h later (T24). Paired analyses indicated a significant decrease in lactate concentrations from T0 (90.6 ± 44.0 mg/dL) to T24 (38.2 ± 20.8 mg/dL; p = 0.0044), consistent with recovery from acute anaerobic activation. In contrast, CK activity increased significantly from T0 (2,227.8 ± 2,776.9 U/L) to T24 (8,131.0 ± 5,306.7 U/L; p = 0.0012), suggesting delayed enzymatic release associated with muscular strain. These divergent temporal patterns reflect distinct physiological mechanisms and biomarker kinetics following capture. The results highlight the importance of considering sampling latency when interpreting post-capture biochemical values in ecological studies. Funnel traps proved operationally effective, but confinement duration should be carefully managed to minimize physiological stress. Incorporating temporal context into capture protocols can improve the accuracy of physiological assessments in environmental monitoring programs.