Assessment of haematological and biochemical parameters in captive green sea turtles (<i>Chelonia mydas</i>) before release

The green sea turtle (<i>Chelonia mydas</i>), a globally endangered marine reptile, faces significant population declines due to anthropogenic and environmental pressures. Captive rehabilitation programs are critical for conservation, yet captivity-induced physiological deviations may compromise post-release survival. This study establishes haematological and biochemical reference intervals for pre-release captive <i>C. mydas</i> (<i>n</i> = 40) various across juvenile, subadult, and adult life stages, and identifies key deviations from wild baselines. We found pronounced captivity-specific alterations, including elevated immature red blood cell counts and ghost cell counts in juveniles, which indicated dysregulated erythropoiesis and oxidative stress. Ontogenetic shifts revealed maladaptive macrocytic erythrocytosis in adults, likely linked to limited exercise and dietary imbalances. Biochemically, captive adults showed hyperproteinemia (total protein, 73.35 g/l) and dyslipidemia (total cholesterol, 8.98 mmol/l triglycerides, 1.53 mmol/l), indicating high-protein, high-fat diets, while hypoglucagonemia (glucose, 2.83 mmol/l) suggested compromised energy reserves. Age-dependent immune activity was observed, with juveniles exhibiting elevated leukocyte counts (19.34 × 10⁹/l), potentially due to chronic stress. These findings underscore metabolic and haematological adaptations in captivity that may hinder post-release resilience. Key biomarkers, such as immature red cell count, glucose, and lipid profiles, should guide release readiness assessments, thus ensuring rehabilitated turtles are physiologically primed for survival. This study provides a critical framework for enhancing the efficacy of sea turtle conservation translocations.