Stress assessment in Caretta caretta during the rehabilitation period

The rehabilitation of the loggerhead sea turtle, Caretta caretta, involves stressors like handling and confinement. To assess physiological stress responses during rehabilitation, twenty-five C. caretta hospitalized at C.Re.Ta.M. were monitored over a two-month period at three time points (T0, T1, and T2). The cohort included 12 juveniles (CCL: 30.6 ± 5.7 cm) and 13 subadults (CCL: 52.5 ± 10.4 cm). Heterophil/lymphocyte ratios (H/L), corticosterone (CORT), glucose (Glu), creatine kinase (CK), and uric acid (UA) plasma concentrations were assessed. Two-way repeated-measure ANOVA revealed significant time effects on H/L ratio (p < 0.0001), CORT (p < 0.0001), Glu (p = 0.0002), CK (p < 0.0001), and UA (p < 0.05), with a significative group x time interaction observed for CK (p = 0.016), CORT (p = 0.006) and UA (p = 0.035). No group effect was observed in any of the data. In the juvenile group, H/L (p < 0.01) and CORT (p < 0.001) were significantly lower at T2 compared to T0. At the T0 point, CORT levels were significantly higher in juveniles compared to the subadult group. In subadults, significant decreases in H/L ratio (p < 0.001), Glu (p < 0.01), CK (p < 0.001), and UA (p < 0.05) were observed at both T1 and T2 relative to T0. At T0, CK levels were significantly higher in subadults compared to juveniles. No significant correlations were found between CORT and the other measured parameters. Our results suggest that the rehabilitation period is a safety period during which the animals reestablish their homeostasis despite captivity conditions. However, further studies are needed to define other causes of variations in stress levels in rehabilitating C. caretta.