STRESS ASSESSMENT IN CARETTA CARETTA DURING THE REHABILITATION PERIOD

Loggerhead sea turtle (Caretta caretta) is a long-living omnivorous animal and the most abundant species in the Mediterranean Sea. It’s considered endangered, included in the IUCN (International Union for Conservation of Nature) Red List (1) and threatened both by infectious diseases and anthropogenetic activities (chemical pollution, plastic ingestion, entanglement) (2). Therefore, many subjects recoveredat rescue centers, are hospitalized for a long time. During the rehabilitation period turtles are subjected to potential stressors as periodical manipulation, life in tanks, limited movement and artificial feeding; by the way, these factors are necessary to readapt the subjects to the wildlife, as to sustain their ability to survive and reproduce, maximizing the numbers (3). The aim of this study was to evaluate some stress indicators through blood sample analyses of sea turtles hospitalized at rescue center C.Re.TaM (IZS Sicilia, Palermo, Italy). Nineteen C. caretta with different clinical situations (injuries, plastic ingestion, cold stunning) were monitored. For each subject, carapace length (CCL) and weight (Kg) were measured. On the basis of that animals were classified as juveniles (n.12, CCL: 30.6 ± 5.7) and sub-adults (n.7CCL: 52.6 ± 5.7). The following parameters are considered as markers to assess the stress levels in this species: Corticosterone(CORT), Heterophil Lymphocyte ratio (H/L), Glucose, Creatine Kinase (CK) Urea and Uric Acid (UA). Blood samples were collected from the dorsal cervical sinus in litio-heparine and tubes without anticoagulant at three different times: at the moment of recovery (T0), a month later (T1), and two months later (T2). Blood smears were also performed and stained with Diff-Quick stain. Two hundred Leucocytes were counted and classified into Lymphocytes, Heterophils, Eosinophils, Basophils, and Monocytes, and the H/L ratio was calculated. On plasma, CORT concentration was assessed using an ELISA kit (Assay Genie CORT kit). On serum, Glucose, CK, Urea, and UA were assessed by the multiparametric chemistry analyzer BS-480 Mindray. The application of one-way for repeated analysis of variance (ANOVA) showed a decrease of H/L ratio (T0: 0.8 ± 0.8; T2: 0.2 ± 0.1; p-value: 0.093) and CORT (T0: 243.6 ± 129.9; T2: 17.2 ±11.7; p-value: 0.0008) in Juveniles, and a decrease of H/L ratio (T0: 2.3 ± 2.5; T2: 0.3 ± 0.2; p-value: 0.013) and Glucose (T0: 169.1 ± 39.8; T2: 108.4 ± 10.7; p-value: 0.0005) in Sub--adults from T0 to T2. Pearson’s correlation was not statistically significant between H/L ratio and CORT and between the biochemical values and CORT in juvenile and sub-adult subjects for each time interval. This study, as reported by other authors (2,3), suggests that stress levels could be influenced by the injury/pathology of subjects (1,2,3); indeed, hospitalized sea turtles showed high stress level at the moment of arriving at rescue center. Whereas, it seems that the rehabilitation period can be excluded as a primary stress factor. However, further studies are needed to define other causes of variations in stress levels in rehabilitating C. caretta.