Dynamics of fibropapillomatosis in green turtles Chelonia mydas from Babitonga Bay, southern Brazil

Green turtles Chelonia mydas are vital components of marine ecosystems and are recognized as indicators of environmental health. Fibropapillomatosis (FP), a debilitating disease associated with a chelonid herpesvirus, disproportionately affects juveniles in coastal foraging areas. This study presents the first analysis of FP dynamics in Babitonga Bay, southern Brazil, an important habitat for the species. Between 2019 and 2023, 171 juvenile green turtles were monitored using capture-mark-recapture and photo-identification techniques. FP prevalence in Babitonga Bay was among the highest reported in Brazil, reaching 53.2%. Tumors were predominantly located in the anterior region of the body, particularly around the flippers and axillary area, and were mostly small, consistent with mild FP. Disease severity was quantified using an FP index, and its association with body condition was examined, revealing no significant association. Data from recaptured individuals revealed both tumor progression and regression, underscoring individual variability and suggesting the influence of environmental and immunological factors. The predominance of FP in juveniles highlights their heightened vulnerability during early developmental stages. These findings enhance our understanding of FP dynamics in green turtles and support the need for continued health assessments and conservation measures. This research contributes to global efforts to safeguard marine biodiversity, aligning with the goals of the United Nations Decade of Ocean Science for Sustainable Development.