The role of habitat use and sociality on skin lesions in Tamanend's bottlenose dolphins (<i>Tursiops erebennus</i>) in the St. Johns River, Florida

Abstract Photographic analysis of skin lesions is a noninvasive approach to estimate the health of cetacean populations. The St. Johns River (SJR) in NE Florida is an estuarine system inhabited by Tamanend's bottlenose dolphins ( Tursiops erebennus ) that is characterized by high levels of anthropogenic activity. Both environmental factors and social transmission of disease may influence lesion formation in dolphins, thus this study aimed to determine if skin lesion prevalence and extent of coverage differed based on (1) the amount of time spent in the SJR annually and (2) sociality measures. Photos were examined for lesions on the dorsal fin and total visible body. Individuals were categorized as residents, seasonals, or transients based on the monthly sighting rate in cold and warm seasons. The mean nonzero SRI and degree centrality were compared to lesion prevalence and coverage. Residents exhibited the highest prevalence of skin lesions, followed by seasonals and transients. Coverage in affected individuals did not significantly differ among residency groups. Lesion prevalence was higher in the SJR than nearby sites. Associations between sociality and lesion measures were not significant. These results suggest that habitat use primarily drives lesion occurrence in SJR dolphins.