Year

2021

Season

Summer

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Quincy Gibson

Second Advisor

Dr. Adam Rosenblatt

Third Advisor

Dr. Gregory Kohn

Department Chair

Dr. Cliff Ross

College Dean

Dr. George Rainbolt

Abstract

Photo analysis of skin lesions is a non-invasive method to measure the health of cetacean populations. The St. Johns River (SJR) in NE Florida is an estuarine system inhabited by bottlenose dolphins that is characterized by high levels of anthropogenic activity, which can impact dolphin health. Social transmission of disease may influence lesion formation in dolphins; thus this study aimed to determine if skin lesion prevalence and body coverage differed based on 1) the amount of time spent in the SJR annually and 2) sociality measures. The dataset was restricted to three 12-month periods, based on the occurrence of an unusual mortality event (pre, during, and post-UME). High-quality photos were examined for lesions on the dorsal fin and total visible body. Body coverage was categorized as background (50%). Lesion types were recorded based on a categorical system that included potentially pathogenic, rake mark associated, orange, hypopigmentation and hyperpigmentation categories. Individuals within the SJR vary in time spent within the river, and were categorized as residents, seasonals, or transients based on the monthly sighting rate in cold and warm seasons. Sociality analyses included resident and seasonal individuals and the mean half-weight index and degree centrality were compared to lesion prevalence and coverage. Residents exhibited the highest prevalence, followed by seasonals and transients. Coverage in lesioned individuals did not significantly differ among residency groups. Lesion prevalence decreased with each period of study. Overall lesion prevalence was higher than nearby sites, and potentially pathogenic lesions were observed at high levels. Half-weight indexes during the UME were correlated with lesion prevalence and coverage. All other associations between sociality and lesion measures were not significant. These results suggest that environmental factors primarily drive lesion occurrence in the SJR, but that sociality influences health during disease outbreaks.

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