Skin Lesions on Common Bottlenose Dolphins (Tursiops truncatus) from Three Sites in the Northwest Atlantic, USA

Skin disease occurs frequently in many cetacean species across the globe; methods to categorize lesions have relied on photo-identification (photo-id), stranding, and by-catch data. The current study used photo-id data from four sampling months during 2009 to estimate skin lesion prevalence and type occurring on bottlenose dolphins (Tursiops truncatus) from three sites along the southeast United States coast [Sarasota Bay, FL (SSB); near Brunswick and Sapelo Island, GA (BSG); and near Charleston, SC (CHS)]. The prevalence of lesions was highest among BSG dolphins (P = 0.587) and lowest in SSB (P = 0.380), and the overall prevalence was significantly different among all sites (p<0.0167). Logistic regression modeling revealed a significant reduction in the odds of lesion occurrence for increasing water temperatures (OR = 0.92; 95%CI:0.906–0.938) and a significantly increased odds of lesion occurrence for BSG dolphins (OR = 1.39; 95%CI:1.203–1.614). Approximately one-third of the lesioned dolphins from each site presented with multiple types, and population differences in lesion type occurrence were observed (p<0.05). Lesions on stranded dolphins were sampled to determine the etiology of different lesion types, which included three visually distinct samples positive for herpesvirus. Although generally considered non-fatal, skin disease may be indicative of animal health or exposure to anthropogenic or environmental threats, and photo-id data provide an efficient and cost-effective approach to document the occurrence of skin lesions in free-ranging populations

Location of photo-id study sites: Charleston, SC (CHS), Brunswick and Sapelo Island, GA (BSG), and Sarasota Bay, FL (SSB).

<p>Location of photo-id study sites: Charleston, SC (CHS), Brunswick and Sapelo Island, GA (BSG), and Sarasota Bay, FL (SSB).</p

Skin lesion prevalence and 95% CI for bottlenose dolphins photographed in waters near Charleston, SC (CHS), near Brunswick and Sapelo Island, GA (BSG), and Sarasota Bay, FL (SSB) in 2009.

*<p> <i>Indicates a significant difference with a Bonferroni correction for multiple comparisons (α = 0.0167).</i></p><p> <i>“Photographed” - number of dolphins evaluated for lesions with photographs suitable for lesion detection.</i></p><p> <i>“AWL” - number of dolphins photographed with visible skin lesion(s).</i></p><p> <i>“Prevalence” - proportion of ‘Photographed’ that is ‘AWL’.</i></p><p> <i>(p values are reported for comparisons of skin lesion prevalence between sites).</i></p

Proportion of major skin lesion types (<i>P>0.15</i>) and study site comparisons for lesioned dolphins photographed in waters near Charleston, SC (CHS), near Brunswick and Sapelo Island, GA (BSG), and Sarasota Bay, FL (SSB) in 2009.

*<p> <i>Indicates a significant difference (α = 0.05).</i></p>∧<p> <i>Indicates a significant difference after post-hoc multiple comparisons tests (α<0.05; Horne and Plaehn 2007).</i></p

Regression curve for logistic model of the predicted probability of bottlenose dolphin (<i>Tursiops truncatus</i>) skin lesion occurrence using water temperature and study site as independent variables [Charleston, SC (CHS); Brunswick and Sapelo Island, GA (BSG); Sarasota Bay, FL (SSB)].

<p>Regression curve for logistic model of the predicted probability of bottlenose dolphin (<i>Tursiops truncatus</i>) skin lesion occurrence using water temperature and study site as independent variables [Charleston, SC (CHS); Brunswick and Sapelo Island, GA (BSG); Sarasota Bay, FL (SSB)].</p

Prevalence of skin lesion types among lesioned dolphins photographed in waters near Charleston, SC (CHS), near Brunswick and Sapelo Island, GA (BSG), and Sarasota Bay, FL (SSB) in 2009.

<p>Prevalence of skin lesion types among lesioned dolphins photographed in waters near Charleston, SC (CHS), near Brunswick and Sapelo Island, GA (BSG), and Sarasota Bay, FL (SSB) in 2009.</p

Examples of skin lesion types on free-ranging bottlenose dolphins (<i>Tursiops truncatus</i>) photographed in waters near Charleston, SC (CHS), Brunswick and Sapelo Island, GA (BSG), and Sarasota Bay, FL (SSB) in 2009.

<p>Lesion types include: black (a); pale (b); lunar (c); dark-fringed spots (d); white-fringed spots (e); orange patch (f); tattoo-like (g); white velvety (h); lacaziosis-like (i); vesicular (j); mottled (k); and spotted (l). (Categories from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033081#pone.0033081-Wilson1" target="_blank">[3]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033081#pone.0033081-VanBressem2" target="_blank">[5]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033081#pone.0033081-VanBressem3" target="_blank">[9]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033081#pone.0033081-VanBressem4" target="_blank">[12]</a>) Photo credit: B.Balmer, NCCOS/NOS/NOAA, Sarasota Dolphin Research Program.</p

Photo-id study sites [Charleston, SC (CHS); Brunswick and Sapelo Island, GA (BSG); Sarasota Bay, FL (SSB)] and stranding coverage areas for the Coastal Marine Mammal Stranding Assessments Program (South Carolina) and Hubbs-SeaWorld Research Institute (Florida).

<p>Photo-id study sites [Charleston, SC (CHS); Brunswick and Sapelo Island, GA (BSG); Sarasota Bay, FL (SSB)] and stranding coverage areas for the Coastal Marine Mammal Stranding Assessments Program (South Carolina) and Hubbs-SeaWorld Research Institute (Florida).</p