Lacaziosis in bottlenose dolphins Tursiops truncatus along the coastal Atlantic Ocean, Florida, USA.

This study represents the first systematic study of lacaziosis (lobomycosis) in bottlenose dolphins Tursiops truncatus in the Atlantic Ocean along the east-central coast of Florida, USA. Lacaziosis is a chronic infection of the skin caused by the fungus Lacazia loboi, which affects only dolphins and humans. Previous studies have shown a high prevalence (6.8 to 12.0%) of lacaziosis in resident dolphins from the adjacent Indian River Lagoon Estuary (IRL), where the disease is endemic. We examined the prevalence of lacaziosis in this coastal area using photo-identification data collected between 2002 and 2008 to determine the prevalence of lacaziosis in coastal dolphins using photographic methodology shown to have high sensitivity and specificity in prior research. The prevalence of skin lesions compatible with lacaziosis estimated from photographic data was 2.1% (6/284), approximately 3 times lower than that described for the estuarine population using similar methods. To exclude potential bias introduced by differences in study duration and survey effort among areas, an 18 mo period when effort was most equal (January 2006 to June 2007) was chosen for statistical comparison. The prevalence of lacaziosis estimated from photographic data was significantly lower (3.8%: n = 6/160) in the Atlantic Ocean compared to the IRL (12.0%: n = 20/167) (risk ratio = 3.19, 95% CI 1.32 to 7.75, p < 0.01 by chi-square analysis). The lower prevalence of lacaziosis in dolphins found in the Atlantic Ocean and the overall lack of movement of dolphins between these habitats suggests that environmental conditions within the estuary may favor viability of L. loboi, and/or that immune compromise in resident estuarine dolphins is a precursor to the disease.

Home ranges of bottlenose dolphins (Tursiops truncatus) in the Indian River Lagoon, Florida: environmental correlates and implications for management strategies.

Photo-identification surveys conducted between 2002 and 2005 were used to determine dolphin home ranges and site fidelity within the Indian River Lagoon (IRL), Florida. The IRL was divided into six segments based on hydrodynamics and geographic features for purposes of characterization. Among the 615 dolphins with identifiable dorsal fins, 339 had > or =6 sightings and were used in segment and linear range analyses. The majority (98%) of dolphins were seen in < or =3 consecutive segments (331/339); of these, 44% (144/331) occurred in two segments, and 33% (109/331) in one segment. No dolphins were observed in all six segments. The largest number of dolphins was sighted in segment 1C (North Indian River). However, the highest density of dolphins was found in segment 2 (North-Central Indian River). Re-sighting rates for dolphins with > or =6 sightings ranged from 2.8 to 8.7 times observed. The mean linear home range varied from 22 to 54 km. Distributional analyses indicated that at least three different dolphin communities exist within the IRL: Mosquito Lagoon, and the North and South Indian River. No statistically significant correlations were found between the total number or density per km(2 )of dolphins and surface water area, salinity, or contaminant loads within segments of the lagoon. These results suggest that dolphins do not selectively avoid areas with relatively unfavorable water quality. IRL dolphins should be studied on smaller spatial scales than currently practiced, and potential anthropogenic impacts should be evaluated based on geographic partitioning.