Stable isotopes differentiate bottlenose dolphins off west-central Florida

Abstract

Distinguishing discrete population units among continuously distributed coastal small cetaceans is challenging and crucial to conservation. We evaluated the utility of stable isotopes in assessing group membership in bottlenose dolphins (Tursiops truncatus) off west‐central Florida by analyzing carbon, nitrogen, and sulfur isotope values (δ13C, δ15N, and δ34S) of tooth collagen from stranded dolphins. Individuals derived from three putative general population units: Sarasota Bay (SB), nearshore Gulf of Mexico (GULF), and offshore waters (OFF). Animals of known history (SB) served to ground truth the approach against animals of unknown history from the Gulf of Mexico (GULF, OFF). Dolphin groups differed significantly for each isotope. Average δ13C values from SB dolphins (−10.6‰) utilizing sea grass ecosystems differed from those of GULF (−11.9‰) and OFF (−11.9‰). Average δ15N values of GULF (12.7‰) and OFF (13.2‰) were higher than those of SB dolphins (11.9‰), consistent with differences in prey trophic levels. δ34S values showed definitive differences among SB (7.1‰), GULF (11.3‰), and OFF (16.5‰) dolphins. This is the first application of isotopes to population assignment of bottlenose dolphins in the Gulf of Mexico and results suggest that isotopes may provide a powerful tool in the conservation of small cetaceans.

Isotope turnover rates and diet-tissue discrimination in skin ofex situBottlenose Dolphins (Tursiops truncatus)

“…Parnell et al, 2010), and/or changes in residency patterns of the dolphins. Barros et al (Barros et al, 2010) and Gibbs et al (Gibbs et al, 2011) have distinguished populations of coastal/bay resident dolphins from offshore populations using stable isotopes. Recently, Wilson and colleagues (Wilson et al, 2012) examined dolphins living in three Florida Bay systems and distinguished distinct residency patterns consistent with sighting and tracking data (Balmer et al, 2008).…”

Satellite tracking and stable isotope analysis highlight differential recruitment among foraging areas in green turtles

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Stable isotopes of captive cetaceans (killer whales and bottlenose dolphins)

“…The methodology has been used to address a broad range of topics, including the foraging ecology and migration patterns of wild populations [e.g. killer whales (Herman et al, 2005;Newsome et al, 2009); dolphins (Knoff et al, 2008;Barros et al, 2010)], exposure to organochlorides and heavy metals [e.g. killer whales (Krahn et al, 2008); dolphins (Borrell et al, 2006)], and historic ecology and paleoecology [e.g.…”