Stable isotopes differentiate bottlenose dolphins off west-central Florida

Marine Mammal Science
By: , and 

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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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Stable isotopes differentiate bottlenose dolphins off west-central Florida
Series title Marine Mammal Science
DOI 10.1111/j.1748-7692.2009.00315.x
Volume 26
Issue 2
Year Published 2010
Language English
Publisher Wiley
Contributing office(s) Crustal Geophysics and Geochemistry Science Center, Fort Collins Science Center
Description 13 p.
First page 324
Last page 336
Country United States
State Florida