title: Resolving the trophic relations of cryptic species: an example using stable isotope analysis of dolphin teeth.
abstract: Understanding the foraging ecology and diet of animals can play a crucial role in conservation of a species. This is particularly true where species are cryptic and coexist in environments where observing feeding behaviour directly is difficult. Here we present the first information on the foraging ecology of a recently identified species of dolphin (Southern Australian bottlenose dolphin (SABD)) and comparisons to the common bottlenose dolphin (CBD) in Victoria, Australia, using stable isotope analysis of teeth. Stable isotope signatures differed significantly between SABD and CBD for both δ(13)C (-14.4‰ vs. -15.5‰ respectively) and δ(15)N (15.9‰ vs. 15.0‰ respectively), suggesting that the two species forage in different areas and consume different prey. This finding supports genetic and morphological data indicating that SABD are distinct from CBD. In Victoria, the SABD is divided into two distinct populations, one in the large drowned river system of Port Phillip Bay and the other in a series of coastal lakes and lagoons called the Gippsland Lakes. Within the SABD species, population differences were apparent. The Port Phillip Bay population displayed a significantly higher δ(15)N than the Gippsland Lakes population (17.0‰ vs. 15.5‰), suggesting that the Port Phillip Bay population may feed at a higher trophic level--a result which is supported by analysis of local food chains. Important future work is required to further understand the foraging ecology and diet of this newly described, endemic, and potentially endangered species of dolphin.
authors.affiliation: Australian Centre for Biodiversity and School of Biological Sciences, Monash University, Victoria, Australia. kylie.owen3@optusnet.com
authors.forename: Kylie
authors.initials: K
authors.lastname: Owen
authors.forename: Kate
authors.initials: K
authors.lastname: Charlton-Robb
authors.forename: Ross
authors.initials: R
authors.lastname: Thompson
mesh_terms: D000818:Animals; D001315:Australia; D050681:Bottle-Nosed Dolphin / Q000378:metabolism / Q000502:physiology; D004032:Diet; D017753:Ecosystem; D056727:Endangered Species; D004784:Environmental Monitoring / Q000379:methods; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D020387:Food Chain; D007553:Isotope Labeling / Q000379:methods / Q000662:veterinary; D008297:Male; D009587:Nitrogen Isotopes / Q000493:pharmacokinetics; D011156:Population Density; D011157:Population Dynamics; D014070:Tooth / Q000737:chemistry* / Q000378:metabolism
chemical_list: D009587:Nitrogen Isotopes