Stable isotope analysis in two sympatric populations of bottlenose dolphins Tursiops truncatus: evidence of resource partitioning?

Ruth Fernandez, Susana Garcia-Tiscar, M. Begona Santos, Alfredo Lopez, Jose A. Martinez-Cedeira, Jason Newton, Graham J. Pierce

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Abstract

Skin and muscle from 43 bottlenose dolphins (38 juveniles/adults, 5 calves) stranded in NW Spain were analysed to determine whether stable isotope ratios (delta C-13 and delta N-15) could be used to assess dietary variation, habitat segregation and population substructure. Results were compared with published stomach contents data. Stable isotope ratios from 17 known prey species were also determined. Isotope ratios of the main prey (blue whiting, hake) varied significantly in relation to fish body size. Dolphin calves showed significant heavy isotope enrichments compared to adult females. Excluding calves, delta N-15 decreased with increasing dolphin body size, probably related to an ontogenetic shift in diet towards species at lower trophic levels, e.g. on blue whiting as suggested by stomach content results. Bottlenose dolphins were divided into two putative populations (North, South) based on previous genetic studies, and values of delta C-13 and delta N-15 differed significantly between these two groups, confirming the existence of population structuring.

Original languageEnglish
Pages (from-to)1043-1055
Number of pages13
JournalMarine Biology
Volume158
Issue number5
Early online date10 Jan 2011
DOIs
Publication statusPublished - May 2011

Keywords

  • Hake Merluccius-Merluccius
  • Whales globicephala-melas
  • Marine mammals
  • Nitrogen Isotopes
  • Galican waters
  • Diet
  • Carbon
  • Patterns
  • Western
  • SPAIN

Cite this

Fernandez, R., Garcia-Tiscar, S., Begona Santos, M., Lopez, A., Martinez-Cedeira, J. A., Newton, J., & Pierce, G. J. (2011). Stable isotope analysis in two sympatric populations of bottlenose dolphins Tursiops truncatus: evidence of resource partitioning? Marine Biology, 158(5), 1043-1055. https://doi.org/10.1007/s00227-011-1629-3