Isotopic niche overlap between sympatric Australian snubfin and humpback dolphins

Guido J. Parra, Zachary Wojtkowiak, Katharina J. Peters, Daniele Cagnazzi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

Ecological niche theory predicts the coexistence of closely related species is promoted by resource partitioning in space and time. Australian snubfin (Orcaella heinsohni) and humpback (Sousa sahulensis) dolphins live in sympatry throughout most of their range in northern Australian waters. We compared stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) in their skin to investigate resource partitioning between these ecologically similar species. Skin samples were collected from live Australian snubfin (n = 31) and humpback dolphins (n = 23) along the east coast of Queensland in 2014–2015. Both species had similar δ13C and δ15N values and high (>50%) isotopic niche space overlap, suggesting that they feed at similar trophic levels, have substantial dietary overlap, and rely on similar basal food resources. Despite similarities, snubfin dolphins were more likely to have a larger δ15N value than humpback dolphins, indicating they may forage on a wider diversity of prey. Humpback dolphins were more likely to have a larger δ13C range suggesting they may forage on a wider range of habitats. Overall, results suggest that subtle differences in habitat use and prey selection are likely the principal resource partitioning mechanisms enabling the coexistence of Australian snubfin and humpback dolphins.

Original languageEnglish
Article numbere8937
Number of pages11
JournalEcology and Evolution
Volume12
Issue number5
DOIs
Publication statusPublished - May 2022

Keywords

  • cetaceans
  • ecological niche
  • feeding ecology
  • Orcaella heinsohni
  • resource partitioning
  • SIBER
  • Sousa sahulensis
  • stable isotopes

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