Foraging ecology of five toothed whale species in the Northwest Iberian Peninsula, inferred using carbon and nitrogen isotope ratios

Paula Mendez-Fernandez*, Paco Bustamante, Antonio Bode, Tiphaine Chouvelon, Marisa Ferreira, Alfredo Lopez, Graham J. Pierce, M. Begona Santos, Jerome Spitz, Jose V. Vingada, Florence Caurant

*Corresponding author for this work

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

The feeding ecology and habitat use of the most frequently sighted and/or regularly reported stranded or bycaught
toothed whale species of the North Western Iberian Peninsula (NWIP) were examined, with a special
focus on their trophic position (TP) and relationships with their prey. With this aim, the stable isotope ratios
of carbon (d13C) and nitrogen (d15N) of common dolphin (Delphinus delphis), bottlenose dolphin (Tursiops
truncatus), harbour porpoise (Phocoena phocoena), striped dolphin (Stenella coeruleolba) and long-finned
pilot whale (Globicepahala melas) were analyzed in muscle samples taken from stranded and by-caught
animals between 2004 and 2008. Stable isotopes were also measured in 17 species of fish and cephalopods
previously identified as prey species, based on stomach content analyses, and in plankton. The trophic enrichment
factors (TEF) were calculated for all five species and in addition, isotopic mixing models were applied to
estimate the proportional contribution of each prey source to the diet of the common dolphin, which was the
toothed whale species best sampled in our study. Plankton, fish and cephalopods exhibited an increasing
trend in their d13C values (from-19.6‰to-15.3‰) along the offshore-inshore axis, with a less clear spatial
pattern observed for d15N values. Striped dolphins exhibited the lowest mean d13C, d15N and TP values
(-17.6‰, 10.8‰ and 4.3, respectively), which confirms the oceanic character of this species and its lower
trophic position when compared to the other toothed whales analyzed. The common dolphin exhibited
mean d13C, d15N and TP values that were at an intermediate level (-17.0‰, 11.7‰ and 4.7, respectively)
and results of the mixing model indicated that blue whiting (Micromesistius poutassou) was the main component
of the diet. The harbour porpoise, bottlenose dolphin and pilot whale exhibited higher and very similar
isotopic compositions and TPs. The mean TEF obtained between predators and their main prey were 1.4‰ for
d15N and 0.8‰ for d13C. These results provide information on stable isotope incorporation data for toothed
whales, which are essential if conclusions are to be drawn in issues concerning trophic structures and habitat
use in the NWIP.
Original languageEnglish
Pages (from-to)150-158
Number of pages9
JournalJournal of Experimental Marine Biology and Ecology
Volume413
Early online date13 Jan 2012
DOIs
Publication statusPublished - 10 Feb 2012

Keywords

  • Stable isotopes
  • Toothed whales
  • Trophic position
  • Trophic relationships
  • Isotopic mixing model
  • North West Iberian Peninsula
  • Bottle-nosed dolphins
  • Marine mammals
  • Stable-isotopes
  • Galician Waters
  • Food-web
  • Delta-N-15 measurements
  • Stenella-Coeruleoalba
  • Tursiops-Truncatus
  • Northeast Atlantic
  • Feeding ecology

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