Multi-disciplinary approach identifies pelagic nutrient linkage by sawsharks

Patrick J. Burke*, Lauren Meyer, Vincent Raoult, Charlie Huveneers, Jane E. Williamson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Quantifying the trophic role of a species is key to understanding its ecology and ecological role. Their trophic role can influence community composition, ecosystem stability, and nutrient transport and cycling between habitats through ingestion, egestion, and excretion, which requires an understanding of species diet and habitat use. Despite the regular occurrence of sawsharks in Australian temperate fisheries, there remains limited information on their trophic ecology or habitat use, but they are assumed to be benthic consumers. We used fatty acid and stable isotope profiles along with stomach content analysis to investigate the trophic ecology of two sympatric species of sawsharks, the common sawshark (Pristiophorus cirratus) and southern sawshark (Pristiophorus nudipinnis) in south-eastern Australia. Stable isotope analysis of δ13C, δ15N, and δ34S in sawshark muscle revealed that P. nudipinnis fed at a higher trophic level than P. cirratus, and mixing models and stomach contents indicated P. nudipinnis was surprisingly reliant on pelagic and benthopelagic prey sources. In contrast, P. cirratus preyed on more benthic invertebrate species, not found in P. nudipinnis. This bentho-pelagic partitioning between species was supported by P. nudipinnis fatty acid profiles having higher levels of tracers associated with dinoflagellate basal sources (16:1/16:0, 22:6ω3) than P. cirratus, indicating a reliance on pelagic food webs. These data demonstrate that sawsharks are mesopredators that play a substantial role linking pelagic and benthic food webs and highlights the value of incorporating multiple biochemical tracers to provide a comprehensive representation of an animal’s trophic ecology and role in and between ecosystems.

Original languageEnglish
JournalReviews in Fish Biology and Fisheries
Early online date28 Aug 2024
DOIs
Publication statusE-pub ahead of print - 28 Aug 2024

Bibliographical note

Copyright the Author(s) 2024. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Connectivity
  • Fatty acid analysis
  • Sawshark
  • Stable isotope analysis
  • Stomach content
  • Trophic ecology

Cite this