Multi-tissue stable isotope analysis reveals resource partitioning and trophic relationships of large reef-associated predators

Espinoza, Mario, Matley, Jordan, Heupel, Michelle R., Tobin, Andrew J., Fisk, Aaron T., and Simpfendorfer, Colin A. (2019) Multi-tissue stable isotope analysis reveals resource partitioning and trophic relationships of large reef-associated predators. Marine Ecology Progress Series, 615. pp. 159-176.

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Defining the role of reef predators is particularly important given the rapid rate at which some species are declining, yet knowledge of trophic relationships is often lacking, particularly for large wide-ranging species that may use coral reefs seasonally or opportunistically. We used a multi-tissue stable isotope approach to investigate the trophic ecology of common reef predators in the central Great Barrier Reef of Australia. Our study revealed significant trophic separation among reef predators, especially when considering isotopic data from muscle, a slower turnover tissue. Based on muscle data, the bull shark Carcharhinus leucas, a large wide-ranging coastal species, occupied a higher trophic position and had a larger isotopic niche breadth (19.12) relative to smaller predators, including resident sharks (4.5 ± 0.72) and large-bodied teleosts (4.4 ± 1.82). Spanish mackerel Scomberomorus commerson and bull sharks had the largest unique total areas of isotopic niche space (expressed as a percentage) that did not overlap with any other species, 95% and 69.4%, respectively, which means they had lower isotopic overlap. In general, faster turnover tissues such as whole blood and plasma showed higher isotopic overlap and smaller niche breadth for all reef predators. These results suggest that bull sharks use similar prey resources to large and small resident predators, at least during short periods. Our findings highlight the importance of investigating dietary changes in faster-turnover tissues of reef predators, particularly large wide-ranging species, which may have key roles in coral reef food webs through direct predation and competition.

Item ID: 61840
Item Type: Article (Research - C1)
ISSN: 1616-1599
Keywords: Coral reef, Food web, Great Barrier Reef, Shark, Spatial ecology, Trophic ecology
Copyright Information: © Inter-Research 2019.
Funders: National Environmental Research Program (NERP), Australian Research Council (ARC), Canada Research Chairs Program, PADI Foundation, Australian Endeavour Program, AIMS@JCU
Projects and Grants: NERP Tropical Ecosystems Hub Project 6.1, ARC FT1000101004
Date Deposited: 21 May 2020 04:48
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 100%
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