Trophic niches determined from fatty acid profiles of sympatric coral reef mesopredators

Bierwagen, Stacy L., Pethybridge, Heidi, Heupel, Michelle R., Chin, Andrew, and Simpfendorfer, Colin A. (2019) Trophic niches determined from fatty acid profiles of sympatric coral reef mesopredators. Marine Ecology Progress Series, 632. pp. 159-174.

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Previous research has identified similar trophic levels in a wide range of coral reef sharks and large teleost fishes but has been unable to resolve the extent of dietary overlap and resource sharing that lead to interpretation of functional roles and, hence, adequately describe interaction strengths in food webs. We used fatty acid (FA) profiles of muscle and plasma reflecting the diet of several mesopredators to better understand the trophic structure and functioning of Great Barrier Reef ecosystems. Multivariate analysis identified significant dietary overlap between 2 shark species (whitetip reef shark Triaenodon obesus and grey reef shark Carcharhinus amblyrhynchos), but whitetip reef sharks occupied a smaller niche area than grey reef sharks. We also found clear niche separation between sharks and teleost fishes (red throat emperor, coral trout, and grass emperor). All mesopredators sampled had high proportions of polyunsaturated FAs linking them to carnivory, but differences among species in trophic biomarker ratios suggest distinctive dietary sources. However, based on a degree of niche overlap of species sharing common diet, reef-dwelling teleost fishes such as coral trout also derive nutrients from pelagic environments. A faster analytical method to determine FA profiles, proven highly useful in tuna, was tested and deemed viable for muscle tissue of tropical teleost fishes and sharks, while questions remain for use of FA extraction of plasma in ecological studies. These results demonstrate that fine-scale inter-specific differences in diet exist between mesopredators in coral reef ecosystems. Our results raise important questions about the ecological influences of these species and energy flow among mesopredators in coral reef ecosystems.

Item ID: 62205
Item Type: Article (Research - C1)
ISSN: 1616-1599
Keywords: ecological niche; dietary overlap; fatty acids; reef sharks; mesopredators
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Copyright Information: Copyright © 2019 Inter-Research. In accordance with the publisher's policies, this article will be available Open Access from ResearchOnline@JCU from 13 December 2024.
Additional Information:

A version of this publication was included as Chapter 4 of the following PhD thesis: Bierwagen, Stacy L. (2020) Functional roles of reef sharks on the Great Barrier Reef. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Great Barrier Reef Marine Park Authority (GBRMPA), CSIRO, Australian Institute of Marine Science, Paul G. Allen Philanthropies (PGAP)
Research Data:
Date Deposited: 04 Feb 2020 04:56
FoR Codes: 31 BIOLOGICAL SCIENCES > 3101 Biochemistry and cell biology > 310101 Analytical biochemistry @ 50%
41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410203 Ecosystem function @ 25%
31 BIOLOGICAL SCIENCES > 3103 Ecology > 310302 Community ecology (excl. invasive species ecology) @ 25%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 75%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 25%
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