Gut content and stable isotope analyses provide complementary understanding of ontogenetic dietary shifts and trophic relationships among fishes in a tropical river

Davis, Aaron M., Blanchette, Melanie L., Pusey, Bradley J., Jardine, Tim D., and Pearson, Richard G. (2012) Gut content and stable isotope analyses provide complementary understanding of ontogenetic dietary shifts and trophic relationships among fishes in a tropical river. Freshwater Biology, 57 (10). pp. 2156-2172.

[img] PDF (Published Version) - Published Version
Restricted to Repository staff only

View at Publisher Website: http://dx.doi.org/10.1111/j.1365-2427.20...
 
54
5


Abstract

1. Despite widespread recognition of the role of body size in fish trophic ecology, little attention has been focused on this issue in isotopic studies, particularly in tropical systems.

2. We used analyses of stomach contents and stable isotopes to examine size-related shifts in diet in a terapontid fish assemblage in the Australian wetdry tropics. Stomach content analysis identified substantial ontogenetic dietary shifts in all species, corresponding to changes in body sizeisotope trajectories for two species. Shifts away from relatively specialised diets of heavily ¹³C-depleted insect larvae to consumption of a range of items across multiple basal carbon sources appeared to be the proximate cause of observed isotopic changes.

3. Allochthonous organic matter in the form of C3 riparian vegetation was particularly important to smaller terapontids before larger fish shifted to a broad range of dietary items and similarly broad range of basal carbon sources.

4. While there was general agreement between δ¹³C and stomach content analysis, there was minimal concurrence between the latter and δ¹⁵N isotopic derivation of estimates of trophic position. Due to factors such as omnivory, isotopically overlapping basal sources and uncertainties about rates of isotopic fractionation in both predator and prey species, stomach content analysis provides an essential complement to isotopic methodologies in tropical systems.

5. Given that basal sources supporting any individual species can change markedly with ontogeny, consideration of intraspecific, size-related variation is necessary in isotopic studies of food web structure.

Item ID: 23638
Item Type: Article (Refereed Research - C1)
Keywords: body size, feeding ecology, mixing model, omnivory, organic matter
ISSN: 0046-5070
Date Deposited: 10 Oct 2012 05:25
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060204 Freshwater Ecology @ 100%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960506 Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments @ 100%
Downloads: Total: 5
More Statistics

Actions (Repository Staff Only)

Item Control Page Item Control Page