Journal
CORAL REEFS
Volume 31, Issue 2, Pages 357-367Publisher
SPRINGER
DOI: 10.1007/s00338-011-0850-3
Keywords
Elasmobranch; Food web; Acoustic monitoring; Residency; delta C-13; delta N-15
Categories
Ask authors/readers for more resources
Establishing the ecological role of predators within an ecosystem is central to understanding community dynamics and is useful in designing effective management and conservation strategies. We analysed differences in the trophic ecology of four species of reef sharks (Carcharhinus melanopterus, Carcharhinus amblyrhynchos, Triaenodon obesus and Negaprion acutidens) at Ningaloo Reef, Western Australia, by analysing tissue stable isotopes (delta N-15 and delta C-13). We also monitored animals using acoustic telemetry to determine long-term residency patterns in a bay at the southern end of the reef, Coral Bay. Overall, mean delta C-13 was similar among species, ranging between -10.9 and -11.8aEuro degrees, suggesting a food-web dependency on coastal producers. Classification and regression tree analysis identified an effect of species on delta N-15 that separated C. amblyrhynchos and C. melanopterus from N. acutidens and T. obesus. For C. amblyrhynchos and C. melanopterus, animals were also divided by size classes, with smaller sharks having lower average delta N-15 than larger animals; this suggests that delta N-15 increases with size for these two species. Juvenile C. melanopterus, juvenile N. acutidens and adult T. obesus had trophic levels of 3.7, for juvenile C. amblyrhynchos and adult C. melanopterus it was 4, and adult C. amblyrhynchos had a value of 4.3. Trophic-level estimates for C. melanopterus and C. amblyrhynchos corroborate previous conclusions based on diet studies. We found no evidence for a difference in isotopic composition between resident and non-resident sharks. The lack of variation in isotopic composition was consistent with high mean residency of these species recorded using acoustic telemetry, which was 79% (+/- 0.09 SE) of days monitored for T. obesus, followed by N. acutidens (57 +/- A 19.55%), C. amblyrhynchos (54 +/- A 13%) and C. melanopterus (33 +/- A 8.28%). High delta C-13 composition in reef sharks and long-term residency behaviour suggest that coastal marine reserves might provide effective conservation refuges for some species.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available