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The trophic ecology of blacktip reef sharks on a sea turtle nesting site in Peninsular Malaysia, using stable isotope analysis

par Serrurier-Arabadjieva, Margot
Promoteur Mohd Abdullah, Maizah
Co-Promoteur Kochzius, Marc
Publication Non publié, 2024-08-29

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Résumé :

Reef shark populations are declining worldwide, and there is an important gap of knowledgeregarding their ecology in Southeast Asia. This group of species have been commonlyconsidered as apex predators, but spatiotemporal changes in their diet and feeding behaviorhas complicated our understanding of their trophic ecology. In the present study, we usedstable isotope analysis to investigate the trophic ecology of the blacktip reef shark(Carcharhinus melanopterus), a common reef shark in the Indo-Pacific, using fin and bloodtissues over two different years. We assessed the trophic position of C. melanopterusrelative to teleost mesopredators and estimated the contribution of green sea turtlehatchlings (Chelonia mydas) in their diet at a turtle nesting site in eastern Malaysia. Wefound that C. melanopterus shares a similar trophic position with snappers and grouperspresent on the reef, suggesting that they share a common functional role on coral reefs. Wealso found that hatchlings are not a dominant prey in the long-term diet of C. melanopterus,most likely because this prey is only available and abundant during turtle nesting season.However, hatchlings were found to be a prevalent prey during the nesting season, suggestingthat C. melanopterus focusses its predation activity towards this prey when available. As theblacktip reef sharks and the green sea turtle are both endangered species, the present studyreports first valuable insights on their trophodynamics and raises the urgent need for morestudies focussing on the ecology of reef predators in Southeast Asia.