Title

Elucidating the role of competition in driving spatial and trophic niche patterns in sympatric juvenile sharks

Authors

Ornella C. Weideli, PSL Research University; Save our Seas Foundation; Soneva Fushi; Dr Risch Medical Laboratory
Ryan Daly, South African Institute for Aquatic Biodiversity; Oceanographic Research Insitute
Lauren R. Peel, Save our Seas Foundation
Michael Heithaus, Florida International University
Mahmood Shivji, Nova Southeastern UniversityFollow
Serge Planes, PSL Research Institute
Yannis P. Papastamatiou, Florida International University

Document Type

Article

Publication Date

3-17-2023

Publication Title

Oecologia

Keywords

Carcharhinus melanopterus, Coexistence, Difference in dominance, Interspecific competition, Negaprion acutidens

ISSN

0029-8549

Volume

201

First Page

673

Last Page

688

Abstract

The coexistence of ecologically and morphologically similar species is often facilitated by the partitioning of ecological niches. While subordinate species can reduce competition with dominant competitors through spatial and/or trophic segregation, empirical support from wild settings, particularly those involving large-bodied taxa in marine ecosystems, are rare. Shark nursery areas provide an opportunity to investigate the mechanisms of coexistence. We used experimental and field studies of sympatric juvenile sharks (blacktip reef shark, Carcharhinus melanopterus; sicklefin lemon shark, Negaprion acutidens) to investigate how competitive ability influenced realized niches at St. Joseph Atoll, Seychelles. Captive trials revealed that sicklefin lemon sharks were dominant over blacktip reef sharks, consistently taking food rewards. In the field, blacktip reef sharks were captured over a broader area than sicklefin lemon sharks, but daily space use of actively tracked sharks showed a high degree of overlap across microhabitats. While stomach contents analysis revealed that blacktip reef shark diets included a broader range of prey items, stable isotope analysis demonstrated significantly higher mean δ13C values for sicklefin lemon sharks, suggesting diverging dietary preferences. Overall, our results matched theoretical predictions of subordinate competitors using a greater range of habitats and displaying broader feeding niches than competitively dominant species. While separating the realized and fundamental niche of marine predators is complicated, we provide evidence that resource partitioning is at least partially driven by interspecific competition.

Comments

This study was gratefully funded by the Save Our Seas Foundation (SOSF) awarded to OCW (SOSF Keystone Grant 290) and MSS (SOSF Grant 157—genetic analyses).

NSUWorks Citation

Weideli, Ornella C.; Ryan Daly; Lauren R. Peel; Michael Heithaus; Mahmood Shivji; Serge Planes; and Yannis P. Papastamatiou. 2023. "Elucidating the role of competition in driving spatial and trophic niche patterns in sympatric juvenile sharks." Oecologia 201, (): 673-688. doi:10.1007/s00442-023-05355-4.

ResearcherID

G-4080-2013

DOI

10.1007/s00442-023-05355-4