ONTOGENETIC MIGRATION OF SNAPPER LINKS FOOD WEBS ACROSS A TROPICAL SEASCAPE IN THE RED SEA.
Many socio-ecologically important coral reef fishes undergo impressive ontogenetic migrations across tropical seascapes, linking distant habitats, populations, and food webs. We examined ontogenetic migration patterns of Ehrenberg's Snapper (Lutjanus ehrenbergii) populations on coastal and oceanic coral reefs in the Red Sea using a new otolith-based compound-specific stable isotope method. We then applied a new amino acid isotope fingerprinting approach within a Bayesian mixing model framework to identify the sources of primary producers (phytoplankton, coral, macroalgae, seagrass, and mangroves) fueling the local snapper populations during different stages of their ontogenetic migration. We found that seascape configuration played a critical role in determining migratory connectivity of L. ehrenbergii among essential habitats. We also found that L. ehrenbergii occupied fundamentally different resource niches associated with different phases of their ontogenetic migration. For instance, adult L. ehrenbergii on shelf reefs often relied heavily on a seagrass-based food web as juveniles before switching to a macroalgal-based food web once they migrated out to the adult population on shelf reefs. Conversely, adult L. ehrenbergii on offshore oceanic reefs typically showed minimal ontogenetic change in either habitat or baseline carbon source, relying heavily on a water column phytoplankton-based food web throughout their lives. Our work provides insights into the roles that ontogenetic migration plays in linking essential habitats and food webs across tropical seascapes.
McMahon, K. W., University of California, Santa Cruz, USA, firstname.lastname@example.org
Berumen, M. L., King Abdullah University of Science and Technology, Saudi Arabia, email@example.com
Thorrold, S. R., Woods Hole Oceanographic Institution, USA, firstname.lastname@example.org
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