Crossing from shallow inshore to deep continental shelf habitats: Benthic-pelagic coupling and trophic position of the Lane snapper, Lutjanus synagris, in a tropical seascape

N) of L. synagris, basal sources and consumers from both benthic and pelagic pathways to model trophic position (TP) and assess trophic support. TP were consistent regardless of whether basal sources or consumers served as baselines, although the model based on basal consumers produced narrower credible intervals. TP increased from inshore to continental shelf habitats, primarily reflecting increases in fish size; however, no significant differences were observed between shallow and mesophotic shelf areas. Mixing models based on basal consumer baselines further revealed that in seagrass meadows, coastal reefs, and mesophotic shelf habitats, the Lane snapper derives trophic support from both benthic and pelagic sources, whereas benthic support predominates in mangroves and shallow shelf habitats. Pelagic support showed a positive correlation with depth across the continental shelf, which could be related to physical and geological processes, such as upwelling near the shelf break and through submarine canyons, that augment pelagic subsidies, particularly when benthic production is limited at greater depths. In summary, our findings underscore the significance of both physical geological and biological drivers in shaping the trophic dynamics and ontogenetic habitat use of L. synagris. These insights emphasize the necessity of sustaining spatial connectivity among marine protected areas to maintain robust trophic interactions and overall ecosystem health.