Feeding biomechanics of juvenile red snapper (Lutjanus campechanus) from the northwestern Gulf of Mexico.

Juvenile red snapper settle across several complex habitats, which function as nurseries for young fish. Little is known about their life history or feeding biomechanics during this time. However, recent studies have shown higher growth rates for juveniles located on mud habitats adjacent to low profile reefs, perhaps because of varied prey availability and abundance. To further investigate the habitat needs of juvenile red snapper and test hypotheses of feeding development, individuals were collected from a low profile shell ridge and adjacent mud areas on Freeport Rocks, TX, USA, and divided into three size classes (< or = 3.9, 4.0-5.9, > or = 6.0 cm SL). Output from a dynamic lever model suggested an ontogenetic shift in feeding morphology. Biomechanical modeling also predicted that off-ridge juveniles would have slower, stronger jaws compared with on-ridge juveniles. Kinematic profiles obtained from actual feeding events validated the models' predictive ability. Analysis of prey capture events demonstrated that on-ridge juveniles exhibited larger jaw displacements than off-ridge juveniles. Shape analysis was used to further investigate habitat effects on morphology. Off-ridge juveniles differed from on-ridge juveniles in possessing a deeper head and body. Results from model simulations, kinematic profiles, behavioral observations and shape analysis all compliment the conclusion that on-ridge juveniles exhibited more suction feeding behavior, whereas off-ridge juveniles used more biting behavior. Habitat disparity and possibly available prey composition generated variations in juvenile feeding biomechanics and behavior that may affect recruitment.