Trophic Subsidies in the Twilight Zone: Food Web Structure of Outer Continental Shelf Reef Fishes

Douglas C. Weaver and K.J. Sulak
Florida Caribbean Science Center-USGS-BRD, 7920 NW 71st St., Gainesville, FL 32653; Phone: (352) 378-8181; Email: doug_weaver@usgs.gov

Food web structure of reef fishes was examined along the Mississippi-Alabama outer continental shelf. Fish communities on high-profile topographic features are numerically dominated by roughtongue bass, Pronotogramus martinicensis, and red barbier Hemanthias vivanus. Stomach content analysis reveals those calanoid copepods, mollusk larvae and pelagic tunicates dominate the diet of both species, and these fishes in turn serve as prey for large reef predators. Seasonal shifts in the diet of planktivores were also evident. Fish eggs and fish larvae constitute a greater portion of stomach contents in Feb/March samples, and indicate trophic links to pelagic, soft-bottom, and possibly inshore primary production (via spawning aggregations of large, migrating species). Dietary shifts in large predatory species reveals that pelagic plankton and planktivorous reef fishes form the primary trophic pathways through the year for common fishes in the deep reef community.