Texas Great Barrier Reef

Optimizing Artificial Reef Design: Feeding Habits and Forage Area Interactions of Fish Assemblages
Lead Researcher: Stephen Bortone

Project number and duration: R/LR-B-35, 1993-1995

Question: With artificial reefs seen as one solution to decline in fish stocks, scientists would like to know the most effective reef configuration - the size and shape of the artificial reef - for boosting fish numbers. This project sought to begin addressing this question by asking a more fundamental question: What do fish eat at artificial reefs and where exactly do they feed?

Project: Researchers collected specimens representing 25 of the most common reef-dwelling species from bridge rubble artificial reefs between 2 and 5 kilometers offshore in the northern Gulf of Mexico near Panama City. Depending on size, divers speared or netted the fish, which were then preserved using Formalin solution. The researchers then removed the fishes' stomachs and analyzed their contents.

Results: Scientists identified 44 taxa of prey altogether, including two algal divisions and eight animal phyla, including polychaetes (segmented worms in the phylum Annelida), three classes of mollusks, two classes of arthropods, echinoderms and chordates. Seventeen of the 25 fish species had clear dominant prey items. The breakdown included 1) The fish eaters: cardinal fish, Apogon pseudomaculatus, the tomtate grunt, hameulon aurolineatium, the gag grouper, Mycteroperca microlepsis, the gray snapper, Lutjanus griseus, flounder, Paralicthys albiguta and greater amberjack, Seriola dumerili 2) The Xnathid crab eaters: black sea bass, Centropristis ocyurus, cubbyu, Equetus umbrosus, the gulf goadfish, Opasanus beta, Rypticus maculates and the belted sandfish, Serranus subligarius. And 3) Polychaetes eaters: the pigfish, Orthoprists chrysoptera, and the cocoa damselfish, Pomacentrus variabilis. The scientists couldn't determine the preference of seven of the remaining fish species because their stomach contents were unidentifiable. Overall, the study determined that the most important prey items were fishes followed by xanthid crabs, while algae was not an important prey taxa. The study also determined the feeding fish could be organized into seven distinct guilds: lower structure pickers, ambush predators, lower structure crustacean predators, upper structure pickers, upper structure predators, water column pickers and reef associated open water feeders.

Impact: Understanding of what fish feed on, and where they feed, should provide clues to scientists and managers on what artificial reef configurations may impact different fish species.

Publications: Articles about this research appeared in journals including Gulf of Mexico Science.