The Role of Sea-Whip Coral (Leptogorgia sp.) as Habitat of Temperate Near-Shore Fish of Gulf of Mexico Jetties

Abstract

Many fish species use intercoastal jetties throughout their life cycle to migrate to and from the ocean into bays and estuaries. During migration, fish may encounter rock, algae, sand, sea-grass, and coral. Anecdotal information indicates that some migrating fish of intercoastal jetties preferentially select colonies of gorgonian coral (Leptogorgia spp.) vs. any other habitat when encountering a predator.  Since very little information exists regarding Leptogorgia, we focused our study in determining the importance of such coral as fish habitat.  Stationary field sampling was conducted seasonally to determine the abundance of these coral, the type of migrating fish, and the habitat they associated with.  Mesocosm studies were then conducted to determine whether Leptogorgia habitats are important to fish in the presence or absence of a predator.  Five different habitats were compared (rock, algae, sand, Leptogorgia, and seagrass) and 6 species of fish (sergeant major, pinfish, mangrove snapper, spotfin mojarra, pigfish, and red drum). In the field study component, more than 600 colonies of Leptogorgia were observed and 17 different fish species.  The most commonly observed fish were sergeant major, pinfish, mangrove snapper, and spotfin mojarra, however, sergeant majors were the most abundant species using coral as habitat.  The use of mesocosms showed that all fish species significantly selected for structured habitat over non-structured habitat (e.g. sand), but that the fish commonly called ‘sergeant major’ significantly (ANOVA; p ≤ 0.001) selected for Leptogorgia.