Early Life History, Habitat Use, and Microsatellite Allele Frequency of Two Common Reef Fishes (Stegastes partitus and Thalassoma bifasciatum) in Marine Protected Areas of the Northwestern Gulf of Mexico

Abstract

Two common reef fishes, the bluehead wrasse (Thalassoma bifasciatum) and the bicolor damselfish (Stegastes partitus), are used as model species for understanding the function of marine protected areas (MPAs) in the northwestern Gulf of Mexico (GOM). These species have contrasting life histories, which represent a spectrum of common life histories of reef fish. Here, the early life history, habitat associations, and population genetics of these two common reef fishes, in the northwestern GOM are examined to help acquire a better understanding of the nursery, or larval settlement, value of the region. Because the banks examined here are near the northern limits of reef coral growth, and are isolated from other nursery areas such as seagrasses or mangroves they could serve as stepping stones for replenishment and dispersal of larvae throughout this region. East Flower Garden Banks (EFGB) and West Flower Garden Banks (WFGB) are both dominated by scleractinian corals, with higher rugosity, or more varied substrate topography, while Stetson Bank and Sonnier Bank are both dominated by rock, sand, and algae cover, and have lower average rugosities. There does not appear to be a clear substrate preference for either species post-settlement in this region. There was a significant difference in density of bicolor damselfish between banks, but not for bluehead wrasse. There was a significant difference in PLD of bluehead wrasse between banks but not for bicolor damselfish. Bluehead wrasse exhibit a longer less variable PLD than bicolor damselfish. Back-calculations suggested a slightly higher length-at-settlement value for bluehead wrasse compared to surrounding regions, and bicolor damselfish showed an average length-at-settlement value about twice that of surrounding regions. The bicolor damselfish examined here show evidence of local retention while the bluehead wrasse show evidence or broader dispersal, this further supports studies done in surrounding regions such as the Caribbean.