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.
