Bowen 9727048 This research will use molecular genetic technology to investigate the limits of dispersal for reef fishes among the four primary reef habitats of the tropical Atlantic: Caribbean Sea, Brazil, mid-Atlantic ridge (Ascension Island), and Gulf of Guinea (West Africa). DNA sequences will be compared among populations of French angelfish (Pomacanthus paru), blackbar squirrelfish (Myripristis jacobus) and five other species to track patterns of colonization and gene flow across the Atlantic Ocean. Reef fish don't move much as adults, so dispersal is accomplished primarily by drifting eggs and larvae. How far can reef fish disperse as larvae? This question is of fundamental importance for understanding the natural recolonization of reef habitats damaged by anthropogenic factors. Reef habitats in Brazil and the Caribbean Sea are separated by 2000 kms of muddy coastline (between the Orinoco and Amazon River basins). West Atlantic reefs are separated from African reefs by 4000 kms of open ocean. Population genetic assessments at these two geographic scales should resolve the limitations of reef fish dispersal. A central focus of this research is the role of Ascension Island on the mid-Atlantic ridge in facilitating colonization between east and west Atlantic. If Ascension Island functions as a stepping stone for colonization across the Atlantic, then this oceanic island may play a substantial (and previously unrecognized) role in enhancing the biodiversity of West Atlantic reef habitats.
