Abstract

The Florida Keys National Marine Sanctuary is in the process of creating one or more no-take marine reserves in the Dry Tortugas region. Initial recommendations call for the creation of two reserves: Tortugas North, encompassing the northern parts of Dry Tortugas National Park, Tortugas Bank, and adjacent areas; and Tortugas South. encompassing Riley's Hump and deepwater habitats to the south. These areas are expected to be important because tbey include reefs with high coral cover and fish spawning sites upstream from the Florida Keys, yet little is known about the habitat characteristics, reef fish community, and larval dispersal from these areas, especially the proposed Tortugas South reserve. We conducted visual surveys in the Riley's Hump area of the proposed Tortugas South reserve to characterize its habitat composition and reef fish community. Several surveys during the full moon of late May - early June 1999, a time of expected spawning activity, were focused on areas identified as potential spawning aggregation sites for mutton snapper, Lutjanus analis. Satellite-tracked drifter buoys, released al the expected time and location of spawning, were used to examine potential larval dispersal pathways.\Results suggest that, although coral cover is relatively low on Riley's Hump, reef fish diversity is high and includes species that are rare elsewhere in the Florida Keys. Snapper species occurred in relatively high densities, and several female mutton snapper with ripe eggs were collected, suggesting spawning occurred at this time. Larvae spawned on Riley's Hump at this time may have been transported to nursery areas in the Florida Keys and Biscayne Bay, possibly even as far north as Palm Beach. The information we collected is essential to understanding the potential importance of the proposed reserve area for conserving biodiversity, building spawning stock biomass, and supporting fisheries throughout the Florida Keys via larval replenishment.

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