FEMAR

The Florida Keys coral reef extends 400 km southwest along an island archipelago from Key Biscayne near Miami to the Dry Tortugas region west of Key West.

The reef ecosystem is managed by different government agencies with specific spatial jurisdictions. Fisheries are managed by the Florida Fish and Wildlife Conservation Commission and two federal fishery management councils (U.S. South Atlantic and Gulf of Mexico). Fishing regulations can also apply in the Florida Keys National Marine Sanctuary (FKNMS) under NOAA (Department of Commerce); in three national parks (Biscayne, Everglades, Dry Tortugas) and four National Fish and Wildlife Refuges (Department of Interior); and in John Pennekamp Coral Reef State Park (Florida Department of Environmental Protection).

Unique topographic and oceanographic conditions help sustain the highly productive Florida Keys coral reef ecosystem. The coastal marine environment exhibits relatively little topographic variation, although the sea floor abruptly plummets to depths of 1500 m or more several kilometers seaward of the barrier reef tract. Oceanographic dynamics are influenced by the Loop Current in the southeastern Gulf of Mexico which merges with the Florida Current near the Dry Tortugas and then flows parallel to the barrier reef through the Straits of Florida towards Miami. This unique geophysical setting promotes dynamic oceanographic conditions comprised of intricate recirculating gyres and surface currents with some of the highest current speeds in the world (Stommel, 1976; Olson, 2001, 2002). The seaward edge of the barrier reef tract is usually subjected to open tidal exchange from the Florida Straits with its warm, clear, low nutrient waters conducive to coral reef development. These conditions are periodically interspersed with pulses of nutrient-rich waters from locally intense upwelling events along certain deep reef margins where some of the most luxuriant coral habitats are found (e.g., Miller et al., 2001; Olson, 2001, 2002; Ault et al., 2002).

The Florida Keys have a subtropical maritime climate with moderate temperatures and two seasons: the summer wet season (May–October), marked by numerous convective thunderstorms, and the winter dry season (November–April) which features infrequent, fast-moving, dry cold fronts. Water circulation in coastal bays is primarily influenced by tides and wind (Wang et al., 2003). During the wet season, fairly sharp salinity gradients exist in coastal bays in which near-freshwater conditions found along the coastal shoreline progressively change to near-oceanic conditions at the barrier islands.

Benthic habitats exhibit a distinct cross-shelf pattern. Fringing mangrove habitats occur on the land-sea edge of coastal bays and around barrier islands. Coastal bays have three main benthic habitat types: seagrass beds, bare unconsolidated substrates, and oolitic limestone hardbottoms populated with sponges and octocorals. Seaward of the barrier islands, benthic habitat types include stony coral patch reefs and barrier reefs, sponge-gorgonian covered hardbottoms, seagrass beds, and carbonate sands.

The Florida Keys have more than 500 fish species, including 389 that are reef-associated (Stark, 1968), and thousands of invertebrates, including corals, sponges, shrimps, crabs, and lobsters. Species in the snapper-grouper complex utilize a mosaic of cross-shelf habitats and oceanographic features over their life spans (Ault and Luo, 1998; Lindeman et al., 2000). Most adults spawn on the barrier reefs and sometimes form large spawning aggregations (Domeier and Colin, 1997). The Dry Tortugas region, in particular, contains numerous known spawning aggregation sites (Schmidt et al., 1999). Pelagic eggs and developing larvae are transported from spawning sites along the barrier reef tract by a combination of seasonal wind-driven currents and unique animal behaviors to eventually settle as early juveniles in a variety of inshore benthic habitats (Lee et al., 1994; Ault et al., 1999b). Some of the most important nursery habitats are located in the coastal bays and near barrier islands (Lindeman et al., 2000; Ault et al., 2001). As individuals develop from juveniles to adults, ontogenetic habitat utilization patterns generally shift from coastal bays to offshore reef environments.

Relationship of life history and ontogeny of the snapper-grouper complex to cross-shelf habitats and oceanographic processes.

3-D map showing the relashionship between terrestial and marine topography from the Everglades through the coral reef ecosystem (barrier coral reef is red)

Surface currents in the northern Caribbean, Gulf of Mexico, and Straits of Florida.

Surface currents from offshore (Strait of Florida) to inshore (biscayne Bay) in the coral reef ecosystem.

Bisacayne Bay salinity dynamics showing canal discharge points as histograms on the western shoreline.