Figure 3. Example of corals and algae found on Pulley Ridge: The plate corals Leptoseris cucullata (foreground) and Agaricia fragilis; the finger coral Madracis sp., the leafy green algae Anadyomene menziesii, and the branching algae Dictyota sp. Click image for credit and larger view.
Figure 1. Map of Pulley Ridge Habitat Area of Particular Concern (HAPC) showing multibeam sonar. Click image for credit and larger view.
Pulley Ridge is the deepest known photosynthetic coral reef off the continental U.S. Located in the Gulf of Mexico; it lies approximately 66 km west of the Dry Tortugas at the far end of the Florida Keys (Figure 1). Originally discovered in 1950, Pulley Ridge is approximately 300 km in length and 15 km wide.
Only the southernmost 30 km of Pulley Ridge represents a drowned barrier island with photosynthetic corals living between 60 to 75 m in depth. The dominant communities in these reefs, also known as mesophotic coral ecosystems, are coralline algae and scleractinian corals. Fish species present at Pulley Ridge represent a mix of both shallow and deep water species.
According to the U.S. Geological Survey (USGS), the coral on Pulley Ridge was “considerably healthier then coral from shallow water reefs nearly worldwide.” With the well-documented decline of coral reefs in the Florida Keys, the health of reefs on Pulley Ridge provided hope that these reefs may be able to help replenish shallower reefs in the Florida Keys.
Pulley Ridge was designated a Habitat Area of Particular Concern in 2005 by the Gulf of Mexico Fishery Management Council. It is protected from fishing using bottom trawls, longlines, buoy gear, and traps/pots. (For more information on management, see Pulley Ridge: Looking Upstream.)
Figure 2. Some of the species of algae found on Pulley Ridge: unidentified red coralline, leafy green Anadyomene menziesii, and the green calcareous Halimeda tuna. Click image for credit and larger view.
Southern Pulley Ridge has an array of photosynthetic hard corals, macroalgae, sponges, and reef fishes. Based on photographs collected by USGS, Pulley Ridge is dominated by hard coralline algae, which covers 45-65% of the seafloor. It is also home to a wide variety of fleshy macroalgae including Halimeda tuna, Dictyota sp., Kallymenia sp., and the endemic species Anadyomene menzeisii, which looks like a large head of lettuce and can be as dense as tens of plants per square meter (Figure 2).
Figure 4. Red grouper Epinephelus morio in pit with purple reeffish Chromis scotti on Pulley Ridge. Click image for credit and larger view.
Pulley Ridge is home to more than 60 species of shallow and deep reef fish species, including the commercially important species Epinephelus morio – the red grouper (Figure 4). Red grouper form large 6-10 m wide pits in the sand and rubble bottom that provide shelter like an oasis for numerous smaller reef fish.
For more information on Pulley Ridge, see http://coastal.er.usgs.gov/pulley-ridge/index.html.