Habitat and Fauna of Deep-Water Lophelia Pertusa Coral Reefs Off the Southeastern U.S.: Blake Plateau, Straits of Florida, and Gulf of Mexico
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BULLETIN OF MARINE SCIENCE, 78(2): 343–375, 2006 CORAL REEF PAPER Habitat anD Fauna of Deep-Water LOPHELIA PERTUSA CORAL Reefs off the Southeastern U.S.: BlaKE Plateau, Straits of FloriDA, anD Gulf of MEXico John K. Reed, Doug C. Weaver, and Shirley A. Pomponi Abstract Expeditions from 1999 to 2004 for biomedical research explored various deep-sea coral ecosystems (DSCE) off the southeastern U.S. (Blake Plateau, Straits of Florida, and eastern Gulf of Mexico). Habitat and benthos were documented from 57 dives with human occupied submersibles and three with a remotely operated vehicle (ROV), and resulted in ~100 hrs of videotapes, 259 in situ digital images, 621 muse- um specimens, and > 400 microbial isolates. These were the first dives to document the habitat, benthic fauna, and fish diversity of some of these poorly known deep- water reefs. Fifty-eight fish species and 142 benthic invertebrate taxa were identi- fied. High-definition topographic SEABEAM maps and echosounder profiles were also produced. Sites included in this report range from South Carolina on the Blake Plateau to the southwestern Florida slope: 1) Stetson Lophelia reefs along the east- ern Blake Plateau off South Carolina; 2) Savannah Lophelia lithoherms along the western Blake Plateau off Georgia; 3) east Florida Lophelia reefs, 4) Miami Terrace escarpment in the Straits of Florida; 5) Pourtalès Terrace off the Florida Keys; and 6) west Florida Lophelia lithoherms off the southwestern Florida shelf in the Gulf of Mexico. These are contrasted with the azooxanthellate deep-water Oculina reefs at the shelf-edge off central eastern Florida. The fisheries and biopharmaceutical re- source potential of these deep-water habitats remain relatively unknown. Although these habitats are not currently designated as marine protected areas (MPAs) or coral habitat areas of particular concern (HAPCs), they are ecologically diverse, vulnerable to physical destruction, and irreplaceable resources. Activities involv- ing bottom trawling, pipelines, or oil/gas production could negatively impact these reefs. National Oceanic and Atmospheric Administration (NOAA) Fisheries and the South Atlantic Fishery Management Council are currently developing priority mapping sites of the DSCEs within this region, and these data may provide potential targets for new MPAs and HAPCs. Deep-sea coral ecosystems (DSCEs) are common off the southeastern U.S. within the Exclusive Economic Zone (EEZ). These include a variety of high-relief, hard-bot- tom habitats at numerous sites from the Blake Plateau off North Carolina, southward through the Straits of Florida, and in the eastern Gulf of Mexico. However, only a few have been mapped or have had their benthic and fish resources characterized.D eep- water reefs are sometimes defined as coral banks, coral mounds, bioherms, or litho- herms (Teichert, 1958; Stetson et al., 1962; Neumann et al., 1977; Wilson, 1979; Reed, 1980, 2002a,b; Freiwald et al., 1997; Paull et al., 2000; Fosså et al., 2002; Reed et al., 2005a,b). In general, deep-water banks occur below the effects of waves and the cor- als lack symbiotic algae (zooxanthellae). A bioherm is a deep-water coral bank that over centuries has formed a mound of unconsolidated sediment and coral debris and is capped with thickets of coral, such as Oculina or Lophelia (Reed, 2002a,b), where- as lithoherms are high-relief, lithified carbonate mounds, rather than unconsolidated sediment mounds, and also may be covered with thickets of live coral (Neumann et al., Bulletin of Marine Science 343 © 2006 Rosenstiel School of Marine and Atmospheric Science of the University of Miami 344 BULLETIN OF MARINE SCIENCE, VOL. 78, NO. 2, 2006 1977). Rogers (1999) suggested that deep-water coral banks fall within the definition of a coral reef based on their physical and biological characteristics. The dominant corals on deep-water reefs in this region are the azooxanthellate, colonial scleractinian hard corals, Oculina varicosa, Lophelia pertusa, Enallopsam- mia profunda, Madrepora oculata, and Solenosmilia variabilis (Reed, 2002a,b). Numerous solitary coral species are also common (Cairns, 1979, 2000) along with nu- merous species of calcified hydrozoans (family Stylasteridae), bamboo octocorals (family Isididae), and black corals (order Antipatharia). These reefs provide hard- bottom substrate and habitat for sessile macrofauna including scleractinian corals, octocorals (gorgonians), black corals, and sponges, which in turn provide habitat and living space for a relatively unknown but biologically rich and diverse community of associated fishes, crustaceans, mollusks, echinoderms, polychaete and sipunculan worms, and other macrofauna. Lophelia, Enallopsammia, and Madrepora form reefs in 490–900 m on the Blake Plateau from North Carolina to Florida and in the Straits of Florida (Stetson et al., 1962; Milliman et al., 1967; Uchupi, 1968, 1969; Neumann and Ball, 1970; Emery and Uchupi, 1972; Menzies et al., 1973; Mullins et al., 1981; Messing et al., 1990; Sedberry, 2001; Reed, 2002b; Reed and Ross, 2005). In addition, azooxanthellate, deep-water Oculina coral reefs occur in 70–100 m along the shelf-edge off central eastern Florida (Avent et al., 1977; Reed, 1980, 2002a; Reed et al., 2005b). The high-relief limestone outcrops, es- carpments, and bioherms of the Miami and Pourtalès Terraces off southeastern Florida are not Lophelia reefs, per se, but do provide hard-bottom habitat for corals, octocorals, and sponges (Neumann and Ball, 1970; Ballard and Uchupi, 1971; Gomberg, 1976; Reed et al., 2005a). Lophelia bioherms are also present at the base of the Miami Terrace escarpment (~670 m) within the axis of the Straits of Florida, but little is known of their distribution, abundance, or associated fauna (Neumann and Ball, 1970; Cairns, 1979). In the Gulf of Mexico on the southwest Florida slope, a 20-km long zone of high-relief (10–15 m) Lophelia lithoherms at 500 m provides habitat for coral and hard-bottom communities (Newton et al., 1987; Reed et al., 2004). In addition, fairly extensive Lophelia thickets grow on Viosca Knoll in the northern Gulf of Mexico off Alabama (Schroeder, 2002; Reed et al., 2004), and occur in DeSoto Canyon off Ala- bama and Green Canyon off Louisiana (Schroeder et al., 2005). As a result of recent research expeditions (1999–2004) by Harbor Branch Oceano- graphic Institution (HBOI) for biomedical research using human occupied submers- ibles and remotely operated vehicles (ROV), information has been compiled on the status, distribution, habitat, and biodiversity of some of these relatively unknown and newly discovered deep reef ecosystems. We located and mapped nearly 300 mounds during echosounder transects and Johnson-Sea-Link (JSL) submersible dives off the east coast of Florida, many of which proved to be newly discovered deep-water reefs, up to 168 m in height and at depths of 700–800 m. Submersibles and ROVs were used to ground-truth additional deep-water reef sites on the Blake Plateau, Straits of Florida, and eastern Gulf of Mexico documenting their habitat and benthic biodiversity for the first time. We also produced a high-definition topographic SEA- BEAM map at the southwest Florida lithoherm site. The sites described here range from the Blake Plateau off South Carolina to the southwestern Florida slope and include the following: 1) Stetson Lophelia reefs: an extensive region of Lophelia bioherms and lithoherms along the eastern Blake Plateau off South Carolina, including the discovery of a 152-m tall pinnacle with thickets of REED ET AL.: FAUNA OF DEEP-WATER LOPHELIA REEFS OFF SE USA 345 Lophelia (depth 822 m); 2) Savannah Lophelia lithoherms: numerous lithoherms with relief up to 60 m and capped with Lophelia on the western Blake Plateau off Georgia (depth 550 m); 3) east Florida Lophelia reefs: nearly 300, 15–152-m tall mounds that appear to be Lophelia bioherms and lithoherms distributed along a 222-km stretch off eastern Florida (depth 700–800 m); 4) Miami Terrace escarpment: Miocene-age terrace off southeastern Florida with high-relief, hard-bottom habitats and rich ben- thic communites (depth 300–600 m); 5) Pourtalès Terrace: a continuation of Miami Terrace off the Florida Keys (depth 200–460 m) of which habitat and fauna were de- scribed in detail by Reed et al. (2005a); and 6) west Florida Lophelia lithoherms: 15- m tall Lophelia lithoherms off the southwestern Florida shelf slope (depth 500 m). These sites are contrasted to the azooxanthellate deep-water Oculina reefs, which occur at depths of 70–100 m at the shelf-edge off central eastern Florida. Methods and Materials Human occupied submersibles and ROVs were used to conduct benthic surveys from 1999 to 2004 at six deep-water reef sites off the southeastern U.S. HBOI’s R/V Edwin Link (Seward Johnson II) and R/V Seward Johnson supported the Johnson-Sea-Link (JSL) and Clelia submersibles. These submersibles have an acrylic sphere (JSL) or hemisphere (Clelia) that provides >180° field of view to the observers within. Each was equipped with a manipulator arm with a 20-cm clam-shell grab, jaw, and suction hose; twelve 12.7-L Plexiglas buckets, and a CTD data recorder (Seabird SBE 25 Sealogger) that continuously recorded time, temperature, conductivity, salinity, oxygen, and depth. Ship navigation utilized differ- ential GPS (Magnavox MX 200 Global Positioning System), which had an estimated statistical positioning error of 1–5 m. Submersible navigation used Ultrashort Baseline Sonar (USBL) technology, which consisted of ORE Trackpoint II Acoustic Positioning System and Integrat- ed Positioning System (IPS) software that integrated the submersible’s position relative to the ship and calculated the submersible’s real time DGPS position throughout each dive. Analysis of USBL tracking accuracy for a worst-case tracking scenario estimated a maximum statisti- cal positioning error of 9.6 m at a depth of 500 m (J. Kloske, Florida Institute of Oceanography, pers. comm.; Opderbecke, 1997). At each dive site, profiles of bottom topography were made with the ship’s echosounder (SIMRAD EQ50 video echo sounder 38/50 kHz).