USGS Researchers Lead a Collaborative Effort for Further Investigation of the Deep Coral Reef at Pulley Ridge
On June 22, researchers from the U.S. Geological Survey (USGS) and other organizations departed on the Florida Institute of Oceanography (FIO) research vessel Suncoaster to revisit what has been determined to be the continental United States' deepest known hermatypic (reef-building) coral community, situated on the southwest edge of the western Florida shelf (see Sound Waves article, "Coral Reef Off Florida Determined to be Deepest Known on U.S. Continental Shelf"). Interest in this unique deep-water ecosystem launched a multidisciplinary flotilla of research vessels:
This expedition made it possible to use multiple tools and technologies to conduct new investigations of the southern area of coral growth and to explore other benthic habitats in the region.
Dubbed the "Miracle Cruise" by chief scientist Robert Halley (USGS, St. Petersburg, FL), the expedition represented intense efforts to combine the resources and experience of knowledgeable organizations. Participants included researchers from FIO, NOAA, and Mote Marine Laboratory, as well as experts from the Florida Department of Environmental Protection (FDEP) and the Harte Research Institute for Gulf of Mexico Studies at Texas A&M University, Corpus Christi. Deep Ocean Exploration and Research (DOER) Inc. was also a notable contributor, supplying the DeepWorker single-person submersible that proved to be invaluable for data collection. Even the National Geographic Society was involved, when Explorer-in-Residence Sylvia Earle (who is also the founder and chairman of DOER) joined the group to lead a team of submariners.
During the 10-day expedition, the research vessel Suncoaster launched six submersible dives, each lasting an average of 3 hours, and explored 10 ROV sites, despite some rough weather and an extremely strong current at the southern study area. On day 5, June 27, exploration at an ROV site north of the established coral zone revealed an intriguing area filled with dense patches of small calcareous tubeworms. None of the researchers had seen this type of tubeworm colony before, which made for an exciting find and a cruise highlight. On day 7, June 29, deep divers used mixed-gas technology and closed-circuit rebreathers to meet DeepWorker at depths greater than 65 m, coordinating the sampling efforts. The divers' ability to collect specific and fragile samples in such a remote environment was an invaluable addition to the expedition. Samples included hard corals, sponges, invertebrates, micromollusks, coralline algae, and red, brown, and green algae.
The research vessel Bellows team, working to the north, found ancient submerged shorelines at water depths of approximately 90, 80, and 70 m. These shoreline features harbor communities that consist of sponges, black corals, ahermatypic (non-reef-building) stony and soft corals, coralline algae, bryozoans, and mollusks. Dredged rock samples are suspected to be cemented oolitic grainstone and have been sent out for thin sections to confirm this identification.
Expedition participants included Bob Halley and Kate Ciembronowicz (USGS, St. Petersburg, FL); Dann Blackwood and Richard Rendigs (USGS, Woods Hole, MA), operating the ROV; G.P. Schmahl (NOAA), manager of the Flower Garden Banks National Marine Sanctuary; David Guggenheim (Harte Research Institute); Sylvia Earle (National Geographic Society, DOER Inc., Harte Research Institute); James Culter (Mote Marine Laboratory); Bret Jarrett, Al Hine, Beau Suthard (University of South Florida); and Ian Griffith, leading the DOER engineering team.
Pulley Ridge is a series of north-south-trending drowned barrier islands stretching more than 100 km along the southwestern Florida shelf. At its southern part, the ridge hosts an unusual variety of zooxanthellate scleractinian corals, algae, and typically shallow-water tropical fishes not common to that depth or its low-light conditions.
For more information, see the Pulley Ridge Web site.
in this issue:
Further Investigation of Deep Coral Reef