NOAA's Reporter's Coral Reef Tip Sheet
September 8, 1997 - Week 36

SCIENTISTS EXPLORE LITTLE KNOWN DEEP-WATER CORAL REEF IN THE FLORIDA KEYS NATIONAL MARINE SANCTUARY

A team of scientists operating from the vessel Tiburon, out of Key West, were the first researchers to explore a little known deep-water coral reef with spectacular coral cover during a recent reconnaissance survey in a remote area west of the Dry Tortugas islands. Because of its location, the reef has been protected from the human-caused degradation that has affected other reefs in shallower waters of the Keys.
Scientists from NOAA were joined by scientists from the Florida Department of Environmental Protection and the Department of Interior's U.S. Geological Survey, which sponsored this multi-agency effort.

"The corals look like gigantic mushrooms gone wild," said Jim Bohnsack of the National Marine Fisheries Service's Science Center in Miami. "The structural complexity of the reef made ideal fish habitat. When we first descended it appeared that there were hardly any fish present, but after a few minutes they began popping out from all parts of the reef."

The scientific team was surprised by the reef's size and the fact that it is densely covered with coral.

"The abundance and cover of coral in this area is as high as any in the Keys, and it confirms the importance of coral reef habitats in the vicinity of the Dry Tortugas," said G.P. Schmahl, manager of the lower region of the sanctuary and one of the
researchers on the trip. "Due to its location, it has been protected from degradation by human influences, and it could serve as a control area to compare to other reefs in the Florida Keys."

Schmahl pointed out that the reef, which lies in 60 to 100 feet of water, is similar to another coral reef located in the Gulf of Mexico: the Flower Gardens National Marine Sanctuary off the coast of Texas. "This is a spectacular, healthy resource of the sanctuary, and it needs to be studied and protected."

The reef may have been overlooked in the past because it appears to be relatively flat on depth sounders and is too deep to be seen from the surface. The reef was previously known to only a handful of divers as "Sherwood Forest," because during
early morning dives the corals are mysterious looking and reminiscent of a forest canopy. Low light conditions at these depths causes corals to grow in a unique, flat, plate-like form. The reef profile is remarkably uniform, which at first gives a false impression of a flat bottom that is, in fact, five feet above the real bottom. The subsurface of the reef is a maze of valleys and intricate caves and tunnels between corals.

"We were only able to conduct a preliminary survey of the site because of its depth, remoteness, and the fact that the upper 50 feet of the water column was filled with high densities of stinging jellyfish. Several divers suffered from painful stings," said Bohnsack. "We speculate that the reef is very old and exists only because of the unique local conditions. Normally clear water allows sufficient light for coral growth and the depth of the reef apparently protects it from storms and extreme hot summer or cold winter surface waters in the Gulf of Mexico."

The discovery was made as scientists from NOAA's Florida Keys National Marine Sanctuary, Southeast Fisheries Science Center and NOAA Corps; the Florida Department of Environmental Protection's Florida Marine Research Institute; and the U.S. Geological Survey's Biological Resources Division were mapping and collecting data on coral, sponge and fish populations from many sites in the Dry Tortugas National Park and the western Florida Keys National Marine Sanctuary.