Wednesday, July 24, 2024
HomeScuba DivingAmerica's Deepest Coral Reef

America's Deepest Coral Reef

It is with mixed emotions that I sit on my fly-bridge anchored in the Dry Tortugas National Park, Florida, writing these thoughts. It is early June, 2006, nearly a year after I descended 230 feet below the surface of the ocean to be amongst the first to physically touch bottom and photograph the world’s deepest coral reef – Pulley Ridge, the healthiest reef I have seen in my lifetime. On this beautiful summer day a year later, I am hosting my sixth major coral research project in a year and a half,, with a group of National Park Service coral biologists who are revisiting a shallow reef which they have been studying since 1997. They are conducting a monitoring program designed to track the health of this coral reef system, one of the few Florida reefs still more alive than dead. In stark contrast to Pulley Ridge the NPS project sadly is the documentation of a reef in decline as most of our shallow water reefs are these days.


Not unlike a canary in a coalmine, coral is more susceptible to environmental impacts than other creatures (yes – coral is alive and a member of the animal kingdom) and is therefore a good predictor of wider environmental troubles. In eight short years, the shallow reef I am floating over today has seen a decline in living coral cover of 50%*. Unfortunately, this is not an isolated or local phenomenon, all over the world corals may be living their last days on earth.

Over the past ten years and particularly in the last 18 months, I have supervised coral research expeditions aboard my research vessel R/V Tiburon. I have worked with Scripps Institute of Oceanography, Mote Marine Lab, USGS (United States Geological Survey), NOAA, EPA (Environmental Protection Agency), University of Texas, Nova University, National Park Service, Harte Research Institute, Florida State University (FSU), and the University of Miami to understand what coral was once like and what is happening to our reefs today. Their studies are trying to find the cause of this decline; finding a cure is still not much more than a hope and a wish. Nevertheless, when asked scientists agree that three things are the major factors affecting coral health globally: climate changes, coastal pollution and development, and over-fishing. These factors all combine to radically alter the ecosystem and compound the stresses on coral reefs. According to the Nature Conservancy "coral reefs are currently one of the most endangered ecosystems on the planet. If the present rate of destruction continues, 70% of the world’s coral reefs will be killed within our lifetimes." The U.S. Geological Survey (USGS) in their Fact Sheet puts it this way–"[c] oral reefs are home to 25% of all marine species. However, the tiny colonial animals that build these intricate limestone masses are dying at alarming rates. If this trend continues, in 20 years the living corals on many of the world’s reefs will be dead and the ecosystems that depend on them severely damaged." In May of 2006, two coral species in Florida and the Caribbean – Elkhorn (Acropora palmate) and Staghorn (Acropora cervicornis) -were the first corals placed on the Federal threatened list because of dangers posed by human activity, hurricanes, and higher water temperatures observed across the oceans. The Elkhorn and Staghorn coral species have suffered a 97 percent decline in areas off the Florida Keys and in the Caribbean since 1985 nearly obliterating the species while the surviving 3% are hanging on by a mere thread.

What buoy’s my emotions is thinking back on the phenomenal discovery of a new coral reef, seemingly without disease issues called Pulley Ridge. Could this be hope’s reef? Is it a key to understanding the health and sustainability of the corals? Can it help us save the shallow water reefs? Pulley Ridge is a living coral reef that draws its energy from sunlight, a reef that is made up of corals common to shallow reefs all over the Caribbean. The amazing thing about this reef is that it is over 200 feet below the surface of the Gulf of Mexico in U.S. territorial waters. Scientists use the term hermatipic to describe this kind of reef. Simply put, coral shares its space with micro algae called zooxhanthellae. This algae uses photosynthesis to turn sunlight into energy and produces the by-products oxygen and carbon. The coral is able to use this waste product from the algae to build its skeletal structure and thus form vast geological formations. This process has been going on for over 40 million years. Corals are like volcanoes and tropical rainforests combined. They build land mass and capture and store the extra carbon dioxide that contributes to global climate issues. In effect, our reefs and rainforests are carbon dioxide storage units or sinks. Since our atmosphere is made up of 20.7% oxygen and 79% nitrogen, just a small amount of excess carbon dioxide can contribute to a major climatic change.


Today, Pulley Ridge is a healthy coral reef. During the last ice age some 13,000 years ago, in what was called the early Holocene marine transgression, it was dry land. When sea levels started to rise, it retained its structure and is what geologists call today a drowned barrier island. As the sea level rises, most corals grow upwards to chase the sun for the most efficient photosynthesis . At Pulley Ridge it seems the coral has adapted in new ways not yet fully understood growing thin and flat to catch the sun is one adaptation they appear to have utilized. Some scientists think there may also be alternate energy gathering systems, which the zooxhanthellae are utilizing to assist with the development of the corals at these depths. This is yet to be studied and verified. What is known is that this reef is almost 100 feet deeper than what was previously thought of as possible for corals of this kind to survive in and flourish. This chain of drowned barrier islands, now a living coral reef, has a range of almost 125 miles at depths from 200 to 300 feet. It is located on the Florida shelf in the southeastern Gulf of Mexico, about 100 miles west of Key West, Florida. Scientists attribute three factors to the existence of the amazing formation. The elevated topography and lithified substrate are a perfect base for the hard bottom coral community to take hold. The Loop Current of warm water coming north between Mexico and Cuba and almost reaching the shores of Louisiana and then back down to join the Gulf Stream supplies new recruits and warm, clean, clear water to this unique system. Finally, the site is on the edge of the Continental Shelf which drops to thousands of feet, thus creating an upwelling of nutrient-rich waters that bathe the reef.

Among some of the unusual discoveries found there is an algae called Anadyomene saldanhae, a plant which is more common in the 20 to 40-foot depth range. To find it growing at depths of 230 feet, where it receives only 5% of the sunlight that is normal at shallow depths, is a phenomenon worth studying. Far from being an isolated occurrence the large, brilliant green, meter-wide plant can be found carpeting Pulley Ridge as far the eye can see. Could it have a role in supplying oxygen to the ecosystem allowing the corals to grow? Those of us seeing its abundance first hand called it a cabbage patch reef. This, more than anything else, gives Pulley Ridge a look that is unmistakable. Dr. Sylvia Earle states "If dropped on Pulley Ridge, with one look I could distinguish it from any other place on this earth. The blue-purple coral and giant green algae make this unique on the planet."

The area was first discovered in the 1950’s by a malacologist (someone who studies shells and mollusks) named Dr. Thomas Pulley, giving the area its name. When he collected some deepwater benthic samples, he came up with unexpected species of mollusks and bottom-dwelling life forms. Some 50 years later, Brett Jarrett a graduate student from Florida State University while working from Dr. Pulley’s notes, made this location a stop in his studies on sedimentation of the Gulf of Mexico. In the same year, Dr. Sylvia Earle MED81 was underway with a National Geographic Sustainable Seas Project collecting possible dive locations for her Deep Worker submarine. The unusual bottom sample found by Brett was brought to her attention at a Sustainable Seas planning meeting. From that fateful day in 1999 to the summer of 2005, the USGS in conjunction with FSU have made yearly trips to the reef, using remote sensory equipment to map and sample this unique find. Sylvia was able to deploy the Deep Worker submarine as part of her larger Sustainable Seas project, but because of the reef’s low-profile carpet of corals, any close-up observation of this ecosystem required the human element. In spite of the expeditions’ highly scientific equipment, to get up close and personal the task needed old-fashioned diving or perhaps better called new-fashioned diving in the form of closed circuit rebreathers and mixed gas diving.


Jim Culter FN97, a Mote Marine Lab scientist and co-flag applicant with Sylvia and myself, was given the job of gathering and training the team of divers on how to collect samples off the delicate bottom of Pulley Ridge. My team’s responsibilities included expedition support vessel, dive operations logistics, underwater video, and photographic documentation. On our first day underway, while still 35 miles away from our first dive site, we received a message from the submarine-launching platform the R/V Suncoaster headed back to a safe anchorage in the Dry Tortugas. Speaking with the Captain, he informed us that the currents were just too strong to launch the sub and that they were going to wait a day before trying again. With months of planning and at least a week of work getting off the dock it was not the news we wanted to hear. The decision was made more by eye contact and facial expressions than with words, as I suppose many an Explorer has experienced. The looks said we’ve come this far; let’s see it through and give this current at try. Gathering the team together, I briefed them for a drift dive designed to use the strong current to our advantage. This technique can be compared to dropping skydivers out of a plane. If they do not all go at the same time, they might potentially land miles apart. By dropping the divers from the moving boat all at once, they can drop down and ascend as a team with their passageways being defined by the currents.. One member carries a long line with a small grapnel hook at one end and a large orange buoy on the other, the boat can then follow the buoy and stand-by during the several hours needed to perform the dive and the required decompression. Fortunately, Pulley Ridge covers such a large bottom area that locating a precise drop site was not critical and using GPS coordinates was enough to launch the first team. After two successful four-man team deployments, and the collection of unique samples and close-up photographs, we all shared a sense of accomplishment. The ride to the Tortugas was surreal as we basked in this historic moment in time as the first divers to touch down on Pulley Ridge.

Expedition Heroes

After learning to dive in Maine as young boy, I moved to Florida in 1979, for 25 years, I have been diving and working on research projects in Florida, the Bahamas, Mexican and Cuban reefs; I have never seen anything like Pulley Ridge in all my time on the bottom of the ocean, including thousands of dives from 30 to over 200 feet in depth. As I descended I was hovering over the most amazing reef I had ever seen, in that moment I truly understood what it is to feel fellowship with members of a Club that celebrates exploration. That night we traveled 35 miles back to rendezvous with the Suncoaster and transfer my first photographs. It was not until later, while showing these aboard the larger vessel to the scientists, that we realized we had captured the imagery and samples that had proven elusive to all others for the past five years. The success of the divers can best be summed up by Billy Causey, U.S. South Eastern Regional Sanctuaries Manager when he said, "This was possibly the most comprehensive, and focused assessment of deep water coral reef environment ever undertaken".

The ability to take the study of coral to new depths is made possible by mixed gas diving, and more recently, closed circuit rebreathers. This equipment is finding its way into the research field from the cave and deep wreck diving communities. Although slow to be accepted, the future use of this form of advanced technical diving is clear. It allows an expedition team such as mine to accomplish the same tasks today that would have taken ten times the equipment and manpower to do a decade ago. On this expedition the Deep Worker Submarine was able to log 21 hours of observable bottom time compared to our team of divers who logged 18.5 hours** and were better equipped to collect some of the more delicate samples from the reef floor. What will happen to ocean studies when these tools find their way into the hands of scientists and trained naturalists? The possible discoveries are endless. Until then, explorers like Jim Culter, his cave team and myself will act as their eyes and hands, much as the Apollo astronauts did for earthbound geologists crowded around a radio receiver at Houston Control just 35 years ago.


The expeditions conducted on my vessel more often than not include my 8 year-old daughter and 10 year-old son, both open water experienced divers. It is my deepest hope that they will not the only ones of their generation to see these amazing sites. What a terrible legacy would we leave them with if no efforts are made to reverse the current trends caused by mankind.


I am now on the 8th day of the Park Service coral study at anchor, weathering out three days of 30 to 50 knot winds from our first tropical storm of the 2006 season, and my mixed emotions remain. These thoughts can best be described as watching an old friend slowly fade away from a debilitating disease while at the same time the family welcomes a newborn child. Is this deep reef a link to a past healthy reef system? Can it and others like it be refuge for the future recovery of coral reefs? Will they help us to understand what is truly happening to corals around the world today? I believe the answer to these questions is yes and this is what gives me hope. Pulley Ridge then, is for me, Hope’s Reef and it gives me cause to celebrate. Hopefully this and future discoveries will help us find the key to long term sustainability of the corals and the symbiotic ecosystems that will help us save our shallow water corals. At the same time the explorer gene in me beckons to locate and explore more deep coral reefs, for by their very existence I am reminded how little we know about what lies under the ocean’s surface and their discovery may lead to valuable information to help us preserve the reefs. This is a task listed under the "what’s left to explore" category; it will require time, energy, dedication, and properly funded resources if we are to be granted the privilege of discovering new, unique marine ecosystems and then preserving and learning from them.

The article is being emailed from the bridge of my boat to the New York Explorers Club while the scientists are underwater doing their research. It has taken almost ten thousand years for man to transform the planet into what it is today. Reversing the damage will also take time. Man’s knowledge of the natural world today is tenfold that of just a century ago. Living in a time where a single person can share this information instantaneously with another on the other side of the planet, truly shows we have the power to effect change unlike any other time in history, another cause for hope.


Tim Taylor FN 04, discovered Sherwood Forest, considered the centerpiece of the Tortugas Ecological Reserve and one of the healthiest reefs in the Caribbean. He has had the honor or carrying 6 Explorer Club flags in the last several years on projects ranging from lemon and nurse shark behavioral studies, deep marine archeology and mid-range and deep coral reefs. He is currently employing trimix closed circuit rebreathers and high definition imaging to enhance these research projects. He co-owns and operates Aquatic Films Inc., Research Vessel Tiburon, Inc., and is Director of Ocean Outreach, a non-profit formed to help develop multimedia real life content, children’s books and educational materials that help disseminate the work he is doing around the world to help raise the awareness of our oceans. He frequently lectures and is available for public appearances in support of the oceans and their ongoing preservation. For more information or to get involved, please visit,, and

*Information based on survey of randomly sampled areas, transects and historical data archives of multiple research projects by USGS and NPS,  non published data and personal communications with scientist while on site performing ongoing multi year data collection.  Author has personal visited this site for 20 years and witnessed event first hand.

**This is bottom time and does not include the hours of decompression obligations associated with the dive plan.