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Explorers at sea: Pulley Ridge and Tortugas research cruise

First discovered in the 1950’s but only recently explored, Pulley Ridge is an underwater dreamland about 100 miles off the Southwest coast of Florida. Marine Conservation Institute became interested in this series of drowned islands with the deepest known photosynthetic coral in US waters when we did our Gulf Gems report on the most biologically important places in the Gulf of Mexico. We are very grateful that the Waitt Foundation has lent its efforts to further research and public knowledge of the site along with two special marine scientists from Florida State University (Dr. Sandra Brooke) and Florida Atlantic University (Dr. John Reed) who are volunteering their time to investigate the area and help the National Geographic Society document the marine life there. We want to thank all those who are making this expedition to Pulley Ridge possible. Below, we bring you a first-hand report by one of the scientists out on the water, Dr. Sandra Brooke, Senior Conservation Fellow at Marine Conservation Institute.


On Wednesday 4th May, I drove across Florida to West Palm Beach to meet the Waitt Foundation vessel, the M/V Plan B. It started out as a lovely sunny day but quickly deteriorated into a torrential downpour that lasted the rest of the trip. I arrived in West Palm, just in time to load my gear and hop on the boat before it left for Pulley Ridge, a unique mesophotic coral reef in the eastern Gulf of Mexico. Mesophotic or ‘twilight zone’ reefs are on the edge of the depth limits for reef-building corals that need sunlight to support their symbiotic algae. Their depth and distance from shore lends them some protection from high temperatures and human impacts, so they may represent refuges for corals and other reef species that can no longer survive in the degraded shallow areas.


This cruise is part of a larger project that is supported by the Waitt Foundation in collaboration with National Geographic and Marine Conservation Institute. Brian Skerry, a National Geographic photographer, is aboard to collect images that highlight special marine ecosystems. My colleague John Reed (Harbor Branch Oceanographic Inst/FAU) and I are collecting benthic habitat and community data on the Pulley Ridge reefs.  It was a rough trip down with strong winds and high seas, but we arrived at Pulley Ridge late Thursday night ready to start work.



Deploying the Falcon ROV at Pulley Ridge mesophotic reef,

Deploying the Falcon ROV at Pulley Ridge mesophotic reef


We finally caught a break in the weather and deployed the Falcon ROV (Fig. 1) on the main ridge inside the Pulley Ridge Habitat Area of Particular Concern (a special designation under the Gulf of Mexico’s Fishery Management Council). Conditions were not ideal; we were being pushed around by the current and wind, but we saw some large red grouper excavations, each with attendant lionfish unfortunately, fan-shaped green algae that only grows on Pulley Ridge, and large flat plates of coral that are characteristic of these mesophotic reefs. Growing as a plate instead of a boulder allows the corals to take advantage of the limited light (Fig. 2). Towards the end of the dive we were venturing into territory that had not been explored before, and found a massive basin (probably a red grouper excavation) with hundreds of tiny fishes as well as large red grouper, scamp and black grouper. At this point the current pulled us off the reef and signaled the end of the dive.


Saturday and Sunday were again battles with nature with high seas and strong currents, but we managed two ROV dives on the western ridge before having to give up for the day. This part of Pulley Ridge is outside of the small Pulley Ridge HAPC. This area is deeper than the main ridge and has a dense covering of gorgonians, sponges and many other invertebrates and fishes. An expansion of protection for Pulley Ridge has been proposed to the Gulf of Mexico Fishery Management Council as part of a larger effort to protect deep sea corals (those > 50 m depth) in the Gulf of Mexico. Any additional data we can collect on the proposed protected areas may help move them forward.


For more information about Pulley Ridge, see our webpage at


What our scientific partners, Dr. Sandra Brooke and Dr. John Reed, together with well-known National Geographic photographer, Brian Skerry, will find out on Pulley Ridge and the nearby Dry Tortugas Ecological Reserve is still uncertain. But we will be publishing those results and some pictures of the expedition over the next few months as the results come in. We expect some interesting things from this journey to the deepest light using coral reef in US waters –a wonderland of fish and strange corals and algae and a potential refuge for these populations as our oceans warm and acidify with climate change.


Cover Photo:  Large flat plates of Agaricia coral at Pulley Ridge. Image courtesy NOAA-OER.

Originally posted for Florida State University