Posted on July 19, 2010 by Stephanie Farrington-Rogers, Biologist, HBOI/FAU
I joined the fathometer transect team on the bridge this morning at 6:30 a.m., as I have been doing most mornings – knowing that today I was going to dive in the aft chamber of the submersible. We watched the fathometer looking for changes in the bottom topography to determine possible dive sites. There are a few areas in the Gulf that have multibeam data available that we had been using this trip to pick specific dive sites, but not today – today we were dealing with a blank map…
John Reed (my boss, who has 30+ years of experience studying deep-sea coral reefs) had been to a site close to this one before with an ROV (Remotely Operated Vehicle), which, he explained to me, had its umbilical cord entangled in some patches of the deep coral Lophelia pertusa, and it took almost half a day to recover the ROV. So I knew there was a possibility that we might find some coral in this area. While we were transecting perpendicular to the ridge, we watched as the fathometer exposed 20-40-foot high mounds. We asked the mate to steer the boat back the way we came, and we happened to cross over a 100-ft mound. So jokingly, John yelled out: “We’re calling this one ‘Stephanie’s Bump!’” (I, of course, did the I-got-a-bump-named-after-me dance!).
This would be the third time I had the chance to go down in the submersible – once while I was in graduate school doing my Masters on the biogeography of the Straits of Florida and the second on the first day of this expedition. The aft chamber of the JSL is quite cramped; there are two portholes on the sides and a small video screen that shows what the camera in the front of the submersible is recording. At about 1,280 ft, we passed through a “school” of pyrosoma (or pyrosomes: free-floating colonial tunicates that live usually in the upper layers of the warm ocean, although some may be found to great depth) – which was incredible to see because the aft lights were still off, and I could see them glowing in the water column. After about 10 minutes of passing though the water column, we hit bottom – 1,643 feet, my deepest dive to date. We landed looking at the southeast face of the 100-foot tall “Stephanie’s Bump”; only it was not just a “bump” it was a 100-foot tall bioherm – indeed, a deep-sea Lophelia coral reef – the largest Lophelia reef recorded to date on the West Florida Shelf that we know of – and I got to be the one of the four first people on the planet to see it – ever!
Like all ahermatypic corals, Lophelia lacks zooxanthellae – the photosynthetic symbiant that lives in most shallow water corals. This lack of zooxanthellae is what causes Lophelia to appear bright white. Lophelia uses the tentacles on the individual polyps to catch food – as opposed to photosynthesizing – because there is no sunlight at these depths (which is very obvious when the submersible’s lights are off). Lophelia reefs house hundreds of species of deep-sea animals including galatheids (squat crabs), crinoids (sea lilies), golden crabs (Chaceon fenneri), hexactinellids (glass sponges), and brittle stars. Lophelia reefs act as the feeding ground and home to many species of ecologically important fishes.
Lophelia grows about 1 mm per year – so the 2-, 3-, and 4-foot tall bushes we were looking at were … over 1,000 years old! I watch the manipulator arm as we collected a few samples of coral to bring back to the surface and really got a sense of how fragile these corals are – the branches of the coral just crumbled under its touch. I can’t even imagine what kind of damage an ROV could have done – if the umbilical had dragged even 10 feet across the top of this reef it would knock down tens of square meters of 1,000-year old corals in just a few seconds. If there was a commercial fishery here – the devastation would be astronomical.
We surveyed the bioherm taking pictures and videos of the bottom and the species we saw and collecting almost 20 samples of hexactinelids, black corals, Lophelia, Madrepora, anemones, and sediment samples for about three and a half hours before we had to return to the surface to share our discovery with the rest of the research team and crew. I exited the submersible with a huge grin on my face, dumbfounded by the fact that I actually was able to be part of such an awe-inspiring discovery. I am amazed everyday by just how lucky I am to be aboard this ship and doing research with one of the most amazingly engineered pieces of scientific equipment ever created for ocean research.