Underwater footage captured by NOAA’s Okeanos Explorer in the Gulf of Mexico shows for the first time a dense coral garden that scientists say could be more than a thousand years old, recorded at depths previously not known to host such dense communities.
At 2,300 meters (more than 7,500 feet) deep, the unexplored narrow ridge home to the unusually high density of coral is located in a system of canyons on the southern end of the West Florida Escarpment.
“These fans are likely hundreds, if not over a thousand, years old. That gives us the sense that although these look unstable, these rocks have been sitting in their current positions for quite some time,” noted the team. In order for so many corals to thrive in such an environment, the scientists say a lot of factors needed to come together, including “including the right underlying geology, current flow, food availability, coral recruitment, and stability”
A very high density of bamboo corals and glass sponges were observed towards the end of the dive. To date, these are among the deepest high-density communities recorded in the Gulf of Mexico. NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018
According to the team, corals, sponges, and other invertebrates were more common on the rocks than they were in sediment areas. Throughout the dive, the video shows dramatic terrain across the ridgetop whose vertical heights could possible create a microhabitat suitable for the denser colonies of bamboo coral. Many of the coral fans are shown facing the same direction, which could be an indication of which way the current is moving.
“In one area, pronounced scour pits around some rocks were observed, indicating excavation by rapid currents,” said the scientists in a statement. “Towards the later part of the dive, the terrain became steeper and vertical rock walls were observed. Additionally, the ridge crest became very narrow – only a few meters across.”
This glass sponge, observed at 2,280 meters (~7,480 feet), was host to many other organisms, including brittle stars, a gooseneck barnacle, an amphipod, a polychete worm, and a squat lobster. NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.
Exposed rock and boulders along the Escarpment Canyon Ridge are home to corals and sponges, as well as many other animals including, different types of corals, sea pens, anemones, sea stars, bryozoans, benthic ctenophores, barnacles, shrimp, sea cucumbers, fish, and eels.
“We’re starting to see all the different things that have to come together to make really great communities,’ said the researchers. “Those are going to help inform models of coral density so that in the future we can to become even better at predicting where we may find communities like this.
First commissioned in August 2008, the Okeanos Explorer is the only federally-funded US ship assigned to explore the ocean in real-time with telepresence technology. You can follow along with the ship's exploration here.
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