The Gulf of Mexico is one of the most thoroughly studied ocean areas in the world, but even there, the deep sea remains mostly a mystery. Earlier this month, the National Oceanic and Atmospheric Administration’s (NOAA) Okeanos Explorer returned from a 23-day expedition to survey and map the Gulf’s deep ocean ecosystems. Working day and night, the crew of 49 people mapped 21,100 square kilometers (8,100 square miles) of the Gulf and deployed remotely operated vehicles to explore 15 deep-sea locations. Meanwhile, almost 200 scientists were able to watch the dives live and remotely analyze the expedition’s data. The team brought back samples of unknown species, photos of unexplored environments and videos of never-before-seen wildlife behavior.

Still, researchers have only scratched the surface of what is in the Gulf’s depths, says Daniel Wagner, the co-science lead onboard the Okeanos Explorer and a research coordinator at the Southeast Deep Coral Initiative at the National Centers of Coastal Ocean Science, which is jointly operated by NOAA and JHT Inc.

For example, in the 1980s, researchers found in the Gulf a chemosynthetic ecosystem – an underwater community of organisms that depend on chemical synthesis rather than photosynthesis for life. It was the first time anyone had found an environment that wasn’t dependent on the sun to exist. Now, says Wagner, researchers know of about 70 such places in the Gulf as well as elsewhere, but “there are probably hundreds.”

This dark ctenophore was observed with its tentacles fully extended at approximately 1,460 meters (4,790 feet) deep. (Image Courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.)

The uniqueness of these areas prompted NOAA to propose expanding protected marine sanctuaries, such as the Flower Garden Banks Marine National Sanctuary, and the Gulf of Mexico Fishery Management Council is considering new protected areas, such as the De Soto Canyon region south of Florida’s panhandle. Wagner says that part of the goal of the expedition was to collect information and data that could help policymakers decide where, and if, to draw new protected boundaries.

Oceans Deeply spoke with Wagner about the expedition, what new discoveries scientists made and what it means for our understanding of the Gulf and the deep ocean.

Oceans Deeply: One of the stated goals of the expedition was to study deep-sea corals. Can you talk a little bit about why this was such a priority and what you found?

Gulf of A very high density of bamboo corals and glass sponges. To date, these are among the deepest high-density communities recorded in the Gulf of Mexico. (Image Courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.)

Daniel Wagner: Less than 1 percent of the Gulf of Mexico is currently protected from extractive things like trawling or basically anything that can perturb the seafloors. That’s compared to, for example, the U.S. Pacific, where 100 percent of the seafloor you cannot trawl. Same as the U.S. Caribbean. So there’s very little protection there.

A couple of ocean management agencies have looked at creating new marine protected areas. One of the areas that they’re looking to protect is the deep-sea coral areas because they are considered the most vulnerable marine habitats on the planet. They’re composed of a whole bunch of species that are slow growing and long-lived, and as a result if they were to be disturbed they would take a really long time to recover.

Iridigorgia soft coral with squat lobsters in the northwestern Gulf of Mexico. (Image Courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.)

I would say, maybe about a third of the 15 dives’ main missions were to look at deep-sea corals, and we found some incredible things, including the deepest deep-sea coral garden ever known for the Gulf of Mexico at depths of about 2,400 meters. They’ve found densities of coral very similar to what you would see in the shallow-water reefs.

There’s actually four dives we did on areas that are being proposed for [protection]. At each one of those four dives, we documented some pretty remarkable deep-sea coral communities. Lophelia pertusa is a reef-building species that we have in deeper waters, and off western Florida, we’ve done two dives in about 400 to 600 meters and documented these huge coral mounds. They’re about maybe the size of a football field. Just 100 percent coral cover and fishes and lobsters.

Western roughy are a long-lived deepwater fish found from Nova Scotia to Brazil. (Image Courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.)

Again, the Gulf of Mexico is considered relatively well studied, but we found the deepest community of these deep-sea corals on this expedition, and then a whole bunch of the organisms there we didn’t know lived in the Gulf of Mexico. We collected 22 samples, or little fragments of organisms, and 13 of those are going to be of things we either didn’t know existed in the Gulf of Mexico or actually didn’t know existed in the Atlantic Ocean. And a few of those are probably going to end up being completely new species altogether once they’re all analyzed.

Oceans Deeply: You also explored chemosynthetic environments. What did you already know about these chemosynthetic ecosystems, and what were you looking for when you went down there?

A dense and diverse coral community. (Image Courtesy of the NOAA Office of Ocean Exploration and Research)

Wagner: We went to a couple places where we thought we were going to find them because of previous dives in the area. We documented some pretty expansive chemosynthetic communities, I mean, as far as you can see are these mussel beds. And that is really remarkable, because the majority of the sea floor is actually quite sparse. And you have 100 percent cover with animals, and you have the mussels, and then you have tube worms on top, and swarms of little invertebrates swarming through it. It’s quite remarkable.

A yellow crinoid perched on a precious coral (Corallium niobe) that was attached on a topographic high. There was an abundance of bryozoans at the base of this colony. (Image Courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.)

Oceans Deeply: Can you say anything about deep-ocean ecosystems in general from this expedition?

Wagner: The Okeanos Explorer just finished the three-year effort in the Pacific Ocean. That just finished last summer. And we, on this very expedition, recorded a whole bunch of species that were only known from the Pacific, right here in the Gulf of Mexico. That lets you know that these ocean basins are more connected than what they thought they were.

As we’re going to more and more of these places, we’re learning and finding the same things, and it’s basically just a factor that we really haven’t studied the deep sea and haven’t been able to see these stepping stones, if you will, and how these communities are connected.

Oceans Deeply: Is there anything else that you would like to say?

A ROV surveys the steep slope of this section of the northern end of the Florida Escarpment. (Image courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2018.)

Wagner: Well, just how huge of a team effort this all is. We had 200 scientists contribute one way or another, about 50 people on the ship that worked on this, and many more onshore that make this all possible.

We really need to work together, because this is the biggest part of our planet that we know the least amount about. It’s the only way that we’re going to be able to understand these places that cover the biggest portion of our planet.