Explorers discover northernmost Atlantic seeps, deep-sea canyon diversity, off US Northeast

August 5th, 2013
Alongside the diverse coral community in Hydrographer Canyon, ROV Deep Discoverer observed a glass sponge containing cephalopod eggs. If you look closely you can see what looks to be a recent hatchling! (Cephalopods include squids, cuttlefishes and octopuses.) Credit: NOAA Okeanos Explorer Program/2013 Northeast U.S. Canyons Expedition
Ocean explorers in July on NOAA Ship Okeanos Explorer discovered a wide diversity of seafloor features and communities of life in the largely unexplored deep-sea canyons off the northeast U.S. coast. Now through August 16, as the expedition continues, the public can join the mission as "citizen scientists," at oceanexplorer.noaa.gov/okeanos, to see live seafloor video and listen as scientists discuss their observations in real time. During the expedition's July leg, there were nearly 60,000 visits to the live streaming video.

Canyons represent some of the most striking features of the continental slope off the U.S. East Coast and may also be among the most productive areas in the deep sea. Organic matter and nutrient-rich sediments are often concentrated in these areas and strong currents flow through the steep and rugged terrain of the canyons, exposing hard substrates. With an increase in food availability and a variety of different habitat types across varying depths, submarine canyons may contain higher biodiversity and biomass than the adjacent continental slope, and are likely places to observe deep-sea corals, sponges, and other deep-sea marine organisms.

During the July leg of the expedition, the ship's multibeam sonar detected bubbles rising from the seafloor in several locations about 90 nautical miles southeast of Nantucket, Mass. These water-column plumes were traced to seafloor seeps where explorers observed chemosynthetic communities of life supported by chemicals rather than by sunlight. These are the northernmost seeps detected to date on the U.S. Atlantic margin.

The discoveries are expected to help fisheries and other ocean resource managers make better-informed decisions about how to manage, use and protect the ocean and its resources. Scientists believe the need to learn more about these relatively undisturbed canyon ecosystems is becoming more urgent, particularly as the potential for fishing, marine mining, and hydrocarbon exploration extends into the deep sea.

"We found these little-explored canyons are highly dynamic," said Tim Shank, a deep-sea biologist from Woods Hole Oceanographic Institution, who participated from ashore. "With each dive of the ROVs (remotely operated vehicles that are undersea robots with cameras), we documented vertical walls with jagged rock failures, collapsed features, and extensive debris fields. Each canyon also appeared to host different biological communities—even different depths within the same canyon would reveal different types of coral and sponge ecosystems.

Close-up of methane hydrate observed at a depth of 1,055 meters, near where bubble plumes were detected in previous sonar data. Pressure and cold temperatures create methane hydrate where molecules of natural gas are trapped in an ice-like cage of water molecules. Methane hydrates, a hydrate patch and chemosynthetic communities were seen during this dive, but no active seepage was observed. Seeps were investigated at other locations. Credit: NOAA Okeanos Explorer Program/2013 Northeast U.S. Canyons Expedition

"As we explored different sides and depth zones of these canyons, we discovered a broad physical and biological diversity," said Shank. "One canyon would host great animal diversity but low animal abundance and the next canyon would reveal just the opposite. As with any new deep-sea region we explore, we observed many suspected new species and remarkable range extensions of known species. All these observations will be highly informative to design and implement ocean conservation and management strategies in the near future."

Explorers also observed several instances of new coral life establishing itself, hundreds of skate and cat shark eggs on the seafloor and attached to deep-sea corals, and numerous octopus and squid guarding clutches of eggs. Initial impressions revealed these canyons are hot spots for biodiversity, hosting more than 25 species of corals, and hundreds of associated animals.

Andrea Quattrini, a Ph.D. student from Temple University in Philadelphia, said the expedition provided an immense opportunity for the ocean science and management communities to educate and train the next generation of explorers and deep-sea scientists.

"Their ability to interact with thirty to forty scientists with different areas of expertise, and the free exchange of ideas and discussion, further advanced the exploration and findings by defining new questions and outlining exciting avenues for future research," she said.

Teachers may take advantage of an Expedition Educational Module at go.usa.gov/jn2h. The site provides products tied to the expedition including standards-based lesson plans and ocean-career connections.

Brendan Roark, a geographer from Texas A&M University who participated in the expedition from the ship, believes corals in the area may live as long as 4,000 years. "Deep-sea corals provide a new archive that can help us reconstruct past ocean and climate conditions," he said. "They grow in a shrub-like fashion and most importantly, they deposit annual growth rings much like trees do. Because of their extremely long life spans, they may develop high resolution records of oceanographic and climate variability."

An international team of more than 40 scientists and students – partners from multiple federal agencies and academic institutions – located mostly on shore, participated in the expedition's first leg, receiving data and live video from the ship via telepresence-technology, using satellite and Internet pathways. The science team included several scientists at sea and others in Washington D.C., 12 U.S. states and two nations.

Scientists on the expedition's July leg mapped 7,209 square kilometers of seafloor as they explored areas between 560 meters (1,837 feet) and 2,135 meters (7,005 feet) deep, in and between Block, Alvin, Atlantis, Veatch and Hydrographer canyons. The second leg is exploring Welker, Oceanographer, Lydonia, Nygren and Heezen canyons as well as Mytilus Seamount, one of the easternmost seamounts along the submerged northeast New England Seamount Chain within the U.S. Exclusive Economic Zone. Very little information exists for these areas. Scientists on both expedition legs are obtaining valuable data using the latest technologies including state-of-the-art multibeam sonar and NOAA's new 6,000-meter ROV, Deep Discoverer, coupled with the Seirios camera sled and lighting platform.

Provided by NOAA Headquarters

This Phys.org Science News Wire page contains a press release issued by an organization mentioned above and is provided to you “as is” with little or no review from Phys.Org staff.

More news stories

Researchers discover neuroprotective role of immune cell

A type of immune cell widely believed to exacerbate chronic adult brain diseases, such as Alzheimer's disease and multiple sclerosis (MS), can actually protect the brain from traumatic brain injury (TBI) and may slow the ...