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Learning more about international waters, or the "high seas," and other unexplored deepwater areas through exploration is critical to ensuring they are collectively and sustainably managed for the good of the planet.

bathymetry data of the New England Seamounts
New bathymetry data of the New England Seamounts collected with the EM 304 MK II variant during the 2021 North Atlantic Stepping Stones: New England and Corner Rise Seamount Chain (EX-21-04) expedition, overlaid on the Global Multi-Resolution Topography Data Synthesis grid. (Credit: NOAA Ocean Exploration)

Seamounts are underwater mountain ranges, generally comprised of extinct volcanoes. They are most often found in chains that extend hundreds of miles across the seafloor and rise hundreds or thousands of feet high. These interesting marine features increase upwelling of nutrient-rich water, accelerate ocean currents, amplify tides, and generate waves—all of which creates a unique and ideal habitat for a diverse community of ocean wildlife, including deep-sea corals, crabs, sponges, sea anemones, commercially important fish, and much more. Though we know that seamounts provide many ecological benefits and have a big effect on deepwater environments, they remain mostly unexplored. In fact, only 20% of the global seafloor has been mapped with modern high-resolution technology.

Photograph of a red jellyfish
This beautiful red jellyfish in the genus Poralia may be an undescribed species. It was seen during the third transect of Dive 20 of the 2021 North Atlantic Stepping Stones expedition, at a depth of 700 meters (2,297 feet). (Credit: NOAA Ocean Exploration.)

From June 20 through July 29, 2021, NOAA Ocean Exploration, in partnership with USGS, the U.S. Fish and Wildlife Service (USFWS), and other organizations and universities, conducted a telepresence-enabled ocean exploration to collect baseline information about unknown and poorly understood deepwater areas off the eastern U.S. coast and high seas. This expedition, called, the “2021 North Atlantic Stepping Stones: New England and Corner Rise Seamounts,” was focused on the ecosystems of the Northeast Canyons and Seamounts Marine National Monument and other unexplored areas in the New England and Corner Rise Seamounts chain, which extend from near the Mid-Atlantic Ridge to the eastern continental margin of the United States.  

Photograph of bubblegum coral
This large bubblegum coral (Paragorgia arborea) was observed during Dive 19 of the 2021 North Atlantic Stepping Stones expedition. Based on published radial growth rates for this species, this colony is approximately 100 years old! We saw several large coral colonies during the dive, prompting one of our on-shore scientists to refer to the dive site as “the land of giants.” (Credit: NOAA Ocean Exploration.)

USGS scientists Jason Chaytor and Kira Mizell served as the geology science co-leads for the expedition. From land, they worked with multidisciplinary ship- and shore-based scientists to develop the remotely operated vehicle ((ROV) underwater machines that can be used to explore ocean depths while being operated by someone at the water surface) dive plans, lead and narrated ‘Live Dive’ events for a world-wide audience, and coordinated science outcomes. From July 2 to July 28, the team mapped about 40 seamounts, 20 of which had little to no preexisting data, since many of these had yet to be explored until now! Also, because many of these areas had never been seen before, the team had to conduct 14 “map and dives,” meaning they conducted preliminary mapping to determine the optimal location for ROV dives. Several short video interviews with USGS scientists help capture the science that guided the expedition’s activities and highlight their roles and the collaboration between USGS and NOAA as they explore the largely unmapped seafloor. 

Photograph of a multispecies coral garden
During Dive 11 of the 2021 North Atlantic Stepping Stones expedition, we discovered what is defined by the Oslo/Paris Convention (OSPAR) as a multispecies coral garden (100 - 700 coral colonies per every 100 square meter). The coral garden habitat was dominated by Calyptophora clinata whip corals and dotted with other coral species, including Bathypathes, Thouraella, Acanella, Chrysogorgia, and Parantipathes. This image shows part of the large area of coral garden habitat on top of a ledge outcrop. (Credit: NOAA Ocean Exploration.)

The two ‘Live Dive’ events took place on July 14 and 28. The first was hosted by Rachel Gulbraa of NOAA Ocean Exploration. Rachel introduced the expedition and Jason Chaytor (USGS, geology science co-lead), Kasey Cantwell (NOAA, Expedition Coordinator), Rhian Waller (University of Maine, biology science lead), and Chris Mah (Smithsonian National Museum of Natural History) discussed the research aspects related to the expedition and held a question and answer session with a live streaming audience. In case you missed it, the recorded event is available online

On July 28, staff from NOAA Ocean Exploration and Brittany Peterson (USFWS Monument’s Superintendent) explored the Northeast Canyons and Seamounts Marine National Monument through an interactive live event streamed at the Mystic Aquarium, in Mystic, Connecticut, with the visiting public so they could learn about the wildlife and features of their own marine backyard. The team discussed the geologic formations, history, and the unique and newly discovered biology of these areas with remote scientists and viewers. This event was also recorded and is available online.  

Midway through the expedition, Jason and Kira were both asked to share what was most memorable about the research expedition so far. Jason replied, “The dives on the Corner Rise Seamounts provided some of the first opportunities ever to explore seafloor features that have not been mapped or seen, which is always a special experience. The numerous observations of carbonate caps on these seamounts, and the collection of samples (most importantly the nummulite agglomeration sample) that will help reveal the early history of these features, perhaps when they were at or above sea level, has been the highlight of the expedition so far.” Kira said, “As a scientist who studies marine minerals, my favorite dive from the Corner Rise Seamounts was Dive 06 on Castle Rock Seamount. During this dive, we saw thick ferromanganese crusts with very large botryoids (a rock textural feature that looks like a bunch of grapes) coating pillow lavas to create a wonderful bubble-like landscape. I also learned that the freshest, or most recently forming, ferromanganese crusts were observed during our dives to Corner Rise Seamounts in water depths between 2,000 and 2,500 meters (6,562 and 8,202 feet), which gives us clues about sedimentation, currents, and water masses over the long history of this seamount complex.” 

Collecting a rock sample from an unnamed seamount using the manipulator on the D2 ROV (remotely operated vehicle)
Collecting a rock sample from an unnamed seamount using the manipulator on the D2 ROV (remotely operated vehicle). (Public domain.)

The 2021 Stepping Stones ocean exploration is building on two previous expeditions in the New England Seamounts that took place in 2013 and 2014. The ROV and mapping data collected during this expedition will help fill gaps in our collective understanding of the North Atlantic seamount chains and can provide scientists and managers with a better understanding of diversity and distribution of deepwater habitats in this region, allowing for informed resource management decisions.  

This work will also help fill mapping gaps in the high seas in support of Seabed 2030 and in U.S. waters in support of the National Strategy for Mapping, Exploring, and Characterizing the United States Exclusive Economic Zone (NOMEC). It also supports NOAA’s Atlantic Seafloor Partnership for Integrated Research and Exploration (ASPIRE) campaign and leverages international partnerships to support the Galway Statement on Atlantic Ocean Cooperation and the Sargasso Sea Commission. 

To learn more about the expedition, the science team, each individual dive, and more, visit the NOAA Ocean Exploration webpage

 

Remotely operated vehicle Deep Discoverer surveys a large boulder covered in bamboo corals
Remotely operated vehicle Deep Discoverer surveys a large boulder covered in bamboo corals during the 2021 North Atlantic Stepping Stones expedition. Bamboo corals were locally abundant on these large boulders and more spread out throughout different hard-bottom habitats.
Photograph of scattered rock debris sitting on the lobate and pillow lava outcrops
Towards the end of Dive 19 of the 2021 North Atlantic Stepping Stones expedition, we continued to observe the scattered rock debris sitting on the lobate and pillow lava outcrops that we’d seen earlier, suggesting that the pinnacle of Retriever Seamount was perhaps a late-stage eruption site and that it remains largely susceptible to continued erosional modification.
Map of seafloor data collected during the 2021 North Atlantic Stepping Stones: New England and Corner Rise Seamounts expedition
Overview of seafloor data collected during the 2021 North Atlantic Stepping Stones: New England and Corner Rise Seamounts expedition (rainbow gradient), overlaid on the previously collected bathymetry data (blue gradient).

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