Expedition Reveals Rich Life on Deep-Sea Mountains

The deep sea is one of the least-understood parts of the planet, yet it is increasingly gaining attention as a potential source of rare minerals.

Senior Research Scientist Beth Orcutt recently helped lead a research cruise offshore of Hawaii to better understand underwater mountain environments, which are of particular industrial interest. However, the team found that mineral crusts on the rocks were thinner than expected and the biological diversity was greater – including a wide variety of corals and sponges.

“We found an amazing diversity of life on the expedition,” Orcutt said. “Even the animal biologists were surprised at how dense and diverse the communities we observed were. It’s another data point emphasizing how little we know about the deep sea.”

The expedition, coordinated by the Ocean Exploration Trust in partnership with NOAA, included scientists, mapping specialists, educators, and a Hawaiian language expert. Over the 20-day trip, the team used remotely operated vehicles to dive down to 9,600 feet, mapped over 8,000 square miles of territory, and collected over 180 biological and geological samples.

The research was a continuation of work from 2018 to reveal the diversity of life in the deep sea and Orcutt will return to Hawaii this spring on another expedition for the project.

The researchers studied underwater volcanic mountains, called seamounts, which are of great interest for seafloor mining – and environmental concern. The rocks around them can be covered in mineral-rich crusts that are a prospective source of rare metals used in many modern electronics. These crusts also host complex microbial communities that can provide vital environmental services, such as nutrient cycling, carbon production, and waste remediation.

Scientific understanding of these deep-sea ecosystems is severely limited – including their ability to withstand human perturbation. This causes widespread concerns among scientists and conservationists that human activity on the seafloor may fundamentally alter conditions that took millions of years to form.

The research took place in the Papahānaumokuākea Marine National Monument, a marine protected area. Even though mining extraction would not be allowed here, there are similar habitats nearby in international waters that are of interest.

“There's an increasing push for deep-sea mining on the seafloor,” Orcutt said. “But a lot of those conversations are not guided by data about where minerals are on the seafloor and what ecosystems they interact with. I want to better understand the potential consequences of human activity in areas like this.”

The monument is also a place of spiritual and cultural importance for some Native Hawaiians. Among many things, it is considered a sacred area where all life springs from, and spirits return to after death. It is also a place for present-day cultural practitioners to reconnect with ancestors and gods who they believe are manifested in nature. Expedition organizers worked with monument staff and volunteers to inform research priorities and integrate culturally grounded protocols and priorities.

“As a guest in this area, I am trying to honor the worldviews and requests of those with ancestral connection to this sacred place” Orcutt said. “My responsibility is to center this perspective in my approach to the research. I hope to use my expertise to reveal knowledge about the natural world in a way that benefits the communities who are caretakers for this special place.”

The monument, almost 600,000 square miles, is the largest marine protected area in the world. It is also one of the few co-managed with Indigenous people. The Office of Hawaiian Affairs, a state agency that represents the interests of Native Hawaiians, is one of the four groups that oversee it.

“It is such a privilege to be able to work in that space, see how it's managed, and know that it is an example,” Orcutt said. “If we want to have healthy oceans, it is important to highlight these kinds of connections. I don't think that humanity is going to find solutions for our biggest problems if all the connected people don’t have a voice at the table.”

Photo credit: NOAA Ocean Exploration, Ocean Exploration Trust, NA-134