Scientists explore biodiversity of poorly known deep-sea areas targeted for seafloor mining

The team recovering ROV Luukai on the R/V Kilo Moana after a successful dive. Credit: UHM SOEST.

A large sea cucumber, Psychropotes longicauda, on the abyssal plain. Credit: UHM SOEST.

Map of the Pacific Ocean showing the Clarion-Clipperton Zone (CCZ).

An international team led by scientists from the University of Hawaiʻi at Mānoa recently returned from a 34-day expedition to study deep-sea biodiversity and ecological processes in the western Clarion-Clipperton Zone (CCZ). The expedition, aboard the UH-operated research vessel Kilo Moana, studied an area in the Pacific Ocean where numerous manganese nodule mining exploration claims are located.

Said chief scientist Craig Smith, professor of oceanography in the School of Ocean and Earth Science and Technology (SOEST), “The diversity of life in these seafloor areas is really amazing. We found at least 10 species of giant sea cucumbers, a huge squid worm never seen before in the Pacific Ocean, and all kinds of sponges and other animals with really neat adaptations, such as sea cucumbers with long tails that allow them to sail along the seafloor.”

More than one million square kilometers of the abyssal Pacific seafloor have been identified for possible seafloor nodule mining. Manganese nodules are a potential source of copper, nickel, cobalt, iron, manganese and rare earth elements—metals used in electrical systems and for electronics like rechargeable batteries and touch screens.

Deep-sea nodule mining is expected to result in the destruction of marine life and seabed habitats over large areas; this destruction will occur within sites directly mined as well as in adjoining areas disturbed by sediment plumes stirred up by mining activities.

The abyssal plains cover approximately 70 percent of the global seabed and are the biggest habitat on Earth’s surface. These seafloor habitats remain among the most poorly studied on the planet because they are remote and require specialist equipment to study. Yet they may harbor an extraordinary diversity of organisms ranging from giant sea cucumbers to novel bacteria.  

The research cruise, dubbed the DeepCCZ Expedition, was the first to study the wealth of organisms on seafloor plains and seamounts in areas currently designated as “no-mining areas” in the western CCZ. A major goal is to determine whether these protected areas are adequate to conserve the biodiversity in the region from the destructive activities of seafloor mining.

The expedition made 12 successful dives with UH's new remotely operated vehicle (ROV) Lu'ukai, which used robotic arms and deep-sea cameras to photograph and collect animals, manganese nodules and sediments from greater than three miles deep. More than 100 species of large animals were collected or videotaped at the seafloor, many of which appear to be newly discovered species.

In addition to the ROV, the expedition used a broad suite of new deep-sea technologies to study the biodiversity and ecology of abyssal organisms ranging from bacteria to meter-long fish. State-of-the-art equipment designed to function at the enormous pressures of the abyssal ocean (more than 7,000 pounds per square inch) included an autonomous respirometer that descended to the seafloor to measure biological activity and food-web structure of deep-sea sediment communities, and baited stereo cameras that attracted and measured the mobile predators at the top of the deep-sea food chain.

DNA samples were also collected from the environment, and from individual animals, to test new approaches to assess biodiversity and ecological functions of microbes and animals living in sediments, on manganese nodules, and in the waters above. DNA samples from the animals collected will also aid in the identification and description of the many new species, and to assess their occurrence across the abyssal Pacific Ocean.

“Another unexpected find,” said Smith, “was a dramatic difference in the abundance of manganese nodules and animals living on them, over surprisingly short distances of a few hundred miles across the abyssal plain.”

The data collected on this cruise will take many months to fully analyze, and is expected to substantially improve understanding of the biodiversity and ecology of the vast and poorly studied CCZ. The scientists will use these data to help assess the adequacy of conservation measures presently in place to protect deep-sea biodiversity in the face of seafloor mining. 

These data will also be incorporated into a regional synthesis of the CCZ, to be used to make science-based recommendations to the Internaitonal Seabed Authority and other stakeholders concerning environmental protection and management for deep-sea mining in the CCZ.

Said Jeff Drazen, project co-leader and UH oceanography professor, “This cruise was a wonderful opportunity to evaluate if three no-mining zones will be adequate protection for abyssal communities in the region, before seafloor mining begins.”

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The DeepCCZ Expedition was funded by the Gordon and Betty Moore Foundation, the NOAA Office of Ocean Exploration and Research, the Pew Charitable Trusts and the University of Hawai‘i. Project principal investigators include Craig Smith, Jeff Drazen and Erica Goetze of the University of Hawai‘i; Eric Vetter of Hawaiʻi Pacific University; Matt Church of University of Montana; Andrew Sweetman of Heriot Watt University, UK; Adrian Glover of the Natural History Museum, UK; and Thomas Dahlgren of the University of Gothenburg, Sweden.

Researcher contacts:

Dr. Craig Smith
Professor, Department of Oceanography
University of Hawaiʻi at Mānoa, USA
+1 (808) 383-9598 (for direct conversations and texting)
craigsmi@hawaii.edu

Dr. Jennifer Durden
Postdoctoral Fellow, Department of Oceanography
University of Hawaiʻi at Mānoa, USA
jdurden@hawaii.edu

Contact information of the other PIs:

Dr. Jeff Drazen
Professor, Department of Oceanography
University of Hawaiʻi at Mānoa, USA
+1 (808) 956-6567
jdrazen@hawaii.edu

Dr. Erica Goetze
Associate Professor, Department of Oceanography
University of Hawaiʻi at Mānoa, USA
+1 (808) 956-7156
egoetze@hawaii.edu

Dr. Matt Church
Associate Professor
Aquatic Microbial Ecology
Flathead Lake Bio Station
University of Montana, USA
+1 (406) 982-3301 x 238
matt.church@umontana.edu

Dr. Andrew Sweetman
Associate Professor, Lyell Centre for Earth and Marine Science and Technology
Heriot-Watt University, UK
+44 (0) 131 451 3993
a.sweetman@hw.ac.uk

Dr. Adrian Glover
Deep-Sea Systematics and Ecology Group Lead
Natural History Museum, UK
+44 (0) 20 7942 5056
a.glover@nhm.ac.uk

Dr. Thomas Dahlgren
Associate Professor, University of Gothenburg, Sweden
Senior Scientist, Uni Research, Norway
+46 31 786 3670
thomas.dahlgren@marine.gu.se

Dr. Eric Vetter
Professor - Marine Biology
Hawai’I Pacific University
+1 (808) 236-5832
evetter@hpu.edu

Link to cruise video: http://go.hawaii.edu/f4m