[from Deep-Sea Life Vol 12]
Exploration of biodiversity and ecosystem structure on seamounts in the western CCZ
Jeffrey C. Drazen (1), Matthew Church (2), Thomas Dahlgren (3), Jennifer Durden (1), Adrian Glover (4), Erica Goetze (1),
Astrid Leitner (1), Craig R. Smith (1), Andrew Sweetman (5)
(1) University of Hawaii, (2) University of Montana, (3) Univesity of Gothenberg, Sweden, (4) Natural History Museum, London,
(5) Herriot Watt University
More than one million square kilometers of the abyssal Pacific seafloor in a region called the Clarion Clipperton Zone (CCZ) has 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. Nodule mining is expected to result in the destruction of marine life and seabed habitats over large areas, affecting sites that are directly mined as well as adjoining areas impacted by sediment plumes created by mining activities. Despite these impending activities, the seafloor fauna of the western CCZ and its seamounts had never been explored. The DeepCCZ Expedition was the first to study the diversity 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 used a broad suite of state-of-the-art deepsea technologies to study the biodiversity and ecology of abyssal organisms. Twelve dives were conducted 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. An autonomous respirometer descended to the seafloor to measure biological activity and food-web structure of deep-sea sediment communities. Baited stereo cameras attracted and measured the mobile predators at the top of the deep-sea food chain. Water filters were deployed autonomously to the seafloor to capture the larvae of the benthic fauna and in order to evaluate connectivity. Samples for subsequent DNA analyses were 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 overlying waters. DNA samples from the animals collected will also aid in the identification and description of the many new species discovered, and to assess their occurrence across the abyssal Pacific Ocean.
The data and samples collected on this cruise are currently being analyzed, and are expected to substantially improve understanding of the biodiversity and ecology of the vast and poorly studied CCZ. More than 100 species of large animals were collected or videotaped at the seafloor, such as sea cucumbers, sponges and a huge squid worm. Many of these animals appear to be newly discovered species. Baited camera video shows that the fish assemblages on seamounts, with previously unknown aggregations of eels, are different than the neighboring rattail and cusk eel dominated abyssal plains. Many more results are being generated. In addition to being used to assess the adequacy of conservation measures, these data will also be incorporated into a regional synthesis of the CCZ, to be used to make science-based recommendations to the International Seabed Authority and other stakeholders concerning environmental protection and management for deep-sea mining in the CCZ.
The authors wish to acknowledge their funders – Gordon and Betty Moore Foundation, NOAA Ocean Exploration and Research, the Pew Foundation and the University of Hawaii.