Scientists tell House subcommittee the U.S. lacks the baseline science to permit commercial deep sea mining

At the House Science Subcommittee hearing, scientists on the witness panel argued that existing data are insufficient to support commercial-scale deep sea mining in U.S. waters.

Dr. Astred Lightner, an oceanographer and deep sea ecologist at Oregon State University, told members that the deep ocean contains high biodiversity and low biomass, meaning extinction risks can be high for species with small population sizes. "Commercial scale deep sea mining would be one of the largest direct impacts humanity has ever had on the oceans," she said, and she listed major baseline gaps across biological, chemical and physical categories that are needed for environmental assessments and monitoring.

Lightner and others highlighted two distinct impact pathways from nodules and mining operations: (1) direct seafloor disturbance where nodules are removed (nodule substrates do not rapidly regenerate and animals reliant on them may not return), and (2) larger-scale impacts in the water column from plume discharges associated with onboard processing and sediment resuspension. She said these midwater plumes could carry sediments, dissolved metals, persistent organic pollutants and microplastics that spread well beyond immediate mining footprints and could affect fisheries and seafood safety.

Dr. Robert Ballard, an explorer and founder of the Ocean Exploration Trust, backed the call for more exploration and argued that in many places the U.S. has seen only a tiny fraction of its deep seafloor. He said that exploration frequently reveals unexpected ecosystems and resources and that more persistent mapping and multi-vehicle operations are needed to build an evidence base.

Several members echoed the scientific concerns and asked for federal funding to support long-term, independent research, and for industry-collected data to be made publicly available and peer-reviewed. Dr. Lightner recommended region-specific, multi-year research road maps and monitoring programs to understand variability and connectivity before permitting commercial extraction.

The subcommittee did not vote on policy measures at the hearing; members mentioned pending bills and moratorium proposals that would delay commercial permitting until the scientific baseline is substantially improved.