Investigation of an Historic Seabed Mining Site on the Blake Plateau: Environmental Impacts following the 1970 Testing of Seabed Mining Equipment on the Blake Plateau- Quantification of Benthic Communities Across Disturbance Gradients
USGS researchers will characterize the ecology of benthic communities associated with deep-sea environments, including hardground features and adjacent soft sediments, and will build upon previous work conducted in areas off the U.S. east coast under consideration for oil and gas leases.
The Science Issue and Relevance: Critical minerals are important to the economic and national security of the United States, and the marine environment may be a potential source for minerals, such as copper, zinc, and nickel. Marine mineral-rich hard substrates, such as crusts and nodules, can support diverse benthic, or seafloor, communities, including some rare species. However, there is inadequate information about marine minerals’ associations with sensitive deep-sea habitats and species, including corals, sponges, and infauna, or small animals that live within seafloor sediment, to fully assess the potential environmental impacts of mining. Also, basic ecological information in these areas is currently lacking, especially species composition, population sizes, distribution, and connectivity, as well as species response and recovery to disturbances (e.g., dredging and excavation).
The Blake Plateau has a long history of research, exploration, and extraction activities; in the 1970s, experimental deep-sea resource extraction technologies were used at the site, and it now provides an opportunity to investigate long-term environmental impacts of these and related activities. Much of the interest of Blake Plateau relates to understanding the formation and economic potential of ferromanganese (Fe-Mn) nodules and Fe-Mn encrusted phosphorite/carbonate pavements, all containing materials used for a wide variety of purposes, from electronics and green technologies, such as hybrid vehicles, to fertilizer. This study will characterize the ecology of benthic communities associated with deep-sea environments, including hardground features and adjacent soft sediments, and will build upon previous work conducted in areas off the U.S. east coast under consideration for oil and gas leases. This study will advance the efforts of USGS, the Bureau of Ocean Energy Management (BOEM), and the National Oceanic and Atmospheric Administration (NOAA) to study, plan, and manage for potential environmental impacts of critical mineral mining activities on the outer continental shelf (OCS), as directed by current Administration directives.
Methodology for Addressing the Issue: The Blake Plateau study area is 50 km2. High-resolution surveying was used to map areas on Blake Plateau that have experienced disturbance as well as surrounding areas that have not been disturbed. An autonomous underwater vehicle was used to collect high-resolution multibeam bathymetry, side-scan sonar, chirp sub-bottom profiles, and camera images, providing meter to sub-meter resolution of the seafloor. New survey data combined with historical datasets will be used to characterize seafloor morphology and the benthic communities present on Blake Plateau. It will also help scientists and managers identify and map the extent and impact of the seafloor disturbance caused by historical seabed test mining on the Blake Plateau and the level of natural restoration (if any) of the physical and biological seafloor environment.
For the next phase of this study, if time and appropriate sampling capabilities allow, opportunistic sediment core samples will be processed to collect baseline information about the biology, chemistry, and geology of Blake Plateau. Data collection will include quantifying macrofaunal (species that are less than 300 mm, or about the size of a pencil eraser) densities, diversity, community composition, and biomass; quantifying total organic carbon and nitrogen (TOC/TON) and particle size; and estimating pore water hydrogen sulfide content, dissolved oxygen, and redox. In addition, animals collected directly from the seafloor will be analyzed for stable isotopes to characterize the food web. The stable isotope analysis and environmental chemistry work will occur in a subsequent phase of this study.
Future Steps: Once the site has been surveyed historical and recent data will be used to direct sampling efforts, including sediment coring, on future research expeditions. Sediment samples will assist in determining the benthic communities’ response to past seabed mining activities. Results will help managers assess how these communities responded to previous disturbances and what efforts may be implemented to reduce the effects of mining and/or energy exploration on the surrounding habitats and benthic communities.
USGS DISCOVRE: Benthic Ecology, Trophodynamics, Ecosystem Connectivity of Mid-Atlantic Deepwater Hard Bottom Habitats with Emphasis on Canyon and Coral Communities
USGS DISCOVRE: Benthic Ecology, Trophodynamics, and Ecosystem Connectivity – Lophelia II: Continuing Ecological Research on Deep-Sea Corals and Deep Reef Habitats in the Gulf of Mexico
USGS researchers will characterize the ecology of benthic communities associated with deep-sea environments, including hardground features and adjacent soft sediments, and will build upon previous work conducted in areas off the U.S. east coast under consideration for oil and gas leases.
The Science Issue and Relevance: Critical minerals are important to the economic and national security of the United States, and the marine environment may be a potential source for minerals, such as copper, zinc, and nickel. Marine mineral-rich hard substrates, such as crusts and nodules, can support diverse benthic, or seafloor, communities, including some rare species. However, there is inadequate information about marine minerals’ associations with sensitive deep-sea habitats and species, including corals, sponges, and infauna, or small animals that live within seafloor sediment, to fully assess the potential environmental impacts of mining. Also, basic ecological information in these areas is currently lacking, especially species composition, population sizes, distribution, and connectivity, as well as species response and recovery to disturbances (e.g., dredging and excavation).
The Blake Plateau has a long history of research, exploration, and extraction activities; in the 1970s, experimental deep-sea resource extraction technologies were used at the site, and it now provides an opportunity to investigate long-term environmental impacts of these and related activities. Much of the interest of Blake Plateau relates to understanding the formation and economic potential of ferromanganese (Fe-Mn) nodules and Fe-Mn encrusted phosphorite/carbonate pavements, all containing materials used for a wide variety of purposes, from electronics and green technologies, such as hybrid vehicles, to fertilizer. This study will characterize the ecology of benthic communities associated with deep-sea environments, including hardground features and adjacent soft sediments, and will build upon previous work conducted in areas off the U.S. east coast under consideration for oil and gas leases. This study will advance the efforts of USGS, the Bureau of Ocean Energy Management (BOEM), and the National Oceanic and Atmospheric Administration (NOAA) to study, plan, and manage for potential environmental impacts of critical mineral mining activities on the outer continental shelf (OCS), as directed by current Administration directives.
Methodology for Addressing the Issue: The Blake Plateau study area is 50 km2. High-resolution surveying was used to map areas on Blake Plateau that have experienced disturbance as well as surrounding areas that have not been disturbed. An autonomous underwater vehicle was used to collect high-resolution multibeam bathymetry, side-scan sonar, chirp sub-bottom profiles, and camera images, providing meter to sub-meter resolution of the seafloor. New survey data combined with historical datasets will be used to characterize seafloor morphology and the benthic communities present on Blake Plateau. It will also help scientists and managers identify and map the extent and impact of the seafloor disturbance caused by historical seabed test mining on the Blake Plateau and the level of natural restoration (if any) of the physical and biological seafloor environment.
For the next phase of this study, if time and appropriate sampling capabilities allow, opportunistic sediment core samples will be processed to collect baseline information about the biology, chemistry, and geology of Blake Plateau. Data collection will include quantifying macrofaunal (species that are less than 300 mm, or about the size of a pencil eraser) densities, diversity, community composition, and biomass; quantifying total organic carbon and nitrogen (TOC/TON) and particle size; and estimating pore water hydrogen sulfide content, dissolved oxygen, and redox. In addition, animals collected directly from the seafloor will be analyzed for stable isotopes to characterize the food web. The stable isotope analysis and environmental chemistry work will occur in a subsequent phase of this study.
Future Steps: Once the site has been surveyed historical and recent data will be used to direct sampling efforts, including sediment coring, on future research expeditions. Sediment samples will assist in determining the benthic communities’ response to past seabed mining activities. Results will help managers assess how these communities responded to previous disturbances and what efforts may be implemented to reduce the effects of mining and/or energy exploration on the surrounding habitats and benthic communities.