Abstract
Deep-sea hydrothermal vent fields are globally rare (abundant in numbers, but extremely small in area) and are rich in extraordinary life based on chemosynthesis rather than photosynthesis. Vent fields are also sources of polymetallic sulfides rich in copper and other metals. Mineral resources of the international seabed beyond national jurisdictions (referred to as the “Area”) are administered by the International Seabed Authority (ISA), which has the mandate to organize and control mineral resource-related activities and to ensure effective protection of the marine environment from harmful effects which may arise from such activities. To date, the ISA has approved 3 contracts for mineral exploration on the northern Mid-Atlantic Ridge (nMAR) and is developing a Regional Environmental Management Plan (REMPs) for polymetallic sulfide resources in the Area of northern MAR, including the application of area-based management tools to address the potential impacts of mining activities. Several intergovernmental organizations have developed suites of criteria to identify vulnerable, sensitive, and ecologically or biologically significant ecosystems in need of protection. In this case study, we combine criteria developed by FAO for VMEs (Vulnerable Marine Ecosystems), by CBD for EBSAs (Ecologically or Biologically Significant Areas), and by IMO for PSSAs (Particularly Sensitive Sea Areas) to assess whether the 11 confirmed vent fields on the nMAR may meet these criteria. Our assessment indicates that all vent fields meet multiple criteria for vulnerability, sensitivity, and ecological or biological significance, and 10 of 11 vent fields meet all criteria for ecosystems in need of protection.
Highlights
Vent-endemic taxa symbiotic with autotrophic bacteria that dominate the biomass at other known active hydrothermal vent fields on the Mid-Atlantic Ridge are mostly absent at Lost City
The Lost City hydrothermal field is posited as a contemporary analogue for conditions where life on early Earth may have originated [53, 54], where there is abiogenic production of organic carbon [46, 55], and where there are conditions similar to those that might support life within oceans of extra-terrestrial planetary bodies [19]
Trans-Atlantic Geotraverse (TAG) vent field is an important area for breeding and spawning for several species including for example the shrimp Rimicaris exuculata and the shrimp-eating anemone Maractis rimicarivora, which are present in large and stable populations at this discrete site [82, 111]
Summary
The Lost City hydrothermal field was discovered in 2000 during a submersible dive to explore the Atlantis Massif, an Oceanic Core Complex [1, 2]. Vent-endemic taxa symbiotic with autotrophic bacteria that dominate the biomass at other known active hydrothermal vent fields on the Mid-Atlantic Ridge are mostly absent at Lost City. Hydrothermal fluid emissions at Lost City support the growth of sulfur-cycling and methane-oxidizing microorganisms adapted to the high pH and H2- and CH4-rich conditions [6, 17, 18]. Hydrothermal vents contribute to regulating and supporting services including carbon sequestration by biological pump, or microbial oxidation of the greenhouse gas methane [49] and represent major source of iron, an essential trace element that controls marine productivity, in the global ocean [50]. Lost City is globally distinctive with its carbonate chimneys forming through highly alkaline vent fluid and associated microbial communities, in contrast to acidic, sulfideand metal-rich vent fluids at all other known vent fields along the northern MidAtlantic Ridge. The Lost City hydrothermal field is posited as a contemporary analogue for conditions where life on early Earth may have originated [53, 54], where there is abiogenic production of organic carbon [46, 55], and where there are conditions similar to those that might support life within oceans of extra-terrestrial planetary bodies [19]. Lost City may be used as a science or education example of particular geological, geophysical or biological attributes
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