An official website of the United States government
The Southern Hydrate Summit 2 Seafloor study site, situated on the continental slope off the coast of Oregon at a water depth of ~775 meters, hosts abundant deposits of gas hydrates (methane ice) that are buried beneath, and sometime exposed at, the seafloor. The deposits vent methane-rich fluids and bubbles that escape through seeps on the ocean bottom and can rise in plumes several hundred meters above the seafloor, also fueling dense communities of microbes and animals with chemosynthetic symbiotes. These seeps provide a unique opportunity to study ocean chemistry, quantify chemical fluxes from the seafloor, and observe the impacts of methane release on overlying seawater and biota. Methane is a powerful greenhouse gas and, therefore, quantifying the flux of methane from the seafloor into the hydrosphere is critical to understanding carbon-cycle dynamics and the impacts of global warming on methane release, particularly following seismic events. This Medium-Power junction box (MJ01B) rests on the seafloor adjacent to a highly active methane seep called Einstein’s Grotto. Instrumentation at this site is designed to monitor chemistry of the seep, image the seep and associated biota in detail, and image the bubble plume as it rises several hundred meters above the seafloor. This junction box is attached to an electro-optical cable that provides significant power and 1 Gb two-way communications bandwidth, and is co-located with a Low-Power junction box that collects a complementary suite of geophysical and near-seafloor water column measurements.
more »
« less
(2014) Oregon Margin Southern Hydrate Summit 1 Seafloor (RS01SUM1)
The Southern Hydrate Summit 1 Seafloor study site, situated on the continental slope off the coast of Oregon at a water depth of ~775 meters, hosts abundant deposits of gas hydrates (methane ice) that are buried beneath, and sometime exposed at, the seafloor. The deposits vent methane-rich fluids and bubbles that escape through seeps on the ocean bottom and can rise in plumes several hundred meters above the seafloor, also fueling dense communities of microbes and animals with chemosynthetic symbiotes. These seeps provide a unique opportunity to study ocean chemistry, quantify chemical fluxes from the seafloor, and observe the impacts of methane release on overlying seawater and biota. Methane is a powerful greenhouse gas and, therefore, quantifying the flux of methane from the seafloor into the hydrosphere is critical to understanding carbon-cycle dynamics and the impacts of global warming on methane release, particularly following seismic events. This Low-Power junction box (LJ01B) contains geophysical and near-seafloor water column instrumentation, and is attached to an electro-optical cable that provides significant power and 1 Gb two-way communications bandwidth. This junction box is also co-located with a Medium-Power junction box that collects a complementary suite of seafloor and water column measurements.
more »
« less
- PAR ID:
- 10641912
- Publisher / Repository:
- US NSF Ocean Observatories Initiative
- Date Published:
- Subject(s) / Keyword(s):
- FOS: Earth and related environmental sciences FOS: Environmental engineering
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
The Axial Base Seafloor site is located near the base of the Axial Seamount at the far western edge of the Juan de Fuca tectonic plate, at ~2,600 meters water deep. The site contains a Medium-Power junction box (MJ03A) and a Low-Power junction box (LJ03A). Axial Seamount is the largest and most magmatically robust volcano on the Juan de Fuca Ridge, ~350 km from the continental shelf, and represents an open-ocean or pelagic site in the continuum of observing scales represented in the Regional Cabled Array. Here, large-scale currents including the North Pacific Current, the subpolar gyre, and the northern end of the California Current interact. These currents transport heat, salt, oxygen, and biota, all of which are crucial to the region’s ecosystem. Their variability ranges across timescales from daily tides to seasonal winds to interannual El Niño events to Pacific Decadal Oscillations. These junction boxes contain geophysical and near-seafloor water column instrumentation, and are attached to an electro-optic cable that provides significant power and 1 Gb two-way communications bandwidth. This seafloor site is co-located with a Deep and Shallow Profiler Mooring, which collect complementary water column data.more » « less
-
The Oregon Slope Base Seafloor site is located adjacent to the continental slope off the coast of Oregon at a water depth of ~2,900 meters. The site contains a Medium-Power junction box (MJ01A) and a Low-Power junction box (LJ01A). Here, ocean water properties are profoundly impacted by the California Current and internal waves. The coastal region of the Pacific Northwest is a classic wind-driven upwelling system where nutrient-rich deep waters rise to replace warmer surface waters, resulting in high marine productivity that attracts zooplankton, fish, and marine mammals. Near-bottom fauna are periodically negatively impacted by the flow of deep waters with very low oxygen concentrations (hypoxic events), and upwelling of corrosive, acidified waters onto the continental shelf. This area is also adjacent to the Cascadia Subduction Zone, which is characterized by episodic seismic tremors. The seafloor junction boxes contain geophysical and near seafloor water column instrumentation, and are attached to an electro-optical cable that provides significant power and 1 Gb two-way communications bandwidth. This seafloor site is also co-located with a Deep and Shallow Profiler Mooring, which collect complementary water column data. When coupled with other Cabled Array and Endurance Array installations off the central Oregon coast, the Slope Base infrastructure allows for measurements of a variety of coastal phenomena, including cross-shelf and along-shelf variability.more » « less
-
Chemosynthetic ecosystems host unique geological, biogeochemical, microbial and faunistic settings, which provide key ecosystem services for human wellbeing. In the Argentine continental margin, the existence of chemosynthetic ecosystems is still unknown. We present the first finding of chemosynthetic ecosystems in the Argentine deep sea. We assessed and compared biological and geological settings for cold seeps at Malvinas Basin and Colorado Basin and a control site (no gas) at Colorado Basin. We found two cold seeps with crater-like geomorphic features (pockmarks) of 500-m and 1000-m diameter at depths of ⁓500 m. Both cold seeps exhibited methane gas bubbles trapped at the surface of the seafloor, one exhibited seepage into the water column. Cold seeps hosted dense benthic macroinvertebrates (≥300 μm) assemblages consisting mainly of polychaetes, peracarid crustaceans and mollusks. The fauna from Argentinean seeps exhibited δ13C and δ15N stable isotope signatures indicative of multiple trophic levels, supported by both chemosynthetic and photosynthetic sources of energy. The difference in bubbling to the water column was not associated with different trophic input of chemosynthetically-derived sources of energy, suggesting that gas input is mediated by the bubbles trapped in the seafloor sediments. The presence of gas bubbles trapped in the surface sediments of the ocean floor allowed the detection of ecological and trophic characteristics of active chemosynthetic ecosystems. Integration of the sub-bottom dimension can help improve our understanding of the interactions of chemosynthetic ecosystems with seafloor fluid flow in a more reliable manner than the gas plumes. These cold seeps host significant biodiversity and ecosystem functions of the deep ocean. They fall within areas tendered for oil and gas industry development, but have not been a focus of conservation efforts to date. Information provided here can inform effective conservation actions and improve our understanding of the distribution of chemosynthetic ecosystems worldwide.more » « less
-
The Axial Base Deep Profiler Mooring is located near the base of the Axial Seamount at the far western edge of the Juan de Fuca tectonic plate, at ~2,600 meters water depth. Axial Seamount is the largest and most magmatically robust volcano on the Juan de Fuca Ridge, ~350 km from the continental shelf, and represents an open-ocean or pelagic site in the continuum of observing scales represented in the Regional Cabled Array. Here, large-scale currents including the North Pacific Current, the subpolar gyre, and the northern end of the California Current interact. These currents transport heat, salt, oxygen, and biota, all of which are crucial to the region’s ecosystem. Their variability ranges across timescales from daily tides to seasonal winds to interannual El Niño events to Pacific Decadal Oscillations. Because of its close proximity to the magmatically active volcano, instruments on the profiler may also capture perturbed water masses resulting from underwater eruptions at the summit and along the flanks. This mooring contains a Wire-Following Profiler that hosts six scientific instruments and moves through the water column along the mooring riser, continuously sampling ocean characteristics over a specified depth interval (150 meters below sea surface to near bottom) and is connected to an electro-optical cable that provides a large supply of power and bandwidth. The Axial Base Deep Profiler Mooring is co-located with a Low-Power junction box that collects complementary geophysical and near-seafloor water property data.more » « less
