Bowers Ridge

Bowers Ridge
Williamborg · CC BY-SA 3.0 · source
Name	Bowers Ridge
Location	Bering Sea
Type	submarine ridge
Length	approximately 750 km

Bowers Ridge is a major submarine ridge in the southern Bering Sea extending northeast to southwest between the Aleutian Islands and the North American Plate continental margin off Alaska. It forms a conspicuous bathymetric high separating the Bering Sea Basin from the Aleutian Basin and influences regional Pacific Ocean circulation, sediment dispersal, and faunal distribution across the Commander Islands–Pribilof Islands corridor. The ridge has been studied by institutions such as the United States Geological Survey, the Woods Hole Oceanographic Institution, and Russian institutes including the Russian Academy of Sciences.

Geography and morphology

Bowers Ridge lies roughly parallel to the Aleutian Trench and trends from near the Bering Canyon toward the vicinity of the Pribilof Islands, forming a arcuate feature between the Bering Shelf and the deep Bering Abyssal Plain. Its crest rises from depths of about 3,000–4,000 m to about 1,100–1,500 m, creating pronounced escarpments that border the Navarin Canyon and adjacent basins associated with prominent bathymetric gradients studied by expeditions from NOAA and the Lamont-Doherty Earth Observatory. The ridge includes subsidiary highs, notch-like depressions, and transverse ridgelines that interact with channels such as the Kurile Basin outflows, influencing bottom currents measured by moorings deployed by the Scripps Institution of Oceanography and the National Oceanic and Atmospheric Administration.

Geological history and formation

The formation of the ridge has been interpreted within frameworks developed by researchers from the Geological Society of America and the International Association of Sedimentologists who correlated stratigraphy with tectonic events recorded in cores taken by DSV Alvin-equipped cruises and IODP-style drilling proposals. Hypotheses link its origin to Mesozoic–Cenozoic accretionary processes involving fragments of the Pacific Plate and microcontinents comparable to pieces of the Wrangellia Terrane and the Kula Plate interactions, with episodes of volcanism analogous to that in the Aleutian Arc and subsidence events contemporaneous with Paleogene–Neogene global sea-level changes. Detrital zircon studies tying provenance to the Laurentia margin and isotopic work paralleling results from the Kamchatka Peninsula and the Alaskan Range support models invoking long-term oblique convergence, trench migration, and intra-oceanic deformation documented in papers by teams affiliated with the University of Alaska Fairbanks.

Tectonics and seismicity

Bowers Ridge occupies a tectonically active setting influenced by the nearby Aleutian subduction zone, the motion of the Pacific Plate relative to the North American Plate, and the legacy of extinct spreading centers such as the hypothesized Kula Plate ridge systems. Seismicity near the ridge has been monitored by networks including the Alaska Earthquake Center and the USGS National Earthquake Information Center, revealing infrequent but notable earthquake swarms and smaller thrust and strike-slip events similar in style to those cataloged along the Aleutian Range and the Queen Charlotte-Fairweather Fault. Geophysical surveys using multichannel seismic reflection, gravity, and magnetic methods conducted by research vessels of the NOAA Ocean Exploration program and the Russian Academy of Sciences have imaged folded strata, fault-bounded blocks, and possible reactivated basement structures comparable to deformation seen on the Norton Sound margin.

Oceanography and sedimentation

The ridge exerts control on bottom-water pathways and intermediate currents of the Bering Sea such as inflow from the Pacific Ocean through the Aleutian passes, creating upwelling zones and retention areas that affect nutrient fluxes observed by ARGO floats and Global Drifter Program buoys. Sediment cores recovered by joint NOAA–Russian cruises display thick sequences of glacially derived turbidites, hemipelagic drapes, and volcanic ash layers correlated with eruptions of the Aleutian Arc and tephra records used in studies by the International Union for Quaternary Research. Grain-size analysis, radiocarbon dating, and biostratigraphy by teams from the Smithsonian Institution and the Natural History Museum, London have helped reconstruct Pleistocene–Holocene sedimentation rates and paleoceanographic shifts linked to Beringia glacial-interglacial cycles.

Ecology and biological communities

The topographic relief of the ridge provides substrate heterogeneity that supports benthic communities analogous to those found near the Pribilof Islands and St. Paul Island, including filter-feeding sponges, cold-water corals, and sessile invertebrates surveyed by the Monterey Bay Aquarium Research Institute and the NOAA National Marine Fisheries Service. Pelagic processes influenced by the ridge affect foraging grounds for commercially important species such as Pacific cod, walleye pollock, and migratory populations of Pacific salmon, which in turn support fisheries managed by the North Pacific Fishery Management Council and traditional harvests by indigenous communities like the Aleut and Yup'ik. Biological sampling using remotely operated vehicles operated from vessels of the National Science Foundation and biodiversity assessments coordinated with the Convention on Biological Diversity have documented endemic assemblages and biogeographic links to the Gulf of Alaska and Sea of Okhotsk.

Human research and exploration

Research on the ridge has been conducted through cooperative programs involving NOAA, the USGS, the National Oceanic and Atmospheric Administration, Woods Hole Oceanographic Institution, the University of Washington, and Russian counterparts including the P.P. Shirshov Institute of Oceanology. Fieldwork has included multibeam mapping, seismic reflection profiling, coring operations on research vessels such as the RV Ronald H. Brown and the RV Akademik Mstislav Keldysh, and biological surveys using ROV and AUV platforms deployed by the Monterey Bay Aquarium Research Institute and WHOI; publications have appeared in journals like Science, Nature Geoscience, and the Journal of Geophysical Research. Ongoing collaborations aim to refine models of ridge evolution, map habitats for conservation initiatives associated with the Marine Mammal Protection Act-related studies, and improve regional hazard assessments used by the National Weather Service and shipping interests operating in the Bering Sea.

Category:Submarine ridges of the Pacific Ocean