Cobb Seamount is a seamount (underwater volcano) and guyot located west of Grays Harbor, Washington, United States. Cobb Seamount is one of the seamounts in the Cobb–Eickelberg Seamount chain, a chain of underwater volcanoes created by the Cobb hotspot that terminates near the coast of Alaska. It lies just west of the Cascadia subduction zone, and was discovered in August 1950 by the U.S. Fish and Wildlife Service fisheries research vessel R/V John N. Cobb (FWS 1601). noaa.gov AFSC Historical Corner: John N. Cobb, Establishing a Rich Legacy nRetrieved August 25, 2018 By 1967, over of soundings and dozens of samples from the seamount had been collected.
Cobb Seamount is geologically interesting for its terraced, pinnacle structure, and its biological community. Like many other seamounts, Cobb Seamount acts as a biological center of diversity, and supports a dense oceanic ecosystem. Relatively convenient access and an interesting biological setting have made the seamount an object of several scientific cruises and dives.
The summit of the volcano is dominated by a carpet of Hinnites multirugosus, which forms the base of a dense ecosystem of and other small, sessile organisms. The species is otherwise scarce in its distribution in the Pacific; its abundance is accommodated by the scarcity of its chief predator, the sea star Orthasterias koehleri. The reason for the sea star's disparity is unknown, as it is extremely common on nearby seamounts.
The steeper flanks of the volcanoes are carpeted by coralline algae of the Lithothamnion and Lithophyllum genus. In some areas, Borgiola pustulosa is more common. Red-colored colonies of demosponge and related species predominant the ecosystem, which includes , , algae, , and . While overall the species diversity on the seamount is lower than a comparable area on the surface, the species present have grown in greater numbers and have formed larger colonies, to the point that there was little to no bare rock surface on the seamount, and none has been found in expeditionary dives. Some endemism to the seamount has also been noted.
The seamount's abundant sea life has made it a target for heavy fishing since the 1960s. However, the fishing is very difficult to monitor, since Cobb lies outside of the U.S. Exclusive Economic Zone and therefore fishing vessels are not regulated. It is known that it has been the site of trawling, gill net, and long-line fishing for some time, mostly by the Japanese and fleets. In 1993, the National Oceanic and Atmospheric Administration sponsored a study on the seamount, which concluded that concerns about overfishing at the seamount have some merit. The study also notes that fishermen there have different fishing patterns, because of different physical conditions at the seamount.
There was tentative expert interest in installing an experimentation platform on Cobb Seamount. The seamount is an easily accessible distance from shore, and would give scientists the ability to work with Cobb Seamount's unique, isolated, and scientifically significant seamount biology. The idea was proposed by P. L. Peterson et al. in a presentation to the Offshore Technology Conference in 1969.
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