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Seamounts

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Christiana Hanaman
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« Reply #15 on: May 22, 2011, 04:16:07 pm »

Conservation

The ecological conservation of seamounts is hurt by the simple lack of information available. Seamounts are very poorly studied, with only 350 of the estimated 100,000 seamounts in the world having received sampling, and fewer than 100 in depth.[23] Much of this lack of information can be attributed to a lack of technology, and to the daunting task of reaching these underwater structures; the technology to fully explore them has only been around the last few decades. Before consistent conservation efforts can begin, the seamounts of the world must first be mapped, a task that is still in progress.[2]

Overfishing is a serious threat to seamount ecological welfare. There are several well-documented cases of fishery exploitation, for example the orange roughy (Hoplostethus atlanticus) off the coasts of Australia and New Zealand and the pelagic armorhead (Pseudopentaceros richardsoni) near Japan and Russia.[2] The reason for this is that the fishes that are targeted over seamounts are typically long-lived, slow-growing, and slow-maturing. The problem is confounded by the dangers of trawling, which damages seamount surface communities, and the fact that many seamounts are located in international waters, making proper monitoring difficult.[22] Bottom trawling in particular is extremely devastating to seamount ecology, and is responsible for as much as 95% of ecological damage to seamounts.[24]
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Christiana Hanaman
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« Reply #16 on: May 22, 2011, 04:16:46 pm »

Corals from seamounts are also vulnerable, as they are highly valued for making jewellery and decorative objects. Significant harvests have been produced from seamounts, often leaving coral beds depleted.[2]

Individual nations are beginning to note the effect of fishing on seamounts, and the European Commission has agreed to fund the OASIS project, a detailed study of the effects of fishing on seamount communities in the North Atlantic.[22] Another project working towards conservation is CenSeam, a Census of Marine Life project formed in 2005. CenSeam is intended to provide the framework needed to prioritise, integrate, expand and facilitate seamount research efforts in order to significantly reduce the unknown and build towards a global understanding of seamount ecosystems, and the roles they have in the biogeography, biodiversity, productivity and evolution of marine organisms.[23][25]

Possibly the best ecologically studied seamount in the world is Davidson Seamount, with six major expeditions recording over 60,000 species observations. The contrast between the seamount and the surrounding area was well-marked.[16] One of the primary ecological havens on the seamount is its deep sea coral garden, and many of the specimens noted were over a century old.[14] Following the expansion of knowledge on the seamount there was extensive support to make it a marine sanctuary, a motion that was granted in 2008 as part of the Monterey Bay National Marine Sanctuary.[26] Much of what is known about seamounts ecologically is based on observations from Davidson.[14][21] Another such seamount is Bowie Seamount, which has also been declared a marine protected area by Canada for its ecological richness.[27]
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Christiana Hanaman
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« Reply #17 on: May 22, 2011, 04:18:04 pm »



Because of overfishing at their seamount spawning grounds, stocks of orange roughy (Hoplostethus atlanticus) have plummeted; experts say that it could take decades for the species to restore itself to its former numbers.[22]
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Christiana Hanaman
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« Reply #18 on: May 22, 2011, 04:19:27 pm »



Coral earings of this type are often made from coral harvested off seamounts.
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Christiana Hanaman
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« Reply #19 on: May 22, 2011, 04:20:13 pm »

Exploration

The study of seamounts has been stymied for a long time by the lack of technology. Although seamounts have been sampled as far back as the 19th century, their depth and position meant that the technology to explore and sample seamounts in sufficient detail did not exist until the last few decades. Even with the right technology available, only a scant 1% of the total number have been explored,[5] and sampling and information remains biased towards the top 500 m (1,640 ft).[2] New species are observed or collected and valuable information is obtained on almost every submersible dive at seamounts.[6]

Before seamounts and their oceanographic impact can be fully understood, they must be mapped, a daunting task due to their sheer number.[2] The most detailed seamount mappings are provided by multibeam echosounding (sonar), however after more than 5000 publicly held cruises the amount of the sea floor that has been mapped remains miniscule. Satellite altimetry is a broader alternative, albeit not as detailed, with 13,000 catalogued seamounts; however this is still only a fraction of the total 100,000. The reason for this is that uncertanties in the technology limit recognition to features 1,500 m (4,921 ft) or larger. In the future technological advances could allow for a larger and more detailed catalogue.[3]
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« Reply #20 on: May 22, 2011, 04:20:43 pm »

Deep-sea mining

Seamounts are a possible future source of heavy metals. The growth of the human population and, with it, heavy industry, has pressed demands for Earth's finite resources. Even though the ocean makes up 70% of the world, technological challenges with deep-sea mineral mining have severely limited its extent. But with the constantly decreasing supply on land, many see oceanic mining as the destined future, and seamounts stand out as candidates.[28]

Seamounts are abundant, and all have metal resource potential because of various enrichment processes during the seamount's life. Hydrogenic Iron-manganese, hydrothermal iron oxide, sulfide, sulfate, sulfur, hydrothermal manganese oxide, and phosphorite are all mineral resources that are founded by various processes and deposited upon seamounts. However, only the first two have any potential of being targeted by mining in the next few decades.[28]
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« Reply #21 on: May 22, 2011, 04:23:03 pm »




Graph showing the rise in global sea level (in mm) as measured by the NASA/CNES oceanic satellite altimeter TOPEX/Poseidon (left) and its follow-on mission Jason-1.
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« Reply #22 on: May 22, 2011, 04:24:09 pm »

Dangers

Some seamounts have not been mapped and thus pose a navigational danger. For instance, Muirfield Seamount is named after the ship that hit it in 1973.[30] More recently, the submarine USS San Francisco ran into an uncharted seamount in 2005 at a speed of 35 knots (40.3 mph; 64.8 km/h), sustaining serious damage and killing one seaman.[29]

One major seamount risk is that often, in the late of stages of their life, extrusions begin to seep in the seamount. This activity leads to inflation, over-extension of the volcano's flanks, and ultimetly flank collapse, leading to submarine landslides with the potential to start major tsunamis. This is one of the largest natural disasters in the world. In an illustration of the potent power of flank collapses, a summit collapse on the northern edge of Vlinder Seamount resulted in a pronounced headwall scarp and a field of debris up to 6 km (4 mi) away.[7] A catastrophic collapse at Detroit Seamount flattened its whole structure extensively.[10] Lastly, in 2004, scientists found marine fossils 61 m (200 ft) up the flank of Kohala mountain in Hawaii (island). Subsidation analysis found that at the time of their deposition, this would have been 500 m (1,640 ft) up the flank of the volcano,[31] far too high for a normal wave to reach. The date corresponded with a massive flank collapse at the nearby Mauna Loa, and it was theorized that it was a massive tsunami, generated by the landslide, that deposited the fossils.[32]
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« Reply #23 on: May 22, 2011, 04:25:39 pm »



USS San Francisco in dry dock in Guam in January 2005, following its collision with an uncharted seamount. The damage was extensive and the submarine was just barely salvaged.[29]
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« Reply #24 on: May 22, 2011, 04:26:39 pm »

References

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  19. ^ "Introduction to the Biology and Geology of Lōʻihi Seamount". Lōʻihi Seamount. Fe-Oxidizing Microbial Observatory (FeMO). 2009-02-01. http://earthref.org/cgi-bin/er.cgi?s=http://earthref.org/FEMO/loihi.htm. Retrieved 2009-03-02.
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  28. ^ a b "Seamount Mineral Deposits: A Source for Rare Minerals for High Technology Industries". Oceanography. Seamounts Special Issue (Oceanography Society) 23 (1). ISSN 1042-8275. http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/23_1/23-1_hein.pdf. Retrieved 26 July 2010.
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