Davidson Seamount
   HOME

TheInfoList



OR:

Davidson Seamount is a
seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...
( underwater volcano) located off the coast of Central California, southwest of Monterey and west of San Simeon. At long and wide, it is one of the largest known seamounts in the world. From base to crest, the seamount is tall, yet its summit is still below the sea surface. The seamount is biologically diverse, with 237 species and 27 types of deep-sea coral having been identified. Discovered during the mapping of California's coast in 1933, Davidson Seamount is named after geographer George Davidson of the
United States Coast and Geodetic Survey The United States Coast and Geodetic Survey ( USC&GS; known as the Survey of the Coast from 1807 to 1836, and as the United States Coast Survey from 1836 until 1878) was the first scientific agency of the Federal government of the United State ...
. Studied only sparsely for decades,
NOAA The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploratio ...
expeditions to the seamount in 2002 and 2006 cast light upon its unique deep-sea coral ecosystem. Davidson Seamount is populated by a dense population of large, ancient corals, some over 100 years old. The data gathered during the studies led to the Davidson Seamount being added to the Monterey Bay National Marine Sanctuary in 2008.


Geology

A
seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...
is an underwater volcano; Davidson rises above the surrounding ocean floor. Although there are over 30,000 seamounts in the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
alone, only about 0.1% of them have been explored. The aqueous environment of the seamount means that it behaves differently from volcanoes on land. Its surface is mostly blocky lava flows, with some
pillow lava Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of discontinu ...
, more typical of a seamount, prevailing at its deeper flanks. The summit is composed of layered
volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...
and pyroclastic material. These rocks indicate mildly explosive eruptions of gas-rich lava near the summit. The base is likely buried in a deep layers of muds. At long and wide, Davidson Seamount would dominate the landscape similar to
Mount Shasta Mount Shasta ( ; Shasta people, Shasta: ''Waka-nunee-Tuki-wuki''; Karuk language, Karuk: ''Úytaahkoo'') is a Volcano#Volcanic activity, potentially active stratovolcano at the southern end of the Cascade Range in Siskiyou County, California. A ...
. Put in perspective, the size of the seamount is enough to fill
Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area. San Francisco itself is further north along the coast, by about 75 miles (120 km), accessible via California S ...
from the Santa Cruz boardwalk to Monterey's Fishermen's Wharf. Davidson Seamount is part of a group of seamounts off the continental margin, including
Guide A guide is a person who leads travelers, sportspeople, or tourists through unknown or unfamiliar locations. The term can also be applied to a person who leads others to more abstract goals such as knowledge or wisdom. Travel and recreation Exp ...
, Pioneer, Gumdrop, and Rodriguez seamounts, all located roughly between 37.5° and 34.0°
latitude In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at t ...
. This group is morphologically unique, yet very similar to one another. All the seamounts in the group are complex northeast-southwest trending structures, consisting of parallel ridges separated by sediment-filled troughs. The ridges constructed run parallel to an ancient spreading center which has since been replaced in its role by the
San Andreas Fault The San Andreas Fault is a continental Fault (geology)#Strike-slip faults, right-lateral strike-slip transform fault that extends roughly through the U.S. state of California. It forms part of the tectonics, tectonic boundary between the Paci ...
system. They are unique in this origin, as they are formed from the remnants of an old ocean-ridge spreading center. A series of "knobs" are aligned with the ridges; however the distinctive summit crater, evident in many oceanic volcanoes, is absent. This lack of a collapse crater suggests that magma was never stored in a chamber within the structure, as with most other volcanoes. Analysis of
argon–argon dating Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede Potassium-argon dating, potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measur ...
studies indicate that Davidson formed between 9 and 15 million years ago, 5 to 12 million years after the formation of the overlaying oceanic crust.


Ecology

Studies have indicated that a seamount functions as an "oasis of life," with a higher species count and more
biodiversity Biodiversity is the variability of life, life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and Phylogenetics, phylogenetic diversity. Diversity is not distribut ...
than the surrounding seafloor. Although previous analysis has stressed the exceptionalism of the seamount habitat, recent biological analysis, much of it centered on Davidson Seamount, has indicated that this does not necessarily translate into a higher
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
percentage. However, it ''is'' believed that they provide a refuge for rare species that have difficulty surviving elsewhere. There are reasons that seamounts are biologically important. They rise high in the water column, creating complex current patterns that support life on, around, and above the seamount. The surface of the seamount also provides a substrate upon which organisms can attach themselves and grow. This in turn supports the species that feed on them, in turn supporting the whole ecological
food web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Position in the food web, or trophic level, is used in ecology to broadly classify organisms as autotrophs or he ...
. Scientists have found that seamounts often provide a habitat for
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
species that are not found anywhere else. Davidson Seamount is among the best biologically described seamounts worldwide. Six major expeditions to the volcano have yielded over 60,000 species observations. scientists have observed and recorded 168 species of
megafauna In zoology, megafauna (from Ancient Greek, Greek μέγας ''megas'' "large" and Neo-Latin ''fauna'' "animal life") are large animals. The precise definition of the term varies widely, though a common threshold is approximately , this lower en ...
on the seamount. Of these, about 7% of the species at Davidson are
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
, meaning they live only at Davidson. 71% of the species can be confidently classified as cosmopolitan (widespread), and sufficient data exists for 22% of the observed species to strongly suggest that their range is not limited to seamounts. The remaining 7% have only been seen in video footage. Thirteen species have been identified in other areas, but never in other seamounts. The seamount is populated by a large variety of deep-sea corals, most of which in turn provide a habitat for other species. It has in the past been called "An Oasis in the Deep", hosting a vast coral forest, large
sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...
field,
crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...
s, deep-sea fish, basket stars, and a number of rare
benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...
species, some of which have yet to be studied properly or even named. These are all cold-water species, as the temperature even at the top of the seamount is just above freezing—around , as compared to at the ocean's surface. Despite its size, the top of Davidson Seamount remains over below the ocean's surface. This great depth means that the habitats that the seamount supports have not been significantly disturbed by human activity;
anchor An anchor is a device, normally made of metal, used to secure a vessel to the bed of a body of water to prevent the craft from drifting due to wind or current. The word derives from Latin ', which itself comes from the Greek (). Anch ...
ing and trawling typically does not occur below a depth of , and waste disposal and discharge occurs much closer to shore. In comparisons drawn to the nearby Monterey Bay National Marine Sanctuary, the two were shown to be very different biologically. Species that are rare in Monterey Bay are common on Davidson, and vice versa.


Deep-sea coral

The ecology on Davidson Seamount is dominated by an extensive "forest" of ancient deep-sea coral and
sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...
s, some of which are over 100 years old. Although these species also grow elsewhere, they are generally sparsely distributed and far smaller and younger than the coral growth on Davidson. Conversely,
sea cucumber Sea cucumbers are echinoderms from the class (biology), class Holothuroidea ( ). They are benthic marine animals found on the sea floor worldwide, and the number of known holothuroid species worldwide is about 1,786, with the greatest number be ...
s, which are very common on the walls of Monterey Canyon, are all but absent on Davidson, an example of the polarity between Davidson and Monterey Bay. Researchers speculate that Davidson Seamount is an ideal habitat for deep-sea corals and sponges because it has favorable bottom rock (bare lava rock), a steady food supply (supplied by a water current favoring the seamount; see the section above), and has not been disturbed by strong bottom currents than often bother other seafloor areas. Craig McClain, one of the scientists studying the seamount, told
PhysOrg Phys.org is an online science, research and technology news aggregator which re-publishes press releases and stories from news agencies (a business model known as churnalism). In 2012, PhysOrg.com was changed to Phys.org. , Phys.org was posti ...
: Research also suggests that seamounts such as Davidson Seamount may be ecologically valuable to rare species that use them as breeding grounds. The seamounts are likely to be a source of
larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...
that maintains the population of the species in nearby, sub-optimal areas, known as "
sink A sink (also known as ''basin'' in the UK) is a bowl-shaped plumbing fixture for washing hands, dishwashing, and other purposes. Sinks have a tap (faucet) that supplies hot and cold water and may include a spray feature to be used for fas ...
s." Sinks are low-lying areas in which species can live, but do so very poorly; if they are not replenished by nearby population centers, such as at Davidson, they could disappear from the area entirely. DNA studies may in the future help scientists prove seamounts are indeed sources of larvae for their surrounding seafloor.


History


Exploration

Davidson Seamount was initially discovered and mapped in 1933. Davidson Seamount was the first underwater volcano to be classified as "seamount" by the United States Board of Geographic Names, in 1938, and was named in honor of the
United States Coast and Geodetic Survey The United States Coast and Geodetic Survey ( USC&GS; known as the Survey of the Coast from 1807 to 1836, and as the United States Coast Survey from 1836 until 1878) was the first scientific agency of the Federal government of the United State ...
scientist George Davidson, one of the key figures in the survey of America's west coast. Because of its great depth, for a long time Davidson Seamount had been preceded only by a sparse few investigations. Davidson is interesting to volcanologists because of its unique geology, and to
biologist A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...
s for its unique ecology. In 2002 the NOAA sponsored the first modern in-depth study of the seamount. The team included scientists, educators, and resource managers, with the goal of documenting species, taking geologic samples, and describing the ocean environment. The expedition documented many rare, previously undiscovered species that exist nowhere else, not even on nearby seamounts, including ancient coral gardens that are vulnerable to human activity. Recent expeditions to Davidson have focused on its ecology, and specifically on the variety of deep-sea corals, some over 100 years old, that live on its banks. These large colonies are extremely fragile to human interaction. Davidson's proximity to scientific research institutions has helped its exploration, as multiple dives, mappings, and studies have made it one of the better-studied seamounts in the world. In 2006, another exploration, a collaboration of the Monterey Bay National Marine Sanctuary, the Monterey Bay Aquarium Research Institute (MBARI), and Moss Landing Marine Laboratories was undertaken, mainly to test a model that had been developed to predict the availability of coral and to advance the understanding of the seamount's deep-sea coral. The NOAA outlined a set of 4 goals for the expedition: * Understand why deep-sea corals live where they do on the seamount * Determine the age and growth patterns of the bamboo coral * Improve the species list and taxonomy of corals from the seamount * Share the exciting experience with the public through television and the Internet Scientific data on the water currents and food availability of the seamount was collected, as was information on the
age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...
and growth patterns of the corals themselves. The
British Broadcasting Corporation The British Broadcasting Corporation (BBC) is a British public broadcasting, public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved in ...
(
BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...
) filmed the cruise for their series, '' Planet Earth''. A total of 70 hours of observations and 102 deep-sea animal and rock specimens were collected during the cruise. The expedition, which lasted from January 26 through February 4, made use if the MBARI's research vessel ''Western Flyer'' and the ROV ''Tiburon''.


As a marine sanctuary

Following the information learned from the 2002 and 2006 expeditions, there was public support for the making of Davidson Seamount into a marine sanctuary. A key group of research scientists, fishermen, officials, educators, and marine biologists was formed in 2006 to discuss whether or not to make Davidson Seamount a National Marine Sanctuary under the National Marine Sanctuaries Act, and if so whether to make it its own sanctuary, or incorporate it into the nearby Monterey Bay National Marine Sanctuary. The group decided that the seamount was eligible for sanctuary designation, and the majority of the group recommended its incorporation into the nearby Monterey Bay sanctuary. The Monterey Bay advisory group concurred with the findings, and submitted its approval to the
NOAA The National Oceanic and Atmospheric Administration (NOAA ) is an American scientific and regulatory agency charged with forecasting weather, monitoring oceanic and atmospheric conditions, charting the seas, conducting deep-sea exploratio ...
, with whom the final decision rested. In a press release dated November 20, 2008, the NOAA finalized its approval of the plans, and expanded Monterey Bay National Marine Sanctuary by a total of to include Davidson Seamount in its protected area. After a management plan was created, Davidson Seamount was incorporated into Monterey Bay in 2009, 7 years after it was originally proposed.


Oil and gas exploration

In July 2017, under the direction of
Executive Order In the United States, an executive order is a directive by the president of the United States that manages operations of the federal government. The legal or constitutional basis for executive orders has multiple sources. Article Two of the ...
13795 from President
Donald Trump Donald John Trump (born June 14, 1946) is an American politician, media personality, and businessman who is the 47th president of the United States. A member of the Republican Party (United States), Republican Party, he served as the 45 ...
, the U.S. Department of Commerce began re-evaluating the status of the Monterey Bay National Marine Sanctuary, which includes the Davidson Seamount. The move was opposed by many environmentalists and residents.


References


External links


Deep-sea coral research at Davidson (2006)SIMoN imagesSIMon Ecological overview
{{Authority control Seamounts of the Pacific Ocean Landforms of California Oceanography Submarine volcanoes Monterey Bay