Graveyard Seamounts
Encyclopedia
The Graveyard Seamounts are a series of 28 small seamount
s (underwater volcanoes) and ediffices located on the Chatham Rise
, east of New Zealand
. They cover about 140 square kilometre, and stand out from the surrounding oceanic plateau that measures several hundred kilometers. They are named after various morose figures, and the most prominent among the group are Ghoul Seamount, Diabolical Seamount, Voodoo Seamount, Scroll Seamount, Hartless Seamount, Pyre Seamount, Gothic Seamount, Zombie Seamount, Mummy Seamount, Headstone Seamount, Morgue Seamount and Graveyard Seamount (ordered roughly by size).
era. The seamounts are 100 to 400 m (328.1 to 1,312.3 ft) high, stand 1050 to 1200 m (3,444.9 to 3,937 ft) deep at their base and 750 to 1000 m (2,460.6 to 3,280.8 ft) at their summit. Many of the seamounts bears marks of tidal scour
from water erosion, the result of millions of years of wear by a current moving at 1 to 2 cm (0.393700787401575 to 0.78740157480315 in) per second.
(Hoplostethus atlanticus), black oreo
(Allocyttus niger), and cardinalfish (Apogonidae). Orange roughy in particular aggregate on the Graveyard seamounts for spawning
, and their visits here has supported a commercial fishery since the mid 1990s. A number of the seamounts are also home to extensive deep water coral
forests, made up of Solenosmilia variabilis
and Madrepora oculata
, both species not known to be of wide extent near New Zealand until camera surveys of Graveyard Seamounts in 2001 revealed their and extent. These forests offer a home to a diverse invertebrate community that includes squat lobster
s, seastar
s, brittlestars, polychaete worms, and crab
s. In contrast, the seamounts in the group that are affected by bottom trawling
are mostly barren, with few coral and a completely different ecosystem.
In 2001, witnessing the damage of bottom trawling to seamount communities, 19 seamounts off the coast of New Zealand were closed off to bottom trawling, three of them from the Graveyard group. Timed surveys of the seamounts over the years are being used to examine how well a seamount coral community recovers from the effects of dredging over time.
Seamount
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface , and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of depth. They are defined by oceanographers as...
s (underwater volcanoes) and ediffices located on the Chatham Rise
Chatham Rise
The Chatham Rise is an area of ocean floor to the east of New Zealand, forming part of the Zealandia continent. It stretches for some from near the South Island in the west, to the Chatham Islands in the east...
, east of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
. They cover about 140 square kilometre, and stand out from the surrounding oceanic plateau that measures several hundred kilometers. They are named after various morose figures, and the most prominent among the group are Ghoul Seamount, Diabolical Seamount, Voodoo Seamount, Scroll Seamount, Hartless Seamount, Pyre Seamount, Gothic Seamount, Zombie Seamount, Mummy Seamount, Headstone Seamount, Morgue Seamount and Graveyard Seamount (ordered roughly by size).
Geography and geology
The seamounts are the site of volcanism from the late CenozoicCenozoic
The Cenozoic era is the current and most recent of the three Phanerozoic geological eras and covers the period from 65.5 mya to the present. The era began in the wake of the Cretaceous–Tertiary extinction event at the end of the Cretaceous that saw the demise of the last non-avian dinosaurs and...
era. The seamounts are 100 to 400 m (328.1 to 1,312.3 ft) high, stand 1050 to 1200 m (3,444.9 to 3,937 ft) deep at their base and 750 to 1000 m (2,460.6 to 3,280.8 ft) at their summit. Many of the seamounts bears marks of tidal scour
Tidal scour
Tidal scour is an erosion process which is carried out by the tidal movement of water.Examples of this hydrological process can be found in many areas of the world. Two locations in the United States where tidal scour is the predominant shaping force is the San Francisco Bay and the Elkhorn Slough....
from water erosion, the result of millions of years of wear by a current moving at 1 to 2 cm (0.393700787401575 to 0.78740157480315 in) per second.
Ecology
The Graveyard Seamounts are a home to over 50 species of fish, dominated by the orange roughyOrange roughy
The orange roughy, red roughy, or deep sea perch, Hoplostethus atlanticus, is a relatively large deep-sea fish belonging to the slimehead family . The Marine Conservation Society has categorized orange roughy as vulnerable to exploitation...
(Hoplostethus atlanticus), black oreo
Black oreo
The black oreo, Allocyttus niger, is an oreo of the family Oreosomatidae, found around Australia and New Zealand between latitudes of between 43°S and 55°S at depths of between 560 and 1,300 m. Its length is up to 47 cm....
(Allocyttus niger), and cardinalfish (Apogonidae). Orange roughy in particular aggregate on the Graveyard seamounts for spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
, and their visits here has supported a commercial fishery since the mid 1990s. A number of the seamounts are also home to extensive deep water coral
Deep water coral
The habitat of deep water corals, also known as cold water corals, extends to deeper, darker parts of the oceans than tropical corals, ranging from near the surface to the abyss, beyond where water temperatures may be as cold as 4°C...
forests, made up of Solenosmilia variabilis
Caryophylliidae
Caryophylliidae is a family of stony corals. In addition to the tropics they are also found in temperate seas and in very deep water.The coral colonies are often composed of only a few polyps, especially in Catalaphyllia jardinei, living on sandy land in partly cloudy water, associated with partner...
and Madrepora oculata
Madrepora oculata
Madrepora oculata, also called zigzag coral, is a Scleractinia that is found worldwide outside of the polar regions, growing in deep water at depths of 80–1500 meters. It was first described by Linnaeus in 1758. It is one of only 12 species of coral that are found worldwide, including in...
, both species not known to be of wide extent near New Zealand until camera surveys of Graveyard Seamounts in 2001 revealed their and extent. These forests offer a home to a diverse invertebrate community that includes squat lobster
Squat lobster
Squat lobsters are decapod crustaceans of the families Galatheidae, Chirostylidae and Kiwaidae, including the common genera Galathea and Munida. They are not lobsters at all, but are more closely related to porcelain crabs, hermit crabs and then, more distantly, true crabs...
s, seastar
SeaStar
SeaStar may refer to any of the following aircraft designs .* the AAC SeaStar, a two-seat biplane from Canada* the Dornier Seawings Seastar, an amphibious aircraft with two engines in a push-pull configuration...
s, brittlestars, polychaete worms, and crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s. In contrast, the seamounts in the group that are affected by bottom trawling
Bottom trawling
Bottom trawling is trawling along the sea floor. It is also often referred to as "dragging".The scientific community divides bottom trawling into benthic trawling and demersal trawling...
are mostly barren, with few coral and a completely different ecosystem.
In 2001, witnessing the damage of bottom trawling to seamount communities, 19 seamounts off the coast of New Zealand were closed off to bottom trawling, three of them from the Graveyard group. Timed surveys of the seamounts over the years are being used to examine how well a seamount coral community recovers from the effects of dredging over time.
See also
- Jasper SeamountJasper SeamountJasper Seamount is a seamount located in the Fieberling-Guadalupe seamount track, west of Baja California, Mexico. Jasper is the site of detailed geophysical geological and geochemical studies which suggest that many seamounts, big and small, follow the same pattern of growth and death that was...
- Mud volcanoMud volcanoThe term mud volcano or mud dome are used to refer to formations created by geo-excreted liquids and gases, although there are several different processes which may cause such activity. Hot water mixes with mud and surface deposits. Mud volcanoes are associated with subduction zones and about 700...
- Muirfield SeamountMuirfield SeamountThe Muirfield Seamount is a submarine mountain located in the Indian Ocean approximately 130 kilometres southwest of the Cocos Islands. The Cocos Islands are an Australian territory, and therefore the Muirfield Seamount is within in Australia's Exclusive Economic Zone...
- Sedlo SeamountSedlo SeamountSedlo Seamount is an isolated seamount and underwater volcano located in the Northeast Atlantic, northeast of Graciosa Island. It has an elongate structure, roughly . The summit is flat with three peaks. Sedlo Seamount sits on the ocean floor deep, and rises to within of the surface...
- South Chamorro SeamountSouth Chamorro SeamountSouth Chamorro Seamount is a large serpentinite mud volcano and seamount located in the Izu-Bonin-Mariana Arc, one of 16 such volcanoes in the arc. These seamounts are at their largest in diameter and in height...