The Graveyard Seamounts, officially known as the Graveyard Knolls, are a series of 28 small

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 ...

s ( underwater volcanoes) and edifices located on the

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. It is New Zealand's most productiv ...

, east of

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. They cover about and stand out from the surrounding oceanic plateau that measures several hundred kilometers. They are named after various morose figures following the naming of the largest of the knolls as "the Graveyard" as it was a graveyard of fishing gear that became stuck on it. The most prominent among the group of knolls are Ghoul, Diabolical, Voodoo, Scroll, Hartless, Pyre, Gothic, Zombie, Mummy, Headstone, Morgue and Graveyard (ordered roughly by increasing size).

Geography and geology

While the official name for these features refers to knolls,IHO, 2008. Standardization of Undersea Feature Names: Guidelines Proposal form Terminology, 4th ed. International Hydrographic Organization and Intergovernmental Oceanographic Commission, Monaco. researchers in different disciplines see these features in different terms. These features are often referred to as seamounts where a seamount is described as any geographic isolated topographic feature on the seafloor taller than , including ones whose summit regions may temporarily emerge above sea level, but not including features that are located on continental shelves or that are part of other major landmasses. The seamounts are the site of volcanism from the late

Cenozoic The Cenozoic Era ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterized by the dominance of mammals, insects, birds and angiosperms (flowering plants). It is the latest of three g ...

era. The knolls are high, stand deep at their base and at their summit. Many of the seamounts bear marks of

tidal scour Tidal scour is "sea-floor erosion caused by strong tidal currents resulting in the removal of inshore sediments and formation of deep holes and channels". Examples of this hydrological process can be found globally. Two locations in the United St ...

from

water erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. Erosion is disti ...

, the result of millions of years of wear by a current moving at per second.

Ecology

The Graveyard Knolls is a home to over 50 species of fish, dominated by the

orange roughy The orange roughy (''Hoplostethus atlanticus''), also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family (Trachichthyidae). It is bathypelagic, found in cold (), deep () ...

(''Hoplostethus atlanticus''), black oreo (''Allocyttus niger''), and

cardinalfish Cardinalfishes are a family, Apogonidae, of ray-finned fishes found in the Atlantic, Indian, and Pacific Oceans; they are chiefly marine, but some species are found in brackish water and a few (notably '' Glossamia'') are found in fresh water. A ...

(''Apogonidae''). Orange roughy in particular aggregate on the Graveyard Knolls for

spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

and their visits here have supported a commercial fishery since the mid-1990s. A number of the seamounts are also home to extensive

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 . Deep-water co ...

forests, made up of ''

Solenosmilia variabilis ''Solenosmilia variabilis'' is a species of colonial coral in the family Caryophylliidae. It is a deep water, azooxanthellate coral with a semi-cosmopolitan distribution. Description ''Solenosmilia variabilis'' grows into small bushy colonies ...

'' and ''

Madrepora oculata ''Madrepora oculata'', also called zigzag coral, is a stony coral that is found worldwide outside of the polar regions, growing in deep water at depths of 50 to at least 1500 meters. It was first described by Carl Linnaeus in his landmark 1758 ...

'', both species not known to be of wide extent near New Zealand until camera surveys of Graveyard Knolls in 2001 revealed their extent. These forests offer a home to a diverse invertebrate community that includes

squat lobster Squat lobsters are dorsoventrally flattened crustaceans with long tails held curled beneath the cephalothorax. They are found in the two superfamilies Galatheoidea and Chirostyloidea, which form part of the decapod infraorder Anomura, alongs ...

seastar Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish ...

brittle star Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomot ...

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ma ...

s, and

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. In contrast, the knolls in the group that are affected by

bottom trawling Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and Demersal zone, demersal trawling. Benthic tra ...

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.

References

{{Oceanic features of Zealandia, state=collapsed Seamounts of New Zealand Zealandia Former islands from the last glacial maximum Volcanoes of New Zealand

Geography and geology

Ecology

See also

References