The Tasmanian Seamounts (also ''Tasman Seamounts'' and ''Tasmania Seamounts'') are a group of

seamounts 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 volcanoes) located off the southern tip of

Tasmania Tasmania (; palawa kani: ''Lutruwita'') is an island States and territories of Australia, state of Australia. It is located to the south of the Mainland Australia, Australian mainland, and is separated from it by the Bass Strait. The sta ...

. The seamounts were created more than 55 million years ago by the Tasman

hotspot Hotspot, Hot Spot or Hot spot may refer to: Places * Hot Spot, Kentucky, a community in the United States Arts, entertainment, and media Fictional entities * Hot Spot (comics), a name for the DC Comics character Isaiah Crockett * Hot Spot (Tr ...

. The seamounts are ecologically important, and harbor a lush marine ecosystem, but are threatened by

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing Fish stocks, fish stock), resu ...

. For this reason, part of the Tasmanian Seamounts were incorporated into a marine reserve in 1999.

Geology

The Tasmanian Seamounts were created by the Tasman

, a long

mantle plume A mantle plume is a proposed mechanism of convection within the Earth's mantle, hypothesized to explain anomalous volcanism. Because the plume head partially melts on reaching shallow depths, a plume is often invoked as the cause of volcanic ho ...

that is currently the active center of

Mount Erebus Mount Erebus () is the southernmost active volcano on Earth, located on Ross Island in the Ross Dependency in Antarctica. With a summit elevation of , it is the second most prominent mountain in Antarctica (after Mount Vinson) and the second ...

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. The seamounts, created roughly 55 million years ago, are between deep, across, and tall.

Ecology

The Tasmanian Seamounts are an important feature of the south Tasmanian marine environment. While oceans generally contain few nutrients, the presence of seamounts increases the flowing speed of the water current. This effect, created by the topography of the seafloor mountain, clears rocks in the area of sediments and provides food for

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

s. The swept rocks serve as substrate for

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 and

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

s to attach to. Among them are some of the longest–living organisms on Earth, reaching an age of "hundreds and possibly thousands of years". The Tasmanian Seamounts in particular are dominated by the

stony coral Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mo ...

''Solenosmilia variabeles''; these corals provide a roost and living space for

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". ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

echinoderm An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...

s and

crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...

like stone crabs (''Parclamis sp.''), squat lobsters ('' Munidopsis treis''), and top snails ('' Trochidae sp.''), thus solidifying the seamounts' ecology. Although many of these species are also found on the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an islan ...

, they are never found as concentrated or lush as they are on the seamounts. The seamounts have been the site of commercial

trawling Trawling is an industrial method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch di ...

for

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 () ...

for decades. In 1994, the Australian Geological Survey Organization mapped the south Tasmanian seafloor, including the Tasmanian Seamounts; shortly thereafter, Environment Australia (now the

Department of Sustainability, Environment, Water, Population and Communities The Department of Sustainability, Environment, Water, Population and Communities was an Australian government department that existed between September 2010 and September 2013. Scope Information about the department's functions and go ...

) released a report stating that the Tasmanian Seamount fauna was highly diverse, inadequately studied, and vulnerable to overfishing, and recommended that an oceanic reserve be created on the site. An interim three–year ban on trawling was declared to allow
study
of the seamounts to be carried out in 1997 which found 242 distinct species of invertebrates. 26% to 44% of them could not be identified and are thus believed to be new, and about a third are seemingly present only in the seamount environment. Damage from trawling was also examined, and on the most heavily affected seamounts it had destroyed coral aggregations, removed 46% of species, and reduced net biomass by over half. Following the study, the proposed marine reserve, the ''Tasmanian Seamount Community'' or ''Tasmanian Seamounts Marine Reserve'' was created as part of the

Environment Protection and Biodiversity Conservation Act 1999 The ''Environment Protection and Biodiversity Conservation Act 1999'' (Cth) is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and cult ...

. The reserve banned fishing, especially trawling, within an area of . It contained 70 seamounts, a fifth of the known Tasmanian seamounts, all of which were low-trawl areas and thus still in relatively unaffected form. In a 2007 audit it was merged into the Huon Commonwealth Marine Reserve. A more detailed bathymetric survey the same year found a total of 123 seamounts within the reserve, many of which were previously unknown.

References

{{coord, 44, 18, S, 147, 00, E, region:AU-TAS_type:landmark_source:dewiki, display=title Hotspot volcanoes Protected areas of Tasmania Volcanoes of Australia Seamounts of the Pacific Ocean Seamounts of the Tasman Sea Seamounts of the Southern Ocean