The Yeti Crab!? Antarctic Marine Biodiversity and Deep-Sea Hydrothermal Vents Produce New Undiscovered Species of Marine LifePosted: January 5th, 2012 | Author: M.Aaron Silverman | Filed under: Cankler Science News, Ecology | Tags: Antarctic Marine Biodiversity, Deep-Sea Hydrothermal Vents, New Undiscovered Species of Marine Life, Science News, Taxa, Yeti Crab | Comments Off on The Yeti Crab!? Antarctic Marine Biodiversity and Deep-Sea Hydrothermal Vents Produce New Undiscovered Species of Marine Life
A seven-pronged starfish, a mysterious pale octopus and a new kind of ‘yeti’ crab are among a teeming community of previously undiscovered life on the sea floor near Antarctica, British researchers said. The species, described this week on the online journal PloS Biology, were first glimpsed in 2010 when researchers lowered a robotic vehicle to explore the East Scotia Ridge deep beneath the Southern Ocean, between Antarctica and the tip of South America. The dark and remote area is home to hydrothermal vents, which are deep-sea springs that spew liquid at temperatures of up to 382 degrees Celsius, and have previously been found to host unusual life forms in other parts of the world.
“Hydrothermal vents are home to animals found nowhere else on the planet that get their energy not from the Sun but from breaking down chemicals, such as hydrogen sulphide,” said lead researcher Alex Rogers of Oxford University. “The first survey of these particular vents, in the Southern Ocean near Antarctica, has revealed a hot, dark, ‘lost world’ in which whole communities of previously unknown marine organisms thrive.”
Vent ecosystems have been documented from many sites across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. This most recent work by Steven Chown and his team of researchers has brought to the surface some pretty incredible findings, animal communities of the Southern Ocean vent ecosystems are very different to those found at other vent locations around the globe. Much of the biological significance of deep-sea hydrothermal vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life.
Hydrothermal vents were first discovered in 1977 off the Galapagos Islands. The latest discoveries 2,400-2,600 metres deep include several new types of sea anemones, stalked barnacles and unidentified octopi, and a new kind of starfish that was observed feeding on the fauna around the vents.
For most groups of organisms diversity is highest in the tropics. A hectare of rainforest contains more plant species than a similar area of Norwegian boreal forest. Likewise, on average, tropical latitudes are home to more fish, bird, and mammal species than anywhere else. Whilst this foremost pattern of biodiversity has long been known, its nuances and the exceptions to it are less widely appreciated. For example, in terrestrial birds and ants the decline in diversity on either side of the equator is not symmetric. It is steeper in the north, reflecting a broader suite of biological differences among the hemispheres. Perhaps more striking is the far wider variety of biodiversity gradients found in marine groups, and the almost total contrast in many benthic (bottom-dwelling) taxa to the typical terrestrial latitudinal diversity gradient.
The discovery of diverse and unusual Antarctic hydrothermal vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea hydrothermal vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining.
For coastal marine species, such as fish or corals, richness tends to be highest in the tropics, especially the Indo-West Pacific, whilst for more ocean-going, or pelagic species, such as the albatrosses and petrels, diversity peaks are typical of the mid-latitudes . In both cases, diversity still tends to drop off at the sub-polar and polar latitudes. In many benthic groups the pattern is completely different. Diversity does decline in the far north, but does not do so in the Southern Ocean (the region around and to the south of the Antarctic Polar Front—the dynamic location where cold Antarctic and warmer sub-Antarctic waters meet). Rather, some groups show their highest richness here. Taking survey effort and area into account, organisms such as pycnogonids, bryozoans, isopods, amphipods, sponges, ascidians, and echinoderms are remarkably diverse in the Southern Ocean, as much or more so than is typical of many, more equatorial locations. Recent, large-scale surveys, conducted, in part, under the auspices of the international Census of Marine Life have borne out these patterns, highlighting the extraordinary diversity of the Antarctic . Moreover, they have also drawn attention to the considerable endemism, i.e., restriction to a given area (in this case the Antarctic), of much of the benthos.
A new type of blond, furry-legged yeti crab, a species formally known as Kiwa hirsuta which was first seen at hydrothermal vents in the South Pacific in 2005, was also found to have different DNA than those already known to man. Fish were uncommon, and only seen on the peripheries of the hot zones. Researchers were equally intrigued by what they did not find – including many of the giant worms, vent mussels, crabs, clams and shrimp that have been found before at other deep sea vents in the Pacific, Atlantic and Indian Oceans. The differences in species suggest that the geographic conditions of the area may make it a distinct province for certain forms of life, which have been unable to migrate to other parts of the globe’s sea floor.
“These findings are yet more evidence of the precious diversity to be found throughout the world’s oceans,” said Rogers. “Everywhere we look, whether it is in the sunlit coral reefs of tropical waters or these Antarctic vents shrouded in eternal darkness, we find unique ecosystems that we need to understand and protect.”
Researchers on the project came from the University of Oxford, University of Southampton and the British Antarctic Survey.
At the request of the International Seabed Authority, InterRidge (a non-profit organization, promoting mid-ocean ridge research, http://www.interridge.org/about advised that the vents shown here should be protected from exploitation, though with some InterRidge members arguing that all sites should be protected http://www.interridge.org/node/1, Vent biogeographic provinces identified by Bachraty et al.  are indicated in colour, and the two East Scotia Ridge Sites described by Rogers et al.  are indicated with diamonds, just to the east of the Antarctic Peninsula. A full list of vent sites can be found on InterRidge’s pages at: http://www.interridge.org/IRvents. The base map is the NOAA global relief model http://www.ngdc.noaa.gov/mgg/global/global.html.
source: plos biologogy
source: steven l chown
source: aleks terauds
+ © 2012 Steven L. Chown