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January 04, 2012

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Antarctic seafloor geyser found hosting strange community

Jan. 4, 2012
Courtesy of PLoS
and World Science staff

Spe­cies pre­vi­ously un­known to sci­ence have been dis­cov­ered on the seafloor near Ant­arc­ti­ca, clus­ter­ing in the dark­ness around seafloor gey­sers called hy­dro­ther­mal ven­ts, sci­en­tists say.

The find­ings, made by teams led by the Un­ivers­ity of Ox­ford, Un­ivers­ity of South­amp­ton and Brit­ish Ant­arc­tic Sur­vey, in­clude new spe­cies of crab, star­fish, bar­na­cles, sea anemones, and po­ten­tially an oc­to­pus.

Squirming mounds of white crabs near a newly dis­cov­ered hydro­therm­al vent. (Click to en­large; im­age cour­tesy PLoS)

For the first time, re­search­ers have used an un­der­wa­ter ro­bot to ex­plore the so-called East Sco­tia Ridge deep be­neath the South­ern Ocean, where hy­dro­ther­mal ven­ts, cre­ate a un­ique en­vi­ron­ment that’s pitch-black but rich in cer­tain chem­i­cals. The ven­ts in­clude “black smok­ers” named af­ter the dusky sub­stances that is­sue from their hot spouts, which reach tem­per­a­tures of up to 382 de­grees Cel­si­us (720 Fahren­heit). 

The sci­en­tif­ic team re­ports its find­ings in this week’s is­sue of the on­line re­search jour­nal P­LoS Bi­ol­o­gy.

“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 Pro­fes­sor Al­ex Rog­ers of Ox­ford Un­ivers­ity’s De­part­ment of Zo­ol­o­gy, who led the re­search. “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.”

High­lights in­clude im­ages show­ing huge col­o­nies of the new spe­cies of yeti crab, thought to dom­i­nate the Ant­arc­tic ven­t ec­o­sys­tem, clus­tered around ven­t chim­neys. Else­where the ro­bot spot­ted num­bers of an un­de­scribed pred­a­to­ry sea-star with sev­en arms crawl­ing across fields of stalked bar­na­cles. It al­so found an un­iden­ti­fied pale oc­to­pus, nearly 2,400 me­ters (2,600 yards) down, on the seafloor.

“What we did­n’t find is al­most as sur­pris­ing as what we did,” said Rog­ers. “Many an­i­mals such as tube­worms, ven­t mus­sels, ven­t crabs, and ven­t shrimps, found in hy­dro­ther­mal ven­ts in the Pa­cif­ic, At­lantic, and In­di­an Oceans, simply weren’t there.”

An unidentified white oc­to­pus also spot­ted near the site. (Cour­tesy PLoS)

The team be­lieves the dif­fer­ences be­tween the groups of an­i­mals found around the Ant­arc­tic ven­ts and those found around ven­ts else­where sug­gest that the South­ern Ocean may act as a bar­ri­er to some vent an­i­mals. The un­ique spe­cies of the East Sco­tia Ridge al­so sug­gest that, glob­al­ly, ven­t ec­o­sys­tems may be much more di­verse, and their in­ter­ac­tions more com­plex, than pre­vi­ously thought.

In April 2011 Pro­fes­sor Rog­ers was part of an in­terna­t­ional pan­el of ma­rine sci­en­tists who gath­ered at Som­er­ville Col­lege, Ox­ford to con­sid­er the lat­est re­search on the world’s oceans. A pre­lim­i­nar­y re­port from the pan­el in June warned that the world’s oceans are at risk of en­ter­ing a phase of ex­tinc­tion of ma­rine spe­cies un­prec­e­dent­ed in hu­man his­to­ry.

“These find­ings are yet more ev­i­dence of the pre­cious di­vers­ity to be found through­out the world’s oceans,” said Pro­fes­sor 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.”

The dis­cov­er­ies were made as part of a con­sor­ti­um proj­ect with part­ners from the Un­ivers­ity of Ox­ford, Un­ivers­ity of South­amp­ton, Un­ivers­ity of Bris­tol, New­cas­tle Un­ivers­ity, Brit­ish Ant­arc­tic Sur­vey, Na­t­ional Oceanography Cen­tre, and Woods Hole Oceanographic In­sti­tu­tion.

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Species previously unknown to science have been discovered on the seafloor near Antarctica, clustering in the darkness around seafloor geysers called hydrothermal vents, scientists say. The findings, made by teams led by the University of Oxford, University of Southampton and British Antarctic Survey, include new species of crab, starfish, barnacles, sea anemones, and potentially an octopus. For the first time, researchers have used an underwater robot to explore the so-called East Scotia Ridge deep beneath the Southern Ocean, where hydrothermal vents, create a unique environment that’s pitch-black but rich in certain chemicals. The vents include “black smokers” named after the dusky substances that issue from their hot spouts, which reach temperatures of up to 382 degrees Celsius (720 Fahrenheit). The scientific team reports its findings in this week’s issue of the online research journal PLoS Biology. “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 Professor Alex Rogers of Oxford University’s Department of Zoology, who led the research. “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.” Highlights include images showing huge colonies of the new species of yeti crab, thought to dominate the Antarctic vent ecosystem, clustered around vent chimneys. Elsewhere the robot spotted numbers of an undescribed predatory sea-star with seven arms crawling across fields of stalked barnacles. It also found an unidentified pale octopus, nearly 2,400 metres down, on the seafloor. “What we didn’t find is almost as surprising as what we did,” said Professor Rogers. “Many animals such as tubeworms, vent mussels, vent crabs, and vent shrimps, found in hydrothermal vents in the Pacific, Atlantic, and Indian Oceans, simply weren’t there.” The team believe that the differences between the groups of animals found around the Antarctic vents and those found around vents elsewhere suggest that the Southern Ocean may act as a barrier to some vent animals. The unique species of the East Scotia Ridge also suggest that, globally, vent ecosystems may be much more diverse, and their interactions more complex, than previously thought. In April 2011 Professor Rogers was part of an international panel of marine scientists who gathered at Somerville College, Oxford to consider the latest research on the world’s oceans. A preliminary report from the panel in June warned that the world’s oceans are at risk of entering a phase of extinction of marine species unprecedented in human history. “These findings are yet more evidence of the precious diversity to be found throughout the world’s oceans,” said Professor 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.” The discoveries were made as part of a consortium project with partners from the University of Oxford, University of Southampton, University of Bristol, Newcastle University, British Antarctic Survey, National Oceanography Centre, and Woods Hole Oceanographic Institution.