BERGEN (Norway) - Scientists from the University of Bergen andOregon State University have discovered the northernmost hydrothermalvents in the world along the Mohns Ridge in the Arctic Ocean.
"I've seen a lot of hydrothermal systems all over the world'soceans," said Adam Schultz, a geophysicist from OSU's College ofOceanic and Atmospheric Sciences, "and these Arctic fields arespectacular."
The three-week expedition was led by marine geologist Rolf Pedersenof the University of Bergen, who has been exploring the Arctic Ridgesystem from Iceland to Spitzbergen Island since 1999. The scientists,who were aboard the G.O. Sars research vessel, used a remotely operatedvehicle to explore the vent fields, which they discovered aroundlatitude 71 degrees, north of Iceland.
Much of the Arctic Ridge system is unexplored, and a vent field onthe shelf of Iceland is the only one that scientists have seen in thenorthern latitudes. Unlike that Icelandic field, however, the newlydiscovered vent fields are full of life, according to Pedersen.
"There were huge numbers of chimneys - 30, 40, 50 or more," Pedersensaid. Shrimp, anemones and bacterial mats dominated the animal life atthe site. The researchers also found a type of tubeworm on the ventstructures and in the outlying area - an important discovery, they say,because tubeworms had previously only been observed in Pacific Oceanvent fields.
Schultz used a temperature and flow sensor, called an isosampler, to help document the characteristics of the new vent fields.
"We found two large high-temperature fields and as we explored them,we would come upon a large mound of chimneys with superheated waterjetting out of them," Schultz said. "Then in the distance, we'd seeanother mound and then beyond that, another one, and so on."
Temperatures in one field reached as high as 260 degrees C, and thescientists believe they may have approached 300 degrees C in the secondfield, although they were unable to measure them.
The OSU scientist said there also is a vast low-temperature field inthe region that supports a diverse community of life, including largesea-lilies that "sit atop mineral/bacterial chimney-like structuresthat look at the world like pineapples."
"That is a particularly strange form of vent," Schultz said,"because the fluids coming out of these vents come out at temperaturesonly a fraction of a degree above the temperature of the backgroundseawater and that is very cold - below zero Celsius - which is onlypossible in the Arctic.
"I'm not sure if we can even call these 'hydrothermal' vents," headded. "Perhaps they are 'hydrocryo' vents, meaning vents that emitcold water."
Schultz's team carried out measurements of the water flowing out ofthe vents at both the high-temperature and low-temperature fields. Histeam included Phil Taylor, an oceanic engineer who has a dual facultyappointment with OSU and Cardiff University in the United Kingdom.
They used the isosampler to determine that the fluids flowing fromthe vents had undergone "phase separation," which means they had beensuperheated sufficiently to have boiled - even at the enormouspressures of the deep seafloor. This process produces pure water vapor,Schultz says, as well as heated seawater and a heated briny fluid.
"This is typical of seawater that has encountered hot magma at depthbeneath the seafloor, then vents out through smoker chimneys," Schultzpointed out. The vent fields were discovered at depths of 500 to 700meters.
Pedersen said the researchers ironically had come close todiscovering the vents on a previous voyage, when they were within about500 meters from the spot the fields were located. Gales and rough seascomplicated those previous efforts, he added.
This time, the researchers were able to locate the fields, which areabout 100 to 200 meters in size. Yet they still had logistical problems.
"The chimneys were so dense that it was difficult in some areas toget the ROV (remotely operated vehicle) in there," Pedersen said. "Infact, we got the ROV cable stuck on one of them. It almost melted."
The researchers plan to return next year to more precisely identifythe animals discovered at the vents, sample the microbes, and performmore detailed studies of the water column above the fields.
The scientists also believe there are additional vents fields to discover.
The study was part of the BioDeep project supported by the NorwegianResearch Council. The project, which includes researchers in Norway,the United States and Sweden, investigates microbial life in theocean's floor. OSU and the University of Bergen are collaborating onthese deep biosphere studies. In addition to Schultz and Taylor, OSUoceanographer Martin Fisk is a key scientist in that collaboration.
More information on the cruise is available online at: http://www.interridge.org/sciencewriteratsea/Norway2005/index.html
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