The course blog for Bio 412 - Marine Biology at Ashland University
Monday, March 15, 2010
Scientists find evidence of hyrothermal vents off of the coast of Antarctica
In the past several decades, more than 220 hydrothermal vents have been found around the world. Up until recently, no one has ever looked for them in the freezing cold waters of Antarctica. Hydrothermal vents are known for releasing volcanically heated water from deep within the planets underwater mountain ranges. The chemicals found in these vents are known to influence the biodiversity and chemistry of the ocean, much like sunlight on land. By analyzing thousands of oceanographic measurements, a team of scientists were able to place six hypothetical vents on the Pacific Antarctic ridge. These vents were pinpointed using two important facts; 1) they are areas where the ocean is stratified with layers of lighter water sitting on top of denser water, 2) when a seafloor vent erupts, it releases gases rich in Helium-3, which mixes with ocean water and stays within a density layer that forms a plume that can stretch thousands of miles. When these scientists were analyzing Helium-3 content in the water, they came across a random plume in the southern portion of the Pacific Ocean. This plume was located below a well known plume coming from the East Pacific Rise. But the new plume was too deep to have the same source. Using approximately 25,000 salinity, temperature and depth measurements, the researchers compiled a map of ocean density layers in that region. They located the plume along a single density layer and compared that layer to the topographic map of the region to find out where the plume would intersect. The sites they identified cover 340 miles of ridge line with a chain of volcanic mountains that lies about 3 miles below the oceans surface. They haven't found the vents, but they have narrowed down the places they could look. The map that these scientist created will be helpful in narrowing down the search sites. Once they are within a few kilometers of the vent, they will be able to detect the rich minerals flowing out of it. Study of the vents on the Pacific Atlantic Ridge will offer valuable insight into how the biodiversity varies between the Pacific and Indian Oceans.