Featured Research

from universities, journals, and other organizations

Students discover methane seep ecosystem

Date:
July 26, 2012
Source:
University of California, San Diego
Summary:
During a recent oceanographic expedition off San Diego, graduate student researchers discovered convincing evidence of a deep-sea site where methane is likely seeping out of the seafloor, the first such finding off San Diego County.

Alexis Pasulka (left), Ben Grupe and Ron Etter examine a sediment core sample aboard R/V Melville.
Credit: Image courtesy of University of California, San Diego

During a recent oceanographic expedition off San Diego, graduate student researchers from Scripps Institution of Oceanography at UC San Diego discovered convincing evidence of a deep-sea site where methane is likely seeping out of the seafloor, the first such finding off San Diego County.

Such "methane seeps" are fascinating environments because of their extraordinary chemical features and often bizarre marine life. The area of interest, roughly 20 miles west of Del Mar, is centered on a fault zone known as the San Diego Trough Fault zone. Methane, a clear, highly combustible gas, exists in Earth's crust under the seafloor along many of the world's continental margins. Faults can provide a pathway for methane to "seep" upward toward the seafloor.

The Scripps graduate students made the discovery during the recent San Diego Coastal Expedition a multidisciplinary voyage conceived and executed by Scripps graduate students. The cruise was funded by the University of California Ship Funds Program, which supports student research at sea and provides seagoing leadership opportunities.

While conducting surveys in search of methane seeps aboard Scripps' research vessel Melville, the graduate students mapped a distinct mound on the seafloor at 1,036 meters depth (3,400 feet), spanning the size of a city block and rising to the height of a two-story building. The area had been recommended by Jamie Conrad, Holly Ryan (U.S. Geological Survey) and Charles Paull (Monterey Bay Aquarium Research Institute), who surveyed the faults in 2010.

"Below the mound," described Scripps geosciences graduate student Jillian Maloney, "we observed a disruption in subsurface sediment layers indicative of fluid seepage."

The Scripps researchers then deployed instruments to collect sediment cores, gathering further evidence such as seep-dwelling animals, sulfidic-smelling black mud and carbonate nodules. These samples are currently being analyzed in Scripps laboratories for chemical clues and other telling elements of the environment.

Organisms collected from the site include thread-like tubeworms called siboglinids and several clams. Siboglinids lack a mouth and digestive system and gain nutrition via a symbiotic relationship with bacteria living inside them, while many clams at seeps get some of their food from sulfide-loving bacteria living on their gills.

While food is scarce in much of the cold, dark ocean depths, it is abundant at seeps due to the bacteria that proliferate around the methane source. Microbes there are eaten by worms, snails, crabs and clams, leading to a rich and productive community that helps sustain the surrounding deep-sea ecosystem.

"These chemosynthetic ecosystems are considered 'hot spots' of life on the seafloor in an otherwise desert-like landscape," said San Diego Coastal Expedition team member Alexis Pasulka, a Scripps biological oceanography graduate student. "New forms of life are continuously being discovered in these environments. Therefore, it is important to study these ecosystems not only to further appreciate the diversity of life in our oceans, but also so that we can better understand how these ecosystems contribute to overall ocean productivity and the carbon cycle."

Methane is a potent greenhouse gas, and researchers don't yet fully understand the magnitude to which seeping methane in the ocean contributes additional carbon to the atmosphere. Moreover, on many continental margins, frozen methane hydrates could represent a future energy source. Along the West Coast, methane seeps are known to exist off Oregon, California (near Eureka, Monterey Bay, Point Conception and Santa Monica), in the Gulf of California and off Costa Rica.

"This is a significant and exciting discovery in part because of the possibilities for future research at Scripps," said biological oceanography graduate student Benjamin Grupe, a member of the seep contingent on the San Diego Coastal Expedition. "The existence of a methane seep just a few hours from San Diego should allow Scripps scientists to visit frequently, studying how this dynamic ecosystem changes over days, months and years. Such regular data collection is difficult at most cold seeps, which rarely occur so close to ports or research institutions."

Grupe will lead a follow-up cruise in December that will revisit the newly discovered seep to collect additional samples and learn more about this ecosystem. The team of graduate students hopes to raise funds to employ technologies such as video-driven coring instruments and towed video cameras that will give them an up-close look at the methane seep.

The search for local seeps was one focus area of the multidisciplinary San Diego Coastal Expedition, which included teams of students investigating the oceanography and marine ecosystems off San Diego and led by chief scientist Christina Frieder. In addition to Grupe, Pasulka and Maloney, other members of the seep team included geophysics graduate students Valerie Sahakian and Rachel Marcuson.

R/V Melville, the oldest ship in the U.S. academic fleet, is owned by the U.S. Navy and has been operated by Scripps Oceanography for all of its 41 years.

"The students should be congratulated on their hard work and perseverance leading to this exciting find," said Lisa Levin, a Scripps professor who has studied methane seep ecosystems in most of the world's oceans. "Other scientists have suspected that methane seeps were present in the San Diego region, but these new data and samples provide the first convincing evidence. We know very little about what lives in deep waters-the planet's largest ecosystem-so it is not unexpected to find surprises on the deep-sea floor right in our own backyard. Having a 'local' seep should be a great boon to deep-sea research, education and public outreach at Scripps."


Story Source:

The above story is based on materials provided by University of California, San Diego. Note: Materials may be edited for content and length.


Cite This Page:

University of California, San Diego. "Students discover methane seep ecosystem." ScienceDaily. ScienceDaily, 26 July 2012. <www.sciencedaily.com/releases/2012/07/120726135149.htm>.
University of California, San Diego. (2012, July 26). Students discover methane seep ecosystem. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2012/07/120726135149.htm
University of California, San Diego. "Students discover methane seep ecosystem." ScienceDaily. www.sciencedaily.com/releases/2012/07/120726135149.htm (accessed October 21, 2014).

Share This



More Earth & Climate News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

How Detroit's Money Woes Led To U.N.-Condemned Water Cutoffs

Newsy (Oct. 20, 2014) The United Nations says water is a human right, but should it be free? Detroit has cut off water to residents who can't pay, and the U.N. isn't happy. Video provided by Newsy
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
White Rhino's Death In Kenya Means Just 6 Are Left

White Rhino's Death In Kenya Means Just 6 Are Left

Newsy (Oct. 20, 2014) Suni, a rare northern white rhino at Ol Pejeta Conservancy, died Friday. This, as many media have pointed out, leaves people fearing extinction. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins