Featured Research

from universities, journals, and other organizations

Unexpected interaction between ocean currents and bacteria may weaken ocean's ability to absorb carbon dioxide

Date:
September 13, 2013
Source:
University of Southern Denmark
Summary:
For the first time, researchers have successfully demonstrated an interaction between ocean currents and bacteria: The unexpected interaction leads to the production of vast amounts of nitrogen gas in the Pacific Ocean. This takes place in one of the largest oxygen free water masses in the world -- and these zones are expanding. This can ultimately weaken the ocean's ability to absorb CO2.

Illustration. Purple area: This ocean water holds less than 10 per cent oxygen. Blue area: The Oxygen Free Zone off Peru/Chile, where bacteria produce huge amount of nitrogen. Black Arrow: Ocean current that transports the bacteria through the Oxygen Minimum Zone.
Credit: Illustration: Bo Thamdrup/SDU

For the first time, researchers have successfully demonstrated an interaction between ocean currents and bacteria: The unexpected interaction leads to the production of vast amounts of nitrogen gas in the Pacific Ocean. This takes place in one of the largest oxygen free water masses in the world -- and these zones are expanding. This can ultimately weaken the ocean's ability to absorb CO2.

Three places in the world harbor extensive oxygen free water masses, called Oxygen Minimum Zones. In these zones, microbes produce atmospheric nitrogen gas -- the gas that accounts for almost 80 per cent of Earth's atmosphere. Researchers from the University of Southern Denmark now report to have found the reason behind the huge nitrogen gas production in the largest of the three Minimum Oxygen Zones, located in the Pacific Ocean off Chile and Peru. The nitrogen gas is produced by a steady stream of bacteria who, when they feed, produce lots of nitrogen gas.

"The bacteria flow with an ocean current, that comes from the Equator and is heading towards the South Pole. On their way south the bacteria rid the water of ammonia, which they eat and transform into nitrogen gas in the Oxygen Minimum Zone," explain the scientists, postdoc Loreto De Brabandere and Professor Bo Thamdrup from the Nordic Center for Earth Evolution at the University of Southern Denmark.

Behind the research are also colleagues from Aarhus University, Monterey Bay Aquarium Research Institute, USA, and Universidad de Concepciσn, Chile.

In the western Pacific off New Zealand heavy and nutrient-rich water sinks below the surface and begins to flow as an underwater current; first towards and along the Equator and then it changes course and heads south, when it approaches the coast of South America. During this long journey oxygen disappears from the current's water, and off Peru and Chile the hungry bacteria go to work.

The hungry bacteria in the ocean current from the Equator are called anammox bacteria; they get energy to grow by allowing nitrite to react with ammonia and form nitrogen gas. Anammox bacteria and their impact on the global nitrogen cycle were only discovered a few years ago.

The scientists are surprised, that this type of bacteria is responsible for the production of nitrogen gas in the giant Oxygen Minimum Zone in the Pacific Ocean.

"In the other zones we find that another nitrogen gas producing type of bacteria is responsible, namely the so-called denitrifying bacteria," says Loreto De Brabandere.

Denitrifying bacteria also produce nitrogen gas, but they do it from nitrate and nitrite when combusting organic material -- not from ammonia as anammox bacteria do.

"But here we show that the denitrifying bacteria simply do not get enough organic food to form nitrogen gas, so they are virtually pushed out of the way by anammox bacteria that come with the water from the Equator. The result is that anammox bacteria account for almost the entire nitrogen gas production," explains Bo Thamdrup.

If the anammox bacteria did not come with ocean currents along the coast of South America, significantly less nitrogen gas would be produced in the oceans as a whole. The denitrifying bacteria would probably never be able to find enough nutrients to produce the same amount of nitrogen gas.

"The exciting news is that the explanation for the large production of nitrogen gas off Chile is found near the Equator, over a thousand kilometers further north. It is the first time we see such an interaction between ocean currents, bacteria, and nutrient cycling," says Bo Thamdrup.

There are no indications that the ocean current may be disturbed by climate change or other factors, and thus there will probably be no changes in its cargo of anammox bacteria.

"However there are signs that the Oxygen Minimum Zones around the world are expanding, and this can lead to an increased production of atmospheric nitrogen. An increase in nitrogen gas emission leads to fewer algae in the water, and thus there is less food for marine microorganisms. Ultimately, it means less food for the fish," explains Bo Thamdrup.

Expanding Minimum Oxygen Zones may also weaken the ocean's capacity to absorb CO2, explains Loreto De Brabandere: "It gives more room for the nitrate-eating bacteria, and thus there is less nitrate available to marine plankton. Plankton is effective at absorbing CO2, and if there is less plankton there will be less CO2 absorbed."

The Minimum Oxygen Zones

There are three Minimum Oxygen Zones in the world: in the Pacific Ocean off Peru/Chile, north of the Equator off Mexico/Guatemala and in the Arabian Sea. The zones are underwater pools, not in contact with the surrounding seawater, and they do not contain any oxygen. The zones are located app. 100 -- 500 meters below the surface and they make up app. two per cent of the oceans. They are nevertheless very important, as they account for a third of the oceans' removal of nitrogen. Just a little variation in their size will have great impact on how much nitrogen is removed. No animals can live in the Minimum Oxygen Zones. Only bacteria that do not need oxygen, can thrive here.


Story Source:

The above story is based on materials provided by University of Southern Denmark. The original article was written by Birgitte Svennevig. Note: Materials may be edited for content and length.


Journal Reference:

  1. Loreto De Brabandere, Don E. Canfield, Tage Dalsgaard, Gernot E. Friederich, Niels Peter Revsbech, Osvaldo Ulloa, Bo Thamdrup. Vertical partitioning of nitrogen-loss processes across the oxic-anoxic interface of an oceanic oxygen minimum zone. Environmental Microbiology, 2013; DOI: 10.1111/1462-2920.12255

Cite This Page:

University of Southern Denmark. "Unexpected interaction between ocean currents and bacteria may weaken ocean's ability to absorb carbon dioxide." ScienceDaily. ScienceDaily, 13 September 2013. <www.sciencedaily.com/releases/2013/09/130913101817.htm>.
University of Southern Denmark. (2013, September 13). Unexpected interaction between ocean currents and bacteria may weaken ocean's ability to absorb carbon dioxide. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2013/09/130913101817.htm
University of Southern Denmark. "Unexpected interaction between ocean currents and bacteria may weaken ocean's ability to absorb carbon dioxide." ScienceDaily. www.sciencedaily.com/releases/2013/09/130913101817.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) — Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) — The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) — A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) — The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. 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:
from the past week

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