Featured Research

from universities, journals, and other organizations

Ocean acidification changes nitrogen cycling in world seas

Date:
December 21, 2010
Source:
National Science Foundation
Summary:
Increasing acidity in the sea's waters may fundamentally change how nitrogen is cycled in them, say marine scientists. Nitrogen is one of the most important nutrients in the oceans. All organisms, from tiny microbes to blue whales, use nitrogen to make proteins and other important compounds.

This image shows water samples in the Sargasso Sea being collected for studies of ocean acidification.
Credit: Cheryl Chow

Increasing acidity in the sea's waters may fundamentally change how nitrogen is cycled in them, say marine scientists who published their findings in this week's issue of the journal Proceedings of the National Academy of Sciences (PNAS).

Nitrogen is one of the most important nutrients in the oceans. All organisms, from tiny microbes to blue whales, use nitrogen to make proteins and other important compounds.

Some microbes can also use different chemical forms of nitrogen as a source of energy.

One of these groups, the ammonia oxidizers, plays a pivotal role in determining which forms of nitrogen are present in the ocean. In turn, they affect the lives of many other marine organisms.

"Ocean acidification will have widespread effects on marine ecosystems, but most of those effects are still unknown," says David Garrison, director of the National Science Foundation (NSF)'s Biological Oceanography Program, which funded the research along with NSF's Chemical Oceanography Program.

"This report that ocean acidification decreases nitrification (the amount of nitrogen) is extremely important," says Garrison, "because of the crucial role of the nitrogen cycle in biogeochemical processes-processes that take place throughout the oceans."

Very little is known about how ocean acidification may affect critical microbial groups like the ammonia oxidizers, "key players in the ocean's nitrogen cycle," says Michael Beman of the University of Hawaii and lead author of the PNAS paper.

In six experiments spread across two oceans, Beman and colleagues looked at the response of ammonia oxidation rates to ocean acidification.

In every case where the researchers experimentally increased the amount of acidity in ocean waters, ammonia oxidation rates decreased.

These declines were remarkably similar in different regions of the ocean indicating that nitrification rates may decrease globally as the oceans acidify in coming decades, says David Hutchins of the University of Southern California, a co-author of the paper.

Oceanic nitrification is a major natural component of production of the greenhouse gas nitrous oxide. From the seas, nitrous oxide then enters the atmosphere, says Beman. "All else being equal, decreases in nitrification rates therefore have the potential to reduce nitrous oxide emissions to the atmosphere."

Oceanic emissions of nitrous oxide are second only to soils as a global source of nitrous oxide.

With a pH decrease of 0.1 in ocean waters (making the waters more acidic), the scientists estimate a decrease in nitrous oxide emissions comparable to all current nitrous oxide emissions from fossil fuel combustion and industrial activity.

An important caveat, they say, is that nitrous oxide emissions from oceanic nitrification may be altered by other forms of global environmental change such as increased deposition of nitrogen to the ocean, or loss of oxygen in some key areas.

"That could offset any decrease due to ocean acidification, and needs to be studied in more detail," says Hutchins.

Another major implication of the findings is equally complex, the researchers say, but just as important.

As human-derived carbon dioxide permeates the sea, ammonia-oxidizing organisms will be at a significant disadvantage in competing for ammonia.

Over time, that would shift the available form of dissolved nitrogen in the surface oceans away from forms like nitrate that are produced by nitrification, and toward regenerated ammonium.

With a decrease in average ocean pH from 8.1 to 8.0 (greater acidity), the scientists estimate that up to 25 percent of the ocean's primary production could shift from nitrate- to ammonium-supported.

The consequences of such a shift are not easily predicted, says Hutchins, but would likely favor certain drifting, microscopic plant species over others, with cascading effects throughout marine food webs.

"What makes ocean acidification such a challenging scientific and societal issue is that we're engaged in a global, unreplicated experiment," says Beman, "one that's difficult to study--and has many unknown consequences."

Other co-authors of the PNAS paper are: Cheryl-Emiliane Chow, Andrew King, Yuanyuan Feng and Jed Fuhrman of the University of Southern California; Andreas Andersson and Nicholas Bates of the Bermuda Institute of Ocean Sciences; and Brian Popp of the University of Hawaii.


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Journal Reference:

  1. J. Michael Beman, Cheryl-Emiliane Chow, Andrew L. King, Yuanyuan Feng, Jed A. Fuhrman, Andreas Andersson, Nicholas R. Bates, Brian N. Popp, and David A. Hutchins. Global declines in oceanic nitrification rates as a consequence of ocean acidification. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1011053108

Cite This Page:

National Science Foundation. "Ocean acidification changes nitrogen cycling in world seas." ScienceDaily. ScienceDaily, 21 December 2010. <www.sciencedaily.com/releases/2010/12/101220163258.htm>.
National Science Foundation. (2010, December 21). Ocean acidification changes nitrogen cycling in world seas. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2010/12/101220163258.htm
National Science Foundation. "Ocean acidification changes nitrogen cycling in world seas." ScienceDaily. www.sciencedaily.com/releases/2010/12/101220163258.htm (accessed July 25, 2014).

Share This




More Earth & Climate News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Higgins Breaks Record at Mt. Washington

Higgins Breaks Record at Mt. Washington

Driving Sports (July 24, 2014) Subaru Rally Team USA drivers David Higgins and Travis Pastrana face off against a global contingent of racers at the annual Mt. Washington Hillclimb in New Hampshire. Includes exclusive in-car footage from Higgins' record attempt. Video provided by Driving Sports
Powered by NewsLook.com
Storm Kills Three, Injures 20 at Virginia Campground

Storm Kills Three, Injures 20 at Virginia Campground

Reuters - US Online Video (July 24, 2014) A likely tornado tears through an eastern Virginia campground, killing three and injuring at least 20. Linda So reports. Video provided by Reuters
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