Featured Research

from universities, journals, and other organizations

Calcifying microalgae are witnesses of increasing ocean acidification

Date:
August 18, 2011
Source:
Helmholtz Association of German Research Centres
Summary:
For the first time researchers have examined on a global scale how calcified algae in their natural habitat react to increasing acidification due to higher marine uptake of carbon dioxide.

For the first time researchers have examined on a global scale how calcified algae in their natural habitat react to increasing acidification due to higher marine uptake of carbon dioxide. In the current issue of the journal Nature they explain that coccolithophores, a certain group of algae, form thinner calcite skeletons when the pH value in the ocean drops. In marine ecosystems, changes in the degree of calcification are much more pronounced than presumed to date based on laboratory tests.

These changes have an impact on the global carbon balance since the examined microalgae influence the carbon dioxide exchange between ocean and atmosphere.

Around one third of the anthropogenic carbon dioxide is being absorbed by the oceans where it forms carbonic acid and its reaction products. The mounting combustion of fossil energy sources led to increased acidification of the ocean over the past century and has affected marine ecosystems. Calcifying organisms like corals and certain microalgae, so-called coccolithophores, react extremely sensitively. These microscopic algae number among the phytoplankton and form a skeleton of calcite platelets.

The group of coccolithophores is very widespread and produces a large portion of the marine lime -- a process that has led to lime deposits, such as the chalk cliffs on Rόgen, over geological time scales. The reactions of calcified microalgae to ocean acidification in their natural environment have not yet been studied on a global scale. Using a method developed by Dr. Luc Beaufort, CNRS researcher at the French research institute CEREGE (Univ. Aix-Marseille/CNRS), it has now been possible to analyse a large number of plankton and sediment samples that document the changes in the calcification of coccolithophores in the present-day ocean as well as over the past 40,000 years.

The results show that coccolithophores form less lime when the water contains less carbonate ions, i.e. when it has a lower pH value (is "acidic"). "The reactions in the natural system are much more pronounced than assumed up to now," reports Dr. Bjφrn Rost from Germany's Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association, who is involved in the study. Laboratory experiments have already shown that the degree of calcification decreases, as water gets more acidic, i.e. the algae form a thinner skeleton.

In the marine ecosystem, however, there is a shift in species composition from strongly to weakly calcified species and strains. "Even small physiological differences in their reactions to environmental changes may have great ecological consequences if this influences their competitiveness," explains Rost. As ocean acidification increases, species that have to invest more energy to form their calcite skeleton may be displaced. Consequently the group of coccolithophores might take up less carbon in future -- with uncertain consequences for the global carbon cycle.

However, the study also shows that there may be exceptions to this general trend. In the coastal zone of Chile, where the "most acidic" conditions in the present-day oceans prevail (pH values of 7.6 to 7.9 instead of 8.1 on average), scientists found extremely calcified coccolithophores. Genetic analysis showed that a distinct strain of the coccolithophore species Emiliania huxleyi has evolved here. This strain has evidently succeeded in adapting to environmental conditions that are unfavourable for calcification. In view of the currently rapid pace of climate change, however, it is extremely questionable whether other representatives of the coccolithophores are able to adjust to this pace.


Story Source:

The above story is based on materials provided by Helmholtz Association of German Research Centres. Note: Materials may be edited for content and length.


Journal Reference:

  1. L. Beaufort, I. Probert, T. de Garidel-Thoron, E. M. Bendif, D. Ruiz-Pino, N. Metzl, C. Goyet, N. Buchet, P. Coupel, M. Grelaud, B. Rost, R. E. M. Rickaby, C. de Vargas. Sensitivity of coccolithophores to carbonate chemistry and ocean acidification. Nature, 2011; 476 (7358): 80 DOI: 10.1038/nature10295

Cite This Page:

Helmholtz Association of German Research Centres. "Calcifying microalgae are witnesses of increasing ocean acidification." ScienceDaily. ScienceDaily, 18 August 2011. <www.sciencedaily.com/releases/2011/08/110803133517.htm>.
Helmholtz Association of German Research Centres. (2011, August 18). Calcifying microalgae are witnesses of increasing ocean acidification. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2011/08/110803133517.htm
Helmholtz Association of German Research Centres. "Calcifying microalgae are witnesses of increasing ocean acidification." ScienceDaily. www.sciencedaily.com/releases/2011/08/110803133517.htm (accessed September 17, 2014).

Share This



More Plants & Animals News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Some Tobacco Farmers Thrive Amid Challenges

Some Tobacco Farmers Thrive Amid Challenges

AP (Sep. 16, 2014) — The South's tobacco country is surviving, and even thriving in some cases, as demand overseas keeps growers in the fields of one of America's oldest cash crops. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

AFP (Sep. 16, 2014) — Scientists say a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com
Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) — Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Ivorians Abandon Monkey Pets in Fear Over Ebola Virus

Ivorians Abandon Monkey Pets in Fear Over Ebola Virus

AFP (Sep. 16, 2014) — Since the arrival of Ebola in Ivory Coast, Ivorians have been abandoning their pets, particularly monkeys, in the fear that they may transmit the virus. Duration: 00:47 Video provided by AFP
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