As CO2 acidifies the oceans, scientists develop a new way to measure its effect on marine ecosystems

November 19, 2014 by Dov Smith
Figure 1: An aerial photo of a coral reef. Researchers developed a new tool to quantify the effect of ocean acidification on calcifying organisms. Credit: Boaz Lazar, Hebrew University

Following a 5,000 km long ocean survey, research published in the Proceedings of the National Academy of Sciences presents a new way to measure how the acidification of water is affecting marine ecosystems over an entire oceanic basin.

As a result of man-made emissions, the content of CO2 in the atmosphere and oceans has increased dramatically during recent decades. In the ocean, the accumulating CO2 is gradually acidifying the surface waters, making it harder for shelled organisms like corals and certain open sea plankton to build their skeletons.

Since this process impacts the functioning of many , it has been intensively studied in recent years. However, getting an accurate measure is complicated because the effect of ocean acidification on the rates of calcium produced by marine organisms is highly variable and species specific. Since scientists tend to use local and site-specific field measurements, treating reef environments and open sea environments separately, their measurements reflect the local response of individual organisms to elevated CO2 levels, and not the overall picture.

To get a clearer picture of how is affecting large marine areas, a group of Israeli researchers studied a 5,000 km long strip of ocean, from Eilat to the Seychelles crossing the Red Sea, the Gulf of Aden and the Western Indian Ocean.

The group was led by Profs. Boaz Lazar and Jonathan Erez and the Ph.D. student Zvi Steiner, together with Prof. Amitai Katz, all from the Fredy and Nadine Herrmann Institute of Earth Sciences at the Hebrew University of Jerusalem, together with Prof. Aldo Shemesh and Dr. Ruth Yam of the Weizmann Institute of Science.

A Google Earth image of the research cruise showing the sampling stations along the ~5,000 Km oceanographic transect described in the PNAS paper.

The researchers developed a new method to simultaneously assess the overall calcification rates of coral reefs and pelagic (open sea) plankton over a whole oceanic basin, based on variations in surface water chemistry. These variations result from the tendency of organisms that precipitate calcium carbonate skeletons to replace some of the calcium in their skeletons with other elements (e.g. the element strontium). These replacements depend on growth conditions and are typical for each group of organisms. Owing to this characteristic, corals produce calcium carbonate with a different chemistry than calcareous (composed largely of calcium carbonate) plankton, and their overall effect alters the chemistry of the ocean water. This is the first study that demonstrates the feasibility of quantifying this type of information on an oceanic basin scale.

The group estimated that pelagic plankton precipitate 80% of the Red Sea calcium carbonate, and coral reefs precipitate about 20%. This data is a crucial milestone if we wish to track the effect of anthropogenic activity originating from human actions, since it is not possible to quantify change without having objective baseline conditions.

Monitoring the variations in coral and plankton growth rates every few years can provide essential information regarding rates of environmental change in tropical and subtropical seas like the Red Sea, Caribbean and South China Sea.

The research was published in PNAS (Proceedings of the National Academy of Sciences) as "Basin scale estimates of pelagic and coral reef calcification in the Red Sea and Western Indian Ocean". The research was supported by the Israel Science Foundation, the Bill and Melinda Gates Foundation and the Israeli Ministry of Science and Technology.

Explore further: Can coral save our oceans? Researchers discover soft coral tissue may help protect reefs

More information: www.pnas.org/content/111/46/16303.long

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9 comments

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gkam
2.2 / 5 (13) Nov 19, 2014
We are in the fight of our lives, or for our lives, yet those with political prejudice are opposing our efforts to save the Earth for Humanity.

It is crazy, but these few folks, bankrolled by Filthy Fuels are stopping us from saving ourselves.
gkam
1.8 / 5 (10) Nov 19, 2014
If the Deniers will identify themselves, we can send them some Hydrion Papers.
aksdad
2.6 / 5 (5) Nov 19, 2014
it is not possible to quantify change without having objective baseline conditions

Exactly. This is a laudable effort to establish a baseline, providing a perspective that is frequently missing when talking about climate change, as evidenced by this bit of hyperbole from the article:

As a result of man-made emissions, the content of CO2 in the atmosphere and oceans has increased dramatically during recent decades.

Here's an example of how "dramatically" CO2 content has risen in the oceans:

http://www.epa.go...ity.html

Not very much. At that rate, it will take another 160 years for the pH of oceans to match the lowest levels seen (pH 7.9) in the last 7,000 years. Oceans varied by as much as pH 0.4 over that time and have slowly decreased from a peak 2,000 years ago of about pH 8.3. It is highly likely human CO2 emissions will diminish significantly over the next century as technology continues to improve.
gkam
1.9 / 5 (9) Nov 19, 2014
Yeah, don't worry, this guy knows lots more than them pointy-head scientists.

All those articles of changing pH affecting the copepods is just talk. Don't worry until they die, . . then we can eat Soylent Brown.
gkam
2.3 / 5 (6) Nov 20, 2014
The Deniers want European vacations.

http://phys.org/n...air.html

I suggested Beijing.
peter_piasecki_92
2 / 5 (4) Nov 20, 2014
Gkam sounds just like Hitler, he will send you to the camp of his choice based of grant money science.
gkam
1.8 / 5 (5) Nov 20, 2014
Peter, is that it? Is that what you are screaming across the playground?

Does your mother wear Army boots?
mbee1
3 / 5 (2) Nov 21, 2014
The problem is the headline, the ocean is not acid and never will be acid in the lifetime of the human race. It is slightly less basic and well within normal tolerances in ocean water. The PH of the oceans changes depending on the source of the water and the time of year. Water from deeper in the oceans is less basic than surface water. Ocean PH ranges from 7.4 to 8.2 and has not actually changed much despite all the claims to the contrary.
gkam
2.3 / 5 (6) Nov 21, 2014
The decrease in pH is called, correctly, acidification.

And I suggest you look into biology if you think there is no effect.

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