Ocean acidification could have broad effects on marine ecosystems

December 17, 2008,

Concern about increasing ocean acidification has often focused on its potential effects on coral reefs, but broader disruptions of biological processes in the oceans may be more significant, according to Donald Potts, a professor of ecology and evolutionary biology at the University of California, Santa Cruz, and an expert in coral reef ecology and marine biodiversity.

Potts will give an invited talk on "Geobiological Responses to Ocean Acidification" at the Fall Meeting of the American Geophysical Union (AGU) in San Francisco on Wednesday, December 17.

Ocean acidification is one of the side effects of the rising concentration of carbon dioxide in Earth's atmosphere due to the burning of fossil fuels. The oceans can absorb enormous amounts of carbon dioxide from the atmosphere, but as the gas dissolves it makes the water more acidic. Increasing acidity can make life difficult for corals and other marine organisms that build shells and skeletons out of calcium carbonate.

Scientists fear that acidification will slow the growth of these organisms and cause calcium carbonate structures to dissolve. Potts agrees that dissolving shells will certainly be a problem for many marine organisms, but he thinks the disruptions will run much deeper.

"It's not just a question of coral reefs, and it's not just a question of calcification," he said. "What we are potentially looking at are disruptions of developmental processes and of populations and communities on many scales."

The term "acidification" refers to a slight lowering of the pH of ocean water, pushing it closer to the acidic end of the scale, although it is still slightly alkaline. A small decrease in pH affects the chemical equilibrium of ocean water, reducing the availability of carbonate ions needed by a wide range of organisms to build and maintain structures of calcium carbonate.

Many phytoplankton--microscopic algae that form the base of the marine food web--build calcium carbonate shells to protect themselves from microscopic predators called ciliate protozoa. A disruption of the ability of phytoplankton to build their shells could have ripple effects throughout the marine food web, Potts said.

"It's going to change the dominant organism in the food chain, and there's a very real danger that it may short-circuit the food chains," he said. In other words, ciliate protozoa gorging on unprotected phytoplankton may flourish at the expense of other organisms higher up the food chain.

But calcification of shells is not the only biological process affected by acidification, Potts added. "All biochemical physiological reactions are potentially going to change," he said. Developing organisms are most likely to be affected, due to their low range of environmental tolerances, but it is unclear what the ecological ramifications will be.

Ocean acidification may not affect all parts of the oceans equally. Within 100 kilometers (62 miles) of shore, the pH of ocean water is more variable than in the rest of the ocean. Fresh water and wind from the land can carry chemicals that alter the pH of near-shore water, making it either more acidic or more alkaline. There may be organisms in this region that are already starting to adapt to changes in ocean acidity, Potts said.

"We should be thinking in terms of triage," he said. "We want to be predicting where are the organisms that are most likely to survive or survive the longest, and this is where we should be concentrating our conservation and management efforts, given finite resources."

Source: University of California - Santa Cruz

Explore further: Coral reef experiment shows: Acidification from carbon dioxide slows growth

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2.5 / 5 (8) Dec 17, 2008
Off Topic:

Al Gore just purchased a $500,000 hovercraft that he will be launching from his brand new houseboat. When asked why a hovercraft instead of a jetski, Al responded, "Well... this thing is just so cool I had to get it, for one thing it is air-conditioned and also I can enjoy the water without actually getting wet. Besides it gets almost three miles to the gallon which is very impressive for this type of craft!"
2.1 / 5 (9) Dec 17, 2008
"Ocean acidification could have broad effects on marine ecosystems"

Yeah, it could be beneficial.
3.8 / 5 (6) Dec 17, 2008
Sure, more beneficial to organisms that do better in a more acidic environment. Which are unlikely to be the same organisms that thrive today. And, since humans are adapted to today's environment, including today's organisms, we are unlikely to be among those benefiting from increased ocean acidity.
2.3 / 5 (6) Dec 18, 2008
"The term "acidification" refers to a slight lowering of the pH of ocean water, pushing it closer to the acidic end of the scale, although it is still slightly alkaline."

IF it is happening at all...
3 / 5 (6) Dec 18, 2008
"The term "acidification" refers to a SLIGHT lowering of the pH of ocean water, pushing it closer to the acidic end of the scale, although it is STILL slightly ALKALINE."

Hmmm... Why call it "acidification" then? It does sound scary doesn't it.

"And, since humans are adapted to today's environment,"

You mean humans used to be able to adapt to changes in the past? Too bad we forgot how to do that.

3.6 / 5 (7) Dec 18, 2008
Acidification is a relative, concise, and very accurate term to use. What better term would one use?

There are absolutely no guarantees humans can adapt to any particular environment, even one in which we've lived in the past. There is nothing to prevent us from going extinct. I'm rather fond of humans, though, and would rather not run the experiment to see if we can adapt to increasing oceanic acidity. Perhaps others feel differently about the species.
3.3 / 5 (7) Dec 19, 2008
How about "dealkalinization"? The word is concise and accurate. The water is not being "acidified".
The alkalinity is being moderated.

"I'm rather fond of humans, though, and would rather not run the experiment to see if we can adapt to increasing oceanic acidity."

Again you are using scare tactics. The ocean is NOT acidic, and therefore it is not becoming increasingly acidic.

If my body weight slowly dropped from 500 to 400 pounds would you say I am becoming increasingly skinny or less fat?

1.6 / 5 (13) Dec 20, 2008
You, MikeB, are dead wrong.

If you don't understand the terminology, don't speak.
3 / 5 (8) Dec 21, 2008
You, MikeB, are dead wrong.

If you don't understand the terminology, don't speak.
He's not wrong.

The term acidification is being used to make the change seem far larger than it is. The oceans are at 8.13 pH, that's alkaline. Lowering to 8.129 pH is technically acidification, Mike agrees that this term is correct, however, what is the first thing that pops into the average person's mind when they hear the term acidification?

Boiling steaming seas capable of dissolving metal rods.

When the truth is there isn't enough CO2 in the atmosphere to drop us below 7.5 pH let alone below 7.0, into the world of acidity.

Now as for the term increasingly acidic, to become increasingly acidic you would have to be acidic in the first place, which we're not talking about that. We're talking about becomming less alkaline and more acidic.

More and increasingly are not the same.

This argument is a big nitpick and waste of time.
1.6 / 5 (13) Dec 24, 2008
You, MikeB, are dead wrong.

If you don't understand the terminology, don't speak.
He's not wrong.

You and MikeB are certainly stuborn blokes.

While the two of you may view matters through the eyes of your noted "average person," that does not make your interpretation(s) superior to the understanding of those who are the better informed.

You "average" people lack the ability to engage in rational discussions of matters of Science.

You both need to study and come to understand the distinction between SCALAR and VECTOR.
2.3 / 5 (3) Dec 29, 2008
Backhanded insults must be the sign of a great scientist if your input is to be taken as an example.

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