CO2 and Reefs

[obtusewit]

I thought this might be of interest to all

Carbon dioxide inhibits coral growth, biologists find
By JULIET EILPERIN
Washington Post
Increased carbon dioxide in the atmosphere will damage coral reefs, according to research published last month in the Journal of Geophysical Research: Oceans.
The two authors — Chris Langdon, an associate director with the University of Miami's Rosenstiel School of Marine and Atmospheric Science, and Marlin Atkinson at the Hawaii Institute of Marine Biology — studied how doubling carbon dioxide affected two coral species critical to reefs in Kaneohe, Hawaii.
They found that as the seawater became more acidic as a result of increased carbon dioxide levels, coral skeletal growth decreased by 50 percent.
"The ocean is known to absorb carbon dioxide, causing measurable changes in seawater chemistry of the surface ocean," Langdon said. "If this process continues at the current rate, we expect carbon dioxide levels, and consequently the acidity of the ocean, to increase 200 to 300 percent in the next 50 to a hundred years."

[GaryP]

CO2 will decrease the alkalinity because the carbonate is used up in neutralizing the carbon acid that the CO2 is converted into.

I thin NaCl_H2O ran into this in his home. He found a partial solution by venting his monster skimmer into the attic where the air didn't have as much CO2. So, there are some anlogies to the aquarium hobbyist. The CO2 that you generate through respiration, from your pets, from cooking and heating, and from smoking are similar to what we are seeing in the global warming models being discussed in this article.

[::pete::]

and arent CA Reactors adding more?

[Thunderkat]

Seems a little misleading to me though, the title though is more exciting if you say CO2 is dangerous as opposed to abnormal pH being dangerous.

[matt]

and arent CA Reactors adding more?

I don't think so if they're working correctly; however, they can contribute to ph drops because of the low ph of the effluent. Ideally, I think the CO2 that's injected into a reactor and dissolved in the water turns into carbonic acid and reacts with the carbonate media, thus it's not entering the tank as dissolved CO2. I'm sure in reality, though, a little gets in there. It "should" get neutralized by the increased presence of carbonate in the effluent.

Ironically, CO2 provides the source for carbonate in calcification, and so it is necessary for coral growth. However, when the CO2 dissociates into carbonate, a bi-product is a hydrogen ion, which is responsible for the ph drop. Too much of this and the low ph inhibits calcification. So thunderkat is right in that the title is a little misleading; it should say "CO2 lowers ph which then inhibits coral growth" but then only us reef geeks would read the story.

As Gary said, atmospheric CO2 from a sealed crowded house is much more likely to cause ph problems than a well adjusted CA reactor.