Carbonic Acid

[StefanB]

My question is, do you think increased Carbonic Acid within a reef tank from atmospheric Co2 causes irritation to soft coral tissue?

I believe that low PH due to increased Carbonic Acid affects carbonate and arogonite formation. Could this be a cause for RTN within hard corals. Acros and SPS? Thank you!

@Randy Holmes-Farley

 

[Dan_P]

My question is, do you think increased Carbonic Acid within a reef tank from atmospheric Co2 causes irritation to soft coral tissue?

I believe that low PH due to increased Carbonic Acid affects carbonate and arogonite formation. Could this be a cause for RTN within hard corals. Acros and SPS? Thank you!

@Randy Holmes-Farley

Isn’t this the same concern as that of increasing acidity of the ocean?

 

[Rico's Reefnecks]

Here's a nice discussion with some literature references. My take-away is that even within SPS the effects are species-specific, but most focus seems to be on skeleton formation rather than tissue damage per se.

The Secret of Higher pH | Queen City Corals

Corals Live Corals Aquarium Saltwater

www.queencitycorals.com

In particular, one of the papers referenced seems to indicate that pH changes in this range don't seem to affect the coral tissue metabolism (photosynthesis rates etc) very much, and the authors note that other studies have been equivocal. But the calcification rate in the skeleton is more strongly affected (with acropora seemingly more sensitive than a stylophora, pocillopora).

Effects of light and darkness on pH regulation in three coral species exposed to seawater acidification - Scientific Reports

The resilience of corals to ocean acidification has been proposed to rely on regulation of extracellular calcifying medium pH (pHECM), but few studies have compared the capacity of coral species to control this parameter at elevated pCO2. Furthermore, exposure to light and darkness influences...

www.nature.com

But its an intriguing idea - maybe there's some other injury/immune compromise not measured here that makes them vulnerable to infections etc. Most likely one of many factors.

Interested to see the perspectives of others here.

 

[Dan_P]

Here's a nice discussion with some literature references. My take-away is that even within SPS the effects are species-specific, but most focus seems to be on skeleton formation rather than tissue damage per se.

The Secret of Higher pH | Queen City Corals

Corals Live Corals Aquarium Saltwater

www.queencitycorals.com

In particular, one of the papers referenced seems to indicate that pH changes in this range don't seem to affect the coral tissue metabolism (photosynthesis rates etc) very much, and the authors note that other studies have been equivocal. But the calcification rate in the skeleton is more strongly affected (with acropora seemingly more sensitive than a stylophora, pocillopora).

Effects of light and darkness on pH regulation in three coral species exposed to seawater acidification - Scientific Reports

The resilience of corals to ocean acidification has been proposed to rely on regulation of extracellular calcifying medium pH (pHECM), but few studies have compared the capacity of coral species to control this parameter at elevated pCO2. Furthermore, exposure to light and darkness influences...

www.nature.com

But its an intriguing idea - maybe there's some other injury/immune compromise not measured here that makes them vulnerable to infections etc. Most likely one of many factors.

Interested to see the perspectives of others here.

Thanks for these links.

 

[Garf]

My question is, do you think increased Carbonic Acid within a reef tank from atmospheric Co2 causes irritation to soft coral tissue?

I believe that low PH due to increased Carbonic Acid affects carbonate and arogonite formation. Could this be a cause for RTN within hard corals. Acros and SPS? Thank you!

@Randy Holmes-Farley

My coral definately seem happier with pH at 8.2 or above. The difference was very noticeable with regard to polyp extension at night and its ability to spread out on to the rock. There was a noticeable white band around the coral base, I presume this is the coral preparing the way for growth. This coincided with maintaining night time pH and obviously not directly related to increased ability to calcify through higher pH. I posted this observation on my bubbly CO2 scrubber thread a while back.