[Coral-List] Ocean acidification beneficial in short term to Corals?

Delbeek, Charles CDelbeek at calacademy.org
Fri Feb 6 14:44:52 EST 2015

I presented at the 2014 Aquality Symposium last fall and also touched on this in my presentation to Aquarium professionals on water quality requirements for live corals. Many of us see coral growth and color at PO4 levels of 2-3 ppm and even higher, as well as elevated NO3 levels of 40 ppm or more,  yet all seems well. However, at what cost? Several publications have noted decreased fecundity at elevated N and P levels, as well as increased susceptibility to disease.

Scott's thinking brings up similar questions on wild reefs, however, in our captive reefs we are also keeping carbonate alkalinity levels of 3 -3.2 meq/L, combined with Ca ion concentrations of 420-480 ppm. Several studies have shown that when alkalinity is elevated higher nutrient levels do not impede calcification.


Best regards,

J. Charles Delbeek, M.Sc.
Assistant Curator, Steinhart Aquarium
California Academy of Sciences

Desk: 415.379.5303
Cell: 415.859.0420
Fax: 415.379.5304

cdelbeek at calacademy.org

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-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Scott Wooldridge
Sent: Thursday, February 05, 2015 2:51 PM
To: coral-list at coral.aoml.noaa.gov
Subject: Re: [Coral-List] Ocean acidification beneficial in short term to Corals?

For those who are interested, I have recently published a Think Again (perspective) article on these very issues.

Wooldridge SA (2014) Assessing coral health and resilience in a warming ocean: why looks can be deceptive. BioEssays 36(11):1041-1049

Abstract: In this paper I challenge the notion that a healthy and resilient coral is (in all cases) a fast-growing coral, and by inference, that a reef characterised by a fast trajectory toward high coral cover is necessarily a healthy and resilient reef. Instead, I explain how emerging evidence links fast skeletal extension rates with elevated coral-algae (symbiotic) respiration rates, most-often mediated by nutrient-enlarged symbiont populations and/or rising sea temperatures. Elevated respiration rates can act to reduce the autotrophic capacity (photosynthesis:respiration ratio) of the symbiosis. This restricts the capacity of the coral host to build and maintain sufficient energy reserves (e.g. lipids) needed to sustain essential homeostatic functions, including sexual reproduction and biophysical stress resistance. Moreover, it explains the somewhat paradoxical scenario, whereby at the ecological instant before the reef-building capacity of the symbiosis is lost, a reef 
 can look visually at its best and be accreting CaCO3 at its maximum.


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