[Coral-List] From a Keys farmer

terrasubaqua at peoplepc.com terrasubaqua at peoplepc.com
Sat Mar 31 13:55:35 EDT 2007

I would add a personal observation to the global warming discussion based on ten years (~4 one week visits /yr) at the same spot off Plantation Key.
There is a fundamental chemistry link between the solubility of calcium salts and water temperature, and we can see the local biochemical link to crustose coralline algae (CCA) growth rate at work each Fall. During this seasonal change, our aquaculture substrate coquina rock gathers a nice coating of CCA over a period of several weeks, commencing just as the water temperature drops. The CCA appears to cover substrate much more rapidly in the Fall months than at any other time of year, it's a very colorful phenomenon and one we watch closely because CCA means added value to our live rock products. We see that, with other variables held to a (roughly) narrow range, the rate of CCA coverage growth seems largely related to the degree of saturation of the calcium salts in the seawater. 
This may have global ramifications, with global water temperatures rising and considering the significance of calcium carbonate deposition to the global sequestration of carbon dioxide. I wonder how rising water temperatures affect the global deposition of calcium carbonate? Though we might assume from controlled experiments it would be detrimental, some biological factors such as faster overall growth, reproduction rate, and/or coverage of CCA in warmer water, or over water temperature changes spanning particular ranges, might control natural feedback mechanism(s) assisting CCA (and possibly other calcium carbonate 'bio-consumers'?) in global- scale sequestration. Even though CCA seems to grow much more slowly (if at all) in mid-winter at our site, the warmer global water temperatures we encounter may also enhance reproduction or otherwise benefit overall growth over the span of a year. It would be interesting to see some large scale/long term field research on this topic as we struggle with the questions surrounding globally rising temperatures and CO2.

Tim Birthisel 

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