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From: JAHAYES@MIAMIU.BITNET (Josh Hayes)
Newsgroups: sci.bio,sci.aquaria,sci.environment
Subject: Re: coral reefs, C02, food, and farming.
Message-ID: <90337.112001JAHAYES@MIAMIU.BITNET>
Date: 3 Dec 90 16:20:01 GMT
References: <720@sierra.stanford.edu>
Organization: Miami University - Academic Computer Service
Lines: 33

Corals grow quite slowly in most cases (though members of two families,
the Acroporidae and the Pocilloporidae, tend to be ramose or branching
in colony structure and can sustain rapid rates of extension, like in
the neighborhood of 15 cm/year), usually 1 cm/yr or less. The amount of
CO2 taken up and then immobilized in skeleton is probably, therefore,
rather small, by comparison with the CO2 taken up by the zooxanthellae
(symbiotic algae), converted to energy-bearing compounds, and trans-
located to the coral tissues then used in respiration and re-released
to the water as CO2. The zooxanthellae might be really cranking along,
contributing as much as 70% of the daily requirement toward animal
respiration (Muscatine et al. 1981). Plants are MUCH better at taking
up CO2, but again, it is not immobilized for long at all. Still,
an increase in the size of even a temporary CO2 sink would be helpful.
 
I am a little concerned about the blithe assertion that calcium is
not limiting here; releasing Ca from CaHCO3 leaves free bicarbonate
ions floating about, which as you recall from your human physiology
class associates with free hydrogen ions to form carbonic acid, which
dissociates to water and CO2....thus regenerating CO2. I dunno how
seriously this process would bollix up the sinking of CO2 on the whole,
but it needs examining.
 
We now return you to your regular broadcast....
 
Muscatine, L., L.R. McCloskey and R.E. Marian. 1981. Estimating the
  daily contribution of carbon from zooxanthellae to coral animal
  respiration. _Limnol._ _Oceanogr._ 26(4): 601-611.
 
-------------------------------------------------
Josh Hayes, Zoology Department, Miami University, Oxford OH 45056
voice: 513-529-1679      fax: 513-529-6900
jahayes@miamiu.bitnet, or jahayes@miamiu.acs.muohio.edu
"I am the Supreme Being, you know; I'm not completely dim."


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