I found this paper (while researching iodine of all things!) out of the University of Miami, which studied the effect nitrate levels on zooxanthellae poulation versus stony coral skeletogenesis (calcification/growth rate). I found this to be very interesting, and confirms what people with both low nutrient/nitrate who have also been carbon/vodka dosing have been saying. It appears that the zooxanthellae and the corals both compete for the available carbon (sugars) produced by the zooxanthellae. Carbon is growth limiting. Slow growth appears to be especially</em> affected the presence of any significant nitrate.
Nitrate: effect on zooxanthellae vs growth
- Thread starter ichthyoid
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The premise is that a lack </em>of carbon and/or presence</em> of either nitrate or</em> ammonia above minimal amounts, to all be growth limiting. I'm thrilled by this! There is some evidence that phosphate limits, but it appears not as much as nitrogen in the forms of nitrate and/or ammonia.
As Ricky would say, this 'splains a lot!
As Ricky would say, this 'splains a lot!
After reading the abstract, break this sentence down for me into laymans terms. I don't posess a scientifically wired brain...
"...A model is presented which suggests that the diffusion limited supply of CO2 from surrounding seawater is used preferentially by the enlarged zooxanthellae population for photosenthesis, thereby reducing the availability of inorganic carbon for calcification..."
"...A model is presented which suggests that the diffusion limited supply of CO2 from surrounding seawater is used preferentially by the enlarged zooxanthellae population for photosenthesis, thereby reducing the availability of inorganic carbon for calcification..."
The rate that zooxanthellae can obtain CO2 from seawater, is limited, and that limits their production of sugar (carbon).
They have to start dealing with overcrowding when too many other zooxanthellae are present. They compete with each other for the available CO2, which can only diffuse into them at a certain fixed rate.
Remember, they are really just tiny plants, living in symbiosis within the coral.
Good point. I should have read this in context before responding. They are speaking about why skeletogenesis slows, after the zoox. population has been increased by higher nitrate levels. Bottom line: the available/limited carbon from CO2 goes into photosynthesis, with less then available for skeletogenesis.
This explains why you can have more zoo's, yet slower skeletogenesis (calcification).
This would also seem to explain why corals growing in water with even a little nitrate tend to 'brown up', due to more zooxanthellae.
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