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Chl a conversion ratio

Tue, 05/22/2007 - 10:44am — nick
The chlorophyll a conversion ratio was mentioned in another topic for which I have a slightly different question. Why is the default conversion ratio for chlorophyll a to algae biomass 145? According to standard methods chlorophyll a is 1-2% of the algae dry weight biomass. It suggests using 1.5% as an average value which corresponds to a conversion of 67. Again, where does 145 come from? The user's manual gives no reference for the value it uses. Thanks
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Water Quality
Fri, 05/25/2007 - 1:17pm — chris

Nick, I'm not sure why 145 was chosen for the default value, but it is representative of certain species of diatoms (Asterionella formosa, for example). A good reference is: Reynolds, C. S. (1993). "The Ecology of Freshwater Phytoplankton." Cambridge University Press, New York, NY. which has a table listing ratios for specific species. This reference also states that chlorphyll a can account for between 0.5% to 2% dry weight biomass. Hope this helps, chris