[Coral-List] PAM measurements with Acropora

[McGill.Cheryl at epamail.epa.gov]

Monica,
We have used PAM on the branching coral, P. damicornis. We have also run 
into your problems of shading and trying to get in the exact location of 
the coral every time PAM is measured. There are many different opinions on 
how to go about correcting these problems. Our P. damicornis frags were 
fairly small in size so we were able to position them horizontally. This 
way when we took PAM measurements we always measured the top half of the 
nub which is the half that is receiving direct solar radiation. I'm not 
sure how large your Acropora frags are, so this may not be feasible for 
you. When we took PAM measurements we took the measurements at the base of 
the nub (on the top side). To get the exact location every time would be 
nearly impossible. There are arguments against a horizontal position for a 
branching coral. We will be soon be placing our P. damicornis vertically, 
and will have to deal with your current dilemma. One possibility is to 
take a reading from both the top and the side of the frag and get an 
average.  I don't believe there is one correct way in dealing with these 
issues. You must decide what information is most important to you and 
whether your setup will allow slight alterations.

Regards,
Cheryl McGill