[Coral-List] Using the Diving PAM

[Esther Borell]

Hi Steve,

 

no I dont think that the PAM standard settings are appropriate for your measurements - you wont get a strong enough flourescence signal - especially if you want to monitor temperature related responses.

Its best to have a high measuring intensity and also high ´gain out`, so that your signal, in case your specimens lose chlorophyll will still be reliable - if the chlorophyll signal is too low (below 120isch) you will get an error output .... (am doing tem/bleaching experiments with S.pistillata and G. fascicularis in Indonesia and had the problem ..... when they started to bleach I didnt get reliable readings anymore) 

 

The signal output is a function of distance, MI and output amplification ....so there is a lot of scope to optimize the setting to whatever fits best with your samples

The distance of the fiber probe to the specimen will also depend on your initial signal . Bear in mind that a lot of technical papers of PAM protocols use plants, which  - at 10mm give you a good signal because they tend to have a homogeneous surface and often a higher absorbance value....? As long as you stick to the same distance though I would say you can take whatever you want - unless you do repeated measurements at a very high actinic intensity, e.g. induction cureves, a very small distance may lead to a rapid decrease in chlorophyll at that site. 

Best thing is to make some trial measurements. Regarding Fv/Fm max, it really depends what you are looking at. Taking it before LC measurements makes sense (dark adapted) as it gives you information about the plasticity of  PS2, but I it wont be necessary before every Fv/Fm´ measurement if you want to measure the ´working flourescenz` at ambient light .....

 

Hope that helps!

 

cheerio

esther


Steve Dalton <sdalton at nmsc.edu.au> wrote:I am currently setting up a lab experiment to monitor photosynthetic 
efficiency of a subtropical coral species at different temperature. In 
addition I will be monitoring corals affected by disease to determine if 
zooxthanthellae and coral tissue in front of the disease margin are 
stressed prior to death using a Walz diving PAM. Having not used the 
diving PAM before, I was wondering if anyone could provide a protocol that 
is appropriate in determining fluorescence yield and relative election 
transfer. I am planning to place fragments of Turbinaria frondens into 
glass aquariums located in a controlled environment room where the 
temperature is set a 21 degrees, and light is provided by 10000K and 
actinic four foot tubes. Treatments for the experiment include 21 degrees 
(control), 24, 26 (temp where T. frondens bleach in situ), and 28 degrees 
aquariums in which individual fragments will be placed. Four fragments 
located in separate beakers in each aquarium will be monitored for 
photosynthetic efficiency 1, 2, 4 and 8 hours and 1, 2, 4 and 8 days after 
the experiments starts. I will hopefully be measuring the maximum quantum 
yield (dark adapted) and effective quantum yield for each sample during 
each specified time. Not sure if I have to measure maximum yield before 
each effective yield measurement, could you please advise. Also I wish to 
determine electron transfer rates and produce rapid light curves.
Also, wondering if the standard PAM settings are appropriate to use for 
this experiment, where the fragments are not subjected to normal in situ 
light intensities and the correct distance to place the optic fiber from 
the sample. The PAM manual suggest 10mm, however, related publications 
generally use 5mm.
If anyone can provide me with an idea of how to use the PAM correctly or 
point me to publications that describe the correct use of the PAM your 
guidance is sincerely appreciated.

Regards

Steven Dalton
PhD student
University of New England
NMSC Postgraduate Representative
National Marine Science Centre
Bay Drive, Charlesworth Bay
(PO Box J321)
Coffs Harbour, NSW Australia 2450
Ph: 6648 3928
sdalton at nmsc.edu.au


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