[Coral-List] PAM Question
dr_iamacdonald at yahoo.co.uk
Thu Nov 5 06:55:56 EST 2009
I came across a PAM study in Qatar looking at differentiating when the corals where stressed in the local environment, which i found rather amusing at first glance - when are the poor chaps not stressed!. Given that the seawater temperature fluctuates between 17 in the winter and 35+ in the summer (DO likewise varies) and salinities range 38ish to 42ish, plus the high light intensity, algae overgrowth, local turbidity issues yet PAM will be able to detect stress?? When are these corals not stressed? but they still reproduce and can grow at near record breaking rates so there must be sufficient scope for growth.
Is the PAM technique that tested a technique outside of rather clear water, constant environmental parameters and does it have the resolution for such use in marginal coral growth environments? How does polyp retraction / zooxan shifting further into the skeletal matrix affect this?
Forgive my ignorance and lack of reading on the subject, i should probably go bury my head in the library first if it wasnt for this new job and new baby!!
Thanks and best regards,
Dr Iain Macdonald
Qatar Carbonates and Carbon Storage Research Centre (QCCSRC)
Department of Chemical Engineering
Imperial College London
South Kensington Campus
London SW7 2AZ
Tel: + 44 (0)20 759 45587
Fax: + 44 (0)20 759 45629
--- On Wed, 4/11/09, walzusa1 <mail at walz-usa.com> wrote:
From: walzusa1 <mail at walz-usa.com>
Subject: [Coral-List] PAM Question
To: coral-list at coral.aoml.noaa.gov
Date: Wednesday, 4 November, 2009, 17:37
Dear Dr. Keshavmurthy,
Regarding your questions about the Diving-PAM... I think you are
taking the German translation into English too literally. While the
Diving-PAM is optimized for taking the photosynthetic Yield (Genty
parameter) this is not the instruments sole function or sole
speciality. For instance, the Light Curve, an automated test that
subjects the sample to different light intensities and the Induction
Curve, are quite useful in interpreting physiological status and
detecting/studying the subtle effects of environmental stress.
The passage you site in the manual is to underscore the convenience
of the set-up for the user not to imply that Diving-PAM is only
useful for single point Yield tests. I can certainly see how it could
be taken so literally though so we'll have to change it in the new
manuals. We stress the convenience of this parameter as diving is a
time sensitive activity and until the recent developments of our
Underwater Monitoring-PAM, which is an automated, continuos
photosynthesis measuring system, getting a lot of measurements fast
was of utmost import and the only way to do it.
On another point, there is a PAR sensor with the Diving-PAM that
helps you make sense of the fluorescence readings. As you pointed
out, the light intensity from site to site can differ greatly and if
you are not measuring light intensity along with fluorescence, it can
be difficult to determine the organisms photochemical efficiency.
You do not always have to dark adapt a sample. Tests like the Yield,
ACT+Yield, which subject the sample to a fixed amount of light for a
defined period of time, the Light Curve and Induction Curve can be
used instead of or to complement Fv/Fm or traditional Dark Adapted
tests. I think you may be hoping to find that one parameter that is
definitive and unfortunately, that is both the good thing and bad
thing about PAM measurements. All these different tests and
parameters help you pinpoint what type of stress or where along the
photochemical pathway inhibition is occurring. However, one stress
might show up in Test A or parameter A while another type of stress
might show up in Parameter B.
I invite you to visit our web site for a list of publications and an
overview of PAM fluorometry which provides greater detail. Please
feel free to contact me directly with any further questions. I will
be more than happy to go over your experiment goals and help you
figure out how best to utilize the PAM to get the information you need.
mail at walz-usa.com
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