Use of pulse amplitude modulated (PAM) flourometry for in SITU measurements of photosynthesis of porites lobata, Samae San, Thailand. Is there evidence for photoinhibition and/or photodamage?
Issued Date
2007
Resource Type
Language
eng
Rights
Mahidol University
Suggested Citation
Phillips, Wayne (2007). Use of pulse amplitude modulated (PAM) flourometry for in SITU measurements of photosynthesis of porites lobata, Samae San, Thailand. Is there evidence for photoinhibition and/or photodamage?. Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/35031
Title
Use of pulse amplitude modulated (PAM) flourometry for in SITU measurements of photosynthesis of porites lobata, Samae San, Thailand. Is there evidence for photoinhibition and/or photodamage?
Author(s)
Other Contributor(s)
Abstract
Objective: To determine whether different faces of a large hemispherical
shaped Porites coral head respond differently to ambient light at different times
of the day.
Methods: A portable underwater Diving-PAM fluorometer was used for
chlorophyll fluorescence measurements on distinct areas of a large Porites
lobata coral head (diameter >2.5m) oriented in a north, south, east and west
direction. Photosynthetic response to irradiance was measured as rapid light
curves (RLCs). From these RLCs a number of parameters were derived. Fv/Fm –
the maximum photochemical efficiency of photosystem 2 (PS2) and the relative
maximum rate of electron transport at saturating light intensities (rETRmax). All
measurements were carried out at 1000hrs, 1300hrs and 1600hrs over a three
day period.
Results: The top surface of the coral showed the lowest Fv/Fm values (e.g. 0.49
on day 1 at 1300hrs) with the north-facing side showing the highest values (e.g.
0.69 day 1 and 2 even at 1300hrs). Although Fv/Fm showed consistent decreases
according to orientation and time of day, rETRmax showed less consistent
variation with time or orientation. The top surface of the coral and the southfacing
side showed significantly lower Fv/Fm than other orientations especially
at 1300hrs.
Conclusion: Mid-day depression in Fv/Fm with little or no change in rETRmax
indicates dynamic photoinhibition.
Description
Research Seminar on Research for MUIC Development, Mahidol University International College, Thailand.