Mireille Consalvey PhD Thesis - University of St Andrews

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The following day the tank was moved outside and placed in an area that
would not be subject to shading over the course of the day. The first fluorescence
measurements (F,, and Fn; n= 5) were made at 07: 30 (the time that the site
would be exposed). Fluorescence measurements (F,, 15 and F,, 15) were taken
approximately every hour until darkness. In all instances the same area of biofilm
was monitored for the duration of the study. Low tide was at 12: 00. The site
would have been immersed at 16: 29. Table 5.1. shows the times that
fluorescence measurements were recorded.
Time
oph\
Table 5.1. Timing of fluorescence measurements
Cumulative time
(minutes) Time
Cumulative tmie
(minutes)
07: 30 0 15: 30 480
08: 30 60 16: 2 535
09: 30 120 18: 10 640
10: 30 180 19: 20 710
LT 12: 00. 270 20: 15 765
13: 00 330 20: 451 795
14: 30 4201 21: 451 855
3 PAR measurements were taken and averaged approximately every 15
min using a LI-COR Ll 189 radiometer and recorded as photosynthetic photon
flux density (PPFD; gmol photons M-2 s-1). The PPFD prior to each dark
adaption period was always recorded. Irradiance profiles (n = 5) were taken
every 2h in the upper layers of sediment/biofilm using fibre optic microsensors
and from these profiles the light attenuation co-efficient (k) was calculated.
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