| Species Investigated |
| Bazzania trilobata (n=4) |
Pleurozium
schreberi (n=4) |
| Sphagnum fimbriatum (n=3) |
|
| Each bryophytewas divided into three parts, and each part was assigned to one
of three conditions: |
1) Maintained in low light (positive control)
2) Exposed to high intensity artificial light ranging from 890 µmol m-2s-
2000 µmol m-2s-1 (negative control)
3) Exposed to an an LED beam originating from a source 5 cm away, for 60 seconds at a
constant rate of 0.15 cm/second in a dark room. |
| Prior to exposure to any conditions, all samples were dark-adapted for a
minimum of 10 minutes. |
| Fv/Fm* was measured using a pulse amplitude
modulation fluorescence technique measured with a Mini-PAM (Walz, Heinz Walz GmbH, Effeltrich,
Germany): |
1) Prior to exposure to experimental conditions
2) Immediately following exposure to experimental conditions
3) 24 hours following exposure to experimental conditions. |
In order to ensure that water availability was not a
confounding variable, sample masses were monitored and all Fv/Fm measurements
were made on samples whose mass was the same (+/- 0.2 g) as originally measured.
*The ratio Fv/Fm
is a good indicator of photosystem damage in bryophytes. Photosystems in healthy
bryophytes typically range from 0.6-0.7. When photosystems are damaged, this ratio
is decreased. (For more information on Fv/Fm, click here). |
