caulerpa taxifolia in moreton bay - Centre for Marine Science ...

Caulerpa taxifolia in Moreton Bay
For chlorophyll analysis, a 2 cm section of the second-youngest seagrass leaf was
clipped off 2 cm above the leaf sheath. Sample surface area and wet weights were
determined prior to analysis. The leaf sections were macerated with a razor blade
then ground in a darkened room using a mortar and pestle in 10 ml of 90% acetone.
The extracts were stored at 0 °C in the dark for 24 hours and then centrifuged in an
IEC Centra-3C centrifuge at 2400 rpm for 15 minutes to settle any suspended
material. Absorbances of the extracts were measures in a Pharmacia LKB Ultrospec
III spectrophotometer at 725, 663 and 645 nm (Dennison, 1990). Chlorophyll a and b
concentrations were calculated from these absorbances (Arnon, 1949).
3.4.6 Statistical analyses
Six tanks were located along the north-east wall of the planthouse and six along the
south-west wall (Figure 9). To test for any potential difference in light regime
received by the two rows of tanks, ‘Block’ was included as a factor in the repeated
measures analysis of variance (ANOVA) model. Tank arrangement had a negligible
effect on the response variables, therefore measurements were pooled. PAM
fluorometry, shoot density, morphology (leaves per shoot and maximum leaf length),
and pigment values were analysed using a repeated measures analysis of variance
(ANOVA) model. All measurements within a tank were pooled. Biomass values
were analysed using a one-way ANOVA model and a Fisher’s post-hoc LSD test was
used to test for differences between means.
N
Block 1
Block 2
Figure 9. Conceptual diagram depicting the arrangement of the tanks within the planthouse at Moreton
Bay Research Station, North Stradbroke Island.
Jane Thomas -17-
Materials and Methods