Loading...
Publication
Compared photophysiology of native seagrasses with an invasive macroalga in Sydney Harbour, Australia
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 302.41 KB | Adobe PDF |
Advisor(s)
Abstract(s)
The comparative photophysiology of the seagrasses Zostera capricorni and Halophila
ovalis and the invasive macroalgae Caulerpa taxifolia was investigated in a shallow mixed
meadow at Chowder Bay (Sydney, Australia), where the three species coexist. This study was
developed under the auspices of the COST Action “Seagrasses: from genes to ecosystems”,
targeting one of its objectives, the development of innovative devices for the continuous
measurement of seagrass photosynthesis. Automated multi-channel chlorophyll fluorometers
were deployed for 24-hour periods to examine and compare the changes in the photosynthetic
efficiency and energy quenching mechanisms of the 3 species. Tissue samples were collected
at predawn and noon, frozen and analysed by HPLC for detailed pigment analysis. The invasive
C. taxifolia showed generally higher photosynthetic efficiency than both Z. capricorni and H.
ovalis. Both seagrass species showed down-regulation of photosynthesis at noon, evidenced
by the low quantum yield and the significant reduction of the antennae pigments between
pre-dawn and noon. In contrast, C. taxifolia showed no reduction in antennae pigments or
total photosynthetic pigments along the day. While both seagrasses showed 3- to 7-fold
increases in the epoxidation state of xanthophyll cycle pigments between pre-dawn and noon,
in C. taxifolia there was no significant change. Our results show that C. taxifolia is better
adapted to high light conditions than Z. capricorni and H. ovalis, which means that, from the
photophysiological point of view, this invasive macroalgae constitutes a serious competitor for
seagrasses in shallow areas with high irradiance.
Description
Keywords
Zostera capricorni Halophila ovalis Caulerpa taxifolia Photosynthesis Chlorophyll fluorescence Photosynthetic pigments Xanthphyll cycle
Citation
Silva J, Runcie J, Barrote I, Costa M, Santos R (2012) Compared photophysiology of native seagrasses with an invasive macroalga in Sydney Harbour, Australia. Proceedings of the 10th International Seagrass Biology Workshop (ISBW10), Armação dos Búzios, Brasil (J C Creed and S S Oigman-Pszczol, eds). Instituto Biodiversidade Marinha, Rio de Janeiro, Brazil, p 60