Development of a rapid Hormosira banksii bioassay using chlorophyll a fluorescence
- Publication Type:
- Thesis
- Issue Date:
- 2006
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A wealth of information exists for chlorophyll a fluorescence applications in ecophysiology.
However, the use of chlorophyll a fluorescence in marine ecotoxicology
has been limited and this is especially true of macroalgal ecotoxicology.
The primary objective of this thesis was to develop and describe a bioassay protocol
that uses improvements on past macroalgal assay techniques to allow the
photosynthetic capacity of Hormosira banksii gametes to be assessed using
chlorophyll a fluorescence measurements. Two protocols (using H. banksii eggs or
sperm) have been developed that allow for rapid assessment of toxic impact (less
than 8 h) on macroalgal gametes. This rapid time-to-result allows for timely
management decisions to be made. This is significant since past macroalgal
bioassays have necessitated up to a 48 h delay before results are available to decision
makers.
In addition to this much improved rapidity of result, comparison between a
germination based endpoint and the fluorescence endpoint has shown the
fluorescence measure to be more sensitive to some classes of toxicant, more precise
(in terms of Coefficient of Variation), and can also offer information on mechanistic
pathways of toxicants.
In order to validate 'real-world' use of the new fluorescence protocol, the sperm
fluorescence bioassay was effectively applied to the assessment of interactive effects
displayed by mixtures of anti-foulant compounds. Furthermore, a level of eco-relevance
was demonstrated for the chlorophyll a fluorescence endpoint %PSII
Inhibition. This is significant in that eco-relevance has not previously been
experimentally demonstrated for a chlorophyll a fluorescence endpoint in
ecotoxicology and the demonstrated link to higher level effects may have favourable
implications as to future acceptance of fluorescence data into water quality
guidelines.
Essentially, this work describes the development of, and also the successful
application of, a novel, fluorescence macroalgae bioassay that not only has
advantages over currently employed methods, but also offers a powerful tool in both
the rapid assessment of toxic impact on near-shore macroalgal communities, and as
an effective toxicity screening tool.
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