research - environment
Our research combines laboratory and field studies to determine
the factors that influence the composition of phytoplankton in Australian
coastal waters, estuaries and fresh waters. These include:
- studies of the interaction and growth responses of microalgae
to nutrients;
- population dynamics and cycling in aquatic environments; and
- life histories and .their importance as adaptive strategies
for survival.
Algal blooms and toxin production
Over 200 strains of coastal marine, estuarine and freshwater species
responsible for harmful algal blooms are held in the CSIRO
Collection of Living Microalgae. These include hepatotoxic and
neurotoxic cyanobacteria, and dinoflagellates that produce paralytic
shellfish toxins. Extensive research into algal bloom dynamics and
control of toxin production has been undertaken to aid environmental
management. Recent studies include:
- the phytoplankton dynamics of the Huon Estuary south-east Tasmania
(as part of the CSIRO/ Fisheries Research and Development Corporation,
Huon
Estuary Study; and
- the interaction of physics, biology and nutrient regimes on
the initiation and development of algal blooms, as part of the
National Eutrophication Management Program funded by Land and
Water Resources Research and Development Corporation and carried
out in collaboration with the University of Tasmania.
Sampling Australian biodiversity
The CSIRO Collection of Living Microalgae
holds ecologically significant strains representing some of the
unique microalgal biodiversity in Australian waters, from the tropics
to Antarctica. Ongoing research implies the repository of biodiversity
is increased with new strain acquisition. CMARC has a commitment
to acquire and hold strains important to Australia’s aquatic
biodiversity.
Pigment and lipid (oil) signatures for biological oceanography
Microalgae form the base of marine food webs and are the major
source of new production of organic matter in the sea. The sources,
fate and transport of this organic matter in marine waters and sediments
can be traced using some of the unique carotenoid and chlorophyll
pigments and distinctive lipid biomarkers synthesized by the different
groups of microalgae. For example, the unusual C30 sterol dinosterol
is synthesized by many dinoflagellates and has been used successfully
to identify organic matter contributed by dinoflagellates in many
marine settings. Its chemically reduced counterpart, the hydrocarbon
dinosterane, has also been found in many ancient sediments and crude
oils, thus testifying to the importance of this algal group since
the Cretaceous.
Biogeochemical research: global carbon cycle
The abundance and composition of lipids preserved in marine sediments
can provide much information about changes to the earth's carbon
cycle due to climate change. Haptophyte algae, and in particular
coccolithophorids belonging to the genera Emiliania and Gephyrocapsa,
synthesize unique long-chain compounds called alkenones. The ratio
of two of these compounds, the 37:3 and 37:2 methyl alkenones, changes
systematically with growth temperature and thus measurement of this
ratio in sediments can be used as proxy for past sea surface temperature.
The absolute abundance of these compounds in sediments can also
be used as a proxy for changes in paleoproductivity.
Last updated
21/08/07
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