Hitchhiking pests uncovered
A test for
toxic algae could help save our coastal waters from attack by invading
pests
Coastal waters around the world are threatened by
invaders lurking in the ballast water of cargo ships.
A new global agreement will require ships to meet strict
regulations to ensure they do not harbour any unwanted invaders. New
technologies are therefore needed for treating ballast water on board. But which
treatments will work? Some of the most dangerous algae can play dead.
CSIRO researcher Monique Binet has developed a new method
for determining which ballast water treatment works, and which doesn’t. Her test
will do in one day what previously took up to six months.
“Ballast water is essential to balance the ship’s
cargo,” says Monique, one of the Fresh Science winners for 2004. “But some
15,000 species are hitchhiking lifts around the world with the water each week.”
“A particularly notorious type of algae are the toxic
dinoflagellates which are capable of poisoning shellfish. These poisoned
shellfish can be lethal if eaten by humans. Several international organisations
have suggested that these algae should be one of the benchmarks used to assess
new treatment technologies.”
“The trouble is that these are tough critters. The
dinoflagellates form dormant cysts which can survive for years in the ballast
tanks. So testing the different treatment technologies relies on the ability to
distinguish between live and dead cysts.”
Until now this has meant painstaking hours of microscopic
examination, followed by a wait for up to 26 weeks to see if the cysts germinate
into live, swimming algae.
And that’s where the new method developed by Monique and
her colleagues at CSIRO’s Centre for Environmental Contaminants Research (CECR)
comes in.
“Using a technique called flow cytometry, we can now
analyse each and every cyst for its size, structure and fluorescence. Based on
these characteristics and the use of a DNA stain, we can tell which cysts will
germinate into live cells in a matter of minutes” says Monique.
“The trick was first washing the cysts for 24 hours to
remove their mucous coatings, and selecting the right staining conditions, so we
can now determine cyst viability within 1 day, instead of the conventional 3-26
weeks.”
The research has attracted interest from around the world
with Monique presenting at conferences in Germany and New Zealand.
Monique now plans to apply this method to other species
of toxic dinoflagellates as well as other micro-organisms that hitch a ride in
the ballast water tanks. Enabling the rapid assessment of ballast water will
help prevent these pests from spreading any further.
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| As
found in the sediment of ballast water tanks - the dinoflagellate
Alexandrium catenella in its resting cyst form with surrounding
mucous. |
The
dinoflagellate after a wash. The surrounding mucous has been removed
allowing it to be analysed with flow cytometry |
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| The
dinoflagellate in its motile form, a cell chain. This can bloom into red
tides |
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