| Big cuttlefish 'at risk' from desalination|
|The largest species of cuttlefish in the world is at risk from a huge desalination plant being proposed in South Australia, say researchers.|
The comments, from a marine ecologist and oceanographer, come on the eve of the release of an Environmental Impact Statement (EIS) covering the plant.
BHP Billiton defends the impacts of the plant, which it wants to build in the Upper Spencer Gulf for its expanded Olympic Dam uranium, copper and gold mine.
"BHP Billiton will reveal in the EIS the outcome of a great deal of research which demonstrates that there will be no adverse impact on cuttlefish from the operation of the desalination plant," Richard Yeeles of BHP Billiton said in a statement today.
But, marine ecologist Associate Professor Bronwyn Gillanders of the University of Adelaide says her research suggests otherwise.
Gillanders is co-author of a recent study, published in the journal Marine Environmental Research, which examined the impact of brine on the giant Australian cuttlefish.
The cuttlefish (Sepia apama) are the largest in the world and a master of disguise, changing both their texture and colour to fit in with their surroundings, says Gillanders.
She says the Upper Spencer Gulf is a hotbed of breeding for the cuttlefish, which she believes are a species of their own.
"You get tens to hundreds of thousands of individuals and that's the only known breeding aggregation of cuttlefish in the world so it's really quite unique," she says.
Gillanders says the cuttlefish breed only once a year and then die, so anything that interrupts their breeding and development will have a serious impact on their population.
Her study, funded by the university, measured the survival of cuttlefish eggs under different concentrations of brine.
Gillanders found that 100% of eggs survived at normal background levels of to salinity of 38 to 40 parts per thousand.
But, survival rates dropped off once salinity reached 45 parts per thousand, with all eggs being killed at 50 and 55 parts per thousand.
"The level that would potentially be discharged would be much higher than that," she says.
Gillanders is concerned that if the salinity is not dispersed the cuttlefish will be adversely affected.
BHP Billiton was unavailable today for further comment, but their website states that currents in the area are strong and able to help disperse the brine.
Oceanographer Dr Jochen Kaempf of Flinders University in Adelaide has modelled currents in the sheltered Spencer Gulf and says they do not bode well for the cuttlefish.
"There is a unique feature with the tidal currents," he says. "The tidal currents disappear on a fortnightly basis."
Kaempf says for a few days every fortnight the currents move at only a few centimetres per second.
He says this means there is little mixing of water from the upper part of the gulf with the lower part, and it would take about two years for any pollution to be dispersed from the upper level.
Without dilution, the more dense saline water sinks to the sea floor where it uses up oxygen and affects marine life, says Kaempf.
"Whatever pollution you introduce to that region can have long-term detrimental effects on cuttlefish and other species in that region," he says.
"We don't fully know what would happen but it's the region of the lowest flushing. There are alarm bells ringing in my brain."
Kaempf's modelling was funded by the university. He may soon receive funding from the fishing industry to work on a response document to BHP Billiton.