Massive blue-green algae outbreak
A massive outbreak of blue-green algae, reportedly the world's largest, is threatening dugong feeding grounds off the coast of Queensland.
An eight square km area near Deception Bay and a massive 30 square km patch off Stradbroke Island, near Moreton Bay have been invaded by the marine algae, known as lyngbya. A taskforce responding to the outbreak has been told there is no way to stop the current bloom.
Associate Professor Bill Dennison from the University of Queensland's Botany Department says the problem will get worse. "It's happened so fast and it's a really difficult problem logistically with the hundreds to thousands of tonnes of lyngbya we have in the bay currently."
Andrew Watkinson, a biologist with the University of Queensland School of Botany, said the algae threatens important seagrass beds off Stradbroke Island, a major feeding ground for dugongs.
The algae live on the seafloor where they attach to seagrass stalks and form a long, hair-like mat. The lyngbya, once it gets to a certain critical mass, eventually breaks free of the bottom and floats to the surface, tearing away the seagrass from the sea floor.
Mr Watkinson said the outbreak was caused by warm water, high light levels, and an as yet to be identified, source of iron phosphorous which interacts with organic material on the sea floor.
The blue-green algae needs iron and phosphorous to survive, and Dr Watkinson said scientists suspect the iron may be coming from soil disturbance on land.
Moreton Bay is an important commercial and recreational fishing area, and there are new canal developments being built in the area.
The outbreak has affected commercial fishing operations, both by fish avoiding some affected areas and by the physical inability of fishermen to work their nets in the areas where the algae occurs.
Queensland Environment Minister Minister Rod Welford said outbreaks often occur during the hotter months but this is the first time that it has been a serious problem.