Nemo And Pals Take The Fish Highway South

[mrmoshe]

Nemo and pals take the fish highway south

Nick Evershed

July 12, 2009

SYDNEY is set for an increase in colourful tropical fish as a changing climate warms our waters.

In the film Finding Nemo, one of the scenes depicts the clown fish's father hitching a ride to Sydney on the East Australia Current. Far from fiction, scientists say this is a fairly accurate depiction of the powerful current, which acts as a conveyor belt for fish distribution, sweeping species from the Great Barrier Reef down the continent's east coast.

David Booth, a marine ecologist from the University of Technology, Sydney, said that with rises in ocean temperature, and an increase in the strength of the current, more tropical fish species are able to arrive and survive in the waters off Sydney.

Professor Booth has been conducting research over the past nine years to track movement of fish via the East Australia Current, and the survival of fish once they reach our cooler waters.

"More and more of the fish are surviving winter down here," he said. "So long as the temperature environment is correct, a lot of them will do just fine."

Beginning life as a larva spawned on the Great Barrier Reef, species such as butterfly fish and moorish idols are swept thousands of kilometres south along this "fish highway", powered by warm waters from the Coral Sea driving against the continental shelf, forming a strong current that reaches down as far as Tasmania.

Dee Why local David Strike, who has been diving off Sydney for more than 30 years, said: "Certainly we are noticing more tropical species."

Peter Doherty, director of the Australian Institute of Marine Science, said as well as bringing reef fish south, the warming current has also allowed the NSW black sea urchin to take hold in Tasmanian waters. The urchin devastates kelp beds, reducing the sea floor to a barren wasteland.

Professor Booth said that the trend towards warmer waters and tropical species in Sydney is indicative of global climate change.