Volcanoes replenish Great Barrier Reef

Posted by Emma Woollacott

With concern mounting about the future of the Great Barrier Reef, scientists have discovered a natural mechanism that could help save it: volcanoes.

A Queensland University of Technology team says that the pumice that surges into the ocean when a volcano erupts in the south-west Pacific could not only help replenish the reef, but could even be the way it was formed in the first place.

The team studied the westward flow, or rafting, of floating pumice after volcanic eruptions in Tonga in 2001 and 2006 - and found plants and tiny animals, including corals, hitching a ride as it was swept by ocean currents towards north-eastern Australia.

"The pumice raft created after the 2006 Home Reef volcano erupted in Tonga initially formed at least a 440 square kilometre floating mass," says geologist Dr Scott Bryan.

"This mass slowly broke up into streaks and millions to billions of marine organisms such as cyanobacteria, barnacles, molluscs, corals, anemones, and crabs began hitching a ride."

Some of this biological cargo latched on in the waters around Tonga and Fiji, while more came aboard elsewhere along the raft's 900-day journey. And when these tiny corals, coralline algae, anemones and other reef dwellers arrived in north-eastern waters they became part of the Great Barrier Reef.

"This is good news, because we know the reef is being replenished as a result of volcanic activity in the south-west Pacific - and volcanic activity is frequent, with eruptions in the area occurring every five to 10 years," says Bryan.

"On the downside, marine pests, for example some species of sponge or mussel, can also be carried along on the pumice. While our research has not yet recognised designated marine pests, even if migration occurred at a very low rate in the future, pumice rafting could bring an invasion of millions to billions of pests that we don't yet know how to deal with."