The 150 sq km field of floating rock was created by an underwater volcanic eruption near Tonga

This article is more than 1 year old

This article is more than 1 year old

A giant raft of pumice, which was spotted in the Pacific and is expected to make its way towards Australia, could help the recovery of the Great Barrier Reef from its bleaching episode by restocking millions of tiny marine organisms, including coral.

The pumice raft, which is about 150 sq km, was produced by an underwater volcano near Tonga. It was first reported by Australian couple Michael Hoult and Larissa Brill, who were sailing a catamaran to Fiji, on 16 August.

Great Barrier Reef suffers 89% collapse in new coral after bleaching events Read more

“We entered a total rock rubble slick made up of pumice stones from marble to basketball size,” the couple said in a Facebook post.

“The waves were knocked back to almost calm and the boat was slowed to 1 knot. The rubble slick went as far as we could see in the moonlight and with our spotlight.”

The yacht’s steering became temporarily jammed by rocks between rudders and hull, but they managed to clear it and warn other vessels in the area.

7NEWS Gold Coast (@7NewsGoldCoast) A raft of rock, the size of 20,000 football fields is floating towards Queensland. The pumice was created when an underwater volcano erupted off Tonga. Scientists say it'll bring millions of new coral to the Great Barrier Reef. @ErinEdwards7 @QUT #7NEWS pic.twitter.com/W7pKdowYw2

Since then, the pair have been working with Queensland University of Technology geologist Scott Bryan by providing pictures and samples of the volcanic rock.

Bryan said the raft will be the temporary home for billions of marine organisms. Marine life including barnacles, corals, crabs, snails and worms will tag along as it travels toward Australia and become a “potential mechanism for restocking the Great Barrier Reef”.

“Based on past pumice raft events we have studied over the last 20 years, it’s going to bring new healthy corals and other reef dwellers to the Great Barrier Reef,” Bryan said.

Pumice forms when frothy molten rock cools rapidly and forms a lightweight bubble-rich rock that can float. The pumice raft comes from an unnamed but only recently discovered underwater volcano that satellite images reveal erupted about 7 August.

It should begin to hit Australian shores in about seven months’ time, passing by New Caledonia, Vanuatu and reefs in the eastern Coral Sea along the way as coral begins to spawn.

David Attenborough says it's 'extraordinary' climate deniers are in power in Australia Read more

“It’s the right timing. So it will be able to pick up corals and other reef building organisms, and then bring them into the Great Barrier Reef,” Bryan said.

“Each piece of pumice is a rafting vehicle. It’s a home and a vehicle for marine organisms to attach and hitch a ride across the deep ocean to get to Australia.”