Millions of chunks from a giant pumice ‘island’ that, this time last year, was twice the size of Manhattan have started washing ashore in eastern Australia.
Researches traced the rocks’ origin to an underwater volcano that erupted near the Tongan island of Vava’u in August 2019.
The volcanic rocks picked up an array of marine organisms along the voyage, making it a ‘vitamin shot’ for the ailing Great Barrier Reef, according to scientists.
The giant raft of rock was initially spotted shortly after it formed by an Australian couple on a Pacific cruise.
It measured 60 square miles, or more than one-and-a-half the size of Disney World and was six inches thick in some places.
Scientists traced its trajectory and found it lined up with an eruption from an unnamed underwater volcano, designated Volcano F.
Huge eruption plumes were captured by satellite imagery at around the same time, according to a December 2019 report in the Journal of Volcanology and Geothermal Research.
Images of the surface water showed traces of an active underwater eruption, including plumes of vapor and ash.
Pumice forms when lava erupts from a volcano and lands in the sea, where it quickly cools.
Gasses bubbling up through the frothy magma give it its porous, lightweight structure.
Some pumice will immediately sink to the seafloor, but other pieces can float along the ocean for months, even years.
Fragments from Volcano F started washing ashore in April, spreading across the coastline from Townsville in Queensland to northern New South Wales.
Now more of them have completed the 1,900-mile journey.
Their arrival is good news for marine life, since they picked up plenty of ‘hitchhikers,’ plants and animals that can help restock the world’s largest coral reef system.
‘Pumice rafts alone won’t help mitigate directly the effects of climate change on the Great Barrier Reef,’ Scott Bryan, a geologist with the Queensland University of Technology, said in a statement.
‘This is about a boost of new recruits, of new corals and other reef-building organisms, that happens every five years or so. It’s almost like a vitamin shot for the Great Barrier Reef.’
Bryan has been collecting specimens from the raft to learn more about their fantastic properties.
So far, more than a hundred different species have been identified on the porous rock.
‘Anything that is looking for a home out in the ocean tends to find a home on this pumice,’ Bryan said.
‘Each piece of pumice has its own little community that has been transported across the world’s oceans – and we have had trillions of pieces of this pumice floating out there following the eruption.’
This year, Bryan was part of an international team that used underwater robots to collect samples from Volcano F.
‘We’ve been able to see how life has come back to the summit of this volcano after this eruption, and see that restoration of life,’ he said.
‘For the first time, we’ve been able to collect samples from the vent, from the seafloor so soon after the eruption.’
Over the next few years, he said, Volcano F will transform into an island.
He’s been studying pumice rafts for nearly 20 years, and describes them as part of a ‘very ancient process’ in which marine life has been transported around the Earth for hundreds of millions of years.
‘This shows that the Great Barrier Reef has connections to coral reefs that are thousands of kilometers further east,’ Bryan said. ‘In terms of the health of the Great Barrier Reef, it’s also important that these distant reefs are taken care of.’