No, The Floating Pumice Raft Is Not Going To "Save" The Great Barrier Reef
It's a stunning picture: a raft of pumice the size of a city floating along the Pacific Ocean. While some news outlets have hailed it as a possible answer to saving the dead and dying coral of the Great Barrier Reef off the coast of Australia, it's by no means an answer to coral reefs' battle against warming waters as global ocean temperatures rise. "No," said Mark Eakin, director of Coral Reef Watch, a program that monitors global coral reef systems. "Floating pumice is not going to save the Great Barrier Reef. It's that simple."
Coral is a single animal made up of hundreds to thousands of small creatures called polyps. Microscopic algae live inside the coral's tissue and provide coral with their colour and about 90 per cent of the energy they need to grow.
But these algae, called zooxanthellae, are extremely sensitive to their surrounding water temperature. A difference of even 1 C of warming can cause the algae to leave the coral, leaving behind only the skeleton, what's called a bleaching event. That doesn't mean the coral is dead, but over time, because it is more susceptible to disease, it can die.
The misguided idea that has been perpetuated by some media outlets is that some of the algal larvae — or other marine life — can latch onto something like pumice and hitch a ride then be deposited onto coral, which could help revive it. "This floating pumice moving from Tonga to the Great Barrier Reef has been going on for decades," said Eakin, who is also a coral reef specialist with the U.S. National Oceanographic and Atmospheric Administration (NOAA). "We've known about it for decades. So this is nothing new."
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https://www.cbc.ca/news/technology/great-barrier-reef-pumice-raft-1.5261123