Underwater Speakers Used To Trick Fish Into Returning To Great Barrier Reef

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It's long been documented that Australia's Great Barrier Reef is facing a tough time due to the effects of climate change and general human interference. New research suggests a radical new approach might be able to help its degrading coral cover and it involves mimicking the sound of a thriving coral reef using speakers.

The Great Barrier Reef's Secret Climate Change Weapon Is This Switzerland-Sized Meadow Of Seagrass

Tourists frequently flock to Lizard Island, off the northeastern coast of Australia, to marvel the Great Barrier Reef. Among the dugongs, sea turtles, and jewel-toned corals, though, there’s another organism that doesn’t get nearly as much credit as it deserves: seagrass.

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The study, published in Nature in November, was conducted by Australian and British researchers over six weeks in late 2017 near Lizard Island, an island on the Great Barrier Reef. The researchers wanted to take a look at how they could draw fish back to dead or degraded coral reefs, which had become silent due to sea life migrating away from them. The plan was to use underwater speakers to bring the sound of a healthy reef back to the decrepit seascapes in order to trick fish and sea life into returning.

Gizmodo Australia spoke to Dr Mark Meekan, a fish biologist at the Australian Institute of Marine Science, who was involved in the study. Dr Meekan explained the famous reef's coral cover had been declining steadily over the years and the new research gave scientists hope.

"Coral cover has been declining over several decades and the major culprit seems to be bleaching events, cyclones and outbreaks of crown-of-thorns starfish," Dr Meekan told Gizmodo Australia.

"These do happen naturally, but our efforts at warming the planet have sped up the frequency that these destructive events occur. Coral communities are very resilient and can recover over a period of a decade, but they aren’t getting enough time between these disturbance events.

"Anything that might speed up recovery is therefore potentially useful in saving at least some parts of the reef."

When Dr Meekan and the team deployed underwater speakers playing the sounds of healthy reefs in affected areas, they found twice as many fish returned to them compared with areas that didn't have the speakers. But it didn't just bring back fish, other sections of the food web returned including herbivores, detritivores, planktivores and predatory piscivores.

"Our study just shows the first part of this process — the fact that we can use sound to attract young fish to the reefs is important because it means that we could rebuild fish communities quicker and we know that many of these species will aid coral recovery," Dr Meekan said.

"The next stage of the work will focus on a longer term study that will compare recovery rates of reefs where we have enhanced recruitment of fish (through the use of sound) with those of reefs that have accrued young fishes naturally."

But while the idea of using underwater speakers to artificially draw fish and other sealife back to the reef sounds like an arduous task, Dr Meekan explained it would just be required to bring the young fish over to the degraded reefs. Something which should, in theory, take a few weeks or months.

"The speakers only play natural reef noise at levels that already occur on healthy reefs so they are not a threat to anything. The idea would be to deploy speakers over a few weeks or months during the time when young fish are arriving on reefs after spawning," Dr Meekan said.

The scientists are convinced the research is promising in aiding the restoration, partial or otherwise, of coral reefs in the Great Barrier Reef and around the world, but it wouldn't be able to work in isolation.

"We still need to tackle a host of other threats including climate change, overfishing and water pollution in order to protect these fragile ecosystems," Professor Andy Radford, co-author of the study, said in a media release.

In a December 2019 report submitted to UNESCO, the Australian government admitted the reef's degradation was primarily due to the effects of climate change.

"The size of the property is becoming a less effective buffer to broadscale and cumulative threats, primarily due to climate change," the Australian government's report read.

"Climate change is having a detrimental impact on some critical regulating processes such as sea temperature, reef building and recruitment (the addition of new young to the population) which means the ability of the system to ‘bounce back’ is weakening."

The report also outlines Australia's "strong action" to limiting the effects of climate change in accordance with the UN's Paris Agreement.

But others, like Greens Senator Larissa Waters, have argued that the damage done to the reefs is going to take a lot more than a commitment to keeping rising global temperatures to below 1.5 degrees Celcius. A target Australia is not on track to meet, according to Australia's Climate Council.

New research like the implementation of underwater speakers is needed but without governments taking appropriate action to mitigate the effects causing the situation in the first place, it's just fighting a rising tide. Literally.

Politicised Science On The Great Barrier Reef? It's Been That Way For More Than A Century

The controversy surrounding the A$444 million given to the Great Barrier Reef Foundation by the federal government shows how politicised science has become on the Great Barrier Reef. One reef scientist, who declined to be named, was quoted saying that the grant was “obviously” political, and accused the federal government of seeking to deny the opposition the chance to make the Great Barrier Reef an election issue. But the politicisation of reef science, and particularly the Great Barrier Reef itself, is not new. It has a long history, stretching back to the time when the British empire was at it's most powerful.

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