Dying coral reefs are killing fish by masking their predators

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When Coral Reefs Die, Fish May Lose Survival Instincts

The death of coral reefs in Australia may be doing more than wiping out habitats for fish: It may be changing their behavior.

Researchers recently put young fish in controlled environments, half with healthy coral and the other half with bleached coral.

SEE ALSO: Great Barrier Reef at risk of dying within 20 years

Then they exposed them to a chemical that fish release when they're attacked. Young fish sense this alarm signal and associate it with the predator.

The problem is for one species of fish tested, only those in the living-coral environment hid when the chemical was released by researchers.

Stunning images of the Great Barrier Reef:

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Dying coral reefs are killing fish by masking their predators
A photo taken on September 22, 2014, shows fish swimming through the coral on Australia's Great Barrier Reef. The 2,300-kilometre-long reef contributes AUS$5.4 billion (US$4.8 billion) annually to the Australian economy through tourism, fishing, and scientific research, while supporting 67,000 jobs, according to government data. According to an Australian government report in August, the outlook for the Earth's largest living structure is 'poor', with climate change posing the most serious threat to the extensive coral reef ecosystem. AFP PHOTO/William WEST (Photo credit should read WILLIAM WEST/AFP/Getty Images)
A photo taken on September 22, 2014, shows fish swimming through the coral on Australia's Great Barrier Reef. The 2,300-kilometre-long reef contributes AUS$5.4 billion (US$4.8 billion) annually to the Australian economy through tourism, fishing, and scientific research, while supporting 67,000 jobs, according to government data. According to an Australian government report in August, the outlook for the Earth's largest living structure is 'poor', with climate change posing the most serious threat to the extensive coral reef ecosystem. AFP PHOTO/William WEST (Photo credit should read WILLIAM WEST/AFP/Getty Images)
A photo taken on September 22, 2014, shows a turtle on Australia's Great Barrier Reef. The 2,300-kilometre-long reef contributes AUS$5.4 billion (US$4.8 billion) annually to the Australian economy through tourism, fishing, and scientific research, while supporting 67,000 jobs, according to government data. According to an Australian government report in August, the outlook for the Earth's largest living structure is 'poor', with climate change posing the most serious threat to the extensive coral reef ecosystem. AFP PHOTO/William WEST (Photo credit should read WILLIAM WEST/AFP/Getty Images)
Great Barrier Reef - Aerial View - Whitsundays, Queensland, Australia
School of Surgeon fish on Great Barrier Reef Australia
Upolu Cay Island in the Coral Sea Great Barrier Reef
An aerial view of the islands of the Great Barrier Reef in Queensland, Australia
Aerial view of the Great Barrier Reef
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"Their counterparts on dead coral failed to pick up the scent," one researcher said.

The study says it's unclear whether these fish just didn't respond appropriately to the hypothetical predators or if they actually failed to learn what to do in case of an attack.

Australia's Great Barrier Reef is suffering a massive bleaching event right now. If fish's survival instincts are lost with it, a lot of Australia's biodiversity is at stake.

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