Bleaching hit to baby coral

SCIENTISTS claim baby coral numbers have “crashed” on the Great Barrier Reef, due to consecutive mass coral bleaching events.

A new James Cook University study, being released today, suggests the damage cause to the Reef – particularly in the Far North – by global warming has compromised the capacity of corals to recover.

Research published in scientific journal Nature states the number of new corals settling on the Reef dropped by 89 per cent during mass coral die-offs during 2016 and 2017.

Using tiles placed underwater at several reefs within the marine park, the study examined the relationships between adult coral stock and larval recruitment of corals before and after the back-to-back bleaching events, and how many new corals were produced to replenish the Reef last year.

The JCU researchers said loss of adults resulted in a crash in coral replenishment, compared to levels measured in previous years before mass coral bleaching.

“The number of coral larvae that are produced each year, and where they travel to before settling on a reef, are vital components of the resilience of the Great Barrier Reef,” said study co-author Professor Andrew Baird.

“Our study shows that reef resilience is now severely compromised by global warming.”

Last year, marine scientists reported one of the largest coral spawning events in many years, with millions of coral sperm and eggs being released onto Far Northern reefs.

JCU researcher Professor Morgan Pratchett said, however, it was highly unlikely the Reef would escape a fifth or sixth mass coral bleaching event in the coming decade.

“We used to think that the Great Barrier Reef was too big to fail – until now,” he said.

“For example, when one part was damaged by a cyclone, the surrounding reefs provided the larvae for recovery. But now, the scale of severe damage from heat extremes in 2016 and 2017 was nearly 1500km – vastly larger than a cyclone track.”