Coral Reproduction On Great Barrier Reef Dropped Almost 90 Percent Due To Recent Bleaching Events, Study Says

A stock photo depicting the Great Barrier Reef in Australia.
yuejun gao / Pixabay

A new study suggests that bleaching events that affected Australia’s Great Barrier Reef in 2016 and 2017 could be responsible for the massive decline in coral regrowth in the system.

According to a report from BBC News, a team of scientists recently determined that the number of new corals on the Great Barrier Reef had gone down by 89 percent in 2018, in comparison to the historically high rates of replenishment recorded in the 1990s. The phenomenon was blamed on the global warming-driven bleaching events of the prior two years, which had damaged two-thirds of the reef’s adult corals.

“Dead corals don’t make babies,” commented James Cook University professor Terry Hughes, lead author on the new study.

The study, which was published Wednesday in the journal Nature, began last year, as scientists took a look at the adult corals that had survived the 2016 and 2017 bleaching events and sought to determine the rate of reef replenishment that took place in the year that followed. According to study co-author Andrew Baird, the decline in coral regrowth which he and his fellow researchers observed came as a shock, as it could possibly be the first large-scale regrowth problem of its kind.

“Babies can travel over vast distances, and if one reef is knocked out, there are usually plenty of adults in another reef to provide juveniles,” Baird, a professor at James Cook University, told BBC News. “Now, the scale of mortality is such that there’s nothing left to replenish the reef.”

Aside from the aforementioned findings, which were blamed on a rise in sea temperatures, the researchers also discovered that the bleaching events drove a change to the blend of baby coral species on the Great Barrier Reef. As noted by BBC News, Hughes, Baird, and their colleagues found that there was a 93 percent decrease in the population of Acropora, a species whose presence is usually seen as a sign of a healthy reef. The outlet added that Acropora corals can also ensure a reef’s health by providing habitats for “thousands” of other coral species.

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Going forward, the researchers believe that coral replenishment could, in theory, return to normal levels in about five to 10 years from now, provided that the Great Barrier Reef isn’t affected by any more bleaching events. However, they also noted that there’s a very slim chance of the coming years being event-free, as Baird explained that “local solutions” to avoid bleaching have become “almost pointless.”

“The only thing that matters [at this point] is action on climate change,” he added.

Likewise, CNN quoted another study co-author, Morgan Pratchett, as saying that it’s “highly unlikely” that the Great Barrier Reef could avoid another bleaching event or two “in the coming decade,” as it can no longer be said that the system is “too big to fail.”