The Great Barrier Reef is undergoing what scientists are calling a “complete ecosystem collapse”.
Scientists, led by Coral Watch chief investigator Justin Marshall, studied the reef near Lizard Island in Queensland for over a week in March 2016, Kron4.com reported.
They found many of the fish species that swam around the area have now vanished.
“The lack of fish was the most shocking thing,” Marshall told the Guardian. “In broad terms, I was seeing a lot less than 50 percent of what was there [before the bleaching]. Some species I wasn’t seeing at all.”
Coral bleaching occurs when ocean waters warmed by climate change cause coral communities to release the algae that provided their color and food. The corals can’t cool down and find new algae fast enough, which causes them to die out and become a milky shade of white before they begin to decompose and attract turf algae, according to Weather.com.
Scientists said the drop in the fish population was a huge clue into the collapse of the Great Barrier Reef.
According to Coral Watch, the primary factor that determines whether a coral survives after a bleaching event is the amount of time that it’s exposed to high temperatures under high light conditions. The longer it’s exposed, the more likely it’s going to die.
Corals can recover quickly once the sources of stress are removed and, in some cases, corals regain their color within days, Coral Watch also reports. However, each bleaching event weakens the overall health of the reefs over time.
“One-quarter of all marine life lives in or around a reef,” writes Coral Watch. “What happens when these reefs disappear? Current predictions are that coral reefs worldwide could be gone within 25 years. How much will be left after this global bleaching event? How much will be left for future generations? This is a worldwide coral bleaching event–not just Australia.”
