Last month was the hottest May on record—and with heat comes death for many of the world’s more fragile organisms. We've seen reports that coral bleaching has reached alarming levels this year, threatening the world’s greatest reefs. Even the Great Barrier Reef off the coast of Australia is not immune. Now, it appears that there’s yet another human-induced risk:
Scientists have also found that a common ingredient in sunscreen is killing and mutating corals in tourist spots.
The new evidence of harm to corals comes as the most the most widespread coral bleaching event in recorded history is sweeping the world’s oceans. Water temperatures have been driven up by a run of record-breaking hot years, caused by climate change and the El Niño phenomenon. Very warm water causes corals to lose the algae that normally live inside them and help them feed.
The suspected culprit is one of the ingredients in some formulations of sunscreen, called oxybenzone. It’s not merely divers who apply sunscreen and then enter the water. Scientists found a correlation between high tide and damage to the corals, which probably means any sunscreen used by sunbathers that winds up on the beach seeps into the water during high tide.
Oxybenzone is a double whammy for corals already weakened by warming waters. The substance both directly harms them and renders any survivors sterile, giving rise to the new term “zombie” corals: The walking dead of the sea.