Getting infected with a virus is almost always a terrible, horrible, no good, very bad time, even if you’re a coral reef in Australia.

The world is in the middle of the third global coral bleaching event, and almost 4,633 square miles of reef could be dead by the time it’s over. Bleaching causes the symbiotic algae that live on corals to flee, leaving the corals a pale white color. Coral bleaching is tied to warmer ocean temperatures, caused by climate change or cyclic environmental changes like El Nino. And, as if coral reefs didn’t have enough to worry about already, a new study published in Frontiers in Microbiology suggests those same factors could also usher in an explosion of viral activity on the reef.

Using part of the Great Barrier Reef in Australia as a natural laboratory, researchers took samples of coral from the reef just before it went through a bleaching event.

The researchers examined the corals in nature and also put some samples through stresses, simulating higher temperatures, more UV light, and high rainfall, all environmental factors known to strain corals. The experimental corals not only went through a bleaching event, but they also contained large amounts of viruses–amounts 2 to 4 times higher than had ever been recorded in corals before. Viruses are common in nature, but the surprising outbreak of the virus on the already-stressed reefs were worrying to researchers.

“People all over the world are concerned about long-term coral survival,” Rebecca Vega-Thurber, an author on the study said. “This research suggests that viral infection could be an important part of the problem that until now has been undocumented, and has received very little attention.”

Among the viruses found in the coral were herpes-like viruses that seemed particularly prevalent. They aren’t the same as herpes viruses that infect humans, but people are concerned that the additional stress of a viral outbreak on already stressed reefs aren’t doing any favors for the health of coral reefs around the world. In the future, the researchers hope to examine other stressed-out reefs and see if they are suffering from similar virus outbreaks.