Fish Can Sniff Out Bad Coral Neighborhoods: The Smell Test for Reefs (VIDEO)

It turns out that a bad neighborhood smells pretty bad--especially when it comes to damaged reefs. Scientists have found that Pacific corals and fish avoid settling in bad regions by sniffing out chemical cues.

Currently, coral reefs are in decline around the world. Coral bleaching and coral diseases are taking their toll, but overfishing is also having a huge impact on coral collapse. It depletes the herbivorous fish that remove seaweed that sprouts in damaged reef. Once a tipping point is reached, the seaweed can take complete hold.

Because damaged corals are becoming more and more common, the scientists decided to investigate damaged reefs a bit more closely. The researchers looked at three marine areas in Fiji that had adjacent fished areas; the country has actually established no-fishing areas in order to protect its healthy habitats and to allow damaged reefs to recover over time.

The researchers found that the juveniles of both corals and fishes were repelled by chemical cues from overfished, seaweed-dominated reefs. Yet there were attracted to cues from coral-dominated areas where fishing was prohibited. This, in particular, has important implications for setting up marine protected areas.

"If you're setting up a marine protected area to seed recruitment into a degraded habitat, that recruitment may not happen if young fish and coral are not recognizing the degraded area as habitat," said Danielle Dixson, the new study's first author, in a news release.

What's more interesting is the fact that the juveniles can be pretty discriminatory when looking for a new home. It's not just a matter of "good" versus "bad." Instead, it's a matter of how good.

"Not only are coral smelling good areas versus bad areas, but they're nuanced about it," said Mark Hay, the study's senior author. "They're making careful decisions and can say, 'settle or don't settle.'"

The findings reveal that it may be necessary to take more drastic actions to restore reefs. Scientists plan to remove plots of seaweed from damaged reefs in the future to see if that will impact reef recovery.

Want to learn more? Check out the video below, courtesy of YouTube.