Young Corals, Fish can 'Smell' Bad Reefs

Young corals and fish use chemical signals to distinguish between good and bad coral reefs, a new study has found.

The researchers say that damaged coral reefs emit chemical cues that the young corals detect and use the information to choose good neighbourhoods.

Seaweed invasion is one of the several critical factors damaging coral reefs worldwide. Overfishing leads to decline in the number of herbivoure fish in the reefs, which in turn leads to growth of seaweed. Rise of seaweed in a reef decreases coral population.

The study shows that merely designating a reef as a threatened environment might not be enough to resurrect the local ecosystem.

"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, an assistant professor in the School of Biology at the Georgia Institute of Technology in Atlanta, and the study's first author.

The research was based on data from three marine areas in Fiji. The country has established several no-fishing areas to restore coral habitats.

Young corals and fish were placed in special chambers and were offered a choice between water from healthy and damaged reefs, BBC reported.

Scientists found that young corals could smell 'bad water' and were repelled by water samples taken from damaged reefs.

"Not only are coral smelling good areas versus bad areas, but they're nuanced about it," said Mark Hay, a professor in the School of Biology at Georgia Tech and the study's senior author, according to a news release. "They're making careful decisions and can say, 'settle or don't settle.'"

The study is published in the journal Science and was funded by the National Science Foundation (NSF), the National Institutes of Health (NIH), and the Teasley Endowment to Georgia Tech.