Vocal Coral Reefs Signal Chemical Beacon, Tell Goby Fish to Destroy Toxic Seaweed

Coral reefs are vocal, says Georgia Institute of Technology's Mark Hay.

The professor and his team discovered that coral polyps known as Acropora nasuta emit chemcial signals to goby fish when seaweed encroaches on their territory, according to Planet Save report. The Paragobidon enchinocephalus and Gobidon histrio goby species rush to the scene and remove the deadly growth in return for protection from predators within the reef.

Hay states, "The symbiotic relationship between the fish and the coral on which they live is the first known example of one species chemically signally a consumer species to remove competitors. It is similar to the symbiotic relationship between Acacia trees and mutalist ants in which the ants receive food and shelter while protecting the trees from both competitors and consumers."

He adds, "These little fish would come out and mow seaweed off so it doesn't touch the coral. This takes place very rapidly, which means it must be very important to both the coral and the fish. The coral releases a chemical and the fish respond right away."

The scientists found that the gobies reduced the volume of seaweed by 30 percent over three days, effectively containing the threat and reducing coral damage by about 80 percent.

"The coral gets a bodyguard in exchange for a small amount of food. It's kind of like paying taxes in exchange for police protection...By studying the contents of the fish digestive systems, the researchers learned that one species - Gobidon histrio - actually eats the noxious seaweed, while the other fish apparently bites it off without eating it. In the former, consuming the toxic seaweed makes the fish less attractive to predators," says Hay.

An account of the study, which took place near the Fiji Islands, was published in the journal Science.