When corals are in trouble they call on their fish “bodyguards” for help.
Scientists from Georgia Institute of Technology have found evidence that certain fish respond to chemical signals sent by the coral (Acropora nasuta) when it is threatened by noxious alga (Chlorodesmis fastigiata). In just minutes, the fish–inch long gobies–come to the rescue by trimming back the seaweed.
The gobies (Gobidon histrio and Paragobidon enchinocephalus) spend their whole lives in the crevices of certain corals. It’s a mutualistic relationship because the gobies help the coral survive while the coral provides the gobies with shelter. It is the only known symbiotic relationship where one species chemically signals another to remove competitors.
“This species of coral is recruiting inch-long bodyguards,” said Mark Hay, a professor at Georgia Tech’s School of Biology. “There is a careful and nuanced dance of the odors that makes all this happen. The fish have evolved to cue on the odor released into the water by the coral.”
“This takes place very rapidly,” Hay explained. “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.”
“These kinds of positive interactions needs to be better understood because they tell us something about the pressures that have gone on through time on these corals,” said Hay. “If they have evolved to signal these gobies when a competitor shows up, then competition has been important throughout evolutionary time.”
The research was part of a long-term study of chemical signaling on Fiji Island coral reefs. The goal of the project is to help understand the local ecosystems and search for new chemicals that could be used as pharmaceuticals.
To learn more:
- Check out the full news release from Georgia Tech: Corals attacked by toxic seaweed use chemical 911 signals to summon help
- Find the full paper, published in the journal Science, here: Corals Chemically Cue Mutualistic Fishes to Remove Competing Seaweeds
Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.