Corals under attack by toxic seaweed do what anyone might do when threatened they call for help. A study reported this week in the journal Science shows that threatened corals send signals to fish "bodyguards" that quickly respond to trim back the noxious alga which can kill the coral if not promptly removed.
Scientists at the Georgia Institute of Technology have found evidence that these "mutualistic" fish respond to chemical signals from the coral like a 911 emergency call in a matter of minutes. The inch-long fish known as gobies spend their entire lives in the crevices of specific corals, receiving protection from their own predators while removing threats to the corals.
This symbiotic relationship between the fish and the coral on which they live is the first known example of one species chemically signaling a consumer species to remove competitors. It is similar to the symbiotic relationship between Acacia trees and mutualist ants in which the ants receive food and shelter while protecting the trees from both competitors and consumers.
"This species of coral is recruiting inch-long bodyguards," said Mark Hay, a professor in the School of Biology at Georgia Tech. "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, and they very quickly take care of the problem."
The research, supported the National Science Foundation, the National Institutes of Health and the Teasley Endowment at Georgia Tech, was reported November 8 in the journal Science. The research was done as part of a long-term study of chemical signaling on Fiji Island coral reefs aimed at understanding these threatened ecosystems and discovering chemicals that may be useful as pharmaceuticals.
Because they control the growth of seaweeds that damage coral, the importance of large herbivorous fish to maintaining the health of coral
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Georgia Institute of Technology Research News