Fish Rescue Coral from Seaweed Attack

Photo Credit: Danielle Dixson

When corals are threatened by toxic seaweed they do what any self-respecting sea creature does: they call for help. Scientists at the Georgia Institute of Technology have been studying a coral reef in Figi. They discovered that when a toxic green seaweed gets on the corals, the corals send chemical signals to Gobis. The inch-long fish respond by nibbling off the seaweed.

The scientists did a number of experiments. In one they moved filaments of a toxic seaweed onto coral. Within a few minutes, two species of gobies moved in and began trimming off the seaweed.

In corals where gobies lived, the fish mowed off the seaweed and reduced seaweed damage significantly. Corals without gobies were damaged by the seaweed. The scientists analyzed the fish digestive systems and learned that one of the gobi species actually eats the seaweed. The other fish apparently bites it off and leaves it.

For the fish that eat the seaweed, the toxic chemicals may make the fish less attractive to predators. In exchange for cleaning the coral, the fish receive shelter. It’s a win-win situation: the fish protect the coral and in return they get a place to live. 

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