‘Beautiful’ sponge threatens reefs
By Ken Kaye From Sun Sentinel
FORT LAUDERDALE, Fla. — It’s such a vibrant orange that divers think it’s part of South Florida’s colorful coral reefs.
But it’s a destructive sponge that for the past decade has been spreading and threatening corals, which already are deteriorating around Florida and the Caribbean.
“It’s a beautiful orange sponge, but it is an excavating sponge, able to bore inside the coral,” said Andia Chaves-Fonnegra, a Ph.D. student at the Nova Southeastern University Oceanographic Center in Dania Beach, who is heading a research project into the scourge.
The current mortality rate for local reefs has been high because of seaborne diseases and warmer waters. That has given the orange sponge — which can reproduce three to five times per year — more room to grow, said Chaves-Fonnegra, 34, of Delray Beach. “The sponge is not what we call an invasive species, but it is a strong competitor, specifically with coral,” she said.
For now, the sponge’s spread is being monitored. But to stem its growth, Chaves-Fonnegra said, ocean pollution should be reduced, as it is nurtured by sewage and other materials.
Sea sponges are classified as animals, even though they don’t have circulatory, digestive or nervous systems. They survive on the power of water flowing through their bodies to obtain food and oxygen.
Chaves-Fonnegra, with help from others at NSU, recently discovered that the orange sponge, formally called “Cliona delitrix,” is proliferating because its larvae attach to dead parts of corals.
When it leaches onto corals, it takes up space where new corals — made up of colonies of tiny animals that secrete calcium carbonate — would otherwise start to grow.
“The sponge makes holes inside the coral and dissolves the calcium carbonate,” she said. “It erodes the coral’s three-dimensional structure.”
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