Touched to Death

A barrel sponge more than 8 feet across, located at 60 feet at San Juan in Curacao, was once visited weekly by ten divers from Coral Cliff Diving. After 1993 however, it was pictured in dive magazines with more dive operations opening — e.g., Captain Don’s — it was visited almost daily, greatly increasing its touch rate. In January 1997, a brown spot appeared on the inside. Soon, the tissue turned white, became brittle and started to disintegrate, creating a funnel-shaped hole, around which fish feed. In mid-April, a new hole more than a foot in diameter appeared. No other barrel sponges in the vicinity were afflicted. By mid-May, the sponge was dead and brittle, and fell to pieces when touched. Parrotfish, wrasse and goatfish fed on the dead tissue. A few days later the sponge was gone. Scientists concluded that frequent touching by divers apparently caused lesions facilitating infection of the sponge tissue.

Nagelkerken, I., Laboratory of Aquatic Ecology, University of Nijmegen, The Netherlands, Reef News, Fall 2000.

e-mail:i.nagelkerken@sci.kun.n1