Red-Band Disease in Sea Fans

Deborah Santavy and Andrew Bruckner have been studying red-band disease in sea fans, which resembles the black-band and red-band diseases that affect hard corals.

Red-band disease on a sea fan Gorgonia ventalina, Puerto Rico Photo by A. Bruckner
Appearance	A "band" of fine filamentous material approximately 0.25 to 1 inch (0.5 to 2.5 cm) wide occurs on the sea fan blade, moving from the base of the blade to the tip. The "band" is a microbial mat that is brick red in color and easily dislodged from the surface of the sea fan.
Close-up photo of red-band disease on a sea fan Gorgonia ventalina, Puerto Rico Photo by A. Bruckner
Cause	The band in red-band disease appears to be composed of different cyanobacteria and microorganisms than those found in black-band disease and the microbial mat movement is different; the types of microbes present might be different depending on the coral host, but little is known about this (Richardson, 1992; Santavy and Peters, 1997). Several scientists are studying the composition of these microbial mats to determine how they differ from the black-band disease mats found on corals.
Distribution	Thus far, red-band disease on sea fans has only been reported from reefs off Belize and Puerto Rico.
Impact	The loss of sea fan tissue leads to fouling of the skeleton with filamentous algae and sediment accumulations. The entire sea fan might be killed or live portions might remain if the microbial mat disappears.