New disease threatens sponges

Marine sponges in the Caribbean's coral reefs are under threat from a new disease.

Scientists from the University of Alabama, have described a new disease called Aplysina red band syndrome (ARBS) in a paper in the journal Diseases of Aquatic Organisms, after studying the condition in Caribbean rope sponges from the Aplysina genus on shallow reefs in the Bahamas.

Aplysina red band syndrome causes Aplysina to develop one or more rust-coloured leading edges to develop their structure, sometimes with a surrounding area of necrotic tissue so that the lesion causes a contiguous band around some or all of the sponge's branch. "The study is one of the few to document coral reef diseases in organisms other than corals."Further analysis of the necrotic margin of the infected sponges has revealed that a species of rust-coloured cyanobacteria was responsible for the red banding, however, although the rust colour has been used to characterise the disease sponges, it is not yet known whether the cyanobacterium is directly responsible for the disease itself.

The authors believe that the syndrome is contagious: "The prevalence of ARBS declined significantly from July to October 2004 before increasing above July levels in January 2005. Transmission studies in the laboratory demonstrated that contact with the leading edge of an active lesion was sufficient to spread ARBS to a previously healthy sponge, suggesting that the etiologic agent, currently undescribed, is contagious. Studies to elucidate the etiologic agent of ARBS are ongoing."

The study is one of the few to document coral reef diseases in organisms other than corals.

For more details on the disease see the paper: Olson JB, Gochfeld DJ, Slattery M (2006) - Aplysina red band syndrome: a new threat to Caribbean sponges. Dis Aquat Organ. 2006 Jul 25;71(2):163-8.