Black Sea Urchin Plague


Category 3 (Host Not in Canada)

Common, generally accepted names of the organism or disease agent

Black sea urchin plague, Black sea urchin mass mortality.

Scientific name or taxonomic affiliation

Unknown, but thought to be a waterborne pathogen transported by ocean currents. Gram-positive, anaerobic, rod-shaped bacteria, Clostridium perfringens and Clostridium sordelli were isolated from moribund, laboratory-held, black sea urchins thought to be affected with the same disease that caused the mass mortalities. Both species of bacteria were virulent for black sea urchins in the laboratory.

Geographic distribution

Extensive throughout the Caribbean Sea from Venezuela to Bermuda.

Host species

Diadema antillarium, none of six other coexisting sea urchin species suffered unusual mortalities.

Impact on the host

Caused high mortalities (about 98%) within 10 days of detecting the first signs of the disease in a new locality. Diseased sea urchins (with external signs of balding) were less cryptic than normal animals and weakly attached to the substrate leaving them vulnerable to attack by reef fish and being washed away. At least one year after the main die-off, some of the remaining sea urchins or new recruits had similar signs of the disease and died. Unlike bald-sea-urchin disease which appeared to be confined in distribution, black sea urchin plague spread throughout the Caribbean (3.5 million square kilometres ) reducing population densities to 1-7% of former levels

Diagnostic techniques

Gross Observations: Initially, affected urchins have abnormally high amounts of colourless mucous-like material on many of their spines. Within 36 hours of the appearance of mucous, the urchins were less responsive to prodding by divers, appeared listless, and many began to lose spines. Large areas of the test developed lesions, particularly in the interambulacrae.

Methods of control

No known methods of prevention or control.


Avila, M.H. 1990. Black sea urchin plague: emergency information requested. Fish Health Section of the American Fisheries Society Newsletter 18: 7.

Bak, R.P.M., M.J.E. Carpey and E.D. Ruyter van Steveninck. 1984. Densities of the sea urchin Diadema antillarum before and after mass mortalities on the coastal reef of Curaçao. Marine Ecology Progress Series 17: 105-108.

Bauer, J.C. and C.J. Agerter. 1987. Isolation of bacteria pathogenic for the sea urchin Diadema antillarum (Echinodermata: Echinoidea). Bulletin of Marine Science 40: 161-165.

Hughes, T.P., B.D. Keller, J.B.C. Jackson and M.J. Boyle. 1985. Mass mortality of the echinoid Diadema antillarum Philippi in Jamaica. Bulletin of Marine Science 36: 377-384.

Lessios, H.A., D.R. Robertson and J.D. Cubit. 1984. Spread of Diadema mass mortality through the Caribbean. Science (Washington D C) 226: 335-337.

Levitan, D.R. 1988. Algal-urchin biomass responses following mass mortality of Diadema antillarum Philippi at Saint John, U.S. Virgin Islands. Journal of Experimental Marine Biology and Ecology 119: 167-178.

Liddell, W.D. and S.L. Ohlhorst. 1986. Changes in benthic community composition following the mass mortality of Diadema at Jamaica. Journal of Experimental Marine Biology and Ecology 95: 271-278.

Citation Information

Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Black Sea Urchin Plague.

Date last revised: September 1996
Comments to Susan Bower

Date modified: