Diadema antillarum mass mortality

The long-spined urchin Diadema antillarum is an important grazer in Caribbean coral reef ecosystems, where it consumes benthic algae that competes with corals for space. The species experienced mass mortality from 1983 – 1984, reducing overall population densities to a small fraction of their earlier abundance. Together with eutrophication, fishing, and other stressors, the loss of this important herbivore contributed to the decline of coral reefs in the region. The cause of the early 1980s mass mortality was never determined, but the geographic spread of the condition between adjacent locations and unpublished experiments suggested that a microbial agent that moved in ocean currents was to blame.

Beginning in January 2022, this species once again has experienced mass mortality. The condition was first observed in the northeastern Caribbean (US Virgin Islands), before spreading to the Caribbean Netherlands, windward islands, and Hispanola. Working with The Atlantic and Gulf Rapid Reef Assessment (AGRRA) network and collaborators in the region, at the University of South Florida, Florida Fish and Wildlife Commission, US Geological Survey, and several other organizations, the team has been working to figure out what causes this catastrophic condition. The investigation is a multi-disciplinary effort spanning biological oceanography, disease ecology, and microbiology.