Scientists sample a long-spined sea urchin, Diadema antillarum, in the lab

Diadema antillarum, the long-spined sea urchin, is an ecologically important species in Caribbean coral reef habitats where it controls algal growth and coverage and helps keep reef surfaces clear for corals to grow and settle. In early 2022, the remaining D. antillarum populations began experiencing mass mortality in the Caribbean. With reefs already under tremendous stress from changing environmental conditions, warming and rising seas, and coral disease, identifying and stopping the spread of this fatal urchin event is critical for protecting coral reefs into the future.

Drs. James Evans and Christina Kellogg of the St. Petersburg Coastal and Marine Science Center (SPCMSC) are part of an international team working to identify the pathogenic microbe—a critical first step to addressing this disease and helping managers develop effective disease mitigation strategies. Using molecular and pathology approaches, they determined that a scuticociliate most similar to Philaster apodigitiformis is the organism responsible for the urchins’ mass mortality.

Here, Isabella Ritchie (University of South Florida College of Marine Science) holds a small black, spiny sea urchin in her hand while James Evans (USGS SPCMSC) collects a sample in the aquarium room at USFCMS, where part of the investigation took place.