USVI Coral Reefs in Danger as Sea Urchin Die-Offs Linked to Microscopic Parasite

Scientists have discovered a new threat to coral reefs, as a microscopic parasite causes massive die-offs of the long-spined sea urchin, Diadema antillarum, a release issued to the Consortium Wednesday has made known. This keystone species plays a critical role in maintaining healthy coral reefs by eating algae, which allows coral to thrive and support other marine life.

Researchers began investigating the issue in early 2022 when large numbers of long-spined sea urchins in St. Thomas started dying rapidly. The cause was identified as a scuticociliate protozoan parasite, similar to Philaster apodigitiformis. The parasite has since devastated sea urchin populations across the Caribbean, including off the Florida coast.

Don Behringer, UF/IFAS professor of marine disease ecology and a member of the UF Emerging Pathogens Institute, led the research effort funded by a National Science Foundation RAPID grant. Behringer explained that the parasite caused the majority of long-spined urchins to be wiped out at specific sites within a couple of weeks.

These mass mortality events can drastically alter marine ecosystems, as seen in the 1983 die-off where 98% of sea urchins were lost in 13 months, with some coral reef systems still feeling the effects today. Researchers were unable to determine the cause of the 1983 die-off, leaving questions about how to protect reefs from similar events in the future.