LAUSR

Significance A historically abundant sea urchin has been struck by two mass mortalities separated by 40 y. The 1983 event was across the Western Atlantic and populations never fully recovered. The 2022 event has thus far has reduced population densities in many regions of the Caribbean. On St. John, US Virgin Islands, the geographical epicenter of the 2022 event, these sequential mortality events transitioned the distribution of D. antillarum from highly abundant prior to 1984, to a locally patchy species associated with small areas of high coral recruitment, to a rare species in 2022, eliminating their characteristic grazing that once promoted coral recruitment and survival.