Protracted recovery of long-spined urchin (Diadema antillarum) in the Bahamas

In 1983–1984, an unknown waterborne pathogen caused the mass mortality of long-spined sea urchin (Diadema antillarum) across the Caribbean and western tropical Atlantic. After approximately 15 years, urchin populations began to recover at some locations, yet few have reached pre-mortality densities. To date, no study has documented a recovery in the western tropical Atlantic outside of the Caribbean. Over a 25-year period (1991–2015), we documented an 8–17% population growth rate of D. antillarum in the central Bahamas. However, our mean observed densities, 0.06–0.38 urchins m −2, remained below pre-pandemic levels. Combined with observations from other locations in the Caribbean, it appears that D. antillarum populations are increasing, yet have not fully recovered from their 1980s mass mortality throughout much of their geographic range