Bulletin of Marine Science
The 1983–1984 caribbean-wide mass mortality of the once ubiquitous long-spined sea urchin Diadema antillarum Philippi, 1845, is one of several factors considered responsible for coral reef change throughout the region. Unfortunately, there is a paucity of pre-mortality event density data for D. antillarum in the Florida Keys, making it difficult to determine pre-1983 population density levels. results from surveys conducted during 1970–1973 in the lower Florida Keys, in shallow (<12 m) fore reef habitats, yielded relatively abundant and widespread D. antillarum densities in qualitative transects at five reefs prior to the 1983–1984 die-off. In quantitative surveys at one reef, Middle sambo reef in 1972, up to 7.9 individuals m–2 were recorded using quadrats in high-relief spur and groove habitat. A second mortality event in the Florida Keys, beginning in April 1991, again depressed urchin densities that had begun to recover from the 1983–1984 mass mortality. By 1992, D. antillarum densities (<0.01 m–2) were two orders of magnitude lower than pre-die-off estimates (range of 0.07–0.57 m–2 from several spur and groove reefs in the lower Florida Keys) and remained so through 2009. The pre-mortality echinoid density estimates detailed in the Florida Keys provide a baseline to compare with their current population status and should help inform managers about realistic recovery or restoration targets for D. antillarum.
Donald L. Kissling, William F. Precht, Steven Miller, and Mark Chiappone. 2014. Historical Reconstruction of Population Density of the Echinoid Diadema antillarum on Florida Keys Shallow Bank-Barrier Reefs .Bulletin of Marine Science , (2) : 665 -679. https://nsuworks.nova.edu/occ_facarticles/734.