Persistent Predation, Declining Rugosity, and Spiny Lobsters: Learning More about the Keystone Urchin Species, Diadema antillarum.

Abstract

Diadema antillarum are a keystone urchin species in Caribbean coral reefs because of the amount of macroalgae they remove from reef surfaces. The mass die-off the species experienced in the 1980s has left the species at much lower density levels, and they have not been able to fully recover from this event. Recently, a reef system in Honduras, Banco Capiro, was discovered to have greater Diadema density than anywhere else in the Caribbean. This discovery has allowed for many researchers to investigate reasons why Diadema have not recovered by comparing this reef to other Caribbean reefs, like the reefs found of the coast of Utila. However, previous studies have not considered if there are interactive effects between reef rugosity and the effects of predation, nor did they include Panulirus in their assessment of predators. This study showed that while there is no interaction between predator density and rugosity on Utila, but there is some interaction on Banco Capiro. As there is no interaction between these variables on Utila, but there is interaction at Banco Capiro, the interactive effect is likely not a barrier to recovery. Finally, the results of this study suggest that there is no impact in including Panulirus in predator densities.