Haley, Michael P.; Solandt, J.L.
Author Affiliation, Ana.
Centre for Marine Sciences
Population fluctuations of the sea urchins Diadema antillarum and Tripneustes ventricosus at Discovery Bay, Jamaica: A case of biological succession?
Caribbean Journal of Science
Date of Publication
Populations of Diadema antillarum and Tripneustes ventricosus were monitored on the forereef and backreef at Discovery Bay, Jamaica, from 1995 to 2000. On the primarily coralline substrate of the forereef, T. ventricosus densities were normally low but showed a ten-fold increase in 1998, followed by a decline to normal levels. On the backreef, with both coral and seagrass, T. ventricosus densities were normally higher but a similar peak occurred in 1999. Diadema antillarum densities remained relatively constant on the backreef but declined on the forereef in 1998, and then increased rapidly. Both urchins remained on their respective coral and seagrass habitats on the backreef, but occurred together in similar habitat on the forereef. We propose that the appearance and subsequent decline of T. ventricosus enabled D. antillarum to increase after T. ventricosus had mechanically cropped macroalgae to levels easier for D. antillarum to manage. This explanation suggests that the ephemeral appearance of T. ventricosus on coral covered with macroalgae can act as a successional stage for the reestablishment of D. antillarum.....