Echinoderms have been labelled as a boom-and-bust phylum . A Caribbean-wide population bust of the long-spined sea urchin Diadema antillarum in the early 1980s is the most extensive mass-mortality event reported for any marine animal. This die-off was a major contributor to coral reef decline throughout the region. Meanwhile, the variegated sea urchin Lytechnius variegatus , which shares part of its range with D. antillarum , has exhibited protracted population booms in seagrass leading to hectares of bare area in formerly dense meadows.
Larval biology (e.g., morphology and developmental rate) can mediate recruitment potential and is likely to influence urchin demographics . The desire to understand larval development also stems from the potential to produce small juvenile animals for use in co-culture with sexually propagated corals as a part of reef restoration programs. Finally, there is interest in directly stocking some species of cultured urchins to coral reefs to replace ecological function lost following the D. antillarum die-off.
This presentation will describe experiments on larval and juvenile D. antillarum , L. variegatus , and Tripneustes ventricosus, a coral reef- associated species that is of interest for coral co-culture as well as ecological restoration. Turbulent shear levels driven by water velocity were found to affect larval development and settlement rates to differing degrees among the three species. A subsequent experiment found that, while juveniles of all three urchin species reduced benthic algal cover relative to a negative control, intraspecific differences existed in the algal communities curated and in effectiveness for coral co-culture.