TY - JOUR AU - Soto Santiago, Francisco J. AU - Irizarry Soto, Emmanuel PY - 2013/05/22 Y2 - 2024/03/29 TI - The Sea Urchin Diadema antillarum (Echinodermata, Equinoidea), algal cover and juvenile coral densities in La Parguera, Puerto Rico JF - UNED Research Journal JA - URJ VL - 5 IS - 1 SE - Articles DO - 10.22458/urj.v5i1.238 UR - https://revistas.uned.ac.cr/index.php/cuadernos/article/view/238 SP - 33-40 AB - <p>Grazing by the black sea urchin Diadema antillarum reduces algal cover and enhances coral recruitment. The overall goal of this project was to examine if there is a relationship between densities of D. antillarum with algal cover and abundance of juvenile corals. Population densities of the black sea urchin, juvenile coral abundances and algal cover were assessed along four 20m2 transects at two depth intervals (0-3 and 3-8m) within each of two inner shelf coral reefs off La Parguera Natural Reserve (San Cristóbal and Enrique) in southwest, Puerto Rico using a 1m2 quadrat (divided into 100 areas of 100cm2, each area encompassing 1% of the quadrat). Juvenile coral densities were counted and identified to genus or species. Algal cover and composition was measured using each 1% square of the 1m2 quadrat. Urchin population densities were significantly higher at 0-3m at the two sites studied. Population densities were higher at Enrique at 0-3m than at San Cristobal but at 3-8m Diadema was not seen at Enrique. A total of 30 juvenile corals belonging to eight different genera were found. Juvenile coral densities were higher at 3-8m at the two reef sites studied. Algal cover and composition was mainly composed by crustose coralline algae at 0-3m at both reef sites. Macroalgal cover was low at both reefs. The results of this study suggest that densities of coral recruits at inner shelf reefs in La Parguera, Puerto Rico are driven mainly by differences in habitats (depth).<br /><br /><strong>KEY WORDS</strong></p><p><strong></strong>coral recruitment, abundance, Diadema antillarum, densities, composition, correlation</p> ER -