Abundance and composition of juvenile scleractinian corals on a fringing reef (Little Reef) off San Andres Island, Colombian Caribbean

Abstract

Abstract: Colombian Caribbean reefs have deteriorated significantly over the last three decades. Coral recruitment is an important demographic process that determines the replenishment of populations and the natural potential for recovery of reef ecosystems after perturbations. We studied the composition and abundance of juvenile corals on a fringing reef (Little Reef) off San Andres Island, Colombia, using 1 m2quadrats (N = 33) spread randomly on the reef. We surveyed a total of 190 juvenile corals belonging to seven families and 15 species, with a total density of 5.75 ± 3.47 (mean ± SD) juveniles m−2. The population of juvenile corals was dominated by species of the genera Favia, Agaricia and Porites (85.8%), while the adult population was dominated by Diploria, Acropora and Orbicella (78.4%). Most (71.6%) juveniles were between 1.1 and 2.0 cm. The most abundant species was Favia fragum (67 individuals), while Agaricia agaricites was the most frequently occurring (26.9%), covering the highest percentage (76.9%) of the substrate and having the largest Importance Value Index (44.6%). The community of juvenile corals on Little Reef was dominated by species that brood planulae while the adult community was dominated by species that spawn gametes. Furthermore, the two most abundant juvenile coral species had negatively skewed size–frequency distributions, indicating low recent recruitment. This study provides a demographic baseline for monitoring future changes in recruitment patterns.