Among-genotype variation for sediment rejection in the reef-building coral Diploastrea heliopora (Lamarck, 1816)

Abstract

Sediment settling on corals interferes with their feeding and photosynthesis. Near-shore construction and dredging activities can result in increased sedimentation and significantly impact coral reefs. It is well known that coral species differ in their ability to cope with sediment stress, yet within-species variation for sediment rejection is much less understood. In this study, fragments of Diploastrea heliopora retrieved from four different colonies (genotypes) were subjected to three levels of acute sediment (silicon carbide powder) exposure in a controlled aquarium tank environment. After five hours, significant differences in surface area cleared were found for both treatment and genotypes. Significant differences among genotypes were also found for mass of sediment removed. Previous researchers have discussed how reefs under stress may become populated by hardy genotypes and our results suggest that the necessary intraspecific variation exists for such a process in Singapore. © National University of Singapore.