Comparison of two reef sites in the Wakatobi Marine National Park (SE Sulawesi, Indonesia) using digital image analysis

Coral reefs are complex ecosystems characterized by nonlinear relationships between biotic and abiotic components. The availability of light limits the depth distribution of corals, where turbidity and sedimentation can have marked effects on their growth (Meesters et al. 1998) and morphology (Meesters et al. 1996; Kaandorp 1999). Although there have been many studies of coral growth rates (e.g. Dodge and Vaisnys 1975; Bak 1976; Hubbard and Scaturo 1985; Crabbe et al. 2002), there have been few of the influence of sedimentation on the growth rate and morphology of branching corals. Here, we used digital videophotography and computer image analysis to monitor coral cover, species richness, sedimentation rates, underwater (u/w) visibility, and growth and morphology of Acropora colonies at two sites, Kaledupa and Sampela, separated by about 1.5 km in the Wakatobi Marine National Park, SE Sulawesi, Indonesia. There was significantly higher species richness, coral cover and rugosity at Kaledupa than at Sampela. Our results suggest that the increased sedimentation and consequent lowered light levels at Sampela have altered the growth rates and morphology of the Acropora corals there. The scleractinian coral community of Sampela is severely impacted by sedimentation, mostly from a Baujo village, which can lead to the suffocation of corals and to decreased growth and calcification rates resulting from reduced light penetration.