Effect of sediment on scleractinian corals community in derawan islands, east kalimantan

Abstract

There are some indications that run-off from Berau River gives negative impact on scleractinian corals community in Derawan Islands. Many activities occured in the upland beside of the Berau River such as deforestation, coal and sand mining increased the sedimentation in the Derawan Islands waters, direct or indirectly. Sediment through shading and smothering cause corals in stress condition and eventually death for some species. The purpose of this research is to study about the effect of sedimentation on scleractinian corals in Derawan Islands, East Kalimantan. The quadrate transects placed at each station to estimate live coral coverage. The stations represent distance from Berau River. Rapid Ecological Assessment (REA) used to get coral species richness by The Nature Conservancy (TNC) in 2003. A sediment trap placed for 14 days in each station to have sedimentation rate. Sample of sediment were analyzed in the laboratory. Sedimentation rate (mg/cm2/day) decrease in number from station Panjang Island to Maratua Island. The coverage and species richness of coral reefs have negative correlation to sedimentation rate, which mean high sedimentation tend to cause low species richness and coral coverage. The lowest number of species richness and scleractinian coral coverage found in Station 1 which nearest distance to Berau River with high sedimentation rate.