Impacts of sedimentation on coral reefs in Inner Ambon Bay, Indonesia

Abstract

Sedimentation is one of the limiting factors for coral life. Suspended and deposited sediment have negative effects on the coral community. The rate of sedimentation can lead to low coral cover, low growth rate and low recruitment. Sediment that enters inner Ambon bay comes from 8 rivers around the bay. In this research, we assess coral reefs condition, calculate the rate of sedimentation, analyze effects of sedimentation on the coral reefs, and observe the change of coral reefs condition in inner Ambon Bay. Distribution and general condition of coral reefs was observed using manta tow method. Three places were then chosen to be surveyed in detail using line intercept transect to determine the percentage of coral cover. Resuspendedsedimet were measured by using sediment traps placed on coral reefs for 3 days. Sea water was collected with Niskin bottle, filtered and analyzed in laboratory to determine suspended particulate matter. The results showed that percentage of coral cover in Hunut, Kate-Kate and Halong are 5.62%, 5.26%, and 8.92% respectively and fall into the category of poor coral reef condition. The percentage of coral cover decreased progressively since 1985. The suspended particulate matter in three locations is more than 20 mg/l and resuspension sediment at Kate-kate is 18.39 mg/cm2/day, Hunut 16.29 mg/cm2/day, and Halong 10.12 mg/cm2/day. The degree of sedimentation in inner Ambon Bay is at the level of moderate to severe.