Marine Biology

Sedimentation

Sedimentation in the marine is a process caused due to the freshwater runoff from the adjoining land mass. Sediment suspended in the water, settle out on the coral reefs, has an adverse effect on the corals. Many corals can remove limited amounts of sediment by trapping it in mucus and carrying it off by ciliary action. Most hermatypic corals, however, cannot withstand heavy sedimentation, which overpowers their ciliary-mucus cleansing mechanism, clogs their feeding structures, and smothers them. Sediment in the water (turbidity) also reduces the light necessary for photosynthesis by the zooxanthellae in the coral tissue. As a result, coral reef development is reduced or eliminated in areas of high turbidity. When this sediment is carried by rivers or streams, the combination of reduced salinity and excess sediment is also responsible for the absence of reefs.