Sedimentation rates fluctuate throughout the year based on currents, upwelling, etc. But generally, in a healthy reef system sedimentation rates would be very low, as corals are easily stressed by sediment. Sediment is also a medium for bacteria growth, and reefs with high sedimentation rates tend to have higher rates of disease. Sources of sedimentation tend to stem from on-land activates such as agriculture, construction, deforestation, development, etc. This is usually most pronounced following storms. In sea sources of sediment include dredging, trawling, and other activities which disturb the sea bed.
In our program, we monitor sedimentation rates using sediment traps. These are essentially cups that are left on the reef for a set period of time then collected. The contents are then filtered, dried, and weighed to measure the rate of sedimentation for that reef.