Sediments from urban and agricultural run-off can cause stress and kill corals. However, specific kinds of corals that live in sheltered locations may tolerate the naturally higher levels of dissolved and suspended matter that color the water.
Corals on these sheltered reefs may benefit from the screening of sunlight by suspended particles that scatter light, and by colloids and colored dissolved organic matter (CDOMs) that absorb light.
Screening Factor (0:50)
Rod Salm discusses screening as a possible factor that increases resilience to bleaching.
Turbid water caused by excessive nutrient run-off or other land-based sources of pollution do not provide screening protections to corals. These conditions are harmful and weaken the resilience of corals exposed to them for even short exposure periods.