Sediment and the settlement of larvae of the reef coralPocillopora damicornis

The larval settlement rate of the Indo-Pacific reef coral,Pocillopora damicornis, on bare glass was compared with the rate on glass covered with measured amounts and area of fine sediment. Larval settlement in all sediment treatments was significantly less than on bare glass. Sediment cover of 95% completely prevented settlement. There was no increase in settlement when sediment cover was reduced from 90% to 50% of the glass surface area. If planulae of many coral species behave in a similar fashion in nature, sedimentation at a level that only partially covers the substrate and that is not directly harmful to adult colonies could significantly reduce larval recruitment by inhibiting settlement.