Recurrent thermal stress events and intensified precipitation alter the ocean environment resulting in the decline of coral populations. However, the influence of these changes on larval survival and settlement is not well understood. We examined the effect of salinity (15, 20, 25, 30, 35, and 40 ppt) and temperature (27 °C, 30 °C, and 33 °C) on settlement and survival of larvae of the octocoral, Heliopora coerulea. Larvae settled successfully at salinities from 25 to 30 ppt. On the other hand, larval survival and settlement decreased with increasing temperature. A combination of 25-35 ppt and 27-30 °C resulted in highest survival and settlement. These results indicate that early life stages of H. coerulea are negatively impacted by thermal stress but may be able to survive at reduced salinity. The wider tolerance range of H. coerulea larvae compared to most scleractinian larvae may thus contribute to the success of this coral on disturbed reef ecosystems.
Keywords: Blue coral; Brooding coral; Octocoral; Philippines; Planulation.
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