Effects of elevated temperature on larval survival and settlement of the broadcast spawning coral Acropora robusta

This study investigates the effects of elevated temperature on the survival and settlement of larvae from broadcast spawning coral Acropora robusta. Five-day-old larvae were incubated at 27℃ and 30℃ for 7 days， and larval survival and settlement were assessed. It showed that survivorships of A. robusta larvae were not affected by elevated temperature with survival rate >90% at the two treatments after 7 days. Moreover， in the presence of crustose coralline algae （CCA） Hydrolithon onkodes， the settlement rate of A. robusta larvae at 30℃ was 75% higher than that at 27℃. In particular， the temperature elevation changed the settlement behaviors of coral larvae. Increased temperature did not affect the percentage of larvae settling rate on the surface and skeleton of H. onkodes， but there were about 13 times more larvae metamorphosing on plastic surface at 30℃ than at 27℃. The results suggest that a 3℃ higher in surface temperature do not alter the larval survivorship but promote the settlement， thus curtailing the pelagic phase and potentially altering patterns of larval dispersal and population connectivity.