Impacts of elevated temperature and pCO2 on the brooded larvae of Pocillopora damicornis from Luhuitou Reef, China: evidence for local acclimatization

In this study, we tested whether larvae brooded by the reef coral Pocillopora damicornis from a naturally extreme and highly variable environment are preadapted to cope with predicted increases in temperature and pCO(2). We exposed larvae to two temperatures (29 vs. 30.8 degrees C) crossed with two pCO(2) levels (similar to 500 vs. similar to 1000 mu atm) in a full-factorial experiment for 5 d. Larval performance was assessed as dark respiration (R-D), net and gross photosynthesis (P-N and P-G, respectively), survival, settlement, and the activity of carbonic anhydrase (CA), the central enzyme involved in photosynthesis. The results showed that R-D was unaffected by either elevated temperature or pCO(2), while elevated temperature and/or pCO(2) stimulated P-N and P-G and increased the ratios of P-N to R-D, indicating a relatively higher autotrophic capacity. Consequently, larval survivorship under elevated temperature and/or pCO(2) was consistently 14% higher than that under the control treatment. Furthermore, elevated temperature and pCO(2) did not affect host CA activity, but synergistically enhanced symbiont CA activity, contributing greatly to the stimulated photosynthetic capacity. These results suggest that brooded larvae of P. damicornis larvae from Luhuitou may be preadapted to cope with projected warming and ocean acidification. More generally, it appears that corals from highly variable environments may have increased resilience to the widespread climate change.