In the face of a changing global climate, being able to predict the response of organisms and to assess their vulnerability is essential for the development of successful management and conservations strategies. We hope to study the impacts of ocean acidification on two important members of the Moorea coral reef ecosystem: the sea urchin Echinometra mathaei and the coral Pocillopora damicornis. In Winter 2010, we propose to examine how these species will respond to low pH, low carbonate waters that are predicted for global oceans by 2100 in an ocean acidification scenario. For these experiments, we will raise cultures of E. mathaei and P. damicornis larvae at control and elevated CO2 levels, using our portable CO2 system. Mortality and possibly morphometrics will be measured in Moorea, and mRNA samples will be shipped back to UCSB for analysis using qPCR and DNA microarrays. The results will enhance our understanding of and ability to predict future impacts of anthropogenic stress on two ecologically-important tropical invertebrate species.