Impact of ocean acidification and warming on the productivity of a rock pool community

Abstract This study examined experimentally the combined effect of ocean acidificationand warming on the productivity of rock poolmulti-specific assemblages, composed of coralline algae, fleshy algae, and grazers. Natural rock poolcommunities experience high environmental fluctuations. This may confer physiological advantage to rock poolcommunities when facing predicted acidification and warming. The effect of ocean acidificationand warming have been assessed at both individual and assemblage level to examine the importance of species interactions in the response of assemblages. We hypothesized that rock poolassemblages have physiological advantage when facing predicted ocean acidificationand warming. Species exhibited species-specific responses to increased temperature and pCO 2 . Increased temperature and pCO 2 have no effect on assemblage photosynthesis, which was mostly influenced by fleshy algal primary production. The response of coralline algaeto ocean acidificationand warming depended on the season, which evidenced the importance of physiological adaptations to their environment in their response to climate change. We suggest that rock poolassemblages are relatively robust to changes in temperature and pCO 2 , in terms of primary production.