The potentially devastating effects of ocean acidification on coral reefs are well known, but the methods used to evaluate the threats are often focused on individual species, viewed in isolation, and often in a laboratory. For this episode of BioScience Talks, we're joined by Peter Edmunds of California State University, Northridge, who describes that issue and talks about the broad-scale inter-species and inter-population dynamics that may have unforeseen consequences for ocean ecosystems. In particular, differences across scales--from organisms to populations, to communities and ecosystems--will have major impacts on reefs. For instance, differently responding symbiotic species could alter a reef's community structure--and, ultimately, the health of the reef as a whole