Host–parasite interactions: a litmus test for ocean acidification?

The effects of ocean acidification (OA) on marine species and ecosystems have received significant scientific attention in the past 10 years. However, to date, the effects of OA on host–parasite interactions have been largely ignored. As parasites play a multidimensional role in the regulation of marine population, community, and ecosystem dynamics, this knowledge gap may result in an incomplete understanding of the consequences of OA. In addition, the impact of stressors associated with OA on host–parasite interactions may serve as an indicator of future changes to the biodiversity of marine systems. This opinion article discusses the potential effects of OA on host and parasite species and proposes the use of parasites as bioindicators of OA disturbance.