Seawater carbonate chemistry and germination of eelgrass (Zostera marina L.) seeds

Our study investigated the combined effects of ocean acidification and P. gemini infection on germination of eelgrass seeds. We conducted a two-level factorial experiment crossing four pH levels (Δ0, - Δ0.3, - Δ0.6, -Δ0.9; relative to the average pH at the sampling site) with three infection levels (infected, non-infected, exposed) to determine germination rate and infection response. Prior to experimentation, flowering shoots were collected and held in flow-through seawater tanks where seeds ripened naturally. Once collected, seeds were held in copper sulfate solution (27.37 ± 1.57 ppt) and stored in darkness to mimic winter dormancy (4 ◦C). Before the start of the experiment, viable seeds were cultured on oomycete selective growth media to determine infection status.