OFI SF7 Assessing the effects of Ocean Alkalinity Enhancement (OAE) on the marine microbiome

Ocean alkalinity enhancement (OAE) is rapidly gaining support within the proposed ocean-basedcarbon dioxide removal (ocean-CDR) approaches. Theoretically, OAE is a CDR approach that should have minimal adverse impact on the marine ecosystem, while having the potential torestore the detrimental effects of anthropogenic CO2-enhanced ocean acidification in impacted regions of the ocean (e.g. coral reefs). However, there is a lack of experimental datadocumenting the OAE effect on marine life and an urgent need to obtain this data for the marine microbiome (phytoplankton, bacteria and archaea) given their position at the base of the foodchain. Planetary Technologies is developing OAE-based CDR and is planning to use BedfordBasin as a pilot study site. The applicant proposes to conduct bioassay experiments to assess the potential effects of OAE on the microbiome. The bioassay experiments consist of short-term (up to 72 hours) bottle-incubations with natural microbial communities from the Bedford Basin with (treatment) and without (control) the addition of the alkaline substrate magnesium hydroxide,during four seasons over a 12-month period. High-throughput sequencing of nucleic acids (DNA and RNA) extracted from the microbiome of the control and treatment incubations will becompared to each other and to the initial community obtained from ongoing time-seriessampling. The experimental results and database will be shared with Planetary and othershareholders to establish a baseline for environmental assessment and guide the initial trials oftheir approach to minimize the potential unforeseen effects of OAE on the living ecosystem.