Response of bacterial communities in Barents Sea sediments in case of a potential CO₂ leakage from carbon reservoirs

Carbon capture and storage sites in Barents Sea shelf are currently in progress as part of climate change mitigation activities. However environmental impacts of a possible CO₂ seepage on bacterial community are lacking knowledge. This work addressed potential consequences on bacterial communities from Snøvit region in Barents Sea sediments. Long-term experiment (92 days) was carried out mimicking realistic conditions of pressure (∼30 bars) using the unique hyperbaric chamber (Karl Erik TiTank). The experiment was divided in three stages: i) 21 days of no CO₂, ii) 50 days of simulation of carbon dioxide leakage (depletion of pH to 7.0) and iii) 14 days emulating a leakage cessation. Results suggested that bacterial communities can adapt to a CO₂ leakage in short term. However, bacteria showed negative effects in terms of activity, community structure, and number of cells after long term CO₂ exposure. After CO₂ leakage cessation, bacterial communities did not show a significant recovery. These findings highlighted that, even though marine bacteria showed adaptation to the new conditions (acidified environment), in case of a small but continuous CO₂ leakage marine bacteria might not be recovered upon pre-exposure status.