The Kallisti Limnes, carbon dioxide-accumulating subsea pools

Natural CO(2) releases from shallow marine hydrothermal vents are assumed to mix into the water column, and not accumulate into stratified seafloor pools. We present newly discovered shallow subsea pools located within the Santorini volcanic caldera of the Southern Aegean Sea, Greece, that accumulate CO(2) emissions from geologic reservoirs. This type of hydrothermal seafloor pool, containing highly concentrated CO(2), provides direct evidence of shallow benthic CO(2) accumulations originating from sub-seafloor releases. Samples taken from within these acidic pools are devoid of calcifying organisms, and channel structures among the pools indicate gravity driven flow, suggesting that seafloor release of CO(2) at this site may preferentially impact benthic ecosystems. These naturally occurring seafloor pools may provide a diagnostic indicator of incipient volcanic activity and can serve as an analog for studying CO(2) leakage and benthic accumulations from subsea carbon capture and storage sites.