Sulphidic aquifer of South Dobrogea - Romania

The Sulphidic aquifer of South Dobrogea offers Mars-analogue sites in the form of isolated subsurface habitats characterised by the presence of toxic compounds (H2S, CH4, NH4+) dissolved in suphidic water and an entire ecosystem based on chemosynthesis that has been isolated for over 5.5 million years (since the Messinian Crisis when organisms retreated underground to find shelter and humidity as well as a sustainable source of nutrients provided by the microbial biofilms thriving on the chemicals dissolved). The various physical-chemical features of microniches of this ecosystem (darkness, lack of O2, increased levels of H2S and CH4 – in Movile Cave; strong light, high temperature (up to 40°C in summer) and O2 – in the terrestrial sulphidic springs; dim light, increased concentration of salts, variable temperature – in the case of submarine springs) are mirrored by different structures of the microbial communities providing insights on the origin of such ecosystems and a better understanding of how an isolated subsurface ecosystem evolves and adapts to such conditions. The aquifer has numerous resurgences in the form of terrestrial and underwater (on the bottom of the sea) sulphidic springs.