The installation unit has a humidified air production unit (40) comprising a closed tank (42) whose lower part is fed out of sea water and a high part that comprises an output opening for humidified air. A generator (52) generates bubbles when immersed in sea water (46), and is arranged in the lower part of the tank. A pressurized ambient air source (60) is connected to the generator. A drain (32) connects the opening of the high part to an opening of a lower part of a culture vat for supplying with fresh water humidified air.
