Pressure-stat aquarium system designed for capturing and maintaining deep-sea organisms

A novel pressure-stat aquarium system has been developed for the study of living deep-sea multicellular organisms under high hydrostatic pressure. The system is designed for operation by submersibles and captures deep-sea organisms with a suction servomotor. The system can maintain an inner pressure of 20 MPa (1 bar≈0.1 MPa) even when the submersible surfaces from the deepest sea bottom. The system can control the pressure range up to 20 MPa within a fluctuation of ±0.1∼0.2 MPa by exchanging seawater. A specimen of the deep-sea fish Ebinania brephocephala collected by trawl net was kept alive under pressure in the pressure-stat aquarium system for 64 days. Oxygen consumption rate of a deep-sea fish E. brephocephala (total length 12.9 cm, wet weight 61.1 g) was calculated as 0.10 μl O2/mg wet weight/h. Based on the calculation, two deep-sea fishes of the same size could be kept alive in the system. We also succeeded in maintaining the deep-sea fish Zoarcidae sp. captured by the submersible Shinkai 2000 at a depth of 1171 m in Sagami Bay, Japan.