Hypoxia in the central areas of the Bohai Sea was reported for the first time in this study. The survey in August 2014 suggested that the hypoxic zone was 1200 km~2 in area and the minimum DO concentration was 2.30 mg/L. The hypoxic zone was on the southwest side of the investigated area(119.1°–119.6°E, 38.3°–38.8°N). The DO(4 mg/L) isoline indicated that the hypoxic layer reached 10 m under the water. There were differences in the temperature and density between the surface and the bottom layer(δT and δρ),...