From the coast to the deep sea, changing oxygen levels affect marine life in different ways

Earth's atmosphere maintains a constant level of oxygen, whether it is a wintry, rainy day or hot summer. Across the ocean, oxygen concentrations vary enormously between different places and over time. Sometimes oxygen levels change within the course of a day, while in some deep parts of the ocean, oxygen concentrations remain constant. In certain places, there's no oxygen at all but life still thrives.