Oxygen is primarily produced in the ocean through photosynthesis, which is carried out by phytoplankton and marine plants, just as it is on land through terrestrial plants. Phytoplankton are tiny, plant-like organisms that float in the upper layers of the ocean and use sunlight to convert carbon dioxide and water into oxygen and organic compounds through photosynthesis. This process contributes a significant portion of Earth's oxygen production. However, it's important to note that the overall balance between oxygen production and consumption in the oceans is complex and influenced by various factors.

Carbon dioxide (CO2) and oxygen (O2) behave differently in seawater due to their solubility and chemical properties:

In summary, while both oxygen and carbon dioxide play essential roles in ocean ecosystems, the behavior of these gases in seawater differs. Oxygen is produced through photosynthesis by marine plants and phytoplankton, contributing to the oxygen balance of Earth's atmosphere. Carbon dioxide dissolves more readily in seawater than oxygen and is a crucial factor in ocean acidification and the global carbon cycle.

Dr Gaurav H Tandon thank you for your contribution to the discussion

The ocean generates 50 percent of the oxygen we need, absorbs 25 percent of all carbon dioxide emissions and captures 90 percent of the excess heat generated by these emissions. It is not just 'the lungs of the planet' but also its largest 'carbon sink' – a vital buffer against the impacts of climate change. Prochlorococcus and other ocean phytoplankton are responsible for 70 percent of Earth's oxygen production. However, some scientists believe that phytoplankton levels have declined by 40 percent since 1950 due to the warming of the ocean. Ocean temperature impacts the number of phytoplankton in the ocean. It's important to remember that although the ocean produces at least 50% of the oxygen on Earth, roughly the same amount is consumed by marine life. Like animals on land, marine animals use oxygen to breathe, and both plants and animals use oxygen for cellular respiration. Oceanic plankton is responsible for the production of an estimated 50-80% of the oxygen on earth. Plankton takes its form in algae, plants, and photosynthetic bacteria. One specific bacterial species, known as Prochlorococcus, is responsible for producing a whopping 20% of the oxygen on our planet. That's right more than half of the oxygen you breathe comes from marine photosynthesizers , like phytoplankton and seaweed. Both use carbon dioxide, water and energy from the sun to make food for them, releasing oxygen in the process. In other words, they photosynthesize. And they do it in the ocean. Carbon dioxide, also called CO2, is found in water as a dissolved gas. It can dissolve in water 200 times more easily than oxygen. Aquatic plants depend on carbon dioxide for life and growth, just as fish depend on oxygen. Carbon dioxide is more soluble in water as compared to oxygen gas. Some fraction of carbon dissolved forms carbonic acid with water and it is readily dissolvable because of formation of strong hydrogen bonds. Oxygen in dissolved form is necessary for survival of aquatic life and it forms weak vander waal bonds. The molecular arrangement of carbon dioxide makes it more soluble in blood compared to the solubility of oxygen. The solubility of carbon dioxide is 20-25 times higher than oxygen. The values for carbon dioxide correspond to the total CO2 in water of zero alkalinity or to the free CO2 and H2CO3 in sea water. It is seen that carbon dioxide is much more soluble than the other two gases and that oxygen is about twice as soluble as nitrogen. Carbon dioxide, also say CO2, is found in water as a dissolved gas. It can dissolve in water 200 times more easily than oxygen. Aquatic plants depend on carbon dioxide for life and growth, just as fish depend on oxygen.