Dissolved oxygen and carbon dioxide are vital for marine life. Marine plants use dissolved carbon dioxide, sunlight and water to make carbohydrates through the process of photosynthesis. This process releases oxygen into the water. All marine organisms use oxygen for respiration, which releases energy from carbohydrates and has carbon dioxide and water as byproducts. Marine animals with gills, such as fish, use these organs to extract oxygen from the seawater.

Gases and Life