13/01/2026
Algae communities are no doubt of great importance to life on Earth 🌍
Oxygen on Earth is mainly created through photosynthesis, a process where organisms use sunlight to turn carbon dioxide and water into food, with oxygen as a by-product. While most people think trees and forests make most of our oxygen, scientists have found that the ocean plays an even bigger role.
The surface layer of the ocean is filled with tiny plant-like organisms called phytoplankton, along with seaweed and algae. These all photosynthesize like land plants and release oxygen as they grow. Because the ocean covers such a large part of the planet, these microscopic life forms collectively produce a huge amount of oxygen.
Researchers estimate that these ocean-based photosynthesizers produce at least half of the Earth’s oxygen, and in some studies the number is suggested to be even higher, possibly up to 80 percent. This means that every breath you take is strongly linked to life in the ocean, especially tiny plankton that you cannot see without a microscope.
Land plants, including forests, still create oxygen, and they are vital to ecosystems worldwide. But when you look at the total global oxygen production, ocean photosynthesis is a leading contributor because of the immense number of microscopic producers in the sea.