How Much Do Marine Plants Contribute to Earth’s Oxygen Supply?

Although we typically think of jungles and rainforests such as the Amazon as being the "lungs" of the planet, that's not exactly true. Although we do owe much of the planet's oxygen to trees and other land plants, at least half of the oxygen actually comes from the oceans. A key component of ecosystems in oceans, seas, and freshwater basins, the photosynthesizing microorganisms known as phytoplankton contribute an estimated 50 to 85 percent of the oxygen in the Earth’s atmosphere. You’re probably breathing oxygen right now that was produced by these single-celled plants.

Tiny plants with a big role:

• The name "phytoplankton" comes from the Greek words phyton (meaning plant) and planktos (meaning wanderer or drifter).
• Phytoplankton are too small to be seen individually, but in large numbers, they are noticeable as colored patches on the water surface, appearing green because of the plant’s chlorophyll content.
• Phytoplankton use energy from the sun to convert carbon dioxide and nutrients into organic compounds, which form new plant material and create oxygen in a process known as photosynthesis.