Earth’s Oxygen is Produced by Ocean
When was the last time you thought about breathing? Take a breath right now and think about it. You breathe because you need oxygen, a gas which makes up 21 percent of the Earth’s atmosphere. You might already know that it comes from photosynthetic organisms like plants. But did you know that most of the oxygen you breathe comes from organisms in the ocean?
That’s right—more than half of the oxygen you breathe comes from marine photosynthesizers, like phytoplankton and seaweed. They use carbon dioxide, water and energy from the sun to make food for themselves, releasing oxygen in the process. In other words, they photosynthesize. And they do it in the ocean.
Oxygen Producers in the Ocean
Photosynthesizers have been in the ocean for a long time. One particular species, Prochlorococcus, is the smallest photosynthetic organism on Earth. But this little bacteria produces up to 20% of the oxygen in our entire biosphere. That’s a higher percentage than all of the tropical rainforests on land combined. One in every five breaths you take, you owe to Prochlorococcus. Another of the ocean’s photosynthesizers is impressive for a different reason. 886 feet below the ocean’s surface, you would barely be able to see light. But a type of red algae called Corallinales can still photosynthesizes at that depth. The red color of Corallinales comes from a pigment which enables it to absorb blue and green light, which is just about the only kind of light that manages to filter down to the improbable depths at which Corallinales lives. This photosynthesizers produce oxygen despite only being able to access the tiniest fraction of sunlight.
Threats to Marine Photosynthesizers
Ocean water temperature
One of the most significant factors is the temperature of the water. Colder water holds more dissolved oxygen, which means that areas with colder water tend to have higher oxygen concentrations. Conversely, warmer water holds less dissolved oxygen, which can lead to areas of low oxygen known as hypoxic zones. As the world’s oceans warm due to climate change, this will adversely affect the ability of the planet’s largest source of water to hold oxygen.
Nutrient availability in the oceans
Another factor that can affect oxygen production in the oceans is nutrient availability. Phytoplankton require certain nutrients, such as nitrogen and phosphorus, to grow and photosynthesize. If these nutrients are in short supply, phytoplankton growth and oxygen production can be limited. On the other end of the spectrum, excessive nutrient input, often caused by agricultural runoff or wastewater discharge, can lead to algal blooms and oxygen depletion in certain areas (which can lead to dead zones).
Increase in human activities
Human activities such as fossil fuel burning and deforestation also contribute to decreased oxygen levels in the atmosphere. As carbon dioxide levels increase, the oceans absorb more of this gas, which can lead to ocean acidification. This process can reduce the ability of phytoplankton to photosynthesize, which in turn reduces the amount of oxygen produced by the oceans.
Conclusion
Marine photosynthesizers are indispensable to our survival. If they weren’t around, we wouldn’t be breathing. So, once in a while, take a moment to remember the ocean and its photosynthesizers. They’re helping you out with every breath you take.
