What is the role of plankton in carbon sequestration?

Plankton plays a crucial role in carbon sequestration by absorbing carbon dioxide during photosynthesis and storing it in the ocean depths.

Plankton, both phytoplankton (plant-like) and zooplankton (animal-like), are microscopic organisms that float in the world's oceans and other bodies of water. They are a vital part of the marine food chain and play a significant role in the global carbon cycle. During photosynthesis, phytoplankton absorb carbon dioxide (CO2), a greenhouse gas, from the atmosphere. This process converts the carbon dioxide into organic carbon, which is then used to build their bodies and support their growth.

When plankton die or are eaten, they can sink to the deep ocean, taking the carbon stored in their bodies with them. This process is known as the 'biological pump'. The carbon can remain sequestered in the deep ocean for hundreds to thousands of years, effectively removing it from the atmosphere and mitigating the impacts of climate change. This is a natural form of carbon sequestration, which is the long-term storage of carbon in plants, soils, geologic formations, and the ocean.

Zooplankton also contribute to carbon sequestration. They feed on phytoplankton and other smaller zooplankton, incorporating the carbon into their own bodies. When they excrete waste or die, they too can sink to the ocean depths, taking the carbon with them. Some species of zooplankton even undertake daily vertical migrations, feeding near the surface at night and returning to the depths during the day, which can enhance the transport of carbon to the deep ocean.

However, the efficiency of the biological pump can be influenced by various factors, including temperature, nutrient availability, and the types of plankton present. Changes in these factors due to human activities or climate change could potentially alter the effectiveness of plankton in sequestering carbon. Therefore, understanding the role of plankton in carbon sequestration is not only important for understanding the global carbon cycle, but also for predicting future climate change and developing strategies to mitigate its impacts.