How Does Underwater Plants Get CO2?

Underwater plants, also known as aquatic plants or oceanic plants, make up a significant part of our aquatic ecosystem. These plants play a vital role in maintaining a healthy aquatic environment and supporting aquatic life. However, one may wonder, how do these plants get the necessary nutrients, particularly CO2, to sustain their growth and survival? In this article, we explore some of the ways that underwater plants get CO2.

Aquatic Respiration

Just like any other living organism, underwater plants need oxygen to survive. However, instead of relying on the oxygen in the air, these plants obtain oxygen from the water through a process called aquatic respiration. During this process, the plants release CO2 into the water, which then diffuses into the surrounding water. The concentration of CO2 in the water is usually low; thus, the plants need to adapt to this low CO2 concentration for them to absorb sufficient CO2 for their growth.

Diffusion From The Atmosphere

Although CO2 concentration is low in water, higher concentrations are present in the atmosphere. Some of this CO2 gets dissolved in water and can be absorbed by aquatic plants. During day time, the concentration of CO2 in the water is low as the plants are photosynthesizing, using CO2 and producing oxygen. However, at night or in darker conditions, the concentration of CO2 in the water can increase, making it possible for plants to absorb CO2 through diffusion from the air.

Bicarbonate Formation

Aquatic plants can also absorb dissolved inorganic carbon (DIC) in the form of bicarbonate (HCO3-) from the surrounding water. However, the concentration of HCO3- in the water is too low for the plants to absorb all the necessary DIC. Some nutrients like the ions released from the weathering of rocks and sediments, can react with CO2 in the water to produce bicarbonate. This process increases the concentration of HCO3- in the water, making it possible for aquatic plants to absorb more inorganic carbon, including CO2.

CAM Photosynthesis

CAM (Crassulacean Acid Metabolism) photosynthesis is another way that underwater plants obtain CO2. These plants absorb CO2 at night when the stomata are open and store the CO2 as an organic acid. During the day, the stomata close to prevent loss of water, and the organic acid is broken down to release CO2 for use in photosynthesis. CAM photosynthesis is common in floating or submerged plants that grow in shallow waters with fluctuating water levels.

Conclusion

Underwater plants play a vital role in maintaining a healthy aquatic ecosystem. These plants rely on various mechanisms to obtain CO2 for their growth and survival in a low CO2 concentration environment. Aquatic respiration, diffusion from the atmosphere, bicarbonate formation, and CAM photosynthesis are some of the ways that underwater plants obtain CO2. Understanding these mechanisms is crucial in establishing effective conservation and management practices to sustain healthy aquatic ecosystems and support aquatic life.