Module 4 • Ecology: Case Study Phytoplankton and Carbon
When people say that the ocean is a “carbon sink,” they’re really talking about phytoplankton. Like other marine shellfish, many forms of phytoplankton have small plates or shells made from calcium carbonate—which is made from CO2.
Based on your class discussion of this process, sketch the phytoplankton carbon sink in the space below and number each step in the process using the key.
Key
1. Carbon dioxide (CO2) is released on land by natural processes (e.g., respiration of animals). 2. CO2 is released on land from human burning of fossil fuels (in cars, power plants, furnaces, etc.) 3. CO2 becomes airborne, mixing with the atmosphere. 4. Over the oceans, CO2 mixes with the water.
5. Phytoplankton use energy from the sunlight to fuse water molecules with CO2 to create the carbohydrates from which their calcium carbonate shells are built.
6. Phytoplankton drop to the bottom of the ocean when they die and are compressed into limestone.