Blue carbon credits are a way to recognize and value the role that coastal and marine ecosystems, such as mangroves, salt marshes, and seagrasses, play in sequestering and storing carbon dioxide (CO2) in the oceans and seafloor. These ecosystems are known as blue carbon sinks because they capture and store organic carbon through their natural processes. Blue carbon sinks have been responsible for sequestering more than 60% of the CO2 emitted by humans in the past 150 years.

Carbon can be stored through the growth of marine plants, such as mangroves and wetlands, which absorb CO2 as they grow and deposit it in the soil. This carbon can remain stored in the soil for thousands to millions of years. Another way that blue carbon is stored is through the process of photosynthesis in phytoplankton, small marine microorganisms that form the base of the aquatic food chain. When phytoplankton die or are consumed, their skeletons sink to the seafloor and are covered by sediment layers over time, effectively storing the carbon for thousands of years. However, if the sediment layer is not thick enough, the carbon may be released back into the ocean. Seagrasses, wetlands, and mangroves are among the most efficient blue carbon sinks, as they are able to effectively store carbon in the soil for long periods of time.

Coral reefs, marine algae, and mangroves are all important coastal and marine ecosystems that can sequester and store significant amounts of carbon dioxide (CO2). However, they differ in terms of their carbon sequestration potential and the mechanisms by which they capture and store carbon.

Coral reefs are formed by the calcification of coral skeletons, which are made up of calcium carbonate (CaCO3). Coral reefs sequester carbon through this process of calcification, as well as through the growth of coral and other marine organisms that are able to absorb CO2 through their tissues. Coral reefs are highly productive ecosystems that are able to sequester large amounts of carbon, but they are also vulnerable to destruction and degradation from human activities, such as pollution and overfishing, as well as from climate change.

Marine algae, also known as phytoplankton, are small marine microorganisms that are able to absorb CO2 through the process of photosynthesis. Like coral reefs, marine algae are highly productive ecosystems that are able to sequester large amounts of carbon, but they are also vulnerable to destruction and degradation from human activities and climate change.

Mangroves are coastal trees and shrubs that grow in saline or brackish water. They sequester carbon through the growth of their roots, leaves, and branches, as well as through the accumulation of organic matter in the soil. Mangroves are able to store large amounts of carbon in their soils, and they are relatively resilient to destruction and degradation compared to coral reefs and marine algae. However, mangroves are still vulnerable to human activities, such as deforestation and land conversion.

Each of these ecosystems has the potential to sequester and store significant amounts of carbon, and all three play important roles in the global carbon cycle. It’s important to carefully assess the carbon sequestration potential of a particular ecosystem and to design and implement appropriate conservation and management strategies in order to maximize its carbon sequestration benefits.