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10.1 Introduction
Coral reefs are not explicitly included as part of the blue-carbon ecosystem, so you
might wonder why coral reefs are included as a chapter in this book. In the tropics
and subtropics, coral reefs often overlap seagrass beds and mangrove forests
(Fig. 10.1) and are therefore strongly linked to blue-carbon ecosystems. Often there
is also hydrodynamic connectivity or interaction among these tropical coastal habitats (Guannel et al. 2016).
This chapter briefly explains the general characteristics of coral reefs in terms of
carbon-cycle components such as primary production and calcification. The resultant CO 2 sinks and sources, and carbon storage and export in coral reefs are then
Fig. 10.1 World distribution of coral reefs, mangrove forests, and seagrass beds. The areas with
high diversity for each ecosystem overlap, especially around Indonesia, Malaysia, Papua New
Guinea, and the Philippines. (Source: https://www.grida.no/resources/7766 (credit: Hugo
Ahlenius))
A. Watanabe and T. Nakamura