Kelp Forests

Abstract

Kelp forests are comprised primarily of brown algae in the order Laminariales and dominate shallow rocky coasts of the world’s cold-water regions. Kelp forests are highly productive ecosystems that produce large amounts of fixed carbon, but they are not known to store blue carbon in soft sediment; kelp sediment is coarse grained or is composed of consolidated rock. Kelp detritus settles within kelp beds and is also exported to adjacent and distant habitats, such as sandy beaches and the deep-sea where the kelp carbon may accumulate and be stored. The global average rate of detrital production is 706 g C_org m⁻² year⁻¹, accounting for 82% of annual kelp productivity. This production is second only to detrital production in salt marshes and roughly equivalent to production in seagrass beds. As much as 173 Tg C_org year⁻¹ of kelp carbon can be sequestered globally with about 90% of this sequestration occurring through export to the deep-sea and the rest through burial in coastal sediments.