Blue Carbon at the southern tip of Africa: current knowledge and future perspectives for dynamic estuarine environments

Blue Carbon Ecosystems (BCEs), specifically salt marsh, seagrass, mangroves, occur in South Africa’s relatively small, sheltered estuaries that are often disconnected from the ocean. These are dynamic environments where shifts between BCEs and other habitats along ecotones occur in response to mouth changes, floods and droughts, as well as anthropogenic pressures. Although Blue Carbon is becoming well established in South Africa, critical knowledge gaps remain; these are summarised under seven themes and future research and management actions identified. A holistic approach is recommended for Blue Carbon studies in estuaries to measure across elevation gradients (rather than focusing on individual vegetation types) and to include reeds, sedges and forested wetlands. Additionally, quantifying data deficient carbon stocks and processes, modelling future climate change impacts, instilling a sustainable long-term monitoring program, incorporating relevant emerging blue carbon stocks, realizing nationally inclusive restoration and protection co-management plans, and aligning local approaches with global frameworks of reporting are advocated as future recommendations with respect to South African BCEs. South Africa has high biodiversity and unique pressures influencing BCEs and is well positioned to inform the global research agenda. While the limited spatial extent of BCEs restricts the feasibility of carbon credit opportunities, high biodiversity values of these ecosystems hold potential under emerging ‘nature credit’ frameworks. • Blue Carbon research and management actions were identified for South Africa. • Holistic approach recommended with measurements across estuary elevation gradients. • Carbon stock, sequestration and GHG flux measurements missing for most bioregions. • Different biogeographic regions provide opportunities for tracking global change. • Nationally inclusive restoration and protection co-management plans needed.