Valuation of coastal ecosystem services in the Large Marine Ecosystems of Africa

Abstract

The African coastline is bordered by highly valuable marine ecosystems, but the environmental degradation due to anthropogenic pressure alter the benefits that they render to people. Our paper aims at assessing the value of ecosystem services provided by mangroves, seagrass beds, coral reefs, and kelp forests present in the Large Marine Ecosystems (LMEs) of Africa. After the mapping of coastal marine habitats, our valuation relies on the transfer of value of all ecosystem services from reference monetary unit values, extracted from the literature. A habitat functionality index based on the assumption that a higher population density and a higher demographic growth rate lead to a decrease in the functionality and services of marine habitats was then defined and incorporated into the valuation. The surveyed coastal habitats cover about 117,000 km2, with seagrass beds being by far the most extensive habitat. Present all along the coasts of Africa, their surface area represents about 62% of surveyed coastal habitats, followed by the mangroves (23%), coral reefs (15%). Kelp forests are only present in the southern Benguela Current LME. We estimated the annual value of the LME's coastal ecosystem services at 814 billion USD. Coral reefs have the highest value (588 billion USD/year), followed by seagrass beds (135 billion USD/year), mangroves (91 billion USD/year), and kelp forests (0.4 billion USD/year). The results show that ecosystem services from the four coastal habitat types had the highest value in the Agulhas Current LME, representing 38% of the total value, followed by the Red Sea LME (28%) and the Somali Coastal Current LME (10%). The three LMEs of the Atlantic side represent 15% of the total estimated value. Our paper highlighted many gaps that remain to be filled in terms of mapping and ecosystem services assessment in Africa. Nonetheless, our estimated values can facilitate dialogue between decision-makers and managers, and between countries sharing the same habitats and marine resources, toward better management of these ecosystems.