Environmental and bioeconomic characterisation of coastal and marine systems of Cameroon, including risk implications of the Chad–Cameroon pipeline project

Abstract

Abstract We assess the status of Cameroon’s coastal and marine environment, from field survey results and analysis of existing environmental and bioeconomic datasets. The study was undertaken at a broad level, and at greater resolution in the area likely to be influenced by the Chad–Cameroon pipeline. Thirty-six coastal sites are characterised using a proven, robust environmental assessment technique. Solid waste was more prevalent and abundant than beach oil, and both were most common around Douala towards Kribi. Offshore sampling was undertaken at 77 sites, 80% of which were dominated by mud or silt fractions, whereas hard substrata were uncommon. Key biological resources were identified in three main areas of the Cameroon coast, from the analysis of existing environmental data, using a Geographic Information System: (1) northern region around Ndian (mangroves); (2) central region in and around Douala (mainly mangroves and including a protected area); and (3) southern region between Kribi and Campo (mangroves including a protected area). Coastal uses/pressures are greatest around Douala, an area associated with at least five different major uses/pressures. Other parts of the coast appear to have fewer uses/pressures, although these areas are extensive. Coastal areas where concentrated biological resources coincide with coastal uses/pressures are extensive, encompassing much of the coastal zone. These are indicative of resource–use conflicts, where management action should be a high priority. Areas where biological resources coincide with multiple/heavy coastal uses and pressures are fewer and less extensive. Cameroon’s coastal resources (e.g. fisheries) are of direct significance. Their ecosystem services are also important, an estimated US$ 8.3 billion y-1 nationally. This is equivalent to US$ 600 person-1 y-1, a figure approximating per capita gross national product (US$ 610). Within the pipeline project area, ecosystem services may be ca. US$ 1.5 billion y-1, or US$ 105 person-1 y-1. Estimated project benefits from royalties are equivalent to only US$ 4 person-1 y-1 over 30 years and about 1700 jobs. Major project costs are ca. US$ 1.8 billion. Valuations of both ecosystems and the project necessarily make assumptions. Nevertheless, even large reductions in individual habitat values do not undermine the remarkable overall value of ecosystem service and natural capital, nor their importance in cost–benefit analysis. Our assessment of overall risk of coastal oil pollution in the project area combines probability of spillage (based on previous work), and a modified index of environmental sensitivity. This estimates the extent of coastline and habitats at risk, and the associated degree of overall risk. High risk areas include: (1) area between Enyangoe and Ondja (north/central project area); (2) area from Loiaba to south of Biyo (south/central project area); and (3) segment of coast to the north and south of Campo (south project area). The same process can be applied using different oil spill scenarios or more comprehensive datasets.