Blue Carbon Financing of Mangrove Conservation in the Abidjan Convention Region: A Feasibility Study
Figure 9: Relative fishing activity, population pressure, mangrove biomass and oil rigs in West, Central and Southern Africa Sources: Relative fishing activity was determined as the sum of normalized stressor magnitude values calculated for artisanal, demersal, and pelagic fishing activities in 2006 (Halpern, Frazier et al., 2015; Halpern, Frazier et al., 2015); population pressure was defined as the summed presence of three stressors: urban areas in 2001-2002 (Schneider, Friedl et al., 2003; Schneider, Friedl et al., 2009, Schneider, Friedl et al., 2010), high population density areas (>399 people/km2) in 2000 (Bright and Coleman, 2001; Bright and Rose, 2014), and oil rigs for 2004-2006 (Halpern, Frazier et al., 2015; Halpern, Frazier et al., 2015), where 3 = all stressors, 2 = two of any stressors, and 1 = any one stressor); mangrove biomass for mangroves classified <40 m high in 1999-2000 (Fatoyinbo and Simard 2013); 30 mile coastal buffer created in ESRI ArcMap 10.3 from the coast (GADM 2015); 200 nm land buffer (VLIZ 2014).
densities translate to pressures on a coastal ecosystem through conversion due to urban development and sprawl, infrastructure and related pollution on land (roads and houses) and on the coast (ports). These pressures tend to be concentrated near areas of large blue carbon stocks (see Figure 8, Figure 9, Table 11). Beyond these immediate pressures from increasing coastal population densities, West, Central and Southern Africa is also heavily dependent on the region’s ocean economy, which includes fisheries, shipping, offshore oil and subsistence (Table 10, Figure 9 and Figure 10). For example, some of the world’s richest fishing grounds can be found in the large marine ecosystems off the coast of West, Central and Southern Africa, due to highly productive waters fed by nutrient-rich upwelling currents in certain areas (see Table 10). Many of the region’s fisheries depend on mangroves to provide nursery areas and food sources for key species. Fishing intensity — both commercial and subsistence — is
each new iteration of FAO data collection includes a mix of earlier data collected, while different data sets used different data-collection methods. As such, a comparison of the data over time is not robust for purposes of drawing conclusions. Drivers of the trends in the size and distribution of blue carbon stocks in West, Central and Southern Africa are often summarized as the “human footprint” — a quantitative evaluation of human influence on the land surface, based on population density, land transformation, access, and infrastructure (Sanderson, Jaiteh et al., 2002). According to this study, mangroves in the ecological zone termed the Afro- tropical realm (which includes West, Central and Southern Africa) are facing the highest mean Human Influence Index scores of any biome in the region. This intense human pressure on the mangroves of West, Central and Southern Africa is partly due to coastal population densities in some of the top mangrove countries (see Figure 8). Population
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