Determining The Origin And Ecology of A Macroalgae (Ulva clathrata) Bloom Along The Coast Of Western Ghana And Cote d’Ivoire
In November of 1993 communities along the coast from New Town to the Ankobra River, Ghana began reporting a green substance that would clog, or over-fill and split their fishing nets (EPA 1996). Approximately 25% of the coastal population participates in an artisanal fishery that deploys beach seines each day, providing up to 80% of the local diet. During the 1993 (and subsequent) events the sea appears green from copious amounts of small 4-6 cm green “tufts”, hence the local reference to the bloom as “green- green”. In 1996 The Environmental Protection Agency (Ghana) provided the first official report describing socio-economic impacts of the bloom and identified the green substance as a naturally occurring macroalgae, Enteromorpha (Fig 2). Entermorpha is now included in the genus Ulva, so we adhere to this recent botanical reclassification and refer to the macroalgae as Ulva (Hayden et al. 2003). A recent genetic analysis at the Natural History Museum in London determined the species as Entermorpha (Ulva) clathrata (see Figure 1), a morphologically variable filamentous macroalgae that is very responsive to nitrogen enrichment. The EPA study also measured near/offshore water quality and conducted a demographic survey including questions on local knowledge of the bloom at five stations located from New Town and Cape Three Points.