COASTAL EROSION CHANGES IN SPECIES COMPOSITION AND TROPHIC BALANCES

5.4 POLLUTION OF MARINE AND COASTAL ENVIRONMENT

The threats to aquatic biodiversity in the Region come from municipal, agricultural, and industrial activities. The key sources of pollution in the Regions’s coastal Districts are waste products from coconut oil extraction, discharge of human excreta, and solid waste especially plastics into streams, wetlands and the sea. Litter entering the marine environment is known to kill sea turtles, dolphins and sea birds UNEP, 1995. An assessment in 1994 indicated a ‘high’ domestic pollution for Sekondi- Takoradi Metropolis compared to Nzema East, Ahanta West and Jomoro EPA, 2004. The projected pollution indices for domestic and industrial pollution Table 7 indicate that by the year 2020 pollution in the coastal Districts would have increased severalfold from the 1994 estimates. Table 7: Pollution indices in four coastal districts DISTRICT Domestic Pollution Index 1994 Domestic Pollution Index 2020 Industrial Pollution Index 1994 Industrial Pollution Index 2020 Nzema East 249 527 5 100 Ahanta West 261 521 5 111 Ahanta East 672 1702 39 827 Jomoro 194 406 4 74 Source: World BankEPA 1996

5.5 COASTAL EROSION

The Ghanaian coast is exposed to various degrees of erosion with moderate rates occurring in the Western Region World BankEPA, 1996; Armah and Amlalo, 1998. Erosion at Essipon Turtle Cove in the former Shama Ahanta East District, Busua in Ahanta West and Axim in Nzema East District has resulted in loss of sea turtles nesting beaches. In adition fish landing sites at Princess Town, Poasi Nkontonpo and Essipon have been deserted as a result of severe coastal erosion EPA, 2004. Generally, the natural causes of erosion are compounded by the effects of human- induced vegetative loss or deforestation. Re-inforcements of waves due to adjacent headlands and man-made structures like breakwaters at the Takoradi Port, Bosumtwi Sam Fishing Harbour and Naval Base at Sekondi seem to be the most likely cause of erosion at Princess town, Adjoa, Nkontompo, and Essipon. Sand and stone winning activities along the coast especially in Axim have led to considerable sea erosion which continues to threaten some communities in that area. Other human causes arise from improper land use such as bush burning, over-grazing and other forms of agricultural land use. 38

5.6 CHANGES IN SPECIES COMPOSITION AND TROPHIC BALANCES

Some species such as the gastropods Cymbium spp. and the spiny lobster Panulirus sp. appear to be declining in abundance while the sea star Astropecten sp. and other starfishes have disappeared completely. The triggerfish Balistes capriscus was of little interest prior to 1973 but assumed great importance in the demersal fishery from that year Mensah and Koranteng, 1988 to 1987. The species has since disappeared Mensah and Quaatey, 2002 a phenomenon that has been attributed to changes in physical oceanographic parameters in the Gulf of Guinea Koranteng et al., 1996; Aggrey-Fynn, 2007. Collapse of the grey triggerfish Balistes capriscus fishery in Ghanaian waters since its dominance in the demersal fishery in the 1970s and 1980s is a major example of a fish species under threat of extinction.

5.7 INCREASED POPULATION DENSITY