The influence of climatic changes on the coastal oceanography of Ghana
Monthly means of amounts of rainfall recorded at two stations in Ghana over the period 1979-1981 and 1987, rates of river flow and sediment transport recorded at seven stations quite close to the sea and monthly means of zooplankton displacement volumes taken off Tema (Ghana) are analysed. Two patterns of annual rainfall occur in Ghana. In pattern 1 which is dominant, major rains occur during the period May – July but mainly in May and June, while minor rains take place between September and October but most often in October, as it happened in the years 1979-1981. In pattern 2 which is rare, major rains occur in September while the minor rains take place during the period March – May, as it occurred in 1987. The rainfall patterns correlate with the patterns of river flow and sediment discharge into the sea. Rainfall pattern 1 correlates with the major coastal upwelling and is, therefore, more likely to exert immediate positive influence on biological production in Ghanaian coastal waters. Thus, rainfall patterns should be considered in modelling the effects of the environment on coastal pelagic fisheries.