In a recent issue of Ambio, a Swedish scientific journal on the human environment, URI Graduate School of Oceanography biologist Scott Nixon discusses how human sewage and agricultural drainage now support the fertility once provided by the Nile, although the nature of the productive ecosystem now supporting the fishery appears to be quite different from the historical one.
Recent satellite images document the continuing fertility of the Nile valley and delta where continuous irrigation and intensive applications of fertilizer have replaced the traditional flood-based agriculture. Fish landings now greatly exceed those prior to the closure of the high dam, and the landings of prawn have reached 75% of their pre-dam value.
"The fish eaten today in Alexandria and Cairo may taste as good," said Nixon, " but I believe that they have been fed by sources far different from the rain and soils of Ethiopia that served as sources of the nutrients in the historic annual flood."
Nixon discusses three reasons for believing that the amount of phosphorus and nitrogen reaching the Egyptian Mediterranean coast in urban waste water increased dramatically during the 1980s, coincident with the recovery of the coastal fisheries. First, the population had increased substantially since 1965; second, the nutrition of the population had improved in terms of total per capita consumption; and third, there was a remarkable expansion of the public water and sewer systems of Greater Cairo, Alexandria, and other urban areas during the 1980s.