The completion of the Aswan High Dam in 1965 dramatically altered the ecology of the Nile River basin and the adjacent eastern Mediterranean Sea. Before the dam's construction, the annual Nile flood carried millions of tons of nutrient-rich silt into the sea. This nutrient influx stimulated a massive seasonal bloom of phytoplankton, which in turn supported a highly productive sardine fishery along the Egyptian coast. Following the dam's closure, however, the annual flood was halted, and the vital nutrients were trapped in Lake Nasser behind the dam. Consequently, the phytoplankton population collapsed due to the sudden starvation of nutrients. Without this primary food source, the Egyptian sardine catch plummeted by more than ninety percent within a single year. While the dam succeeded in providing electricity and flood control, this sudden decline in marine nutrients devastated the local coastal fishing communities that had relied on the seasonal cycles of the river for generations.
According to the passage, what was the direct cause of the collapse of the phytoplankton population in the eastern Mediterranean Sea?
- AThe generation of electricity and new flood control measures along the coast.
- BThe sharp decline in the population of Egyptian sardines that feed on phytoplankton.
- The trapping of essential nutrients in Lake Nasser following the dam's closure.Cevap
- DAn unprecedented increase in the volume of silt carried by the annual Nile flood.