The phytoplankton of Great Bitter Lake, Egypt, including the impacts of nutrient-laden and heated effluents

摘要

A year-long survey of the phytoplankton and nutrients in Great Bitter Lake indicates that this is a severely eutrophic lake. Chlorophyll levels were consistently high (>30mug/l), especially in summer (>90mug/l). The phytoplankton community comprised mostly diatoms and blue-green algae, although dinoflagellates and green algae were important at times. Local effects of effluent from a drain coming from the city of Ismailia were evident, although the effect of tourist hotels at Palma Beach was not detectable. The discharge of heated water from a thermal power plant raised the water temperature in the impacted area by 13degreeC in autumn and 22degreeC in summer and also caused decreases in chlorophyll and phytoplankton abundance. Dissolved nutrient levels were high and, especially at the offshore station, had a rather constant ratio of dissolved inorganic nitrogen to phosphate. The distribution of phytoplankton and chlorophyll were related more to temporal, presumably seasonal, variation than proximity to point sources of pollution.