The Growth Response of the Diatom Navicula incerta to Selected Concentrations of the Metals: Cadmium, Copper, Lead and Zinc

Abstract

The effective concentrations of the heavy metals; Cd, Cu, Pb and Zn which reduced the population growth of the diatom N. incerta by 50% after 96 h of exposure EC50 were determined; the respective values were 26.8 .mu.M. 164.5 .mu.M, 52.9 .mu.M and 154.5 .mu.M. Cd is the most toxic of the 4 metals followed by Pb, with Cu and Zn being almost an order of magnitude less toxic. The number of days per division were calculated for each metal concentration tested. The trend which was found for all metals tested is that the number of days per division increases with increasing metal concentration. The value of this kind of data to environmental impact assessment studies is discussed.