The effects of lead on algae

Abstract

The effects of lethal and sublethal concentrations of PbCl₂ on reproduction , viability, and motility of a marine unicellular green flagellate alga, Platymonas subcordiformis, were studied under controlled laboratory conditions. The severity of the effects depended primarily upon the concentration of Pb⁺⁺ and the duration of treatment. Log phase cells were more sensitive than stationary phase cells. Sublethal amounts of Pb (2.5 and 10 mg l⁻¹ Pb⁺⁺) tended to retard population growth by delaying cell division and daughter cell separation. A lethal amount of Pb (60 mg I⁻¹ Pb⁺) caused inhibition of growth and cell death. Various intracellular abnormalities resulted from Pb treatment. The flagella were shed or altered in a variety of ways, depending on Pb concentration; motility was least affected by low Pb and completely impaired by high Pb. Normal wild-type cells appeared to be more sensitive to Pb than mechanically sheared (flagella-less) cells and cells of a non-flagellate mutant of Platymonas. Exposure of cells to Pb in non-growth conditions of dark and cold (2°C) had little negative effect.