Influence of Manganese and Zinc on Biochemical Profiles of Selected Algal Species: A Laboratory Study

The present study focused on the responses of six freshwater algal species (Anabaena ambigua, Anabaena subcylindrica, Nostoc commune, Nostoc muscorum, Spirogyra sp., and Spirulina sp.) to manganese and zinc. Laboratory experiments were conducted for the assessment of biochemical responses to manganese and zinc at various concentrations (0.1, 0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 mg/L) for 15 days of exposure. After the incubation period, 10 ml of sample was centrifuged at 6000 rpm for 15 min and the pellets were used for measurement of the various experimental parameters. The toxicological study of manganese on algae showed that Anabaena ambigua was most sensitive algae. Regarding effects of manganese concentrations, chlorophyll, protein, carbohydrate, starch, and amino acid were inhibited 50% (IC₅₀) at 3 mg/L, whereas the toxicological study of zinc on algae Anabaena subcylindrica showed most adverse effects. Regarding effects of zinc concentrations, chlorophyll, protein, carbohydrate, starch, and amino acid were inhibited 50% (IC₅₀) at 1 mg/L. The inhibitory and stimulatory effects of either of the used heavy metals depend on concentration. Different organisms, however, have different sensitivities to the same metal, and the same organism may be more or less damaged by different metals.