Effects of heavy metals on the chlorophylls and anti-oxidant enzymes in Pistia stratiotes in Zaria, Nigeria
The effects of copper and lead on the physiology (chlorophyll a, chlorophyll b, catalase and peroxidase) of Pistia stratiotes were investigated. The experiments were conducted in the laboratory and the effects of copper and lead were evaluated based on the content of Chlorophyll a and b, the enzymatic activity of catalase and peroxidase by Pistia stratiotes. There were significant differences (P≤0.05) in the content of chlorophyll a and b. The metals (copper and lead) reduced chlorophylls a and b in Pistia stratiotes. The lower the concentration of metals, the higher the content of chlorophyll a and b. Lower pigment content was recorded for treatments with high concentration (1mg/L and 1.5mg/L) of metals. Higher contents of chlorophyll a and b were recorded for the control and treatments with lower concentrations (0.5mg/L of copper and 0.05mg/L of lead). The activities of catalase and peroxidase differ significantly (P≤0.05) in Pistia stratiotes. The findings showed that the higher the concentration of copper and lead, the higher the activities of the antioxidant enzyme. This indicated significant roles for the anti-oxidant defense mechanism of Pistia stratiotes. Pistia stratiotes can therefore be used as biomarkers for oxidative stress in aquatic ecosystems exposed to heavy metal stress in Zaria, Nigeria.
Keywords: Catalase, chlorophylls, copper, lead, peroxidase
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