Vol. 13 No. 15-24 (2022): EFFECTS OF METALS ON THE CHLOROPHYLLS AND THE ANTI-OXIDANT ENZYMES IN SALVINIA MOLESTA

The worldwide increasing level of industrialization and urbanization has led to

environmental pollution. Metallic contamination in aquatic environments has received huge

concern due to its toxicity. Heavy metals enter our environment from both natural and

anthropogenic sources. Among the anthropogenic abiotic stresses, copper and lead at high

concentrations have been recognized for their impact on aquatic ecosystems, including

aquatic plants. The effects of copper and lead on the physiology (chlorophyll a, chlorophyll

b, catalase and peroxidase) of Salvinia molesta were investigated. The experiments were

conducted in the laboratory; the experimental design consisted of a factorial combination of

the two metals (copper and lead) in different concentrations. 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 Salvinia molesta . There were significant differences (P≤0.05) in the

content of chlorophyll a and b. The metals (copper and lead) reduced the contents of

chlorophyll a and b in Salvinia molesta . Lower pigment contents were recorded for

treatments with high concentrations (1mg/L and 1.5mg/L) of metals; while 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). Also, the longer the plants stayed

in the medium, the more the reduction in pigment content of the plants. The activities of

catalase and peroxidase differ significantly (P < 0.05) in Salvinia molesta. 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 Salvinia molesta . They may therefore be used as biomarkers for oxidative stress in Salvinia

molesta exposed to Cu and Pb stress in Nigerian aquatic ecosystems.