Abstract
Lead is non-essential toxic metal used in the industrial process causes severe risk to aquatic organisms. This study aimed (aims) to evaluate the effect of Pb on oxidative stress in gills of <i>Mactra corallina</i>. During the experiment, bivalves were randomly divided into four groups, control served as control and D1, D2 and D3 groups were exposed to Pb graded doses (1mg/L, 2.5mg/L and 5mg/L) during 5 days, respectively. Pb accumulation was significantly increased in all treated gills with doses dependent manner. The exposure of M. corallina to PbCl<sub>2</sub> promoted oxidative stress in gills with an increase in malondialdehyde (MDA) and in metallothionein (MTs) levels. Moreover, a decline in glutathione (GSH), non-protein–SH (NPSH) and ascorbic acid (Vit C) levels were detected in all treated groups. Thus, alterations of enzymatic antioxidants systems were confirmed by a significant increase of catalase (CAT) and decreases of glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities in doses dependent manner. The cholinergic function was confirmed by a significant decrease of acetylcholinesterase (AChE) activity in the highest exposure dose. The impairment of the gill function was confirmed by the histological study.
Highlights
Aquatic systems are contaminated by different metals through inputs from human activities [1]
Treated gills at different Pb concentrations showed a significant decrease in their superoxide dismutase (SOD) (-24, -30, -16%) and glutathione peroxidase (GPx) activities (-33,42 and21%) at 1, 2.5 and 5mg/LPbCL2 respectively
The activity of CAT in gills was negatively correlated with SOD and GPx activities whereas it presents a positive correlation with AChE activity (Table 2)
Summary
Aquatic systems are contaminated by different metals through inputs from human activities [1]. Pb is among the most of inputs metals in water and sediment that could be accumulated by most aquatic taxa especially the faunal bivalves [3,4]. These taxa, such as Mactra corallina (M.corallina), are widely reported as bioindicators species in the monitoring applications, because of their filter feeders’ mode, sedentary living and their capacity to accumulate trace elements [5,6,7]. In Tunisia, it has a large repartition from the Northern to Southern sandy beaches, occupying the lower infra-littoral zone (3to100 m depth)
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