Biomarkers of oxidative stress in oyster (crassostrea gasar) and heavy metal levels in the media of Buguma Creek, Niger Delta, Nigeria

Abstract

The study assessed the activities of biomarkers of oxidative stress: superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), lipid peroxidation product, and malondialdehyde (MDA) levels in oysters (Crassostrea gasar) alongside heavy metals: cadmium (Cd), lead (Pb), nickel (Ni), and zinc (Zn) in water, sediments, and oyster (Crassostrea gasar) tissues from Buguma Creek, Niger Delta, Nigeria. Sampling was carried out at three stations: Jordan, Amayanabo, and Orubo, respectively. Analysis of biomarkers of oxidative stress revealed that oyster tissues from Orubo had significantly higher GSH (15.98±2.57 μmol/ml) levels than those from Amayanabo (8.34±3.45 μmol/ml) and Jordan (7.69±0.91 μmol/ml), respectively. Orubo also had lower metal content ppm (Cd: 0.66±0.70; Ni: 0.63±0.22; Pb: 179.90±85.32; Zn: 0.00±0.00) compared to Amayanabo (Cd: 1.01±0.61; Ni: 1.45±0.38; Pb: 486.28±94.52; Zn: 36.91±63.94) and Jordan (Cd-0.72±0.14; Ni-1.45±0.38; Pb-353.12±13.31; Zn-5.81±10.06). This observed pattern was, however, not consistent with results from the other stations. Results of heavy metals in water and sediment samples in all sampled stations revealed metal levels to be within the FEPA and DPR permissible limits for water and sediments, respectively. Ni and Pb in oyster (Crassostrea gasar) tissues in all the sampled stations were above the limits set by FEPA and FAO for food fish. The levels of the analyzed heavy metals were in the following order: oyster > sediments > water. The findings from this study call for caution in the consumption of oysters (Crassostrea gasar), other shellfish, and fish from Buguma Creek.