Levels of oxidative stress markers in the mangrove oyster, <i>Crassostrea gasar</i> from a coastal ecosystem in southwest Nigeria

Abstract

This study investigated biochemical responses in the ecologically important Mangrove Oyster, Crassostrea gasar along a contamination gradient on the Lagos/Badagry lagoon in Lagos, Nigeria. The antioxidant enzymes and oxidative stress biomarkers, catalase enzyme activity (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and Thiobarbituric Acid Reactive Substances (TBARS): Malondialdehyde (MDA) were assessed in gills and muscle tissues of adult Crassostrea gasar using standard biochemical procedures. The muscle tissue of C. gasar exhibited higher oxidative stress enzymes activity than the gills. Relatively higher mean value of MDA was recorded in the gill of C. gasar at Makoko (35.39±1.08 Hmol/mg pro) as compared to the levels in oysters collected from Abule-Agege Creek (26.26±2.78 Hmol/mg pro) and Badagry Creek (25.15±4.54 ± Hmol/mg protein). Similarly, the result of anti-oxidative stress enzyme activities and lipid peroxidation in the muscle tissue of C. gasar from Makoko waters showed significant highest values of SOD (54.24±1.37 Min/mg pro), CAT (6.82 Min/mg pro) and MDA (42.35±0.81 Hmol/mg pro). No significant difference in GPx value was recorded in examined samples of C. gasar across sites. C. gasar collected from Abule-Agege and Badagry Creeks were similar in most values of the measured biochemical enzyme activities. Biological adverse effects were more evident in oysters from Makoko, a recognized contaminated area than those from Abule-Agege Creek and Badagry Creek. The study gave an indication of stress on the health status of the oysters, hence the need for periodic monitoring of the ecosystem.

Keywords: Mangrove Oyster, Antioxidant enzymes, Oxidative stress, Estuary