Antioxidant Defense System Alternations in Four Crab Species as a Bio-Indicator of Environmental Contamination

The ecological health status of aquatic environment is a determinant for the survival and growth of organisms within such niche. An investigative study was carried out on four crab species – Cardiosoma armatum, Goniopsis pelli, Callinectes amnicola, Portunus validusinhabiting contaminated sites in Lagos Lagoon- exploring their anti-oxidant defense mechanism in the light of heavy metal concentration in the crab tissues. Amongst the measured heavy metals, cadmium level proved to be significantly highest (P<0.05) with range concentration of 0.42±0.12mg/kg (G. pelli)- 0.79±0.06 mg/kg (C. armatum). Contrastingly, lead was marginally low with concentration below 0.01 mg/kg in all the crab species. Organismal responses to environmental pollution showed a high level of biomarkers. C. armatum was observed to have elevated level of superoxide dismutase (123.04±0.01min/mg/pro), catalase (7.74±0.05min/mg/pro), glutathion transferase (18.21±0.02 Hmol/mg pro), reduced glutathione (2.92±0.04Hmol/mg pro) and glutathione peroxidase (61.85±0.06 Hmol/mg pro) above other species with C. amnicola recording the lowest concentration of the biomarkers. With the low level of heavy metals and corresponding high concentration of these biomarkers, the pollution indices within the study habitat are quite modest.