K. A. Bawa-Allah

Bio: K. A. Bawa-Allah is an academic researcher from University of Lagos. The author has contributed to research in topics: Clarias gariepinus & Medicine. The author has an hindex of 6, co-authored 13 publications receiving 114 citations. Previous affiliations of K. A. Bawa-Allah include King's College London.

Toxicological Effects of Lead and Zinc on the Antioxidant Enzyme Activities of Post Juvenile Clarias gariepinus

Abstract: Toxicological effects of sub lethal concentrations of lead and zinc salts (Pb(NO3)2 and ZnCl2) on the antioxi- dant enzymes of post juvenile Clarias gariepinus in laboratory bioassays was investigated, using the liver. Oxidative stress enzymes and substrates (Glutathione-S-Transferase (GST), Glutathione (GSH), Superoxide dismutase (SOD), and Catalase (CAT) ) showed irregular activities during the first two weeks of the experiment, but a significant variation (p<0.05) from levels detected in controls after 28 days in fishes exposed to both metals. Increased levels of GST-GSH and reduced levels of SOD and CAT occurred in fishes exposed to ZnCl2 as compared to control while there were no variations in the levels of Malondialdehyde (MDA). In fishes exposed to Pb(NO3)2 however, GST-GSH, SOD, CAT and MDA all reduced when compared to control. There is need for more research on the oxidative defense response of Clarias gariepinus to persistent levels of high concentrations of heavy metals .There is also a need for comparison of existing field and laboratory studies so as to fully exploit the bio markers of oxidative stress as indicators of environmental pollution in tropical fresh water systems.

Differential toxicities of anionic and nonionic surfactants in fish.

Abstract: This study investigated the differential toxicities of anionic and nonionic surfactants commonly used as active ingredients in household cleaning agents. The acute toxicity of the surfactants against Clarias gariepinus were investigated using static bioassays while the sublethal effects on the biochemical parameters and the histopathology of liver and gills of the fish were investigated for a period of 28 days using a static renewal bioassay. The anionic surfactants were found to be more acutely toxic against the fish than the nonionic surfactants. The evaluation of the joint action toxicity of the surfactants against the test species using the concentration-addition model showed antagonistic interactions when the surfactants are present in mixtures. The two groups of surfactants also had varying degree of effects on the antioxidant stress enzymes and the liver function enzymes of the fish. However, only the anionic surfactants caused changes in the histopathology of the gills of the fish. The results obtained from this study have shown that anionic surfactants are more toxic to fish compared to nonionic surfactants. Anionic surfactants are the most commonly used surfactants in cleaning agents, there is a need for stricter regulations governing the use of this class of surfactants in cleaning agents.

Accumulation and Anti-oxidant Enzymes as Biomarkers of Heavy Metal Exposure in Clarias gariepinus and Oreochromis niloticus

Abstract: This study investigated the accumulation of heavy metals in tissues (gill, muscle and liver) and changes in anti-oxidant enzyme activities of edible fish species as biomarkers of heavy metal exposure using laboratory bioassays. Post juveniles of Clarias gariepinus and Oreochromis niloticus were exposed to 10% 96hr-LC50 values of Pb(NO3)2 and ZnCl2 against each species respectively, for 30 days. The two fish species accumulated the heavy metals (Pb and Zn) in their liver, muscle and gill with the highest concentration of the heavy metals in the muscle as observed in results obtained. The biochemical studies showed that the in the level of reduced glutathione (GSH), and the activities of superoxide dismutase (SOD), glutathione-s-transferase (GST) in the liver of fish species reduced significantly (p 0.05) and the increase in the level of Malondialdehyde (MDA) in liver of the exposed fish species was not significant (p > 0.05) after the 30 days exposure period as compared to the control. The need for routine monitoring of aquatic ecosystems integrating field and laboratory studies to assess presence and accumulation of toxic pollutants especially heavy metals in edible fish species and use of antioxidant enzymes as biomarkers of exposures to such pollutants were discussed.

Heavy Metal Pollution Monitoring in Vulnerable Ecosystems: A Case Study of the Lagos Lagoon, Nigeria

Abstract: This comparative analysis was carried out to monitor heavy metal concentrations in the Lagos Lagoon over the last 2 decades. Surface water and sediment samples were collected from stations on the Lagos Lagoon based on their suitability for comparative analysis and future monitoring. Heavy metal content in samples was determined using Flame atomic absorption spectrophotometry (FAAS). The concentrations in the samples were compared to those obtained by Don-Pedro et al. (West African Journal of Applied Ecology 5:103–114, 2004) in previous studies from the same sampling zones. Results show that concentration of most heavy metals analysed has reduced significantly (p < 0.05) in the past 2 decades. However, the concentration of Cadmium (Cd) was found to have increased significantly (p < 0.05) over the same period. Increased concentration of Cadmium poses a threat to ecosystem health thus, it is imperative that safe limits for heavy metal discharge in waste streams should be revised and implemented.

Climate Change 2007: Impacts, Adaptation and Vulnerability.

Abstract: Impatti, adattamento e vulnerabilita Le cause e le responsabilita dei cambiamenti climatici sono state trattate sul numero di ottobre della rivista Cda. Approfondiamo l’argomento presentando il documento: “Cambiamenti climatici 2007: impatti, adattamento e vulnerabilita” votato ad aprile 2007 dal secondo gruppo di lavoro del Comitato Intergovernativo sui Cambiamenti Climatici (Intergovernmental Panel on Climate Change). Si tratta del secondo di tre documenti che compongono il quarto rapporto sui cambiamenti climatici.