title: Assessment of pollution in sewage ponds using biomarker responses in wild African sharptooth catfish (Clarias gariepinus) in Tanzania.
abstract: The interactive effects of mixed pollutants in sewage wastewater on biomarker responses were investigated using wild male African sharptooth catfish (Clarias gariepinus) in Morogoro, Tanzania. A total of 58 fish were used, of which 21 were from Mindu dam (reference site) and 22, 9 and 10 from Mafisa, Mazimbu and Mzumbe sewage ponds, respectively. Liver somatic index (LSI) and gonadosomatic index (GSI) were significantly greater (two- to threefold) and (five- to sixfold), respectively, in fish from all sewage ponds. Haemoglobin concentration and gill filament 7-ethoxyresurufin O-deethylase (EROD) activities were significantly higher (1.2-fold and twofold, respectively) in fish from Mzumbe sewage ponds than in fish from Mindu dam, whereas liver EROD activity was significantly higher in fish from Mzumbe and Mafisa sewage ponds (5-fold). A HPLC method for determination of enzymatically formed p-nitrophenyl-glucuronide (PNPG) was developed and applied to measure UDP-glucuronosyl transferase (UGT) activities that was significantly higher in fish from all sewage ponds (2-2.5-fold) than in fish from Mindu dam. Kinetic characteristics and assay dependence of UGT were studied with microsomal preparations. Metallothionein (MT) content was significantly lower (three- to fourfold) in fish from sewage ponds than in fish from Mindu dam, and corresponded with cumulative levels of cadmium, lead and mercury. Condition factor, vitellogenin (Vtg), acetylcholinesterase (AChE) activities in plasma, eyes and brain, haematocrit, plasma protein and cytosolic glutathione S-transferase (GST) activities were comparable in fish from sewage ponds and Mindu dam. Although specific pollutants other than the metals were not identified by chemical analysis, application of a suite of biomarkers in C. gariepinus demonstrated that all sewage ponds were contaminated by pollutants of public health concern.
authors.affiliation: Faculty of Veterinary Medicine, Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, P. O. Box 3021, Morogoro, Tanzania.
authors.forename: Robinson H
authors.initials: RH
authors.lastname: Mdegela
authors.forename: Marte
authors.initials: M
authors.lastname: Braathen
authors.forename: Resto D
authors.initials: RD
authors.lastname: Mosha
authors.forename: Janneche U
authors.initials: JU
authors.lastname: Skaare
authors.forename: Morten
authors.initials: M
authors.lastname: Sandvik
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D002397:Catfishes / Q000097:blood / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D019363:Cytochrome P-450 CYP1A1 / Q000378:metabolism; D004784:Environmental Monitoring / Q000379:methods*; D005123:Eye / Q000187:drug effects / Q000201:enzymology; D029941:Fish Proteins / Q000378:metabolism*; D005880:Gills / Q000187:drug effects / Q000201:enzymology; D014453:Glucuronosyltransferase / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D006066:Gonads / Q000187:drug effects / Q000254:growth & development; D006454:Hemoglobins / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D008668:Metallothionein / Q000378:metabolism; D019216:Metals, Heavy / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology; D025341:Principal Component Analysis; D018570:Risk Assessment; D012722:Sewage / Q000737:chemistry*; D013636:Tanzania; D014819:Vitellogenins / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D029941:Fish Proteins; D006454:Hemoglobins; D019216:Metals, Heavy; D012722:Sewage; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D008668:Metallothionein; D019363:Cytochrome P-450 CYP1A1; D014453:Glucuronosyltransferase; D005982:Glutathione Transferase; D000110:Acetylcholinesterase