Uptake and loss of absorbed dissolved cadmium to Clarias angullaris fingerlings

The uptake and loss of dissolved cadmium in media by the African mud fish (Clarias angullaris) fingerlings was studied in water of 25 mg/ L hardness, pH 6.8, at 27 ±2°C in a static test system. The uptake experiments involved exposure of fish to 0.5 and 1.0 mg Cd2+/L test solutions from which thefish absorbed and retained 1.1011 mg and 1.3060 mg Cd2+/g wet fish weight, approximately 550 and 653 times the recorded normal tissue level, respectively, after 8 days. In the loss experiments, after fourteen (14) days, the fish that had 0.8320 mg Cd2+/g wet weight in the 0.5 mg Cd2+/L test medium reduced the internal concentration to 0.1121 mg Cd2+/g; and in the 1.0 mg Cd2+/L test solution, the reduction is from 0.9820 mg Cd2+/L to 0.1142 mg Cd2+/L wet weigh

Heavy metal concentrations in Malapterurus electricus and Chrysichthys nigrodigitatus from Ogba River in Benin City, Nigeria

The concentrations of heavy metals in two tropical fish species (Malapterurus electricus and Chrysichthys nigrodigitatus) from Ogba river in Benin City, Nigeria, were investigated between November 2002 and October 2003 in order to ascertain the pollution status of the river. The results showed varying levels of accumulation of Cu, Mn, Zn, Pb, Cr, Ni, and Cd in the fishes. The levels of Cu,Mn, Cr and Ni, in both fishes were higher than the WHO and FEPA recommended maximum allowable standards in food fish, while those of Zn, Pb and Cd were lower than the standards. The results suggest that the Ogba river system is contaminated with heavy metals and the consumption of fishes of the river could pose health hazards to man. Metal levels in water in Ogba River are lower than the recommended limiting standards and could be considered safe for drinkin

Trace metals in some benthic fishes of the Ikpoba river dam, Benin City, Nigeria

The concentration of iron (Fe), copper (Cu), manganese (Mn), zinc (Zn), nickel (Ni), cadmuim (Cd), chromium (Cr) and lead (Pb) in two benthic fish species (Mormyrops deliciosus and Mormyrus macrophthalmus netted from two locations (Okhoro and Low lift pump sites) on the Ikpoba River Dam, Benin City, Nigeria were determined using atomic absorption spectrometric technique. Sediment and water samples were also analysed for their trace metal concentrations. The range of trace metal concentrations (μg/g) in the fishes which is the focus of the study were as follows: Fe = 39.60 - 41.07 μg/g, Cu = 5.04 - 8.04 μg/g, Mn = 0.38 - 1.34 μg/g, Zn = 17.01 - 23.16μg/g, Ni = 0.24 - 0.48 μg/g, Cd = 0.79 - 0.98 μg/g, Cr = 0.38-0.91 μg/g, and Pb = 2.67-3.53 μg/g. Results show that relatively, higher metal levels were recorded in M. deliciosus than M. macrophthalmus. No significant differences (P > 0.05) were recorded between the concentrations of Fe, Mn, Zn and Pb in the two fish species. Significant differences (P < 0.05) were however, recorded between the concentrations of Cu, Ni, Cd and Cr in the fishes. The levels of Pb in the fish species exceeded the limit recommended in fish and fishery products by the Food and Agricultural Organization (FAO) of the United Nations. Also, the levels of Fe and Cd in the water exceeded the levels recommended for portable drinking water by the World Health Organization (WHO).Keywords: Trace metals, benthic fishes, Ikpoba dam, Benin City, Nigeri

The use of the mangrove oyster (Crossostrea gasar) as a bio-indicator for chemical element contamination in the Niger Delta

The study evaluated the concentrations of some chemical elements namely Copper (Cu), Manganese (Mn), Zinc (Zn), Chromium (Cr), Nickel (Ni) and Lead (Pb) in the mangrove oyster (Crossostrea gasar) and water from Golubo creek in the Niger Delta region of Nigeria, to ascertain the impact of these metals on the investigated ecosystem. The evaluation was carried out using Atomic Absorption spectroscopy technique. The mean  concentrations of the aforementioned elements in C.gasar were 1.06 mg/kg, 0.38 mg/kg, 50.13 mg/kg, 0.14 mg/kg, 0.39 mg/kg and 1.55 mg/kg, respectively while the mean concentrations of the elements in water were 0.65 mg/l, 0.04 mg/l, 16.47 mg/l, 0.86 mg/l, 0.85 mg/l and 1.50 mg/l, respectively. Copper, Manganese, Zinc and Lead were  bioaccumulated by C.gasar while the estimated daily intake of these elements ranged from 0.0056 mg/person/day for Chromium to 2.01 mg/person/day for Zinc. The Maximum Acceptable Risk values for Copper, Manganese, Zinc, Chromium, Nickel and Lead in C. gasar were 0.79, 0.05, 24.67, 0.94, 1.08 and 1.94, respectively. The Toxicity Quotient values for the chemical elements in C.gasar ranged from 0.66 for Zinc to 0.93 for Chromium while in the case of water, the range was from 0.65 for Copper to 1.5 for Lead. With regard to health risk to man, the mean concentrations of the chemical elements in the oysters, did not exceed the Federal Environmental Protection Agency (FEPA) maximum allowable limit for chemical elements in food. The mean concentrations of these metals in the bivalve were, therefore, within health limits and therefore do not present an immediate health threat to consumers. It was observed that the mean concentrations of the chemical elements in water were generally below the FEPA maximum allowable limits for chemical elements in drinking water with the exception of Lead. The study, thus, revealed that there is a potential health risk to man as a result of consuming Pb-contaminated water. Based on the findings from this study, it is advocated that the creek be closely monitored for toxic metals in order to avert the occurrence of episodic ecological accidents.Key words: Chemical elements, Oyster, Niger Delt

Histopathological alterations in Senegal sole, Solea Senegalensis, from a polluted Huelva estuary (SW, Spain)

As a component of a large research project to evaluate the effects of contaminants on fish health in the field, histopathological studies have been conducted to help establish causal relationship between pollutants (heavy metals and aromatic polycyclic hydrocarbons—PAHs) and histopathological responses in Senegal sole, Solea senegalensis, from an estuary of SW Spain. Heavy metals (As, Zn, Cd, Pb, Cu and Fe) and 16 PAHs (proprietary USEPA) concentrations in water, sediment and tissues (liver and gills) and histopathological alterations in S. senegalensis from three sampling sites of Ria de Huelva estuary during 2004–2006 years have been analysed. The histopathological studies revealed seasonal and spatial differences in the lesion grade of alterations observing the highest lesion grades in fish from Odiel River and autumn season. No significant differences were observed in the alterations prevalence between sampling sites, but significant differences were observed between seasons observing the highest prevalence in autumn season. However, calculated IPAT demonstrated a low–moderate impact of pollutants on health fish. Correlations between histopathological alterations and pollutants analysed were observed being heavy metals the group that presented a major number of correlations with alterations in several organs of S. senegalensis. In evaluating the general health of fish, the use of histopathological studies in recommended for making more reliable assessment of biochemical responses in fish exposed to a variety of environmental stressors. Statistical analysis using semiquantitative data on pathological lesions can help to establish correlation between cause (stressor) and effect (biomarker)

Impact of urban wastewaters on the diversity and abundance of the fish population of Ogba River in Benin City, Nigeria

The effects of urban wastewaters on the diversity and abundance of the fish population of Ogba River in Benin City, Nigeria were assessed and monitored at 5 sample stations between November 2007 and October 2008. The physico-chemical properties of the water were also monitored during the period. A total of 486 individual fishes made up of 26 different species were recorded, with Clarias macromystax (Clariidae), Malapterurus electricus (Malapteruridae), Xenomystus nigri (Notopteridae), Hemichromis fasciatus and Oreochromis niloticus (Cichlidae) being the dominant species. The water chemistry, fish species diversity and abundance at the study stations were different and were negatively impacted upon by urban wastewaters pollution. It was also revealed that the fish communities of the river were under stress and not in good condition. Consequently, a close monitoring of all effluent discharges and other probable stress-inducing factors in Ogba River is recommended

Petroleum hydrocarbons in the sediments of Areba River, Olomoro, Niger Delta, Nigeria

The concentrations of petroleum hydrocarbons in the sediments of River Areba, Olomoro, Isoko Local Government Area, Niger Delta, Nigeria were investigated from January to December, 2000. Sediment samples were collected monthly from two stations. Station 1, is inundated with oil fields, waste pits, borrow pits, a gas compressor and two flow stations and while station 2, 5.30km downstream of station 1, is free of petroleum hydrocarbon activities. Monthly Total Petroleum Hydrocarbons (TPH) values by Gas Chromatography (GC) analysis ranged from 16.80mg/kg to 256.10mg/kg. Seasonally, TPH values were higher during the dry season in both stations. Five aliphatic components (Undecane, Dodecane, Tridecane, Tricosane, Tetracosane) and three aromatic components (naphthalene, pyrene and benzo(a) pyrene) were detected by Gas Chromatography (GC). The sediments of the two stations were heavily polluted with petroleum hydrocarbons when compared to the values obtained from chronically polluted sediments elsewhere. Keywords: sediments, petroleum hydrocarbons, pollution, river Tropical Freshwater Biology 2003/2004 Vol. 12/13: 85-9