No abstract

The composition and approximate concentrations of three trace metals-iron (Fe), zinc (Zn) and magnesium (Mg)-of 160 samples of Macrobrachium vollenhovenii (African river prawn) from Badagry creek were investigated for four months across the rainy and dry seasons. Length and weight of the prawns varied from 15.0cm-17.6cm and 72.76g-130.65g respectively. The approximate analysis was performed in triplicates and the collected data were analyzed using analysis of variance and T-test. Mean values for protein were 52.18±1.11% (rain) and 43.13±1.13% (dry); lipids were 9.65±0.65% (rain) and 3.50±0.55% (dry); ash were 23.39±1.06% (rain) and 12.00±1.11% (dry); crude fibre were 9.15±0.42% (rain) and 9.35±6.08% (dry); moisture content were 4.08±0.44% (rain) and 31.25±5.23% (dry), and carbohydrate were 1.58±0.07% (rain) and 1.35±0.17% (dry). Protein, ash, moisture and lipids values at different seasons were significantly different (p = 0.05). The trace metal values of the species were within standard recommended range set by World Health Organization. The mean values for zinc (Zn) were 5.10±0.64 (rain) and 5.16±0.27 (dry) mg/100g; magnesium (Mg)-20.00±1.02 (rain) and 18.00±1.10 (dry) mg/100g and iron (Fe)-3.03±0.40 (rain) and 2.59±0.39 (dry) mg/100g. There was no significant difference of Zn and Fe contents between seasons (p = 0.05), but the values for magnesium were significantly different (p = 0.05). This study indicated that, Macrobrachium vollenhovenii, from Badagry creek could be very useful as an alternative source of high-quality protein, energy and mineral supply for human consumption and even for feed formulation for animals because they contain considerable amount of trace metals.

The present study is on the haematological and hepatic responses of the African catfish fingerlings Clarias gariepinus to sublethal toxicity of industrial effluents (IE) from the environment of Ologe Lagoon, Lagos, Nigeria. The fish were cultured in five concentrations of industrial effluents: 0% (control), 5%, 15%, 25%, and 35%. Trials were carried out in triplicates for twelve (12) weeks. The culture system was a static renewable bioassay and was carried out in the fisheries laboratory of the Lagos State University, Ojo-Lagos. Weekly physico-chemical parameters: Temperature (°C), pH, conductivity (ppm) and dissolved oxygen (DO in mg/L) were measured in each treatment tank. Haematological parameters: packed cell volume (PCV), red blood cells (RBC), white blood cell (WBC), neutrophil and lymphocytes etc., and hepatological alterations were measured after 12 weeks. The physico-chemical parameters showed that the pH ranged from 7.82±0.25~8.07±0.02. DO ranged from 1.92±0.66~4.43±1.24 mg/L. The conductivity values increased with increase in concentration of I.E. While the temperature difference remained insignificant with mean value range between 26.08±2.14~26.38±2.28. The DO showed significant differences at p < 0.05. Though survival was 100% during the sublethal study, haematological results showed that C. gariepinus had PCV ranging from 13.0±1.7~27.7±0.6, RBC ranged from 4.7±0.6~9.1±0.1, and neutrophil ranged from 26.7±4.6~61.0±1.0 amongst others. The highest values of these parameters were obtained in the control and lowest at 35%. While the reverse effects were observed for WBC and lymphocytes, the liver shows normal liver cells in the control (0%), but at higher toxic levels, there were: vacoulation, destruction of the hepatic parenchyma, tissue becoming eosinophilic (i.e. tending towards Carcinogenicity) and severe disruption of the hepatic cord architecture. This study therefore shows that disposal of effluents into the aquatic environment affects the health of fishes by impairing normal hepatic functions and hindering vital physiological processes if exposure continues for a long period of time (sublethal effect).

No abstract

No abstract