A study of the haematological and serological parameters (e throcyte and leucocyte numbers, catfish groups from the fish farm of the African Regional Aquaculture Centre, Aluu, Port Harcourt, Nigeria. Erythrocyte and leucocyte counts showed intra-species variability, while fish size was found to be negatively correlated to haemoglobin concentration and haematocrit values; these are significant at P = 0.05 level. The serological results obtained were found to be similar to the pattern in humans.haematocrit, haemoglobin, blood group and genotype) is reporte 7 for four freshwater, pond-cultured

No abstract

No abstract

Acute toxicity of xylene on an African catfish (Clarias gariepinus) was carried out. A total of 210 catfish C. gariepinus juveniles with mean length 15.20±2.3cm, and mean weight of 10.23±2.6g were obtained from the University of Port Harcourt Demonstration Farm. The test was determined for 96hour median lethal concentration using concentrations of 250ml/l, 200ml/l, 150ml/l, 100ml/l, 50ml/l, 25ml/l and 0.0ml/l (control) which gave a LC50 value of 63.965ml/l with upper and lower confidence limits at 106.53 ml/l and 37.82ml/l respectively. The median lethal time LT50 recorded was 55.7 hours. There was a strong correlation between (%) mortality in Probits and the Log10 Dose (R²=0.9772). There was statistical significance (P>0.05) in the number of mortality observed in the six concentrations from 24 hours to 96 hours of exposure and high percentage mortalities were recorded as the concentration of the toxicant increased. No mortalities were recorded in the control. The cumulative mortality recorded after exposure of C. gariepinus to xylene was time dependent. Based on this the high percentage mortalities of the fish species it is therefore recommended that the use of this chemical be minimized and proper contingency plans be carried out before discharging this toxicants into the aquatic environment. Waste from this chemical and spill incidences should be detoxified to a less toxic level before disposing into the aquatic environment. The results obtained may provide valuable information for formulation of environmental policies and serve as a model for bio-monitoring of the aquatic environment.

This article was inspired by a field reconnaissance survey of outcrops along the Nembe-Brass axis of the petroliferous Niger Delta. It reviews various tradeoffs of the impact of upstream petroleum (seismic and production) operations on the mangrove ecosystems in that region, the largest in Sub-Saharan Africa. Mangroves and intertidal shores are considered critical to the economic well-being of this region owing to the people's dual occupation in fishing and farming. The mangrove ecosystem provides a nutrient medium, which serves as a nursery and spawning ground for many fish species and other biota. Oil and gas activities might destroy these spawn areas, causing reduction in resource output and community pressure. Devegetation of the mangrove forest as a result of seismic delineation leaves the fragile soil exposed, unprotected, and susceptible to erosion. Again, loss of vegetation might discourage the natural role of plants in air purification (CO(2) utilization and O(2) production). The release of nutrients (organic N(2), NH(3), and NO$\rm{{_{3};{-}}}$) and polyaromatic hydrocarbons (PAHs) to the environment, with the attendant increase in microbial load, increases biochemical O(2) demand (BOD) and depletes dissolved O(2) (DO) in H(2)O to a level that is beyond the tolerance limit of organisms. This anoxic situation leads to asphyxiation and subsequent fish kill in affected areas. In order of increasing vulnerability, the mangroves and intertidal shores of the Niger Delta fall under categories 8 to 10 on the environmental sensitivity index (ESI) scale, which predisposes the areas to serious long-term effects and clean-up complexity. Thus, there is need to monitor mangrove systems and shoreline changes in the areas of considerable seismic and production activities, especially in the coastal Niger Delta, where pipeline corrosion due to salt intrusion into the swampy environment and 'unsighted fingers' of sabotage have increased the prevalence of oil spills.

No abstract

A feeding trial was carried out to investigate the use of plant oils in the feeding of Oreochromis niloticus fingerlings. Four iso-nitrogenous (30% crude protein) and iso-calorific (17 MJ kg-1 gross energy) diets including a fish oil control were formulated to contain 8%. A basal diet containing 100% FO was completely replaced by Soya oil, groundnut oil, and palm oil. A total of 120 O. niloticus fingerlings (1.20 ± 0.03 g, mean ± SE) were randomly allocated the diets after 7-day acclimation. There were 10 fish tank-1. Fish were hand-fed to apparent satiation twice for 63 days. The result obtained from the trial show that dietary supplementation of lipids significantly influenced growth performance and nutrient utilization of O. niloticus (P<0.05). The fish fed PO had the least weight gain (WG), final weight, protein efficiency ratio and highest compared to FO, SO and GO from d 7-28 (P<0.05). At d 35 the fish fed SO had the highest WG (P<0.05); no significant difference (P>0.05) in WG of fish fed FO, GO and PO diets was observed. The best weekly overall growth at the end of d 56 was in FO group; fish fed PO diet had the least WG, followed by GO. At d 63, WG of fish fed FO diets declined, while fish fed SO and PO diets showed a trend towards increase in growth. Result of ANOVA showed that there were significant differences (P<0.05) in FW (F=11.406, P=0.003), WG (F=11.428, P=0.003), FCR (F=7.274, P=0.011), and PER (F= 10.803, P=0.003) among the diets. At the end of the trial, the best growth in fish was recorded for FO group; however, there were no significant differences (P>0.05) in mean values of FW (P= 0.781), WG (P=0.999), SGR (P=0.991), PER (P=0.997), and FCR (P=0.879) between FO and SO-supplemented diets. The least WG was observed in fish fed PO diet followed by GO. Survival was 100% for all treatments. Whole body moisture and crude protein was least in PO group. FO had the highest (P<0.05) protein compared to all vegetable oils (VOs). However, whole-body protein of fish fed FO and SO were not significantly different (P>0.05). SO had the highest (P<0.5) lipid compared to FO, GO and PO. In conclusion, SO alone and a bend of PO and GO can be used as a alternative to FO without affecting growth performance of O. niloticus.

No abstract