The feeding ecology of bagrid species in River Ase, Niger Delta, southern Nigeria

The feeding ecology of seven bagrid species was studied between March, 1982 and February, 1984. A summary of the food items and condition factors (kf) in relation to sized groups were described for all the seven species while feeding intensity are to sized groups, diel and monthly variations in feeding intensity are provided only for Chrysichthys auratus longifilis (Geoffrey St. Hilaire, 1908) and C. nigrodigitatus (Lacepede 1803) due to data. Variations in food items between dry and rainy seasons were not remarkably different. There were differences in the feeding habits of different sized groups in C. auratus longifilis while in C. nigrodigitatus, all the sized groups consumed mainly detritus. Both C. auratus longifilis and C. nigrodigitatus fed both day and night. Feeding intensity was highest in C. auratus longifilis from 2100 to 2400 (h) and from 2400 to 0300(h) for C. nigrodigitatus. Based on the food items, Bagrus bayad macropterus Pfaff, 1933 was mainly piscivorous in diet while B. domac niger Daget, 1954 fed on fish and decapod crustaceans. C. auratus, C. nigrodigitatus, C. furcatus (Gunther, 1864) and Auchenoglanis occidentalis (Cuvier and Valencienness, 1840) were omnivorous bottom feeders. Clarotes laticeps fed on fish and detritus. The feeding ecology of bagrid species has been discussed and compared with the findings of earlier studies conducted elsewhere. Key Words: Bagridae, feeding ecology, Niger Delta, diets, seasonality Tropical Freshwater Biology 11 (2002) 47-6

Water Quality Assessment of River Areba, Niger Delta, Nigeria Using Physical and Chemical Indices

Water samples were collected from January to December, 2000 and analysed for water temperature, conductivity, pH, turbidity, colour, total dissolved solids, total suspended solids, total solids, dissolved oxygen (DO1), biological oxygen demand (BOD5), chemical oxygen demand (COD), carbonate, bicarbonate, total hardness, nitrate, nitrite, ammonium, phosphate, sulphate, chloride, sodium, potassium, calcium and magnesium. The mean values of turbidity (958.99mg/l), colour (217.75mg/l), phosphate (0.98mg/l), biological oxygen demand (19.52mg/l), ammonium (0.98mg/l) and phosphate (0.78mg/l) were above World Health Organization limits for drinking water. Seasonally, water temperatures, total dissolved solids, biological oxygen demand, chemical demand, nitrate-N, nitrite, ammonium-N, phosphate, sulphate and magnesium were higher during the dry season while other parameters were higher during the rainy season.Keywords: River Areba, Water quality, Monthly variations, seasonality

Impacts of petroleum hydrocarbons on fish communities of river Areba, Niger Delta, Southern Nigeria

The effects of petroleum activities on the fish community of River Areba, a small rainforest river, in Niger Delta, Southern Nigeria were studied for one year, January to December, 2002. Two stations within the river stretch were studied; one close to the area of petroleum activities was marked as station 1 while the other 5.30 kilometers downstream was marked as station 2. A total of 41 fish species accounting for 856 individuals representing 32 genera and 19 families were captured. Forty one (41) species representing 648 individuals, 32 genera and 19 families were caught in station 2 while twenty six (26) species representing 208 individuals, 21 genera (18) and families were captured in station 1. Twenty six (26) species were ubiquitous among the two stations while 15 species were restricted to station 2. The monthly variations of Total Petroleum Hydrocarbons (TPH) fluctuated between 0.13mg/l in March to 45.11mg/l in September in station 1 with a mean of 12.15mg/l while station 2 values ranged from below detection in March and April to 12.68mg/l in September with a mean of 3.72mg/l. The values of Total Petroleum Hydrocarbons in sediments in station I ranged from 34.70mg/kg in April to 256.10mg/kg in March with a mean of 91.05mg/kg while in station 2 values fluctuated between 16.80mg/kg in March to 93.80mg/kg in April with a mean of 33.94mg/kg. Out of sixteen aromatic components recorded, station 1 accounted for 0.09423mg/l while station 2 accounted for 0.00796mg/l.Key words: Petroleum hydrocarbons, impacts, fish species, rainforest river, Niger Delta, Nigeria

Contaminations Of Heavy Metals In Water And Hemichromis fasciatus Of A Waste Pit Influenced By Petroleum Activities

The concentrations of heavy metals (Zn, Cd, Cu, Pb, Ni, Fe, Mn, Co, Cr, V and Hg) in water and Hemichromis fasciatus (a piscivore) in the burrow pit constructed by Shell Petroleum Development Company were studied. Water and fish samples were collected monthly from January to December 2000. The range values (mg/l) of heavy metals in water were: Zn (0.025 – 2.91), Cd (BD – 0.044), Cu (BD – 0.106), Pb (0.001 – 0.252), Ni (BD – 0.14), Fe (0.143 – 5.204), Mn (0.025 – 0.138), Co (BD – 0.202), Cr (0.002 – 0.018), V (BD – 0.005) and Hg (BD – 0.001) while in Hemichromis fasciatus, values (mg/kg) were Zn (15.28 – 90.93), Cd (BD – 5.04), Cu (0.42 – 5.82), Pb (0.03 – 3.43), Ni (0.36 – 1.71), Fe (43.16 – 145.24), Mn (2.16 – 5.74), Co (BD – 1.63), Cr (BD – 1.61), V (BD – 0.12) and Hg (BD =below detection level).Seasonally, Cd, Cu, Pb, Mn, Co, Cr, V and Hg had higher mean values in water during the dry season while Zn, Ni and Fe were higher during the raining season. All heavy metals except Fe were higher in mean values during the dry season in H. fasciatus than during the rainy season. The mean abundance of heavy metals in H. fasciatus was Fe>Zn>Mn>Cu>Cd>Co>Pb>Ni>Cr>V. The monthly concentrations of heavy metals in H. fasciatus were far higher than those in water. The concentrations of Pb, Fe and Mn were above WHO limits for drinking water for some months while Fe and Mn values in H. fasciatus were above WHO limits for food in twelve months with Zn, Cd, Cu, Pb, Ni, Co and Cr exceeding WHO limits for some months. The findings reveal that the water and the fish (H. fasciatus) are contaminated and not fit for drinking and consumption by humans. Keywords: Heavy metals, water, fish, seasonality, distribution coefficients, burrow pit, Niger Delta, Nigeria.Tropical Freshwater Biology Vol. 16 (2) 2007: pp. 45-5

The feeding ecology of schilbeid catfishes in river Ase, Niger delta, Southern Nigeria.

The feeding ecology of Parailia pellucida (Boulenger, 1901), Eutropius niloticus (Rϋppel, 1872) and Schilbe mystus (Linnaeus, 1756) were investigated for two years (March, 1982-February, 1984) in River Ase, Niger Delta, southern Nigeria. A cyclic pattern of fish sampling was used and fish samples were collected from 0600-0900, 0900-1200, 1200-1500, 1500-1800, 1800-2100, 2100-2400, 2400-0300, 0300-0600 (hrs) using various fishing gear. Percentage food items and condition factors (kf) were calculated for each species. Feeding habits in relation to size groups, diel and monthly variations in feeding intensity were described for Eutropius niloticus and Schilbe mystus which had adequate data. The three species P. pellucida, E. niloticus and S. mystus were omnivorous surface feeders. They consumed more food items in the dry season than during the rainy season. Diel variations in feeding habit occurred both day and night with higher intensity at night especially between the hours of 9p.m. and 12 midnight. S. mystus is both day and night feeder. The medium size group of E. niloticus consumed a wider variety of food items than the small and large size groups. S. mystus consumed almost the same food items in both dry and rainy seasons. In the three size groups, most food items were selectively consumed indicating gape size as a limiting factor. The condition factors (kf) of the three species were above 1 indicating well being. Some aspects of the feeding ecology of the three schilbeid catfishes have been discussed and the results compared with the results of earlier investigations conducted elsewhere.Key words: schilbeidae, feeding ecology, diel variation, seasonalit

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