2006

Icthyotoxic assessment of water extract from fresh Euphorbia heterophylla (Limnaeus) plant stem on Barbus occidentalis (Boulenger, 1920) fingerlings was conducted using static bioassay tests over a period of 96 hours. The range finding test was userd to determine the lethal concentration of the botanical on B. occidentalis and was found to induce varying behavioural response in the fish. The 96h median lethal concentration (LC50) of 2.42g/l and safety level of 0.24g/l were determined for B.

A general investigation of the groundwater quality of the Benin City Urban Aquifer of Benin Formation for the effects of athropogenic activities shows the following results: lead (Pb) has mean value of 0.044 mg/l from 25 sampled boreholes. Seven of these borehole waters show anomalous Pb values of over 0.050mg/l. For the 25 boreholes, Pb mean value of 0.044mg/l, 0.055mg/l standard deviation and variance of 0.003mg/l are indicative of high Pb concentration compared with 0.05mg/l W.H.O. limit.

Most urban cities are experiencing population growth and increased industrial activities. This has brought most urban soil and groundwater environments under stress. There are reports of soil and groundwater pollution through landfills, gas and oil pipelines, industrial spills and leakages from underground storage tanks (USTs). Pollutants range from heavy metals to volatile organic compounds (VOCs), light non-aqueous phase liquids (LNAPL) (floaters) and dense non-aqueous phase liquids (DNAPL) (sinkers).

The arthropod succession on buried carrion and decomposition rates of the African rat (Crycertomy gambianus) in both raining and dry seasons were determined. Three sets of the experiment were conducted from December 2002 to October 2003. For each experiment, ten African giant rats with a mean weight of 1.85kg were used. Carcass in the December/March experiment representing the dry season decayed at a faster rate than those in the August/October which, represented the raining season.

In an attempt to determine the responses of soil microarthropods to precipitation regimes, samples were collected during dry season, simulated wet and rainy season periods. Also, biodiversity indices showed variation in soil microanthropod diversity and abundance in relation to cultivated, uncultivated and leaf litter sites. Generally, soil microanthropod abundance and species richness showed preference for the moisture rich sampling sites, with highest biodiversity indices recorded during the rainy periods.

‘Burukutu’ which is an indigenous alcoholic drink has been shown to be rich in bacterial diversity, with a total of thirteen (11) bacterial species isolated from the three stages of production (namely: steeping, mashing and maturation) sampled from two different selling points in Ilorin, metropolis. The bacterial species isolated are Streptococcus sp; Lactobacillus sp; Bacillus sp; Pseudomonas sp; Klebsiella sp; Staphylococcus sp; Enterococcus sp; Escherichia coli; Proteus sp; Leuconostoc sp and Micrococcus sp.

The piscicidal potential of water-extract mesocarp of Azardirachta indica was investigated in static biossay experiment with continuous aeration to determine its acute toxicity. The 96-hLC50 was 97.42mg/l while the threshold value was 31.12mg/l. The extract led to an initial increase in opercula ventilation rates which then decreased significantly. The computed regression equation (y) = 4.624 + 6.352 Logc. (r=0.72) and the fish exhibited respiratory distress, loss of balance and erratic swimming prior to mortality. The usefulness of A. indica as piscicidal plant is discussed.

Key physical characteristics of three dispersants: Corexit 9527, NalcoD4106 and Goldcrew were studied to determine their integrity and toxicity to a brackishwater fish Sarotherodon melanotheron. The results showed that with regards to the physical properties, Corexit 9527 and to a large extent Goldcrew maintained their integrity while NalcoD4106 deteriorated. Observations of the 96h LC50 static bioassay showed that the toxicity of the dispersants to the fish in an increasing order is Corexit 9527 < Goldcrew < NalcoD4106.

The in vitro effect of 10, 30 and 50% (w/v) concentrations of the aqueous and ethanolic extracts of pawpaw (Carica papaya L.) leaf on the radial growth of Fusarium verticilliodes was studied using the pour plate method. The diameters of radial growth of the mycelia of F. verticilliodes were measured at 24 hours intervals for five days. Both extracts retarded the radial growth of F. verticilliodes compared to that of the control, with the ethanolic extract having a greater fungistatic effect at the concentrations tested in this study.

: The copepoda (crustacea) of Lagos harbour system was studied from October 2002 to September 2003. Eighteen copepod species were identified, three of which are being recorded in Nigeria for the first time. Thesze are: Temora, Corycaeus and macrostella species. The copepods comprise of three assemblages, namely: the brackish/marine assemblage, the brackish assemblage and the brackish/freshwater assemblage. Salinity values varied from 33.40% at Lagos harbour to 0.40% at Badagry.