Volume 7 No 2, 2006

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.

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.

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).

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.

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.

Investigations into the seasonality of cyclopoid (crustacean: copepoda) with regards to rainfall variations were carried out in Forcados river. Samples were collected by towing two plankton nets of 55µm and 100µm mush sizes at 5knots for 5 minutes behind an engine boat. Meterological station in Warri gave the rainfall data. Centigrade thermometer was used for measuring the surface water temperature. Results showed low temperature range (27.5ºC – 31.5ºC), while that of rainfall was high (25.8-602.6mm).

The ecology and growth of the shellfish, Tympanotonus fuscatus was studied in a mangrove swamp of the Warri River, Abiotic and Biotic factors such as temperature, salinity, hydrogen ion concentration, nature of substrate, associated fauna and flora, micro – habitat were investigated. Weight/Length relationship of the shellfish was measured to determine the growth rate. Results showed a low range (27.5°C – 31.0°C) in temperature variation and high range (0.3% - 7.1%) in salinity variation, while pH values were between 6.5 – 7.8.