THE POLLUTION OF A TERRESTRIAL ECOSYSTEM FROM HYDROCARBON EXPLOITATION AND ITS OUTCOME ON COLLEMBOLA (ARTHROPODA: INSECTA)M.A. UWAGBAE, J. ROTIMI AND E.J. AGWU
Some oil-impacted sites at Ikarama community Niger Delta (Nigeria) were investigated for arthropod abundance and analyzed for total extractable hydrocarbon content and some physicochemical characteristics. The Arthropods were extracted at varied soil depths of 0-10cm, 10-20cm and 20 30cm from the soils exposed to just about equal concentration of crude oil (50 L). Oil-impacted sites were tagged according to the time of occurrence of spill, Site A - 7 months after spill, Site B 19 months after spill and Site C - 38 months after spill, while Site D was control. Samples were collected for 24 months. A total of 4,118 individuals of Collembola were collected and classified into families and genera. The order Collembola (class Insecta) consisted of five families, namely: Entomobryidae, Onchiuridae, Sminthuridae, Hypogastruridae and Isotomidae and eleven genera. Soil arthropod abundance (mean per gram) of sample at all soil depths was statistically significant (P < 0.05) in Site D but not significant (P > 0.05) in the impacted sites (Site A, B and C) in all soil depths. Some physicochemical parameters such as Total Hydrocarbon Content (THC), soil pH and soil moisture content in all soil depths and in all sites sampled were significant (P < 0.05). Multiple correlation matrices (R) of Collembola abundance and THC and soil pH showed negative correlation only in oil impacted sites at all depths but correlation matrices in Site D (control) was positive. Soil moisture content correlation matrices values were positively correlated in all soil depths and in all sites sampled. Time course contributed in the abundance and distribution of Collembola species that inhabit a typical tropical rain forest soil that have been impacted by series of oil spills. Some Collembola species exhibited diverse preferences to crude oil spillage and affinity and differences to some soil physicochemical parameters.
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