Assessment of the Heterotrophic and Crude Oil Utilizing Microorganisms of Imo River Estuary of the Niger Delta Mangrove Ecosystem
Antai, Sylvester Peter; Unimke, Augustine Agorye; Agbor Reagan Bessong

Abstract
Sediment and water samples from Imo river estuary were analyzed to assess the influence of seasonal variation on the microbial populations. The results obtained shows that the sediment samples had a significantly (P < 0.05) higher counts of total heterotrophic bacteria (THB) than the surface and sub-surface water samples. The counts obtained in the dry season were significantly higher (P<0.05) than the wet season. There were no significant difference (P > 0.05) in the population of THB in the surface water during the wet and dry season (2.23 × 106 ± 2.23 cfuml-1 and 2.39 × 106 ±1.63 cfuml-1) respectively, while there were significant difference (P < 0.05) in the population of total heterotrophic bacteria (THB) in the sub-surface water during the dry and wet season (2.27 × 106±2.00 cfuml-1 and 2.13 × 106 ± 1.84 cfuml-1) respectively. The total heterotrophic fungi (THF) densities in the surface water were 1.17 x 105 ± 0.93 cfuml-1 and 1.38 x 105 ± 0.63 cfuml-1 during the wet and dry season respectively. The mean THF densities of 1.15 x 105 ± 0.63 cfuml-1 and 1.30 x 105 ± 0.48 cfuml-1 were observed in the sub-surface water during the wet and dry season respectively. The mean densities for sediments were 1.42 x 106 ± 1.19 cfug-1 and 1.60 x 106 ± 1.05 cfug-1 during the wet and dry season respectively. Significant difference (P < 0.05) in the population of total heterotrophic and crude oil utilizing microorganisms for crude oil polluted and pristine samples were also observed. It can be concluded that the microbial population of Imo river estuary is higher during the dry season than the rainy season.

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