Influence of Seasonal Variation on the Microbiological and Physicochemical Parameters of Imo River Estuary of the Niger Delta Mangrove Ecosystem
Unimke, Augustine Agorye; Antai, Sylvester Peter; Agbor Reagan Bessong

Abstract
Surface and sub-surface water samples collected from Imo river estuary were analyzed for the seasonal variation in microbiological and physicochemical parameters. The results obtained indicate that there were no significant difference (P > 0.05) in the population of total heterotrophic bacteria (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 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 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. However, there were significant difference (P < 0.05) in the population of total heterotrophic and crude oil utilizing microorganisms. The results further revealed that the water samples show a remarkable variation in physicochemical parameters during the wet and dry season. The temperature ranges for both the surface and subsurface water revealed mesophilic levels. This study has revealed useful information about the periodic and seasonal variations in microbiological and physicochemical gradients that occur in Imo river estuary. Eight (8) species of bacteria and five (5) species of fungi were isolated. The bacteria species were Flavobacterium sp, Micrococcus sp, Vibrio sp, Pseudomonas sp, Klebsiella sp, Escherichia coli, Staphylococcus aureus and Bacillus sp. The fungi species isolated were Cladosporium sp, Penicillium sp, Aspergillus sp, Monilia sp and Fusarium sp.

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