Author(s): Adejumobi KO, Nwankwo DI and Adedipe Joshua

Abstract: Environmental characteristics, plankton diversity and seasonal variation at the Makoko Creek were investigated for eight months (February – September, 2015). Air and water temperatures were high in the dry season (≤ 28.5 °C, ≤ 27.0 °C, and ≥ 29.0 °C, ≥ 29.5 °C, respectively). Transparency was higher in the dry season (18 cm) and the highest value of TDS (24990 mg/L) and TSS (16 mg/L) were recorded in the dry season. The highest water depth (1.39 m) was recorded in the dry season. pH values revealed alkaline conditions (>7.0) while conductivity values were lower in the rainy season. Dissolved oxygen was low (1.34 mg/L) in the dry season while the highest value (4.95 mg/L) was recorded in the rainy season. Biochemical oxygen demand (≥9.0 mg/L) and chemical oxygen demand were higher in the dry season. Salinity level in the creek varied between (14 ‰ and 17 ‰). The micro-nutrients were higher in dry season than the wet season. Heavy metals occurred as trace. Higher values of chlorophyll-a were recorded in the dry season while phytoplankton abundance and diversity were higher in the dry season than in the rainy season. The copepods dominated the zooplankton spectrum of which the calanoids were more abundant. Three divisions of phytoplankton Bacillariophyta, Cyanophyta and Chlorophyta were recorded. The more frequent was Cyanophyta constituting 80% of the total number of 2440 species. Trophic state index depicted eutrophic to hyper-eutrophic conditions.

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