Water quality and plankton biodiversity of a flood retention lake in Benin City, Nigeria

Authors : Emeka Donald Anyanwu, Flora Ebaimoh Mukah, Precious Chizaram Okani, Amarachi Grace Stephen
Pages : 89-102
Doi:10.51756/marlife.1786428
View : 66 | Download : 163
Publication Date : 2025-12-30
Article Type : Research Paper
Abstract :Increased risk of flooding in many cities and regions has necessitated the inclusion of flood retention lakes in flood control systems. Man-made water bodies can provide significant ecological benefits. The water quality and plankton assemblage of a flood retention lake was assessed using two stations in dry and wet seasons. A total of ten water quality variables and phytoplankton and zooplankton diversity were examined using standard analytical and identification techniques. The lake’s richness and trophic status was also evaluated. The range of water quality parameters such as water temperature (24.00-28.00C), pH (6.10-7.20), electrical conductivity (221.00-560.00 µS/cm), total dissolved solids (113.00 - 279.00 mg/L), turbidity (0.30-2.50 NTU), dissolved oxygen (1.80-3.80 mg/L), biochemical oxygen demand (1.50-4.40 mg/L), phosphate (0.04-0.09 mg/L) and nitrate (0.08-0.29 mg/L) were presented. Dissolved oxygen and biochemical oxygen demand values did not conform to limits while station 2 and dry season had higher values. A total of 50 phytoplankton species comprising 1696 individuals and zooplankton with 35 species comprising 980 individuals were recorded. Shannon-Weiner and diversity index was varied from 3.484 to 3.750 for phytoplankton and from 3.056 to 3.360 for zooplankton. Margalef index fluctuated between 5.159 and 7.314 for phytoplankton and between 4.014 and 5.541 for zooplankton whereas Evenness index ranged from 0.8296 to 0.9057 for phytoplankton and from 0.7815 to 0.8224 for zooplankton. Nygaard indices were Myxophycean (0.72), Chlorococcales (1.84), Diatoms (0.14), Euglenophycean (0.32) and Compound Quotient (4.09) while Rotifera, Cladocera, Copepoda (RCC) index was 39.09%. The presence of some pollution tolerant species was an indication that the lake was tending towards eutrophic condition. The general condition of the lake could be due its design and anthropogenic activities. In conclusion, the lake is still suitable to support plankton and fishery development.
Keywords : Plankton, Taşkın Kontrolü, Çeşitlilik, Endeksler, Besleyici

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