Environment & Ecosystem Science (EES)

Zooplankton biodiversity and water quality of the Mfou municipal lake was carried out from April to September 2014, following a monthly sampling frequency. Sampling for physicochemical analyses was carried out by direct sampling at the surface and along the water column using a 6L Van Dorn bottle. Zooplanktons were collected by filtering 100 L of water taken from the seagrass beds of the municipal lake, through a 64 μm mesh sieve. The 100 ml retentate collected was fixed with 10 ml of Formalin 5% and used for identification and counting. Physicochemical analyses revealed that the water of the Mfou municipal lake was relatively hot (25.5 ± 1.31°C), slightly acidic (6.95 ± 0.41 CU), moderately oxygenated (52.72 ± 12.27%), poorly mineralized and low loads of organic matter. A homogeneous quality of the water column (p > 0.05) and a low organic pollution with nitrogen as limiting factor of eutrophication (N/P Ratio = 12.88 ± 12.52) was observed. These characteristics enable to classify the Mfou municipal lake as mesotrophic. Biologically, 42 zooplankton species were recorded, including 29 species of Rotifers (69.05%), 10 species of Copepods (23.81%) and 3 species of Cladocerans (7.14%). A total zooplankton density was 2209 ind/L dominated by Rotifers with 933 ind/L (42%) mainly represented by Brachionus falcatus (188 ind/L), followed by Copepods with 827 ind/L (38%) dominated by Ectocyclops hisurtus (77 ind/L) and Cladocerans with 449 ind/L (20%) mainly represented by Moina micrura (344 ind/L) was recorded during the study period. These zooplanktons were quite diverse (H’ = 4.22 ± 0.27 bits/ind) with a tendency towards an even distribution of species (E = 0.73 ± 0.05). The abiotic typology classifieds the lake into three groups according to the major origin of the pollutants while the biotic typology classifieds them into three groups according to the tolerance of the zooplankton species to organic matter. This lake is experiencing the early stage of anthropogenic disturbance. Regular hydrobiological studies are needed for monitoring the ecology of this hydrosystem.