A study aimed to determine the level of water pollution and phytoplankton diversity of two dam ponds (Ngaikada and Kpokolota) in Bertoua city was conducted from March 2016 to April 2017 using a monthly sampling frequency. Water samples were collected at surface directly using a 1L polyethylene vials and at 1.5 m depth using a 6L Van Dorn bottle. Physicochemicals analyzes were carried out according to the standard methods of APHA and Rodier, while the harvesting of phytoplankton organisms was done by direct sampling and analyzed by the Utermôhl method. The results of the physicochemicals analyzes reveal no significant difference (

This work was conducted with the aim of studying the biodiversity of benthic macroinvertebrates in the Dja River and determining the effect of the Mekin hydroelectric dam on their population in relation to the physico-chemical quality of the water. The study ran from May to October 2020 and samplings were carried out on a monthly basis in four different sampling stations located upstream and downstream of the dam. The physico-chemical analyses were done according to standard methods, while the benthic macrofauna was collected using a turbid net of 400 µm mesh size over a total area of about 6 m2 per station. Physico-chemical analyses revealed a decreasing evolution from upstream to downstream of the dam of nitrogen forms (NO3- (1.67mg/L-0.41mg/L); NH4+ (0.31 mg/L-0.21 mg/L) with p>0.05); Electrical Conductivity (21.45µS/Cm-17.1µS/Cm with p<0.05) and Suspended Solids (11.10mg/L-6.57mg/L with p<0.05); while Dissolved Oxygen (49.82%-78.23% with p<0.05) and velocity (0.04m/s-0.23m/s) increased. Organic Pollution Index revealed that the water was moderately polluted (3-4). In total, 1894 individuals, of which 1044 belonging to 2 phyla, 2 classes, 6 orders, 27 families and 47 genera/species were collected upstream; and 850 belonging to 3 phyla, 4 classes, 8 orders, 28 families and 45 genera/species were collected downstream. Odonata was largely abundant and highly represented Trithemis dorsalis (96.05%); while downstream, Heteroptera was largely abundant and highly represented by Poissonia sp1. (79.78%). These results revealed that restoration of the upstream of the dam impacted by organic pollution and physical degradation of the environment is recommended.

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A study aimed at evaluating the health risks of the water used for fish farming in the Obili pond was carried out in January 2021. The variables retained for this work were measured according to standard protocols and are of meteorological order (brightness, air temperature and humidity); physicochemical (water temperature, pH, TDS, color, turbidity, suspended matter, dissolved oxygen, carbon dioxide, electrical conductivity, alkalinity, total hardness, nitrites, nitrates, ammonium, phosphates and potassium) and biological (bacteria, protozoa and helminths). The results obtained show acidic water, weakly saturated with oxygen, nutrients (nitrogen, phosphates and potassium) on one hand and on the other hand highly charged with solid particles. Mesophilic heterotrophic aerobic bacteria (92.5%) constitute the most abundant group of bacteria. Escherichia coli is found only at the entrance to the pond and contributes 1% of the bacterial density. The protozoan community is dominated by coccidia (43%) and amoeba (41%). Cryptosporidium parvum is the most dominant species of coccidia while Entamoeba histolytica dominates in amoeba with 370 oocysts / L and 244 cysts / L, respectively. Nematodes occupy 2/3 of the helminth community and are dominated by Ascaris (240 eggs / L). Diphyllobotrhium latrum shows the highest density in cestodes (572 eggs / L). The presence of these pathogenic organisms at densities above the standards constitutes a real health risk for the use of this water in fish farming. These parasites can directly infect fish farmers through skin penetration or concentrate on the integument and or flesh of fish and infect humans when consumed.