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.

No abstract

A study aimed at evaluating the abundance and the diversity of staphylococci in surface and underground water points was carried out in the city of Yaoundé during the period from February to August 2020. The bacteria sought were heterotrophic bacteria aerobic mesophiles (BHAM) and staphylococci. They were isolated by the technique of surface spreading on a Petri dish on PCA (Plate Count Agar) and the membrane filter technique on Chapman mannitol medium (Mannitol Salt Agar), for BHAMs and staphylococci respectively. The bacteria isolated were identified by standard methods. Some abiotics parameters were measured according to usual analytical techniques. These analyses show that the abiotic variables have varied throughout from one sampling period to another and from one point to another. Thus, it was noted that the waters are acidic and not very mineralized. The high nitrogen and orthophosphate values recorded at all the sampling points testify to the richness of organic matter in the water analysed. Bacteriological analyses revealed that these waters harbor a high density bacterial microflora consisting of BHAM and bacteria of the genus Staphylococcus. In fact, concerning the BHAMs, their mean densities in CFU per 100 ml were 4, 42 and 4, 13 respectively in the Olézoa stream and the various wells. In addition, Staphylococcus aureus and Staphylococcus epidermidis are the different species of genus Staphylococcus found with an average density of 4, 26 log CFU/100 ml and 2, 79 log CFU/100 ml for Staphylococcus aureus and 1, 11 log CFU/100 ml and 2, 79 log CFU/100 ml for Staphylococcus epidermidis respectively in the Olézoa stream and the different wells studied in the Olézoa watershed. The densities of staphylococci in the wells were less abundant but more diversified than those in watercourse. Significant correlations were observed between these germs and parameters such as electrical conductivity, color, suspended matter, dissolved O2, dissolved CO2, PO43- and NH4+. The degradation of the quality of these waters is favoured by their proximity to the sources of pollution with sampling stations, the exogenous inputs and the poor maintenance of the wells. These waters without any treatment, are not recommended for human consumption according to the World Health Organization standards.

No abstract