In Cameroon, the environmental profile is increasingly marked by anarchic urbanisation, which is strongly illustrated by the discharge of waste into the aquatic environment, leading to pollution. Indeed, the tributaries of the Mfoundi and Mefou river basins have nowadays become dumping grounds and receptacles for all kinds of waste, leading to the degradation of water quality and a reduction in biodiversity. This study aims to evaluate the effect of anthropogenic pressure on the biodiversity of benthic macroinvertebrates in three rivers of the Mfoundi basin (Ebogo, Abiergue, and Ako’o). For this purpose, some physicochemical parameters were measured according to standard methods, and benthic macroinvertebrates were collected according to the multihabitat approach. To this end, the physicochemical analyses revealed that the waters of these different streams are slightly basic and poorly oxygenated, with a saturation rate of 9.725 ± 11.74% and significant organic pollution. Biologically, a total of 5793 benthic macroinvertebrates divided into three phyla, eight orders, and more than thirty families were collected, with a population dominated by the order of insects and a low level of diversity dominated by pollutant organisms such as the Chironomidae, Lumbriculidae, and Physidae, which are saprobionts and saprophilous organisms. A redundancy analysis indicated that the main groups of benthic macroinvertebrates obtained were related to the gradients of the physicochemical parameters measured. The Shannon–Weaver diversity and Piélou equitability indexes showed the low diversity of the organisms within the different courses and their low equipartition, mainly due to the saprobiont and saprophilous groups that dominate the population. The exogenous inputs due to the increase in the population of the city of Yaoundé, which dumps its waste into the waterways, have major repercussions on the quality of the water and the population that abounds in this environment, particularly the benthic macroinvertebrates, which are an important link in the monitoring of water quality.

Urban sprawl leads to the degradation of aquatic environments and, consequently, to the destruction of biodiversity. With the aim of highlighting the distribution profile of benthic macroinvertebrates in the city of Yaoundé and its surroundings according to the level of degradation, this study was carried out in seven rivers. A total of 144 taxa of benthic macroinvertebrates, belonging to 74 families, 15 orders, five classes, and three phyla, were collected from seven rivers in urban, peri-urban, and forest environments on Yaoundé and its surroundings. The self-organizing map (SOM) analysis tool was used to group the collected taxa from all stations into three clusters or affinity cores. The indicator value analysis (IndVal) method was employed to determine, based on their ecological preferences, which organisms were most likely to belong to each group. Out of the 144 collected taxa, only 44 were indicated to represent the three different groups. Thus, three communities were defined: the Hydropsyche community, with Hydropsyche sp. as the predominant taxon in Group III, characterizing well-oxygenated and low-mineralized stations; the Hydrocyrius community, where the species Hydrocyrius sp. predominates in Group I, describing stations with low oxygenation and moderate mineralization; and the Lumbriculidae community, where Lumbriculidae is the taxon associated with environments with high mineralization and critical oxygenation. These two methods contribute to the biomonitoring of tropical aquatic environments, firstly by grouping organisms by affinity and then identifying those that reflect the environment conditions. This facilitates the detection of changes in the quality of hydrosystems and guides management and conservation efforts.

Monitoring of water quality and distribution of some benthic macroinvertebrates was carried out in a few control watercourses in the Mefou watershed, from August 2022 to June 2023 with the aim of identifying some ecological factors that influence the distribution of benthic organisms in forest areas. The evaluation of granulometric and physicochemical quality was carried out following the appropriate methods and the collection of benthic organisms following the multihabitat approach. The analysis of the particle size parameters shows that the coarse fraction dominates all the points explored, although the beginning of siltation was observed in the middle part of the Abouda and Fam rivers. Physico-chemical analyses revealed a relatively stable environment with well-oxygenated water, low values of organic pollution indicator parameters and low and constant temperatures throughout the watersheds. The analysis of the biological structure shows a total of 8483 individuals collected, all belonging to the arthropod phylum and the insect class. From the orders obtained, Hemiptera dominate the benthic fauna with 6 identified families. The organisational structure of the benthic community was analysed through the calculation of diversity and fairness indices and allows us to affirm that the benthic macroinvertebrate community is diverse and well organised.

Water is an essential yet scarce commodity for human life due to its many uses. Depending on their condition, bodies of water can improve or degrade living conditions. The Mvila watershed in southern Cameroon, which experienced archaic urbanization coupled with incivism and urban disorder, was the site of a study examining the relationship between the ecology of benthic macroinvertebrates and abiotic parameters. This study was conducted monthly from December 2018 to December 2019. It involved sampling benthic macroinvertebrates and collecting water samples using standard methods. For the most part, the physicochemical parameters remained within the standards prescribed by the water quality grid. Throughout the study, the Sounou stream had the highest abundance of benthic macroinvertebrates, followed by the Lo'o and Bengo streams. For the trophic groups, predators were the most abundant, while filter feeders were the least abundant. Canonical correspondence analysis revealed that certain physicochemical parameters had a negative influence on benthic macroinvertebrate taxa, while others had a positive impact on them. The parameters that negatively influenced them were temperature, pH, and conductivity, while the parameters that positively influenced them were suspended solids, colour, and turbidity. Finally, Shannon and Weaver's diversity indices and Pielou's evenness indicate a rich and diverse living environment with an equal distribution of organisms among the studied rivers. In conclusion, some environmental factors, such as temperature, pH, conductivity, and dissolved oxygen, influence the diversity and distribution of macroinvertebrates.

Seasonal variations are responsible for many of the disturbances observed in watercourses. This study aims to evaluate the seasonal dynamics of benthic macrofauna in the Metyi, Bengo, Sounou, and Lo’o watercourses in the Mvila Division. Sampling of benthic macroinvertebrates was carried out in 12 stations using the multi-habit/indat approach, using a 30 cm square dip net fitted. 3404 individuals of benthic macroinvertebrates (43.48% relative abundance) were counted in long dry season (LDS), 1839 individuals (23.49% relative abundance) in short rainy season (SRS), 1696 individuals (21.67% relative abundance) in long rainy season (LRS), and 889 individuals of benthic macroinvertebrates (11.36% relative abundance) in short dry season (SDS). In terms of diversity, a total of 174 taxa were identified: 111 in the LDS, 106 in the SRS, 92 in the LRS, and 51 in the SDS. Shannon and Weaver’s diversity index showed the lowest value in SDS, while its highest value was recorded during SRS, as was Pielou J Equitability index. The similarity index suggests that the seasons differ from one another. The LDS had the highest species richness and abundance, while the SRS had the highest diversity value according to Shannon and Weaver.