Comparative approach of the fauna diversity of benthic macroinvertebrates in a stream on ferralitic soil and equatorial climate at 2 seasons in Cameroon (Central Africa)

In order to determine the structure of benthic macroinvertebrates fauna in relation with some environmental factors, a study was carried out in the Esoa river at Nkongsamba in the Littoral region of Cameroon from January 2021 to January 2022. Physico-chemical parameters were measured according to APHA and Rodier recommendations, while benthic macroinvertebrates sampling was done out according to the multihabitat approach at a monthly frequency. The physico-chemical analyses revealed very good oxygenation of the water, a tendency of neutrality for the pH (7.79±0.8 UC) and a low and constant temperature (22.61±1.83 °C). The BMI count showed 3732 individuals, including 4 phyla, 6 classes, 14 orders and 69 families and over 80 species. Besides, the class of insects, and in particular the order of Odonata, supplanted the benthic fauna. The Esoa 2 and Esoa 3 stations recorded the highest relative abundance of BMI (37.43% and 36.99% respectively) with a predominance of pollutant taxa, notably the families of Chironomidae, Physidae, Tubificidae and Lumbricidae. On the other hand, the Esoa 1 station, with low relative abundance (25.56%), was more diversified and dominated by polluosensitive taxa, including Ephemeroptera, Plecoptera and Trichoptera. The high values of the Sӧrensen similarity index (65.62%) showed a high faunal similarity of the Esoa 2 and Esoa 3 stations. The high values of the Shannon and Weaver diversity index (4.6 bits/ind) indicated a high diversity of benthic macroinvertebrates reflecting the good ecological status of the waters of the Esoa stream.