Diversity and Structure of Microalgae in the Mezam River (Bamenda, Cameroon)

Abstract:

Human activities more and more intensify the imbalance of aquatic systems causing the reduction of biodiversity. The aim of the study was to identify the microalgae and to determine their distribution in the Mezam River (Bamenda, Cameroon). Sampling took place monthly from July 2021 to August 2022 using plankton net for phytoplankton and scrubbing for periphyton upstream, middle, and downstream of the river. Species richness of microalgae amounts to 11 classes divided into 45 genera and 75 species. The most represented class was Bacillariophyceae with 42.67% and the dominant family was the Naviculaceae in terms of abundance with 10 species. Shannon-Weaver diversity index ranges from 2.055 (downstream) to 1.313 (upstream). Spatio-temporal variation of genera revealed 3 groups; group 1 brings together the genera exclusive to phytoplankton, upstream: Pleurotaenium, Synechocystis, Microcystis, and Phormidium. Group 2 brings together the genera exclusive to epiphyte, middle: Encyonema, Trachelomonas, Gloeotrichia, Aphanizomenon, and Peridinium. Group 3 brings together the common genera in the different habitats: Fragilaria, Gomphonema, Synedra, Coscinodiscus, Navicula, Cyclotella, Cymatopleura, Cymbella, Eunotia, Tabellaria, Gyrosigma, Melosira, Pinnularia, Diatoma, Cocconeis, Thalassiosira, Achnanthidium, Nitzschia, Luticola, Rhopalodia, Euglena, Clostrium, Ulothrix, Cryptomonas, Scenedesmus, Spirogyra, Uronema, Mougeotia, Oedogonium, Calothrix, Nostoc, Rivularia, Oscillatoria and Gymnodinium. These results show that Mezam River has a highly diversified community of diatoms that can be used as bio-indicators of pollution.