Microalgal structure and diversity in some canals near garbage dumps of Bobongo basin in the city of Douala, Cameroun

Anarchical and galloping anthropization is increasingly degrading the wetlands. This study aimed at determining the structure, diversity and spatiotemporal variation of microalgae from a few canals in the vicinity of garbage dumps of the Bobongo basin to propose methods of ecological management of these risk areas. Sampling took place from March 2016 to April 2019. Pelagic algae as well as those attached to stones and macrophytes were sampled in 25 stations. These algae samples were brought back to laboratory for identification and counting. The specific richness amounts to 13 classes, 34 orders, 52 families, 69 genera and 116 species. The dominant class is that of Bacillariophyceae (33 species) with a proportion of 28.45%. Results based on correspondence factor analysis revealed 3 groups of stations (clusters): the group I from stations 16, 21 and 25 consisted of exclusive species such as Cyclotella ocellata, Cymbella gamma, Gomphosphaeria natans, Navicula cryptocephalla and Tabellaria flocculosa. Group II from stations 18, 22, 23 and 24 consisted of exclusive species such as Aphanizomenon flosaquae, Aphanocapsa holsatica, Astasia limpida and Ulothrix zonata. Group III was made up of species common to all stations. Cyclotella ocellata, Cymbella gamma, Gomphosphaerium natans, Navicula cryptocephalla and Tabellaria flocculosa are hydrocarbon-polluting species. Our analysis is, to our knowledge, the first demonstrate the use of microalgal species as indicators of pollution in the context of environmental management for better monitoring of the quality of watercourses. In addition, these species can be used as bio-purifiers of polluted water in hydrocarbon.