Diversity of Cyanobacteria in Some Polluted Wetlands of Nkwen in Bamenda (North-West, Cameroon)

Abstract

Human activities more and more intensify the pollution of aquatic ecosystems. These pollutants lead to some Cyanobacteria proliferation causing “blooms” or “efflorescence” and disappearance of sensitive species. The aim of the study was to determine the composition and variation of Cyanobacteria community in some polluted wetlands of Nkwen in Bamenda. Sampling of Cyanobacteria took place from October 2022 to September 2023 by using plankton net for phytoplankton and scrubbing for periphyton. Some hydromorphological and physicochemical parameters of water were measured in situ and in the laboratory. Results showed that species richness of microalgae amounted to 11 families divided into 22 genera and 46 species. Oscillatoriaceae constituted the most important family (26.66% with 12 species) of the Cyanobacteria community, in the study sites. Shannon-Weaver’s index was weak and varied between 1.24 (site 6) and 2.65 (site 2). These results showed that wetlands of Nkwen had a Cyanobacteria community more abundant where the water velocity is low, with high nitrates and phosphates contents. Different Cyanobacteria families with strong proliferation in polluted waters (sites 1, 2 and 3) were: Oscillatoriaceae, Gloeotrichiaceae, Rivulariaceae, Nostocaceae, Merismopediaceae, Microcoleaceae, Microcystaceae and Tolypotrichaceae. On the other hand, the families abundantly present in less polluted waters (sites 4, 5 and 6) were: Chroococcaceae, Pseudanabaenaceae and Aphanizomenonaceae. Thus, physicochemical parameters have an influence on the composition and structure of Cyanobacteria community in wetlands of Nkwen in Bamenda. Monitoring, based on biological indices of Cyanobacteria, could be developed to prevent the risks of perturbation of these wetlands.