Drinking water sources in many African countries have been progressively degraded over the past decades. This degradation due to human activities leads to the proliferation of algae, especially toxin-producing cyanoba...Drinking water sources in many African countries have been progressively degraded over the past decades. This degradation due to human activities leads to the proliferation of algae, especially toxin-producing cyanobacteria. The presence of toxigenic algae in water has adverse consequences on human and animal health. This study aimed to determine the diversity and density of Cyanobacteria and Desmids and to identify toxin-producing cyanobacteria and environmental variables that influenced the structure of these groups of microalgae in the Loumbila reservoir in Burkina Faso located in the western part of Africa. Algal samples were collected and physico-chemical parameters were measured. Plankton species were observed under a light microscope and identified using standard methods. Species density was determined by cell counting using a Fuchs-Rosenthal chamber. Kruskal Wallis and Pearson correlation tests were performed using R software. A canonical analysis was performed using CANOCO software. In total, 205 algal species were inventoried, of which 83 species composed of 37 species of Cyanobacteria and 46 species of Desmids were identified. <em>Microcystis aeruginosa</em>, <em>Staurodesmus convergens </em>and <em>Cosmarium connatum </em>var <em>africanum</em> had the highest presence index respectively (100%, 83.333% and 77.77%). Among cyanobacteria species, toxin-producing species (30 species) and microcystin-producing species (28 species) had the highest number. In terms of species density, <em>Microcystis aeruginosa</em> was the most abundant species. The density of toxin-producing cyanobacteria was positively correlated (p < 0.05) with temperature, pH, dissolved oxygen, transparency, nitrates, and orthophosphates. However, at p < 0.05, desmids community was only correlated with dissolved oxygen, transparency, and conductivity. Furthermore, canonical analysis showed that temperature, dissolved oxygen, transparency, and orthophosphates influenced the density of both cyanobacteria and Desmids. These results reveal 展开更多
This paper reports two new species, one new variety and fourteen taxa new to China in three genera of the phytoplankton desmids from Donghu Lake, Wuhan, China.
For compilation and comparison of desmids flora, the authors restudied the species composition, cell density and biomass of phytoplankton desmids collected at six stations in Donghu Lake at intervals of three months m...For compilation and comparison of desmids flora, the authors restudied the species composition, cell density and biomass of phytoplankton desmids collected at six stations in Donghu Lake at intervals of three months monitored from March of 1956 to February of 1957. A total of 122 taxa belonging to 16 genera were identified from qualitative and quantitative samples. Species of Cosmarium were the most popular ones occupy- ing about 41 % of the total species. Based on the observations, the annual mean values of the cell density and biomass were 132.11×102 cells/L and 0.09 mg/L. Cosmarium, Staurastrum, Staurodesmus and Closterium dominated and contributed more than 70 % of the total cell density and biomass at six stations in four seasons. The maximum species number, cell density and biomass in autumn revealed that the highest variety (64 taxa, 1296×102 cells/L and 0.889 mg/L respectively) occurred at Station 3 located in the southern part of Donghu Lake. From then on to the mid 1990s the desmids community decreased sharply in Donghu Lake, resulted clearly from eutrophication in the lake.展开更多
文摘Drinking water sources in many African countries have been progressively degraded over the past decades. This degradation due to human activities leads to the proliferation of algae, especially toxin-producing cyanobacteria. The presence of toxigenic algae in water has adverse consequences on human and animal health. This study aimed to determine the diversity and density of Cyanobacteria and Desmids and to identify toxin-producing cyanobacteria and environmental variables that influenced the structure of these groups of microalgae in the Loumbila reservoir in Burkina Faso located in the western part of Africa. Algal samples were collected and physico-chemical parameters were measured. Plankton species were observed under a light microscope and identified using standard methods. Species density was determined by cell counting using a Fuchs-Rosenthal chamber. Kruskal Wallis and Pearson correlation tests were performed using R software. A canonical analysis was performed using CANOCO software. In total, 205 algal species were inventoried, of which 83 species composed of 37 species of Cyanobacteria and 46 species of Desmids were identified. <em>Microcystis aeruginosa</em>, <em>Staurodesmus convergens </em>and <em>Cosmarium connatum </em>var <em>africanum</em> had the highest presence index respectively (100%, 83.333% and 77.77%). Among cyanobacteria species, toxin-producing species (30 species) and microcystin-producing species (28 species) had the highest number. In terms of species density, <em>Microcystis aeruginosa</em> was the most abundant species. The density of toxin-producing cyanobacteria was positively correlated (p < 0.05) with temperature, pH, dissolved oxygen, transparency, nitrates, and orthophosphates. However, at p < 0.05, desmids community was only correlated with dissolved oxygen, transparency, and conductivity. Furthermore, canonical analysis showed that temperature, dissolved oxygen, transparency, and orthophosphates influenced the density of both cyanobacteria and Desmids. These results reveal
文摘This paper reports two new species, one new variety and fourteen taxa new to China in three genera of the phytoplankton desmids from Donghu Lake, Wuhan, China.
文摘For compilation and comparison of desmids flora, the authors restudied the species composition, cell density and biomass of phytoplankton desmids collected at six stations in Donghu Lake at intervals of three months monitored from March of 1956 to February of 1957. A total of 122 taxa belonging to 16 genera were identified from qualitative and quantitative samples. Species of Cosmarium were the most popular ones occupy- ing about 41 % of the total species. Based on the observations, the annual mean values of the cell density and biomass were 132.11×102 cells/L and 0.09 mg/L. Cosmarium, Staurastrum, Staurodesmus and Closterium dominated and contributed more than 70 % of the total cell density and biomass at six stations in four seasons. The maximum species number, cell density and biomass in autumn revealed that the highest variety (64 taxa, 1296×102 cells/L and 0.889 mg/L respectively) occurred at Station 3 located in the southern part of Donghu Lake. From then on to the mid 1990s the desmids community decreased sharply in Donghu Lake, resulted clearly from eutrophication in the lake.
