Characteristics and Dynamic of Algal Communities in a New Impounded Hydro-Agricultural Dam Lake (Samendeni Reservoir) in Burkina Faso (Western Africa)

Abstract

Proliferation of microalgae is the result of a complex interaction between hydrological and physico-chemical variables influenced by climatic and anthropogenic factors. This study assessed algal communities in the Samendeni Dam Lake to serve as indicators of water quality for sustainable management of hydro-agricultural water resources. Therefore, physico-chemical parameters and microalgae were monitored in three sampling zones from November 2021 to October 2022. A comparison of physico-chemical parameters was realized between sampling zones and between seasons. CCA and RDA were used to establish the relationship between parameters and microalgae. The results show 96 species belonging to 46 genera, 30 families, 19 orders, 9 classes, and 7 phyla. Charophyta dominated microalgal communities in both dry and rainy seasons. Phytoplankton species reached 34 in the dry season and 41 in the rainy season, whereas periphyton revealed 41 species in both seasons. Phytoplankton abundances ranged from 213 to 5440 cells·mL −1 and 3 to 110 cells·cm −2 for periphyton. At p < 0.05, significant correlation of Charophyta with pH (r = 0.39, p-value = 0.04), EC (r = −0.41 - 0.91, p-value = 0.00 - 0.03), Transp (r = 0.73, p-value = 0.03), Ammo (r = 0.48, p-value = 0.01), Nitra (r = 0.81, p-value = 0.01), Nitri (r = 0.91, p-value = 0.00) was observed. Bacillariophyta significantly correlated to pH (r = 0.70, p-value = 0.04), EC (r = −0.51 - 0.94, p-value = 0.00 - 0.04), DO (r = −0.70 - 0.81, p-value = 0.01 - 0.04), Transp (r = −0.71 - 0.73, p-value = 0.02 - 0.03), Nitra (r = 0.84, p-value = 0.00) and OrthoP (r = 0.44 - 0.73, p-value = 0.02 - 0.03). Chlorophyta was significantly correlated to EC (r = −0.41 - 0.95, p-value = 0.00 - 0.03), Transp (r = −0.52, p-value = 0.01), Nitra (r = 0.71, p-value = 0.03), Ammo (r = 0.42, p-value = 0.03). Cyanophyta showed significant correlation with pH (r = 0.43, p-value = 0.02); EC (r = 0.68, p-value = 0.04), Transp (r = −0.44, p-value = 0.02), OrthoP (r = 0.44 - 0.54, p-value = 0.00 - 0.02) and Ammo (r = 0.43, p-value = 0.02). Ochrophyta significantly correlated to Nitra (r = 0.42, p-value = 0.03). While Charophyta and Chlorophyta species in the dam lake indicate relatively good water quality, recorded harmful Cyanophyta species show a possible deterioration of the habitat. Therefore, continuous water quality monitoring since the construction of dam lakes should be performed for careful water management.