Ousmane SANGARE¹, Azonwakin Rodrigue AKOTEGNON^1,, Yabyouré Marc-Florent SAWADOGO², Adama OUEDA², Fanta TOURE¹

The study of the phytoplankton community was conducted during the dry, intermediate, and rainy seasons between December 2018 and December 2019 in order to assess phytoplankton diversity. A 2.5-liter Van Dorn plankton bottle was used for sampling. A total of 2,629 specimens belonging to 11 taxa were collected. These taxa are distributed across the following eleven (11) classes: 54 Cyanophyceae, 72 Euglenophyceae, 50 Conjugatophyceae, 143 Chlorophyceae, 29 Dinophyceae, 28 Rhodophyceae, 55 Zygnematophyceae, 18 Xanthophyceae, and 1,936 Diatoms or Bacillariophyceae distributed across 47 genera. The Diatom class was dominated by Coscinodiscus granii and Cyclotella spp. (representing more than 1.90% and 1.86% of the total species, respectively). The study of seasonal variation of physicochemical parameters on the phytoplankton community in the Fatala estuary showed that the correlation matrix performed to evaluate the relationships between physicochemical and biological parameters revealed significant correlations only between temperature and the phytoplankton community, total diatoms, and pennate diatoms (r = 0.361; 0.356; 0.384, respectively) (p < 0.05). In contrast, salinity was significantly correlated, positively with temperature (r = 0.443) and negatively with nitrates and nitrites. This study provided the first qualitative and quantitative inventory of the phytoplankton community of the Fatala estuary prior to mining activities of the Boffa1 project. These results serve as a reference for future monitoring of the phytoplankton community and for the development of appropriate measures to ensure better protection and sustainable exploitation of the aquatic resources of this estuary.

Seasonal variation, physicochemical parameters, phytoplankton, inventory, Fatala