Taxonomic diversity of phytoplankton and trophic status of the waters

Water quality at the Jacqueville aquaculture station was assessed using physico-chemical parameters and phytoplankton communities. Six stations were surveyed monthly from January to December 2020. In situ measurements were taken using conventional methods. Water samples were taken using polyethylene bottles, a plankton net and a hydrological bottle to analyse nutrient salts and phytoplankton respectively. In addition, taxonomic composition, structure, chlorophyll a and trophic status were determined. A total of 165 phytoplankton taxa were identified, including approximately 35.15% Cyanoprocaryota, 32.12% Chlorophyta, 18.79% Bacillariophyta, 9.02% Euglenophyta, 4.24% Dinophyta and 0.61% Chrysophyta. Variations in the composition of the populations between stations were relatively low, with higher diversity at station S1 (Heterobranchus longifilis rearing, located 130 m from the bank) (117 taxa) and low diversity at stations S5 and S6 (no rearing, located 100 m and 500 m from S1 respectively) (100 taxa). Taxa most commonly encountered during the study were Microcystis aeruginosa, Pseudanabaena limnetica, Peridinium inconspicum, Aphanocapsa incerta and Aulacoseira granulata. Cyanoprocaryota branches is the most abundant taxonomic group at all stations, with 61 taxa in common. Abundance of phytoplanktonic algae reached maximum values in the rainy season at all the stations except station S4 (no breeding, located 30 m from S1). Trophic status based on chlorophyll biomass and the Carlson trophic index shows that the waters of the Jacqueville aquaculture station are eutrophic.