Fluoxetine induces changes in community structure, biochemical composition, antioxidant response and primary productivity of phytoplankton

Domestic and industrial effluents contain substantial amounts of micropollutants, such as pharmaceuticals, which may influence the balance of the phytoplankton community. A mesocosm approach was used to determine the effects of different fluoxetine concentrations (20 ng L⁻¹, 20 µg L⁻¹, and 20 mg L⁻¹) on phytoplankton community structure, biochemical composition, antioxidant response, and primary productivity. The total cell density of the phytoplankton community was in the order of control > 20 µg > 20 ng > 20 mg by the 21st day of the experiment. On day 21, the phytoplankton community had chlorophyll a content in the order of 20 mg > 20 µg > 20 ng > control, but these changes were not significant (p > 0.05). Beta diversity results revealed that fluoxetine significantly affected the community structure and dynamics of exposed phytoplankton. Reactive oxygen species, malondialdehyde and peroxidase levels were significantly altered by changes in fluoxetine concentrations. Protein content increased at 20 µg L⁻¹ and decreased at 20 ng L⁻¹ and 20 mg L⁻¹ by day 21 of the experiment. These results suggest that, even in the ng L⁻¹ range, fluoxetine could contribute to the reshaping of phytoplankton community structure and dynamics in aquatic ecosystems.