Interactions between atrazine and phosphorus in aquatic systems: Effects on phytoplankton and periphyton

► Atrazine has been reported to increase periphyton growth via indirect mechanisms. ► Atrazine commonly co-occurs with high nutrient runoff, which also increases growth. ► We examined effects of atrazine and phosphorus (P) on algae in a 63-d microcosm study. ► P reduced the apparent effect of atrazine on photosynthetic outputs (e.g., DO). ► No treatment-related effects on phytoplankton or periphyton biomass were observed.