Individual and summary effect sizes of cyanobacteria abundance in summer. Shown here are individual effect sizes based on all meta-analysable data during manipulation (D) and 1–3 years after manipulation, and also for each of the first 7 years after manipulation. Summary effect sizes based on the selected dataset are shown during manipulation and the first 5 years after manipulation. ‘Before’ and ‘During’ periods have been defined as in Figures 5 and 6. Forest plots showing individual effect sizes from the selected dataset are presented in Additional file 10 (p. 23).