FIGURE 3 Species number and density of macrobenthos under different treatments at different times. (A) Overview of the composition of macrobenthos, different colors show the different species, the length of bar indicates the density of each species. (B) Species number and (C) density of macrobenthos in different treatments at different times, the different lowercase letters indicate signi fi cant differences between groups (p < 0.05). Red symbols and lines show high concentration plots, green symbols and lines show low concentration plots, blue symbols and lines show untreated control