RDA ordination plot of macroinvertebrate community. Arrows indicate gradients in the three selected variables after stepwise forward selection (i.e. concentration of oxygen = O₂, concentration of total phosphorous = P_tot, and amount of E. coli = E.coli). Labels indicate the macroinvertebrate community composition for each station (D = downstream; U = upstream) on each sampling occasion (year_month). Ellipses represent standard errors around the centroids for the downstream station (solid line) and upstream station (dashed line).