Fig. 7: Interspecific relationships between primary producers.

a Interspecific relationships between primary producers on day 30, b interspecific relationships between primary producers on day 60, c interspecific relationships between primary producers on day 90. The solid arrows indicate the relative growth advantage between Potamogeton maackianus and Hydrilla verticillata in treatment P + H, and the arrows point from advantaged to disadvantaged species; values indicate the specific relative growth advantage (mean ± standard errors). The dotted arrows indicate the inhibition ratio of phytoplankton (IRP) by submerged macrophytes in PM and HV, the values indicate the IRP (µg g⁻¹) or the specific RGA. Red indicates eutrophic conditions and blue indicates oligotrophic conditions. Different lowercase letters represent significantly different RGAs or the IRP between oligotrophic and eutrophic conditions (p < 0.05). The one-way analysis of variance (ANOVA) of the relative growth advantage see Fig. 3d, and the two-way ANOVA of the IRP by submerged macrophytes see Table 1 and Fig. 6.