Phosphorus stoichiometric homeostasis of submerged macrophytes and associations with interspecific interactions and community stability in Erhai Lake, China.

• Submerged macrophytes exhibited phosphorus stoichiometric homeostasis (H P). • H P value dictated submerged macrophyte community stability. • Eutrophication altered interspecific interactions among submerged macrophytes. • Decline of high- H P species reduced community stability. According to stoichiometric homeostasis theory, eutrophication is expected to increase the dominance of submerged macrophytes with low homeostatic regulation coefficients (H) relative to those with high H values, ultimately reducing macrophyte community stability. However, empirical evidence supporting this hypothesis is limited. In this study, we conducted a three-year tracking survey (seven sampling events) at 81 locations across three regions of Erhai Lake. We assessed the H values of submerged macrophyte species, revealing significant H values for phosphorus (P) and strong associations of H P values (range: 1.58–2.94) with species and community stability. Moreover, in plots simultaneously containing the dominant high- H P species, Potamogeton maackianus , and its low- H P counterpart, Ceratophyllum demersum , we explored the relationships among eutrophication, interspecific interaction shifts, and community dynamics. As the environmental P concentration increased, the dominance of P. maackianus decreased, while that of C. demersum increased. This shift coincided with reductions in community H P and stability. Our study underpins the effectiveness of H values for forecasting interspecific interactions among submerged macrophytes, thereby clarifying how eutrophication contributes to the decline in stability of the submerged macrophyte community. [Display omitted] [ABSTRACT FROM AUTHOR]