Impacts of bisphenol A on growth and reproductive traits of submerged macrophyte Vallisneria natans.

Bisphenol A (BPA) is considered a contaminant of emerging concern and interferes with the normal activities of living organisms. The toxicity of BPA is evident in animals and terrestrial plants. However, the response of aquatic plants to low BPA concentrations is still unclear. In the present study, effects of varying BPA loadings (targeting at 0.01, 0.1, and 1 mg/L) on the growth and reproductive traits of the dioecious annual submerged macrophyte Vallisneria natans were assessed through a 5-month experiment. The results showed that BPA inhibited the elongation of V. natans leaves but resulted in an increase in leaf number and ramet number under the highest BPA loading treatment (targeting at 1 mg/L). In addition, detectable biochemical changes in the total carbon and soluble sugar contents were found, which both were significantly higher at the highest BPA loading treatment. However, the total biomass did not alter significantly after the BPA treatments, indicating that BPA did not induce direct toxic effects on the growth of V. natans. At the highest BPA loading treatment, female individuals of V. natans allocated less number for ramet than male ones, showing a clear sexual dimorphism. No significant differences between the five treatments were found for the flower or fruit traits, while the germination rate was significantly inhibited for the seeds collected from the highest BPA loading treatment. In conclusion, V. natans tolerated low concentrations of BPA by making a trade-off between ramet (leaf) number and leaf elongation, as well as modulating the total carbon and soluble sugar contents. However, serious consequence of decline in seed viability implied that the impact of BPA on plant reproduction were usually underestimated.