Stresses of Eutrophic Lake Sediment on Submersed Macrophytes Ι.Effects of Acetic Acid on Germination and Bud Growth of Elodea nuttallii and Potamogeton crispus

Anaerobic digestion of organic matters will produce organic acids,in which acetic acid is dominant.Propagules and buds of Elodea nuttallii and Potamogeton crispus were exposed to acetic acid concentrations from 1 to 16 mmol/L for 3 or 6 days,and then they were subsequently cultured in absence of acetic acid.Results showed P.crispus was more tolerant to acetic acid than E.nuttallii.At acetic acid concentration of 1 mmol/L,E.nuttallii propagules germinated normally,but the buds was significantly inhibited(p<0.05)in growth and the recovery in the subsequent culture was slow. Exposures to(4 mmol/L)or higher caused death of E.nuttallii.In contrast,at concentration of 4 mmol/L,all P.crispus buds survived with significant growth and had a good recovery in the subsequent culture;P.crispus(turions)were remarkably reduced in gerimination rate,but all sprouted in the subsequent culture.(How-)(ever),exposures to 8 mmol/L for 6 days or to 16 mmol/L for 3 or 6 days led to death of P.crispus.The study showed that presence of acetic acid in sediment might cause great difficulties in reestablishing submerged macrophytes in eutrophic lakes,and that P.crispus was more suitable than E.nuttallii to be established as pioneer species.