“…In this study, NH þ 4 -N concentration in the water column is higher than 0.3 mg L À1 most of the year, and the FAA contents of these five aquatic plants (7.01 ± 2.08, 8.56 ± 5.08, 4.14 ± 0.85, 5.01 ± 3.10, and 6.06 ± 2.68 mg g À1 DW on annual average for M. spicatum, P. malaianus, V. natans, T. bispinosa and N. peltata, respectively) are much higher than those reported by Cao et al (2008) (FAA: 4.11 ± 3.33, 3.69 ± 2.21, 2.33 ± 1.42, 1.74 ± 0.68, and 3.05 ± 2.05 mg g À1 DW, respectively) for the plants growing in the lakes of this area. The FAA of the plants in this study are even higher especially during the period ''before the blooms'' when MCs in the water column are low and NH þ 4 is high, indicating that the increase in FAA is due mainly to NH þ 4 stress in the lake, but not to the occurrence or decay of the blooms.…”