Find in Library

<i>Raphidiopsis raciborskii</i>, which harms water supply and ecological security, may expand its range with climate warming. To explore the ecological management method of <i>R. raciborskii</i> blooms, the co-culture system of <i>Eichhornia crassipes</i> and <i>R. raciborskii</i> was established to study the inhibitory effect and inhibition mechanism of <i>E. crassipes</i> on <i>R. raciborskii</i> compared with the shaded culture of <i>R. raciborskii</i> alone. It was found that after co-cultured with <i>E. crassipes</i> (fresh weight, 5.10 ± 0.60 g·L⁻¹) for seven days under initial high nutrient concentration, the algal cell density of co-culture groups with an initial cell density of 1.57 × 10⁸ cells·L⁻¹ and 1.57 × 10⁹ cells·L⁻¹ decreased by 63.19% and 14.87%, respectively. Meanwhile, the algal cell density in the co-culture group was significantly lower than that in the control group (<i>p</i> < 0.01). The algal cell density change showed that the growth of <i>R. raciborskii</i> was inhibited by co-cultured <i>E. crassipes</i>. In addition, <i>E. crassipes</i> could significantly reduce the nitrogen and phosphorus content in the water, but the growth state and photosynthesis of <i>E. crassipes</i> were not inhibited by <i>R. raciborskii</i>. These results suggested that <i>E. crassipes</i> has the potential to control <i>R. raciborskii</i> blooms. The study also found that when co-cultured, there was no significant difference in algal cell density between the groups supplemented with a certain amount of nutrients and the group without additional nutrients. Meanwhile, the inhibition rates of the co-culture groups were over 99% on day 4. These results showed that nutrient factors had no significant effect on the inhibitory effect of <i>E. crassipes</i> in the range of nutrients regulated by the experiment, and other factors played a leading role. In other words, under experimental conditions, nutrient competition was not the primary inhibitory mechanism of <i>E. crassipes</i>. This study also confirmed that <i>E. crassipes</i> had inhibitory allelopathy on <i>R. raciborskii</i>. The contribution and significance of allelopathy and other mechanisms could be studied in the future.