Effect of paraquat on the growth, antioxidant response and allelopathic interaction between Chlorella vulgaris and Selenastrum capricornutum
摘要
The widespread presence of herbicides in aquatic environments has heightened the need to understand their effects on photosynthetic organisms, such as microalgae. In freshwater ecosystems, factors such as nutrient fluctuations and micropollutants, including herbicides, influence the coexistence and succession of microalgae. This study explored the impact of the herbicide paraquat on allelopathic interactions between Chlorella vulgaris UTEX 2714 and Selenastrum capricornutum. Our findings revealed that paraquat reduced cell density in both species under monoculture and co-culture conditions. In the presence of paraquat and C. vulgaris, the growth of S. capricornutum was suppressed, demonstrating complex allelopathic interactions. However, paraquat exposure led to a decline in cell densities in co-cultures. Chlorophyll-a and total chlorophyll contents were stable in co-cultures without paraquat but decreased in its presence. Glutathione S-transferase (GST) activity rose in both co-cultures, regardless of paraquat exposure. Notably, S. capricornutum exhibited a significant reduction in specific growth rate (day−1) when co-cultured with C. vulgaris and exposed to paraquat, indicating susceptibility to oxidative stress-induced growth inhibition. These findings emphasize the influence of paraquat on allelopathic interactions between C. vulgaris and S. capricornutum, highlighting its ecological implications for freshwater ecosystem management.