Water brownification may not promote invasions of submerged non-native macrophytes.
Some environmental factors, such as brownification and eutrophication, may influence the successful invasions of non-native submerged macrophytes. However, few studies have focused on how interactions between these factors influence the performance of exotic submerged plants. Here, we conducted an experiment in 60 indoor containers (170 l) over 68 days using the native species Hydrilla verticillata (L. f.) Royle and the non-native species Elodea nuttallii (Planch.) St. John to test the effects of brownification, eutrophication and their interactions on the growth and competition of native and non-native aquatic plants. Our results showed that the biomass of both H. verticillata and E. nuttallii increased in the brown water treatment and that eutrophication and water brownification did not lead to a shift from a native species-dominated system to a non-native-dominated system. However, brown water treatment decreased the relative competitive ability of E. nuttallii, and this decrease was exacerbated when brown water and nutrient treatments were combined. Our results indicated that some environmental factors, such as water brownification, eutrophication and their interactions, may not benefit the competition of some non-native submerged macrophytes. Further studies with more species are needed to corroborate these conclusions.