Invasive submerged plant has a stronger inhibitory effect on epiphytic algae than native plant

The invasion of submerged aquatic plants potentially results in a loss of native biodiversity in these ecosystems. There has been little attention paid to the impact of invasive submerged plants on epiphytic algal communities. We conducted a 30-day outdoor mesocosm experiment on the shore of subtropical Lake Liangzihu, China, to investigate the effects of two submerged plant species, an invasive species (Elodea nuttallii) and a native species (Hydrilla verticillata), on epiphytic algal communities. We also explored the relationship between macrophyte secondary metabolites and epiphytic algae by conducting a laboratory cultivation experiment. Our results indicate that the epiphytic algal communities on the invasive plant had lower biomass, photosynthesis, abundance, and richness, compared to those on the native species. Secondary metabolites were significantly higher in the invasive plant compared to the native species. Secondary metabolites of plants had the greatest impact on the composition and traits of the epiphytic algal community. The slopes of epiphytic algal community traits were lower across gradients of native plant biomass and secondary metabolites compared to those across gradients of the invasive plant. Our findings suggest that the invasive plant E. nuttallii has a stronger inhibitory effect on epiphytic algae than the native species H. verticillata. This is due to the invasive plant's higher concentrations of secondary metabolites, which limit the growth of epiphytic algae. These findings emphasize the importance of native aquatic vegetation restoration for biodiversity conservation in shallow aquatic ecosystems, considering the impact of invasive species on epiphytic algal communities.

Automated summary

The invasion of submerged aquatic plants potentially leads to a loss of native biodiversity in aquatic ecosystems. This study investigates the effects of invasive and native submerged plant species on epiphytic algal communities and explores the relationship between macrophyte secondary metabolites and epiphytic algae. The results demonstrate the stronger inhibitory effect of the invasive plant species on epiphytic algae, which is attributed to its higher concentrations of secondary metabolites.