Periphyton density is similar on native and non-native plant species

Non-native plants increasingly dominate the vegetation in aquatic ecosystems and thrive in eutrophic conditions. In eutrophic conditions, submerged plants risk being overgrown by epiphytic algae; however, if non-native plants are less susceptible to periphyton than natives, this would contribute to their dominance. Non-native plants may differ from natives in their susceptibility to periphyton growth due to differences in nutrient release, allelopathy and architecture. Yet, there is mixed evidence for whether plants interact with periphyton growth through nutrient release and allelopathy, or whether plants are neutral so that only their architecture matters for periphyton growth.
We hypothesised that (1) non-native submerged vascular plants support lower periphyton density than native species, (2) native and non-native species are not neutral substrate for periphyton and interact with periphyton and (3) periphyton density increases with the plant structural complexity of plant species....