ABSTRACT
This chapter reviews and synthesizes findings of consumer effects on nonnative seaweeds. It also reviewes and summarizes the literature that assessed the effects of herbivory on the competitive outcome between non-native and native seaweeds in a community. In particular, filamentous red non-native seaweeds were of low palatability to native herbivores. Analysis of the herbivore grouping revealed that arthropods and echinoderms found non-native seaweeds less palatable than native seaweeds, whereas molluscs and fish did not show any preference. Marine herbivores affect seaweed biomass and community structure in marine habitats across the globe. Seaweed communities are strongly dominated by generalist herbivores, which are more likely than specialists to include newly encountered species into their diet. Herbivore-plant interactions have long been suggested to be crucial also for the outcome of plant invasions. However, to assess if consumers play a crucial role in seaweed invasions, future research should focus on examining consumer impacts on competitive interactions between non-native and native seaweeds.
