Aquatic macrophytes are aquatic photosynthetic organisms, large enough to see with the naked eye, that actively grow permanently or periodically submerged below, floating on, or growing up through the water surface. Aquatic macrophytes play an important role in the structure and function of aquatic ecosystems and certain macrophytes species are cultivated for human consumption, yet several of the worst invasive weeds in the world are aquatic plants. Many of the threats to fresh waters (e.g., climate change, eutrophication) will result in reduced macrophytes diversity and will, in turn, threaten the faunal diversity of aquatic ecosystems and favor the establishment of exotic species, at the expense of native species.