Polyphenols With Algicidal Activity in the Submerged Macrophyte Myriophyllum Spicatum L.

The role of phenols as defence mechanisms in various terrestrial plants is weil studied. However, in aquatic environments, they are probably involved also in the chemical interactions between species. A periodic shift from dominance by submerged macrophytes to dominance by phytoplankton and vice versa without apparent change in the external nutrient loading is sometimes observed in shallow eutrophic lakes. Due to the fact that nutrient levels are not usually limiting to phytoplankton growth, the release of allelochemicals by macrophytes is suspected to be responsible for poor algal growth.