| Abstract: | The Dry Matter Content (DMC), the total phenolic content, the production of new branches and the plant fragmentation were compared in three macrophyte species (Elodea canadensis, Elodea nuttallii and Myriophyllum spicatum) exposed or not to snail herbivory. Grazing significantly reduced the DMC of M. spicatum and E. canadensis, but had no effect on the DMC of E. nuttallii. The phenolic contents of Elodea species were not modified by snail herbivory, whereas that of M. spicatum significantly increased when exposed to grazers. The number of new branches produced by M. spicatum and E. canadensis plants, and the fragmentation of E. canadensis also increased in response to herbivory. Chemical defences are therefore probably constitutive in Elodea and induced in M. spicatum, and morphological changes can be related to species growth form and synthesis of phenolic compounds. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) |
