Interactions between Macrophytes, Epiphytes and Herbivores: An Experimental Approach

Publisher Website
Google Scholar
Abstract
The influence of grazing by freshwater snails on the growth of the submerged macrophyte Ceratophyllum demersum was studied in a laboratory experiment. Growth rate of the macrophyte was enhanced when epiphyton-feeding snails were present. This is probably due to relaxed competition for light and nutrients when the epiphytic cover is removed. The snail Lymnaea peregra was positively attracted to C. demersum, while epiphyton did not attract the snail. Damaged C. demersum (cut into 5 mm pieces) had lower attraction than the intact plant. The results indicate that dissolved organic matter (DOM) excreted by the macrophyte attracts grazers, which subsequently remove the epiphytic cover. This increases the growth rate of the macrophyte. The macrophyte tissue in itself is protected against herbivore attacks by repellent substances and a hard texture.