Abstract
The epiphyte contribution to the total production of Lake Memphremagog macrophyte beds changed in a predictable fashion with the season, the morphology of the macrophytes, the depth of the bed, and the trophy of the water. In the mesotrophic portion of the lake, epiphytes fixed more carbon than the macrophytes only at the beginning and end of the growing season, whereas under more eutrophic conditions they did so even during summer.