Maximum depth inhabited by aquatic vascular plants

In situ observations of submerged, rooted aquatic plants by a diver equipped with SCUBA have shown that the maximum depth distribution of a number of submerged species in a clear freshwater lake (Lake George, New York) is greater than previously reported. Maximum depth for any species was 12 m for Elodea canadensis. Water clarity is sufficient to allow 10% of the light intensity hitting the surface during midsummer to penetrate to this depth. The number of submergent species drops linearly from 38 at 1 m to one at 12 m. Data are presented for the maximum depth of occurrence for 28 vascular macrophyte species, and population densities of these species at their preferred and maximum growth depths compared. The effect of several environmental parameters on depth inhabited by rooted aquatics is discussed.