DENSITY AND BOUNDARY REGULATIONS OF THE NITELLA MEADOW IN LAKE GEORGE, NEW-YORK

The charophyte Nitella flexilis (L.) Ag., grows in an extensive sublittoral meadow in Lake George as in other oligotrophic lakes with low organic content. Studies were made of its growth rate regulation, growth form, and spatial distribution in the lake. Evidence is presented that boundaries and density of plants in the meadow are under separate controls. Density is believed to be nutrient limited. Phosphate was shown to limit rates of photosynthesis in vitro. In Lake George densities of plants were quite variable, unlike reports of 60 years ago. The most dense meadows were found near lake shore villages, or sources of plant nutrients. Boundaries are suggested to be determined by a photomorphogenetic switch mechanism. Sharp boundaries, depth related length of internodes and depth distribution of both oospore and vegetative reproduction are supportive. Supportive also are the studies demonstrating red-light control of key stages in the development of charophyte shoots. The absence of other plants from the deep boundary and often from the shallow boundary seems to rule out interspecies relationships. Photosynthetic limitation seems ruled out by the size and density of shoots at the lower boundary of the meadow in Lake George. © 1979.