The Role and Interactions of Submersed Macrophytes in a Shallow Wisconsin Lake

Abstract

ABSTRACT Growth and community organization of submersed macrophytes were studied in a southern Wisconsin impoundment in relation to macroinvertebrates, fishes, and phytoplankton. Macrophytes covered 50 to 70% of the lake bed in summer, growing to a water depth of 3.5 m. Total biomass peaked in late July at 130 to 200 g dry wt/m2. Undisturbed macrophyte beds were stratified into canopy, midwater, and basal layers. Narrow-leaved pond-weeds (Potamogeton spp.) dominated among 13 vascular plant species. But mechanical harvesting, in the fourth and fifth years of the study, disrupted vertical stratification and exposed the lake bed to monotypic growths of water stargrass (Heteranthera dubia (Jacquin) MacMillin). Three-fourths of macroinvertebrate species were found on or beneath macrophytes during summer. Few species comprised more than 5% of individuals in plant or bottom samples. Most macroinvertebrates consumed algae and detritus derived from macrophyte decay. Fishes under 120 mm total length were sheltered ...