Effects of Freshwater Macrophytes on Sediment Chemistry

Changes in the vertical distribution of sediment redox potential and nutrient availability were examined during the growth of freshwater macrophytes in a greenhouse facility. Sagittaria latifolia, an emergent macrophyte species with an extensive root system, markedly affected sediment redox, resulting in a change from reduced to oxidized conditions within six weeks. In contrast, Hydrilla verticillata, a submersed macrophyte species with a relatively minor root system, did not appreciably alter sediment redox. Nutrient uptake by both species substantially reduced concentrations of nitrogen and phosphorus in sediments. Decreased concentrations of sediment nutrients appear to have resulted primarily from nutrient uptake by macrophytes rather than from change in sediment redox potential.