Vascular Plants as Engineers of Oxygen in Aquatic Systems

Abstract

The impact of organisms on oxygen is one of the most dramatic examples of ecosystem engineering on Earth. In aquatic systems, which have much lower oxygen concentrations than the atmosphere, vascular aquatic plants can affect oxygen concentrations significantly not only on long time scales but also on time scales of less than a day. Aquatic plants are generally thought of as adding oxygen to aquatic systems through photosynthesis, but the impact of vascular aquatic plants on oxygen varies greatly with plant morphology. Floating-leaved plants that vent oxygen to the atmosphere can strongly deplete oxygen. In some ecosystems where floating-leaved plants have replaced submersed vegetation, oxygen concentrations have been substantially reduced. These oxygen changes can have cascading impacts on nutrient and trace gas chemistry and on the suitability of plant beds as habitat for invertebrates and fishes.