Aquatic Environments; Wetlands; Floodplains; Lakes; Lakes (Artificial); Aquatic Macrophytes; Species (Biological); Community Composition; Threat; Nutrients; Algal Blooms; Water Quality (Natural Waters); Water Quality Control; Water Management
This technical guideline describes a research project conducted in Victoria Park Lake, an ornamental lake near Shepparton VIC, which investigated whether macrophyte dominance could be switched to algal dominance by nutrient enrichment or plant harvesting. The findings generated a number of new discoveries about the responses of macrophytes and algae to nutrient enrichment and the dynamics of nutrients added to shallow lakes and wetlands. The following general management advice is based on the project and related research. Submerged aquatic macrophytes are a desirable component of shallow lakes and wetlands and management activities should ensure their continued presence. Harvesting submerged macrophytes when nutrient levels are high increases the likelihood of algal blooms and may prevent the re-establishment of submerged aquatic plants. Harvesting submerged macrophytes may also result in the establishment of other aquatic plant species not present earlier which could prove problematic. Dense mats of floating plants of algal scum on the water surface can cause de-oxygenation of the water column and the catastrophic loss of submerged macrophytes. When constructing artificial wetlands managers need to be aware of the limitations of using wetlands to treat nutrient-enriched waters because the buffering capacity of sediments will become saturated. It is also cautioned that algal monitoring programs that focus on blue-green algal blooms could miss significant algal blooms caused by other phytoplankton which can cause a decrease in water quality (A).
