MAISRC researchers examining effects of alum treatments on curly-leaf pondweed and native plants
MAISRC is kicking off research to evaluate the effects of alum treatments on native and invasive plants – particularly the problematic curly-leaf pondweed – in metro-area lakes this summer.
The application of alum (aluminum salts) can improve water quality by sequestering phosphorus in the lake sediment, which limits algae’s ability to grow. Whether or not this improved water clarity is enough to encourage the growth of native plants is yet to be determined.
Previous MAISRC research on invasive aquatic plants evaluated several management actions such as common carp removal and herbicide applications, and found that carp removal can enhance the population of both invasive and native aquatic plants, due to an increase in water quality and a reduction in sediment disturbance. However, since invasive aquatic plants were still outcompeting native plants, researchers are working now to determine how to best encourage native plants, particularly in lakes with poor water quality. This will be addressed in three ways:
1. Alum treatments
2. Post-treatment monitoring
3. Transplanting native plants to treated areas if need be
Transplanting native plants could also bolster the native plant community, if the plants did not germinate naturally as a result of the improved water clarity. Delicate aquatic plant communities can quickly be destabilized by invasive plants such as curly-leaf pondweed and Eurasian watermilfoil, which, thanks to their ability to grow abundantly in cool water with limited light, are eagerly taking hold in many Minnesota lakes.
The ultimate goal of this multi-year effort is to reduce invasive aquatic plants and support diverse native aquatic plant communities, which provide many important ecological functions. Learn more about curlyleaf pondweed research at MAISRC here. Funding for this project is provided by the Riley Purgatory Bluff Creek Watershed District.