Aquatic Plant Management
Aquatic vegetative communities form healthy conditions for many pond and lake ecosystems. Various plant communities in the water and at the water’s edge are important for water quality, water oxygen levels, habitat for many aquatic organisms, and as a food source for many pond and lake inhabitants. Aquatic plants can act as a natural filter for excess water runoff, thereby reducing sedimentation and erosion along shorelines. Aquatic plants also absorb excess nutrients, primarily nitrogen and phosphorus, which helps control unwanted algae blooms. Healthy native aquatic plant communities are instrumental in preventing exotic, invasive and nuisance plants such as Eurasian watermilfoil (Myriophyllum spicatum), curly-leaf pondweed (Potamogeton crispus), water hyacinth (Eichhornia crassipes) and phragmites (Phragmites australis).
Aquatic Plant Management
Invasive aquatic plants such as the ones listed above can cause problems in lake and pond environments. Populations of invasive species often dominate native plants for space and nutrient resources. In order to protect native aquatic plants and prevent the spread of invasive aquatic plants, various techniques are employed.
•Physical techniques such as drawdown or bottom plant barrier
•Mechanical plant removal
•Manual plant removal
Physical and mechanical mechanisms can include cutting with specialized tools, unique heavy machinery to pull and pulverize, and hand-pulling plants. These methods are often labor intensive and are less efficient.
Physical techniques, such as water drawdowns, can only be used if an existing water control structure is present. Plant barriers are somewhat successful, but invasive plants tend to be more resilient to these mechanisms than native plants, and this technique has the potential to assist in the proliferation of aquatic invasive plant life while tamping down native plants.
Biological controls can also be effective, but much of the research concerning these methods suggests that these options create an “all or nothing” result. Biological controls, such as grass carp, tend to prefer many native plants over invasive species, thereby creating more favorable conditions for the spread of undesired plants.
Chemical controls are typically the most effective control mechanism in terms of immediate results. Chemicals are required when aquatic plants reach levels that hinder ecological and recreational function of a water body or if “spot” treatments are needed. If proper long-term planning and strategies are utilized, chemical treatments can often be the best method to provide short-term controls and as a bridge to larger scale changes within the watershed. Due to the dynamic nature of managing invasive, exotic and nuisance aquatic plants, EPA-registered chemicals may be used by District ecology staff. Some chemicals may or may not be accompanied by various water-use restrictions for a period of time. Appropriate signage is posted prior to application of chemicals at a site.
Although many techniques for aquatic plant management are listed here, it is important to note that there is no “silver bullet,” and the best management strategy may vary from location to location. Much of the success of aquatic plant management depends on what nuisance species needs to be controlled, how prevalent those species are, and what, if any, native or desirable species are present.
Each management plan is subject to change over time because as strategies and techniques are employed, these actions create dynamic situations that may require different management strategies and techniques in the future.
Why do we care?
Typically, desirable recreation opportunities such as fishing occur on many water bodies. As an angler, the first place to fish is near aquatic plant beds. Aquatic plants provide important niche habitats, including areas for reproduction, foraging and refuge for a host of aquatic organisms including invertebrates and other aquatic wildlife. Aquatic plants are often responsible for the presence and/or absence of aquatic/semi-aquatic creatures. Because aquatic plants provide the base for all of the creatures necessary for healthy ecological function as well as recreational and aesthetic value, it is imperative to make every effort to keep these aquatic plant communities diverse and healthy.