Ecology of Aquatic Invasive Plants

Benefits of Native, Aquatic Plant Communities

     Aquatic plant communities are dynamic components of many Adirondack waters which support the natural and recreational integrity of these ecosystems, similar to our forests and other upland vegetation. For example, aquatic plants provide structural complexity within shoreline areas that enhance biological diversity - providing substrate for colonization of invertebrates, refuge for forage fish, and a food source for waterfowl. They also stabilize the shoreline and improve water clarity by reducing wave erosion and resuspension of bottom sediments. These benefits accrue for humans by enhancing the visual beauty of our lakes, ponds, and rivers while providing high-quality fishing and hunting opportunities.

Impacts of Non-native Invasive Plants

     Invasive plant species are those that establish numerical dominance outside their natural range, disrupting ecosystem processes and native patterns of biodiversity. Rarely are these changes beneficial. In many cases, the impacts of aquatic invasive plants are also detrimental to human use of aquatic resources. The majority of introduced non-native plants do not become dominant within their new environment. However, in the absence of natural predators, diseases, and/or parasites, non-native plants can flourish and out-compete native plants for light, nutrients, and space. In some cases, dense "monocultures" of an invasive species results, with corollary impacts that include reduced oxygenation, local temperature variations, increased nutrient loading, and altered invertebrate and fish populations. Invasive plants with a canopy-forming morphology, such as Eurasian watermilfoil, often modify the environment in this manner. Some native plants can also reach nuisance levels, although their impacts are typically localized.

Is it Possible to Predict if a Non-native Plant Will become Invasive?

     This is a relatively difficult task although many invasive plants share a common suite of physiological and morphological traits. Characteristics which afford these competitive advantages include: efficient use of light, superior nutrient uptake, canopy formation, and prolific reproduction. Many invasive plants are also early-successional species capable of colonizing a broad range of environmental settings, particularly those "disturbed" by natural or human-induced events. For example, increased rates of sedimentation or nutrient loading within lakes owing to human activities can facilitate the expansion of non-native species. The extent and rate of plant invasion may be reduced in areas of high native plant diversity. However, even healthy plant communities are susceptible to invasion.

     Regional movements of aquatic invasive plants can result from the transport of seeds and plant fragments on wildlife, watercraft, and with the mass flow of water in rivers and lakes. New introductions can also result from careless disposal of non-native plants purchased for home aquariums or ponds into area waters. In the case of Eurasian watermilfoil, only a single vegetative fragment is required to propagate a new population. It should be no surprise that the primary cause of inter-lake colonization by this species owes to the transport of plant fragments on boats and trailers.

If you are a lake user, take precautions to prevent the transport of invasive plants from one lake or river to another by removing ALL plant material from your watercraft before and after entering new waters and disposing of the material away from the shoreline on dry land or in the trash.

Distributions in the Adirondack Park

     Aquatic invasive plants have reached nuisance levels in a number of Adirondack lakes and ponds. At present, four of these species are the focus of the APIPP's Aquatic Invasive Plant Project's Volunteer Monitoring Program. These include Eurasian watermilfoil, Curlyleaf pondweed, Water chestnut and Fanwort.

     Eurasian watermilfoil prefers still, shallow waters and roots in mud substrates with fine-textured inorganic sediments. Native to Europe and Asia, it was introduced to the United States in 1890 and first observed in the Finger Lakes Region in New York in the 1940s. As of 1997, Eurasian watermilfoil existed in 41 New York counties which included at least 113 lakes. It is the most widespread of aquatic invasive plants in New York. Eurasian watermilfoil is confirmed in 8 counties in the Adirondack Park and prevalent in north-central and eastern Adirondack waterbodies.

     Water chestnut, also a native to Europe and Asia, was introduced to New York state in Collins Lake near Schenectady in 1884 for its ornamental appearance. Preferring habitats with full sunlight, organic, muddy bottoms, and alkaline waters, it can commonly be found in the Hudson and Mohawk River systems and has been verified to exist in 15 New York counties. Water chestnut has been confirmed in only Lake Champlain in the Adirondack Park.

     Curlyleaf pondweed is tolerant of low light and water temperature and is found in alkaline and high nutrient waters. It was introduced from Europe to the northeastern United States in 1880 and is now found in lakes, ponds, and streams throughout North America. Although its date of introduction into New York state is unknown, Curlyleaf pondweed has been confirmed in 21 New York counties and continues to spread. In the Adirondack Park, Curlyleaf pondweed has been observed in Lake George, Brant Lake, Mayfield Lake, and was recently detected in Franklin Falls and Lake Flower (APIPP, 2003). Due to its growth in late spring and early summer, it may go undetected in numerous other waterbodies.

     Fanwort is frequently found in more acidic lakes, ponds, and quiet streams. It is most abundant in the southeastern United States, but it has been found in shallow lakes on Long Island and lakes in the Catskills. Anecdotal reports suggest Fanwort arrived in New York State in the 1980's. Plant surveys confirmed its presence in the mid 1990's in Saratoga County in Jenny, Hunt, and Efner lakes and more recently in nearby Mill Pond.

Across the Park, these species are not yet dominant but have a high potential to spread. You can assist efforts to raise awareness of invasive species, prevent their spread, and track their distribution by participating in the APIPP's Aquatic Invasive Plant Project's Volunteer Monitoring Program.

Prevent the Spread of Aquatic Invasive Plants

• Remove all plants from watercraft, including motors, trailers, and fishing equipment before and after launching.
  
• Dispose of plants away from the water, either in a trash can or on high, dry land.
  
• Learn to identify and report invasive plants.
  
• Avoid driving, paddling, or swimming through any invasive plant infestations. This can fragment the plants and promote their spread.

What to Do If You Spot an Aquatic Invasive Plant

• Choose a sample of the entire plant, including stems, leaves, and flowers if present.
  
• Wrap the plant in a damp paper towel and place in a sealed plastic baggie.
  
• Label the baggie with lake/pond name, town name, your contact info, date, and location of finding.
  
• Send in immediately or keep refrigerated until able to send or bring in the sample.
  
  • Mail or Bring Plant Sample to:

Adirondack Park Invasive Plant Program
PO Box 65
Keene Valley, NY 12943
518-576-2082