Freshwater aquatic invasive plants are those that are not naturally found in New Hampshire’s lakes, ponds and rivers. Because they are not native, they have no predators or diseases, which allows them to grow quickly and dominate freshwater systems and native plants, fish and aquatic insects already present. Aquatic invasive plants can lead to reduced shorefront property values, water quality impairments and problems with the aesthetic and recreational values of waterbodies. New Hampshire now has nearly 90 infested waterbodies, including 11 infested river systems and dozens of lakes and ponds, most containing variable milfoil (Myriophyllum heterophyllum) as the primary invasive plant, while others have fanwort, Eurasian water milfoil and water chestnut, among other common species. Dense stands of these plants inhabit shoreline areas frequented by water-based recreationalists. Exotic plants can create the following problems:
• Displacing of beneficial wildlife.
• Reducing the aesthetic quality of lakes.
• Littering of beaches with plant fragments.
• Creating difficult or dangerous swimming areas
• Snagging fish lines and stunting fish life.
• Becoming tangled in outboard motor propellers.
• Choking boat traffic lanes.
• Requiring substantial funds for managing.
The spread of these plants to other uninfected waterbodies often occurs by transient boat traffic. If accidentally introduced into a waterbody, they grow at explosive rates, some between an inch to as many as six inches a day! Many times, new infestations are not discovered until the plants become a nuisance requiring expensive control methods. Once fully established, they are virtually impossible to eradicate. Therefore, education, vigilance and early detection are key components in keeping these non-native nuisance plants in check. “Weed Watchers,” a volunteer program dedicated to monitoring the lakes and ponds for the presence of aquatic invasive plants, was formed by the NHDES in 1988. Volunteers are given a special “Weed Watchers Kit,” which contains the following:
• Photographs of exotic plants.
• Detailed drawings of the plants.
• An information bulletin on exotics.
• A list of lakes known to have exotic plants, including a map.
• Recommendations on how to conduct a plant survey.
•A complete set of fact sheets and pamphlets on exotics in New Hampshire.
The Weed Watchers Kit can be sent to you at no expense. Any individual wishing to participate in the “Weed Watchers” program should contact the Exotic Species Coordinator at:
29 Hazen Drive, PO Box 95
Concord, New Hampshire 03302-0095
What does a Weed Watcher do?
All that weed watching involves is a small amount of time during the summer months. Volunteers survey their waterbody once a month from May through September. To survey, volunteers slowly boat around the perimeter of that waterbody and any islands it may contain. NHDES encourages larger waterbodies to have a team of volunteers, who can divvy up the shoreline into segments that volunteers commit to surveying, so one individual is not responsible for an entire waterbody. Using the materials provides in the Weed Watchers Kit, volunteers will then look for any species of concern, and have voucher specimens of those species verified by state biologists. After a trip or two around the waterbody, volunteers will have a good knowledge of its plant community and will immediately notice even the subtlest changes.
What happens if a Weed Watcher finds an exotic plant in a waterbody?
In most cases, volunteers will be instructed to deliver a plant specimen via mail or in person, or email photos of the species in question. Volunteers are encouraged to collect a portion of the suspect plant when it is in flower, but any part of the plant will do if there are no flowers. This may be the only way to precisely identify the plant. If the plant is a state-listed invasive, a biologist will visit the site to determine the extent of the problem and to formulate a plan of action to control the nuisance infestation.
Check out these resources below to learn more about identifying aquatic invasive plant species.