Exotic Plant Species in New Hampshire Lakes
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| Exotic variable milfoil |
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By Amy Smagula, Limnologist, NH Department of Environmental Services
The DES Exotic Species Program coordinates activities associated with the control and management of exotic aquatic plants; as well as activities associated with the implementation of education programs and volunteer plant monitoring programs.
Exotic aquatic plants, such as milfoil and fanwort, have been a problem in New Hampshire lakes and ponds since the mid-1960s. Variable milfoil, by far the most wide-spread exotic aquatic plant in NH, was first found in Moultonborogh Bay in Lake Winnipesaukee. From there it has spread to infest 38 waterbodies. Fanwort, water chestnut, Eurasian milfoil, purple loosestrife, and common reed are also problematic species in this state. There are 950 lakes and ponds greater than 10 cares in NH, and 71 are infested with some type of invasive (this does include some river systems too). This means approximately 7% of our lakes are infested.
Why are these plants such a problem? Native plant communities have evolved together over hundreds of years. Animal and insect grazers have become specialized to feed on these native plants. Since exotic plants are introduced from outside of the state, they have no established relationships with native fauna that would keep their growth in check. When these exotic plants grow without natural controls they encroach into and replace the habitats of native plants, disrupting the food chain, stunting fish growth and degrading wildlife habitat.
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Other states besides NH are also faced with the problem of exotic
plants, and unfortunately, no one has yet found a practical,
ecologically sound means of eradication for these plants. Once in a
waterbody, continuous management and control practices are the only
tools to control the nuisance plant growth.
It therefore becomes increasingly more important to prevent
infestations, and to identify new infestations early. DES biologists
conduct numerous field investigations each summer, but with over 800
lakes and ponds in the state, the efforts of volunteers in monitoring
waterbodies for new infestations become critical. Through materials and
training sessions by DES, numerous lakes and ponds have initiated their
own Volunteer Weed Watching programs.
For more information, please contact the Exotic Species Coordinator at 603-271-2963 or
Amy P. Smagula
Limnologist/Exotic Species Program Coordinator
NH Department of Environmental Services
29 Hazen Drive, PO Box 95
Concord, NH 03302-0095
Phone: 603-271-2248
Fax: 603-271-7894
E-mail: asmagula@des.state.nh.us
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Zebra Mussels
When we speak about Lake Hosting and our attempts to stop the spread of invasive species, I think many folks might wonder "what are invasive species and what makes them such a hazard to our Newfound Lake and watershed?" We often hear about exotic mil foil or fan wort but we don't often discuss zebra mussels. Zebra mussels are a fresh water mollusk. They appeared in North America in 1988 in Lake St. Clair. They have been steadily invading America's lakes and streams at an rapid rate ever since! Zebra mussels live for 4 to 5 years and they have the amazing ability to produce between 30,000 and 1 million eggs per year! Females begin reproduction at 2 years of age so a typical female zebra mussel could produce more than 3 million mussels in her lifetime! Zebra mussels can attach themselves to anything- boats, pilings, water-intake pipes or any hard surfaces including turtles and other native mollusks! Unfortunately, due to their massive reproduction rate, they can destroy ecosystems by threatening native wildlife. They can destroy pristine beaches and create hazards for water navigation. Zebra Mussels have been known to attach to navigational buoys and actually sink the buoys due to the excessive weight! Zebra mussels will attach themselves to boat hulls, anchors or motors and they can be easily transported from lake to lake. (Zebra mussels can be removed from boat hulls with mechanical scrapers, hot water at 140 degrees F, spraying boats with 10 percent bleach solution and allowing the solution to stand for several minutes before washing it off. )This is why the Lake Hosting program is so important. This program allows us to educate boaters on the severe threats that could enter Newfound Lake. Once zebra mussels have colonized a lake or stream, they are impossible to eradicate. Zebra Mussels have already made their way to Lake Champlain in Vermont so they are close! Please be a citizen Lake Host and check your boats every time you enter and leave a water body! You are preventing the spread of a devastating species.
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Purple Loosestrife (Lythrum salicaria) is an herbacious, wetland perennial that grows in a wide range of habitats. It can reach the height of 5-6' on 30-50 square, woody stems, topped by bright magenta-purple flower spikes. Each plant can produce more than 2 million seeds annually. This plant can easily adapt to any type of wetland, and crowds out native vegetation, forming a monotypic stand. In turn the plant chokes out native fish, insects, birds, other plants and wild animals, and can fill waterways. Contact the NLRA to learn how to remove this plant properly so that seeds are not further dispursed.
Purple Loosestrife substitutes
Spiked Speedwell (Veronica Spicata)
Pink Turtlehead (Chelone oblique)
Joe-pye-weed (Eupatorium fistulosum)
Queen of the prairie (Filipendula rubra)
Gayfeather (Liastris spicata)
Swamp rose mallow (Hibiscus palustris)
Purple coneflower (Echinacea purpurea)
Bee balm (Monarda didyma)
Burning Bush substitutes
Enkianthus campanulatus – excellent red foliage
Highbush blueberries
Rhododendron periclyminoides
Physocarpus opulifolius – red color all season
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Good news from the NH Department of Transportation (DOT)! The DOT has just produced a control manual for invasive plants, intended for DOT folks and others like town Department of Public Works. It contains information about best management practices to reduce the likelihood of introducing invasive plants into new areas via maintenance and construction activities.
NH DOT is now preparing hard copies for its staff, and also planning training sessions.
This fulfills a recommendation of the new Water Resources chapter of the Connecticut River Management Plan.
Please share with your town's road crew or selectboard. (those on dial-up might want to wait until the hard copies are available).
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