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Aquatic Exotics
What are they?
How do they affect my lake and what can I do to stop them?
What is happening to our lakes?
Lake users in New Hampshire may soon see a decline in the welcoming pink and yellow blossoms of native water lilies and the bright purple stalks of pickerel weed blooms. Even other organisms, such as fish, may be stunted in their growth.
So what is happening to our lakes? Non-native aquatic plants are proliferating. These nuisance plants enter our lakes and begin taking over. Most of these non-native species grow faster than our native vegetation, choking it out. Some even grow so thick that boating, swimming, and fishing become more of a struggle than an enjoyment. Non-native plants such as Milfoil and Fanwort are slowly taking over a number of lakes in New Hampshire.
Lake Conditions Play a Role
These exotic plants usually prefer quiet coves with little wind and wave action. Mucky or silty bottoms provide plants with needed nutrients. These factors, combined with adequate sunlight and water depth of less than 15 feet, create a favorable environment for the growth of nuisance plants.
More Non-Natives
Non-native species come in animal form as well. Zebra Mussels, which are found as close to New Hampshire as Lake Champlain in Vermont, have a reputation more far-reaching than their geographic location.
These small bivalve animals, with alternating light and dark bands, are generally no larger than one inch in length, but cause great problems for lake ecosystems. By filtering out microscopic algae at a rate of one quart per mussel per day, they are essentially wiping out the base of the aquatic food chain.
These mussels attach to any hard surface by sticky threads. Rocks, pipes, boat hulls, motors, buoys, docks, and even native mussels are all subject to Zebra Mussel invasion.
Zebra Mussels have been known to clog boat motors and intake pipes of water treatment plants. They can even sink marker buoys under their weight.
Where Did These Nuisance Organisms Come From?
Non-native plants first appeared in New Hampshire’s lakes three decades ago. Milfoil was first reported in Lake Winnipesaukee in the early 1970s. Fanwort was first sighted in Milville Lake in the 1960s. Since then, these weeds have infested over 30 New Hampshire waterbodies.
These plants may have been introduced to New Hampshire’s lakes through a dumped home aquarium or by a plant fragment that was attached to a boat visiting from another state. Zebra Mussels entered the United States in the early 1980s. It is believed that ships traveling from Europe to the United States carried larval forms of the mussels in their ballast water.
What Can I Do to Stop the Spread of Non-Native Organisms?
- Be knowledgeable about your lake’s conditions.
- Know which lakes are infested with non-native aquatic organisms.
- Become familiar with invasive species.
- Examine boat hulls, motors, trailers, fishing and diving gear for tag-along weeds and mussels.
- Clean and wash boats, motors, and trailers after every use — while still at the lake or when you get home.
- Discard attached weeds and Zebra Mussels away from surface waters.
What Should I Do if I Think I Have Seen a Non-Native Aquatic Plant or Zebra Mussels?
Contact the NH Department of Environmental Services Biology Bureau. Be prepared to give a description of the plant or animal (and provide a sample if possible) along with directions to the lake and infestation area. When you get home, make sure that you thoroughly inspect and clean your boat and discard away from water any weeds or suspicious organisms.
A Ounce of Prevention
The key to eliminating the problems of nuisance species is to prevent their spread. Once in a lake, they are difficult, if not impossible, to get rid of.
What is New Hampshire Doing to Protect Its Surface Waters from Non-Native Species?
species. They also enforce laws which make it ILLEGAL to sell, distribute, import, purchase,
propagate, transport, or introduce non-native species in New Hampshire.
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