Aquatic Invasive Plants – Education for Answers

What is a non-native species? How do I get rid of those nasty weeds along my beach? Why don’t we just dump herbicides in the water? Unfortunately, when it comes to aquatic invasive species, there are often more questions than answers. Educating the public about the problems and solutions to non-native aquatic plant invasion is the key to constructive management.

Education for Prevention

You’ve probably heard it before: the best control method for invasive species is to prevent their introduction into a new environment. Education campaigns are essential for public awareness and preventing the spread of aquatic weeds. Most aquatic invasives have developed cunning ways of colonizing new areas, often tricking unwitting lake users into aiding and abetting their efforts. Signs should be posted at susceptible waterways identifying nuisance species and instructing visitors to remove any visible plant fragments from boats, trailers, and accessory equipment (anchors, centerboards, trailer hitches, wheels, rollers, cables, axles, canoes, boots, and even pets!) before leaving the water access area. All livewells, bilge water, and transom wells should also be drained and bait buckets emptied on land. Since some plant fragments are very tiny, it is important to wash boats and gear after returning home and before entering any new water body. Several excellent fact sheets and brochures have been developed to explain invasive plant identification and prevention, including the Alien Plant Work Group fact sheets at http://www.nps.gov/plants/alien/pubs/midatlantic/toc.htm, or the New Hampshire Department of Environmental Services fact sheets at http://www.des.state.nh.us/wmb/exoticspecies/facts.htm.

Education for Identification

Even when invasive aquatic plants have been introduced into a new water body, it is possible to prevent their spread. Citizen “Weed Watchers” trained to identify and remove new invasive plant stands can be very effective. Lake users and residents know the lake best, and are often the first to identify new stands of invasive species. Proper education about invasive plant species and native look-alikes is essential, however, as well as training in the proper removal of nuisance species. For example, many native plant species, such as bladderwort, coontail, and native milfoils, closely resemble the invasive Eurasian watermilfoil. Native plants protect shorelines from erosion, provide habitat for fish, waterfowl, and macroinvertebrates, and are often aesthetically pleasing, and should not be removed.

Education for Options

Many readers are thinking at this point, this is all well and good, but what do I do about the enormous mat of weeds ALREADY lurking ever closer to my dock? The best option, or series of options, for controlling invasive plant infestations in a given lake is dependent upon the topography, ecology, and use of the lake. Realistically, the control method of choice often has to do with the political structure and economic wherewithal of the lake association or governing body as well. Careful water quality testing, good communication between stakeholders, and adequate education of the decision-makers are critical in the management process. Most often, an integrated approach is most effective. An integrated (or IPM) approach targets multiple control methods to different areas of the lake or seasons of the year. For example, hand-pulling invasive plants using trained divers is a very species-specific control technique, with little impact on desirable native plants. However, hand-pulling is very time-consuming and expensive, so it is best used for small infestations or ecologically-sensitive areas. It can, however, be useful as a follow-up to more intensive practices such as grass carp stocking, water level drawdown, herbicide application, or benthic mat installation. Many invasive aquatic plant control methods require permitting, so it is critical to contact the local governing body (e.g. Department of Environmental Conservation, Fish and Boat Commission, etc.) or a professional lake manager before implementing any weed control program. If all else fails and frequent weed harvesting is the only viable option for invasive plant control, dead invasive weeds make excellent compost!

Education for Expectations

Of course, none of the available management techniques will completely eradicate invasive plants, even when used as part of an integrated approach. This is why management techniques are commonly referred to as “control” methods instead of “removal” methods, or some other more witty term. An important component of an invasive plant management program is educating lake users about expectations. Most likely, several different control methods will need to be employed over successive seasons before the target species can be reduced to an acceptable level. If lake users are disappointed when their weeds aren’t 100 percent gone after the first year, they might become unsupportive of the effort, so it is important to be up front about program goals from the start.

For more information on invasive species in general, visit http://www.invasivespecies.gov/. For a comprehensive description of aquatic invasive species identification and control methods, keep your eyes open in the coming months for the Pennsylvania Lake Management Society’s (PALMS) Pennsylvania Lake Management Handbook.

Next Month’s Newsletter: Nuisance wildlife