Eurasian Milfoil
The Eurasian milfoil is a delicate looking plant that was once a common plant to find in fresh water aquariums. It did not, however, stay there. Now it is considered an invasive species that threaten North American fresh water streams, rivers, ponds and lakes.
In its native Eurasian environment it is a relatively harmless plant (but still a bit of a pest) but here, out of its normal waters, it takes over and destroys ecosystems, clogs water intakes and power plants, and makes them undesirable for recreational purposes.
Several theories are around that explain its introduction. One is that it hitched a ride on the ballast of a ship coming from Europe or Asia. That is a good guess. When they tested boats leaving invaded water, 25% carried some milfoil with it. The other main theory is it was introduced by people discarding aquarium plants or packing material used to ship live worms.
One of the properties that make this plant so threatening is its ability to live in nearly any American water. It can live in the cold of Washington State or the warmth of Florida. From pristine waters of the Rockies to the brackish waters of the salt marshes it can thrive. To make its life better, nothing seems to like eating it.
Once established it spreads quickly in waters that range from 2 feet to up to 30 feet, matting just below the surface and choking out the native vegetation. Some of these, like millet, are a favorite of water fowl and others serve as the habitat of fry, an important part of the ecosystem. It also impedes the fishing of land animals. Further more, the vast mats keep the wind from properly aerating the water and suffocating adult fish as well as helping spawn algae blooms which further exacerbate the problem.
For humans, it causes problems as well. On top of the declining water quality, the milfoil makes shore lines unusable for swimmers. The lower fish count makes the fishing less desirable. These weed are also a menace for boaters as they wear on engines, reduce areas for water-skiing and make navigation obstacles harder to see.
Industries and communities fair no better. Water intakes or over flows can get blocked leading to shortages in some places and flooding in others. The large mats can also get caught up in dams cause damage and electricity production losses.
Controlling milfoil has been problematic. Generally poisons are out of the question as they destroy the very ecosystem they were meant to save. Physical removal has its own set of problem because of how it propagates, by breaking off into little pieces that take root when they reach the bottom. For that reason the large mechanical harvesters are only used in the worst cases and then only as a first step. There has been some success with vacuum dredging as it picks up all the pieces. In the end, the answer is a little weevil that eats only milfoil, therefore putting nature back in balance.
Milfoil is just one of many examples of invasive species gone amok. When plants or animals are introduced outside their natural environment, you can’t foresee the implications. Just ask the South about kudzu.
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