Milfoil, an Invasive Threat to U.S. Steams
Eurasian milfoil is a soft looking plant that was once a familiar plant to find in fresh water aquariums.
Still, It did not stay there. Now it is thought to be an predatory species that threatens The northern Us fresh water streams, rivers, ponds and lakes.
In its native Eurasian surroundings it is a relatively innocent flora (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 unsuitable for recreational purposes.
Several hypotheses 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 departing occupied water, 25% carried some milfoil with it. The other main theory is it was introduced by individuals discarding fish tank plants or packing material used to ship live worms.
The most hazardous thing about this plant is that it can adapt to live in about every kind of marine habitat in North America. It can live in the cold of Washington State or the warmth of Florida. From clear waters of the Rockies to the brackish waters of the salt marshes it can prosper. To make its life easier, nothing seems to like eating it.
Once established it propagates rapidly in waters that range from 2 feet to up to thirty feet, matting up just below the surface and clogging out the native vegetation. Some floras like millet are given little chance to grow, which causes problems because they are a food source for many and a home for small aquatic creatures. This matted growth also causes difficulty for any mammals or birds that fish for their food. Further more, the huge mats keep the wind from properly aerating the water and choking adult fish as well as helping spawn algae blooms which further exacerbate the problem.
These plants are problematic to people as well. Not only does milfoil decrease water quality but the mats make shoreline swimming impossible. Milfoil hinders fish breeding, which means fewer fishermen. Milfoil is also a problem for sailors because it can become trapped on the engine, cause dangers for water skiers and block navigation hazards from the watermen view.
Communities and businesses are also put at a disadvantage because of this small water flora. Water intakes or over flows can get blocked leading to shortages in some areas and flooding in others. Dams and electricity output can also be affected if the water flora mats get caught up in the dams.
Milfoil control has been hard. Mostly poisonous substances are out of the question as they demolish the very ecosystem they were meant to save. Physically removing the flora isn’t fully productive because the parts that break off can form new plants somewhere else. For that reason the large mechanical harvesters are only used in the worst cases and then only as a first step. Milfoil has been more successfully removed by vacuum dredging, which can pick up any broken pieces left behind. A weevil maybe the answer to the milfoil dilemma as it love to eat the water flora and is a natural way to fight the weed.
Milfoil is just one type of invasive species that has overstayed its welcome; many other unwanted aquatic plants are still thriving across the country. When plants or animals are introduced outside their natural environment, you can’t anticipate the implications.