Eurasian Milfoil Essay, Research Paper
We have the right to swim, fish, water ski and boat in most of the lakes in Minnesota. We have heard for years that in order to keep our lakes beautiful, we must all take responsibility in keeping them clean. We know not to put garbage in the lakes, but how many of us know about the garbage we should not take out of the lakes?
Eurasian watermilfoil is a particularly problematic exotic aquatic weed in North America, due to its ability to reproduce from fragments and spread rapidly. It also has a high growth rate in a range of temperatures and environmental conditions. Its tendency to reach the surface and form extensive mats of plant at the surface can allow it to shade and out compete native vegetation.
Eurasian watermilfoil (Myriophyllum spicatum) is recognized primarily by its whorls of four feather-like leaves around the stems. Each leaf is finely divided into paired leaflets, typically 12 to 21 pairs per leaf. The number of stems per plant increases as the plant ages. Each individual stem branches several times as it nears the water surface. Dense Eurasian watermilfoil beds usually occur in water between 3 and 12 feet deep, although specimens have been found in up to 30 feet of water. The tops of the milfoil plants, both stems and leaves, often turn red in color. The species is perennial, initiating new growth from over wintering root material each spring.
Milfoil is believed to spread from one body of water to another primarily by the introduction of plant fragments. Fragmentation is the principal means of reproduction in this species. A milfoil fragment only a few inches long can form roots and grow into a new plant. Milfoil fragments are most abundant during mid-to-late summer, but can be transported from a lake year round.
The second traditional method of reproduction is through asexual reproduction. The mother plant forms underground runners that develop into other plants. These new plants will separate from the first and a new individual will be produced, causing the plant to spread.
Humans have carried this plant around the globe. When fragments of the plant float to the surface they can be transported to new areas. Stems can become lodged among any watercraft apparatus or sports equipment that moves through the water, especially boat trailers. Milfoil can live out of water for many hours and can quickly rebound to full life once back in water.
The species is also capable of spreading through seed, although at a frequency much lower than the fragments. The current, wind and wave action transport these fragments to their new homes. Birds can also carry the plant to new locations.
There is a general agreement that Eurasian milfoil was introduced to North America, but the exact timing and location of its introduction is disputed. Details of the introduction and expansion are incomplete because Eurasian milfoil was often confused with the native North American species. It is believed that it is native to northern Europe and Asia and arrived to North America sometime between the late 1800 s and early 1940 s. First documented in 1942 from a pond in Washington DC, Eurasian milfoil was probably introduced to the United States around this time frame. It has now taken roots in three Canadian provinces and 45 states in the United States.
Eurasian milfoil likes to live in lakes, ponds, shallow water reservoirs and slow moving rivers and streams. The degree to which Eurasian milfoil invades a body of water varies from one location to the next. Any milfoil invasion has enough potential to seriously disrupt conditions in any body of water. The end result of these invasions is, more often than not, the decimation of the previous aquatic ecosystem.
Some of the most serious problems, short and long term effects, presented by the invasion of Eurasian milfoil are:
+ Milfoil s unique growth form chokes out the native plants growing underneath it. Eurasian milfoil can also reduce the quantities of desirable duck food species.
+ When the native plants can t grow, other aquatic species that rely on the native plants for food and shelter have trouble surviving. Eurasian milfoil s dense growth makes it difficult for invertebrates and other organisms that fish eat to survive. With less to eat and less open water, fish population also decrease. Sport fishing is threatened and Fisheries strength can also be weakened.
+ It reduces the aesthetic appeal of waterbodys due to the accumulation of plant debris and decaying vegetation. It obstructs such water activities as swimming, boating, water skiing and fishing. This can reduce the economic benefits of tourism to areas where these activities are part of their attraction. It reduces property value and appeal for prospective lake-home owners.
+ Eurasian milfoil obstructs flood control methods, water conservation, drainage and irrigation works.
+ Dense stands of Eurasian milfoil may create habitats favorable for the production of blood sucking insects.
+ The weed can alter temperature profiles in a lake by as much as 10 degrees Celsius per month in shallow water.
Although there are not many benefits of Eurasian milfoil, there are a few:
+ The major beneficiaries of Eurasian milfoil are to juvenile and
pan fish and it has even been suggested as a tool for managing some
fisheries. The smaller fish receive protection from the larger nursery area
and this area provides shelter for spawning, increasing fish abundance.
+ Eurasian milfoil provides areas of calm water for waterfowl to rest.
+ In certain lake systems, Eurasian milfoil may also improve lake clarity by
out competing undesirable algae for dissolved nutrients.
Milfoil has not caused extensive problems in every body of water where it is established. In lakes with low water clarity, milfoil has not produced mats in water more than six feet deep, if at all. In areas of lakes where the fertility of the bottom is low, as in sandy areas, the growth of milfoil and aquatic plants in general tends to be low.
Milfoil may cause problems in a lake one year but not the next. This appears to be mainly due to the weather, which can cause variations from year to year in environmental conditions in lakes, especially clarity, temperature and depth of water. These in turn cause large variations in the abundance of aquatic plants, including milfoil.
Again, Eurasian milfoil has made its way around the United States in all but 5 states. It was first reported in the Northeast and has made it s way west over the last 60 years.
Northeast – Researchers feel that milfoil was introduced to Vermont from one of the southern New England states. It was most likely a stowaway fragment attached to a boat or trailer that came to this region. Found in over 46 Vermont lakes, it is mostly concentrated in the western drainages, where it covers thousands of aquatic acres, including large bays in Lake Champlain and Lake Bomoseen. Also found in New York, New Hampshire, Massachusetts, Connecticut, Rhode Island, Pennsylvania, New Jersey, Delaware and Maryland.
Southeast V It is the most abundant submersed species in bays and creeks of the Mobile River Delta in Alabama. It has also been long standing at freshwater reservoirs throughout the rest of the state. Also found in Virginia, North Carolina, South Carolina, Florida, Georgia and Mississippi.
West of Appalachians V Initially introduced to the Tennessee River at Watts Bar Reservoir in the 1950 s, it is established, in shifting populations, through the Tennessee River system today. Spreading through the Cumberland River system in the late 1980 s, it is suspected to be the result of deliberate planting. Also found in West Virginia and Kentucky.
Great Lakes Region – Eurasian milfoil was first seen in Minnesota in Lake Minnetonka in October of 1987. The DNR initially undertook very aggressive management efforts aimed at eradicating or significantly reducing its abundance where it occurred. By the year 2000, Eurasian milfoil spread to 105 Minnesota waters and the DNR has adjusted the strategies used to manage milfoil based on experiences attempting to manage this plant. Also found in Ohio, Indiana, Illinois, Wisconsin and Michigan.
Great Plains V Appearing at scattered sites since 1993 in Iowa, where nutrient loading, sedimentation and the maintenance of artificially high water levels have contributed to the absence of native vegetation. Currently established at Wilson Grove Lake and at Snyder Bend Lake. Also found in North Dakota, South Dakota, Nebraska, Kansas and Oklahoma.
South Central V Eurasian milfoil is considered a serious problem in Lake of the Ozarks and through the Bootheel region of Missouri. Also found in Arkansas, Louisiana and Texas.
Northwest V Although there were reports from pristine areas in Montana and Wyoming about the invasion of Eurasian milfoil, no specimens have been located for verification. It is suspected that it was a case of mistaken identity, Northern milfoil.
It has been monitored at lakes across Washington and along the Columbia, Little Spokane, and Pend Orielle Rivers. It has been replacing native vegetation in shallow lakes found east of Puget Sound, also in Washington. Also found in Oregon and Idaho.
Southwest V Reported for the first time from Colorado during 1998 from the Rio Grande River as it passes through the southern town of Alamosa; its presence in the Rio Grande has caused concern for regional irrigation systems there. Also found in New Mexico, Arizona, Utah, Nevada and California.
Since Eurasian milfoil is just one of the many invasive aquatic plants worldwide, countries and their government agencies all over the world need to do their part in creating and enforcing rules and regulations to protect their own numerous waterbodys. Since this weed is not life threatening or imposing any immediate danger to human or animal life and because this does not pose any international threats, there are no global laws that are established concerning this issue.
There are no national laws that regulate issues regarding Eurasian milfoil. Those laws are left to the individual states because they need to adapt to all the different conditions and waterbodys unique to each state.
Rules and regulations vary state by state. In Minnesota it is illegal to transport a number of species of exotic plants; Eurasian milfoil is one of them. The DNR is obligated to spend 20,000 hours each year inspecting boats at public water accesses primarily on infested waters. You can receive a fine if you are caught transporting this plant. Since all states do not abide by the same laws, it is important to understand the laws. The Minnesota DNR is required to adopt rules, which place exotic species into various regulatory classifications: prohibited exotic species, regulated exotic species, unregulated exotic species and unlisted exotic species.
Minnesota is broken down into many cities. However, there are not separate laws established for each city regarding Eurasian milfoil. Although the DNR has the ability to establish independent laws for each city, the statewide enforcement policies are all the same.
Researchers and scientists are globally united in the cause to support prevention activities, such as identifying potentially harmful species in the world, predicting pathways of spread, and developing and implementing solutions that reduce the introduction and spread of Eurasian milfoil. Many different agencies from around the world are working together to try to find answers for these issues.
They are united at conferences, such as the International Symposium on Watermilfoil, which first took place in 1985 and continues on today to try and work together to find solutions.
They are united through the Internet, which offers Websites such as The Aquatic, Wetland and Invasive Plant Retrieval System. This database has been used many thousands of times by researchers, government agencies, companies, teachers, students and private groups and individuals from all over the world.
The DNR is assigned responsibility for preparing a long-term plan for the statewide management of harmful exotic species of aquatic plants and for coordinating efforts within the state and establishing prevention, management, research and similar activities.
The goal of modern scientists, biologist and researchers around the world is to create balanced and healthy ecosystems while trying to prevent and reduce the invasion of Eurasian milfoil. Since prevention will not likely be 100% effective, control measures will likely be required for established infestations. As with most weeds, there are three general control strategies that can be employed.
Biological control means using natural methods to control a pest. This includes natural predators or disease organisms that eat or infect the pest to kill it or slow its growth. The most effective method is native to North America and normally feeds on our native milfoil. However, if given the choice it prefers to feed on Eurasian milfoil. These little weevils lay their eggs in the stems of the milfoil and when the larvae hatch, they eat the milfoil and cause lots of damage. The use of plant-eating fish such as the grass carp, at native to China, is not specific and will therefore consume many native plants. They are illegal in some states, but not in others.
Chemical herbicides can be applied to Eurasian milfoil every one to three years to control its growth. Since Eurasian milfoil is similar to our native milfoil, the herbicides can often kill the good, native plants that we don t want to hurt. This method can also be expensive and can cost from $200 to $2,000 per acre.
Mechanical and manual control, either by the use of bottom barriers, hand pulling, ranking, harvesting or rotating is effective at reducing current abundance of plants and is useful to clear channels or maintain access. It will not result in long term control and, depending upon growing conditions, several removals may be needed each year and regrowth may be fast unless roots are removed or plants are harvested close to the sediment. This type of control can cost from $300 to $600 per acre.
Many new ideas, such as bacteria or fungi as a control method, although proven highly effective, are still in the experimental stages. Their use as a milfoil control method may prove to be the control of the future.
Many government agencies provide funding to reduce the adverse affects of Eurasian milfoil and to slow the spread of the exotic plants to other lakes. Their goals are usually to manage nuisances but not necessarily achieve long term reductions in the growth of milfoil. This funding is usually available to counties, cities, townships and incorporated lake associations that own property of lakes with Eurasian milfoil and DNR designation.
Studies suggest that the spread of Eurasian milfoil may have slowed due to the public education methods. Education includes brochure distribution, signs at boat launches, poster displays and thorough distributions of educational material like the Boat and Water Safety Minnesota Guide that the Minnesota DNR hands out.
We have to start somewhere. Minnesota is a leader in passing a law that makes the transportation of Eurasian milfoil illegal. By passing a law such as this, and making it the law, which involves a fine, the public becomes more aware of the problem and its seriousness, which is vital in stopping the spread of this invasive plant.
The Minnesota DNR reports that legal measures alone are not enough for the prevention and invasion of Eurasian milfoil. Since this issue is handled state to state, each state has the responsibility of regulating any laws concerning this issue. Road checks in Minnesota have found aquatic vegetation on 23% of all trailered watercraft inspected which legally should have been cleaned before leaving the lake or waterbody it just left. Enforcing this law is extremely difficult, especially in the land of 10,000 lakes!
The social attempts at preventing the spread of Eurasian milfoil have a greater chance at being affective than the legal measures. Since we know that prevention will likely not be 100% effective and control measures will likely be required for established infestations, the most important tool in keeping Eurasian milfoil from spreading is education. Researchers and scientists along with Social Group like the DNR provide the educational materials. Since the greatest cause of this spread seems to be by man, it is individuals who must make a change. First they must know why and then how and that is where the educational materials become so valuable. Once people understand that Eurasian milfoil can change their recreational activities, they may think twice about making sure Eurasian milfoil doesn t enter their lake of choice . The things that people can do to prevent the spread of Eurasian milfoil are:
X Remove any visible plants and animals from your boat, trailer, and other boating equipment before leaving any lake or river.
X Drain water from the motor, live well, bilge, and transom wells at the ramp or access before leaving any lake or river.
X Wash/dry your boat and other boating equipment to kill harmful exotic animal species that were not visible at the boat launch. Before transporting to another lake or river either:
h Rinse your boat and boating equipment that normally gets wet with hot tap water; or
h Spray your boat and trailer with high-pressure water at a car wash; or
h Dry your boat and equipment for at least 5 days.
X Stay clear of large weed patches while operating a speedboat. This will lessen the likelihood of spreading fragments to other sections of the lake.