Sarah S. Roley and Raymond M. Newman of the University of Minnesota conducted a study in order to examine the differences in resistivity to milfoil weevil of three different strains of milfoil: the native northern, invasive Eurasian, and (Eurasian X northern) hybrid. The milfoil weevil is a well known biological control agent for Eurasian milfoil, but concern has been raised regarding the hybrid’s potential for higher resistivity. Roley and Newman tested the resistance of these three strains by adding weevils to an isolated milfoil plant in in vitro aquatic conditions, and after 24 hours of exposure determining the weevil survival rate on the given host. As expected, Eurasian milfoil was the least resistant to the weevil, but the hybrid, having a resistivity in between that of the Eurasian and northern strains, was not as resistant as was predicted. Roley and Newman believe future studies should be focused on the hybrid’s growth and spread abilities to better determine the threat of this strain of milfoil.

Environmental Entomology. Developmental Performance of the Milfoil Weevil, Euhrychiopsis lecontei (Coleoptera: Curculionidae), on Northern Watermilfoil, Eurasian Watermilfoil, and
Hybrid (Northern X Eurasian) Watermilfoil. 2006.

Larson discusses the many downsides to using militaristic metaphors when writing about invasive species. HE states that although militaristic language used can be effective in drawing attention to invasive species, it can also carry unwanted connotations. There are two main problems with using militaristic language the first is that it implies that there are two different sides and that we humans are not part of the problem but a lot of the time we are. War metaphors also lead to the assumption that invasive species can be completely defeated and this is not usually the case. These metaphors could interfere with conservation efforts. Also, after time these metaphors can lose their efficacy if they are used too often and for less problematic situations. According the Larson, by using militaristic metaphors biologists create an artificial feeling of war. Larson advocates using alternative language when writing about invasive species. He suggests that maybe a medical or disease metaphor could be more effective when talking about invasive species.

I found a lot of examples of the type of language Larson was talking about in new articles. When describing an ecologist looking for watermill foil the writer uses “an unusual reconnaissance mission” (Foderaro 2007). He is also described as being “on the front lines of the fight against invasive species” (Foderaro 2007). The writer also uses the phrase “the Adirondacks is girding for war” (Foderaro 2007). I can definitely see what Larson is talking about. I think that metaphors are definitely effective at grabbing attention, however I agree with his argument that they are overused. I do not necessarily agree that they are ineffective, but I think they can overshadow the issues and become problematic.

Foderaro LW. 2007 Battling a Nasty Green Invader From the Deep. New York Times.

Aquatic ecologists are constantly fretting over invasive species, an issue which requires billions of dollars of spending. Any species that enters a non native area and causes negative effects qualifies as invasive. One of the most notorious aquatic invasive species is the Myriophyllum spicatum, a freshwater plant native to Asia more commonly known as milfoil. The plant is often transported in the hull water of ships, and currently exists in nearly every U.S. state. Attention is currently centered on the Great Lakes where milfoil poses a particularly strong threat.

This study examined the impact of the milfoil invasion from multiple aspects, and the results have shown that there is much more to milfoil invasions than meets the eye. The plant poses hazards to boaters and swimmers by clogging waterways, and it threatens plant species native to the area. The milfoil invasion has also caused shoreline property values to sink. It is imperative that milfoil populations are controlled or irreparable damage may be done.

Land Economics 85: 391-409 (2009)

Myriophyllum, more commonly known as “water milfoil”, is an aquatic invasive species originating in Eurasia. This species has recently been discovered in some of the rivers that run through the Adirondacks, very popular spots for fly-fishermen. The most reasonable explanation for the migration of this species from the Eastern to the Western hemisphere is that of ballast-water transportation. Before embarking on a journey, large ships take in a certain amount of water called “ballast water”. This water is used as a type of counterweight – the addition of it to the ship’s weight helps to stabilize the ship and provide proper buoyancy. Upon reaching their destination, these ships release this water into the surrounding bay, dock, inlet, etc. Biologists have concluded that this is the most justifiable reason for the discovery of water milfoil in the United States – particularly the New York area, as it is such an epicenter of the coming and going of ships. One way environmentalists are attempting to reduce the water milfoil population in upstate New York water parks is with devices called “benthic barriers”. This form of eradication is fairly simple – gigantic plastic sheets are taken to the bottom of the lakes and pinned down, covering water milfoil colonies. This prevents sunlight from reaching the plants, and eventually leads to their death. Another method is called “biocontrol”, where certain fish and small marine life are introduced to these ecosystems in order to feed on the watermilfoil population and keep it under control. A curious fact about these plants is that it is seen as a valuable source of biofuel, especially in our day and age where everybody is struggling to “go green”. The battle of whether to kill off milfoil or to try and control it for human use is currently underway.

The mute swan – generally seen as a majestic creature and one that inspires peace and tranquility, this large waterfowl is not understood to be an aquatic invasive species by most of the general public. What makes this bird so destructive? It is typically known as one of the most aggressive species of waterfowl, and it consumes large amounts of underwater vegetation. This vegetation is important to the rest of the ecosystem in that it helps to hide baby crabs, fish, etc. who need the protection of the grass before they are big enough to make it alone in open water. This over consumption of underwater grasses is leading to a decline in those native populations, and a 10% increase in mute swan populations every year (meaning that the population doubles every 7 to 8 years). Right now, officials in the Maryland/Chesapeake Bay area are considering several methods for the reduction of the mute swan population. The least violent of these methods is a process where mute swan eggs are covered with oil which prevents them from hatching. Although reluctant to resort to such a measure, killing the swans (either by shooting or breaking their necks) is provided for as a last resort option. While animal rights activists claim that the mute swans do not have a great effect on bay grasses, studies have shown that the average adult mute swan eats up to 8 lbs of bay grass every day.

Although I could not find any direct information on aquatic invasive species in Texas, I did find this interesting website that lists many of the invasive species found in the state. Some of the more unique ones are electric eels, freshwater sting rays, and piranhas.

http://www.tpwd.state.tx.us/huntwild/wild/species/exotic/

http://en.wikipedia.org/wiki/Mute_Swan#Distribution_and_habitat

http://en.wikipedia.org/wiki/Myriophyllum

Eurasian Watermilfoil has been crowding out species native to the Americas for some time now; its estimated introduction to our continent is 1900. Its introduction may have been caused by its survival in a boats ballast water or the aquarium trade, and its spread is significant due to its reproduction through stem fragmentation. A colony of watermilfoil gets tangled on boat, and stems of the plant are consequently transported.

This invasive species out competes native flora, causing an imbalance in the natural lake ecosystems throughout America. Specifically, watermilfoil tends to dominate nutrient-rich lakes, having less of an impact on ones lower in nutrients. Watermilfoil threatens such ecosystems by dominating the lake surface and encroaching its shallows. This is certainly concern for the native flora, but as for us, the nuisance of thick, ugly vegetation is its only imposition. Therefore, the question is whether the removal or containment of eurasian watermilfoil is worth the money it costs, whether it is our duty to protect the native species.

http://www.invasivespeciesinfo.gov/aquatics/watermilfoil.shtml

http://www.great-lakes.net/envt/flora-fauna/invasive/milfoil.html

The Eurasian watermilfoil has spread far and wide since its initial introduction to the United States. This non-native species can now be found in forty-six out of fifty states, and carries with it effects ranging from undesirable to ecologically threatening. The most prominent of these problems is the “crowding out” caused the watermilfoil’s overgrowth in an area. The plant will block sunlight and otherwise compete with native species in a given body of water, using its ability to create densely infested areas to its advantage. Other issues are related to human use of the water in question, as watermilfoil can make boating, swimming, or fishing nearly impossible.

While it may sound selfish, the effects on human recreation are what interest me the most. As a lifeguard in a pond with a watermilfoil problem, (there is water chestnut as well, but this problem is under control) I have seen the impacts of watermilfoil first hand. The effects on pond use are twofold. First, there are the obvious problems related to human use of the water. Children who may be scared of the water already will refuse to swim because they are scared to touch the watermilfoil under water. Canoeing and kayaking is severely limited in certain areas where boats become ensnared and paddling becomes difficult. Even the fishing population is effected, as fishermen cannot cast a line in large portions of the pond without hooking a watermilfoil stem.

The second set of issues are concerned with the economics of limiting an invasive species. Even considering the above problems, the watermilfoil infestation could be much worse in this pond. It is limited by constant and expensive vigilance on the part of the town, which devotes a large amount of resources to pond maintenance. First, they must pay for the daily operation and maintenance of a weed harvester, essentially a large boat that serves as an underwater lawn mower. Also, netting is laid down in shallow areas each year to try and restrict growth of the watermilfoil. Finally, lifeguards spend a significant amount of time manually uprooting the plant in swimming areas. As a consequence, the town pond runs each summer in the red, losing money in order to preserve the use of the water while it still can. In today’s economy, this level of spending does not look good to town officials, and accordingly the pond is facing budget cuts in the upcoming summer.

NOTE: the last link below is an old version of the pond’s contingency plan for the watermilfoil if you are interested in learning more.

http://el.erdc.usace.army.mil/aqua/apis/PlantInfo/plantinfo.aspx?plantid=33

http://www.lakegeorgeassociation.org/html/eurasian_watermilfoil.htm

http://www.morsespond.org/studies/2005_weed_harvesting_wagner.htm

The state of Connecticut has over six hundred miles of coastline and numerous freshwater lakes and ponds.  There are many native aquatic plants that have inhabited Connecticut’s waters for years, but recently many invasive species have begun to emerge has well.  Three of the most prominent invasive species are a series of milfoil plants: Myriophyllum spicatum, Myriophyllum heterophyllum, and Myriophyllum aquaticum.  More commonly known as Eurasian water-milfoil, variable-leaf water-milfoil, and parrot-feather, these three species have sprung up in significant amounts in the New England area, including Connecticut.  Each has its own characteristics, and has affected Connecticut’s ecosystems in a particular way.

Eurasion water-milfoil is one of the most serious invasive plants in the United States, growing in thick strings, typically about ten feet in length but sometimes up to thirty feet, that eradicate native plants and pose a threat of entanglement to boats and swimmers.  It first appeared in Connecticut in 1979, and has spread throughout the western part of the state.  Variable-leaf milfoil is similar to the Eurasion species, forming thick mats of vegetation that make boating and swimming difficult.  Although it does not grow as long, its thick stems often rise to the surface.  It has spread to thirty or more ponds and lakes in the state.  Parrot-feather grows both below and above the surface of ponds, sometimes extending as far as a foot above the water.  It is a popular plant in aquatic gardens, but as an invasive species it creates shade that can kill algae and it provides habitat for mosquitoes to breed.  Although parrot-feather’s presence in Connecticut is relatively new and not yet widespread, it can survive the state’s harsh winter weather and could expand rapidly in the future.

The presence of these invasive milfoil plants in Connecticut leads to a number of difficult questions.  What efforts should be taken to remove them?  Should they be removed at all?  What will happen if they are left alone?  Is there an equilibrium between native and foreign plants that can be reached?  All three species of milfoil are resistant to standard methods of eradication, as cutting or uprooting them can easily lead to their spread instead of their removal.  Moreover, chemical methods are frowned upon because they can result in the death of all plant life in the body of water, followed by all animals as well.  Some state-approved removal techniques include “winter drawdown”, lowering the water level of a pond during the winter to expose plant roots to the cold, and the introduction of herbivorous fish into pond.  Every method has its flaws, however, and ultimately the question of how far one should go to control the spread of invasive species remains.  It is a question that Connecticut – as well as much of the rest of the world – will have to address in the future.

Sources:

http://nbii-nin.ciesin.columbia.edu/ipane/curriculum/Appendices.pdf

http://www.ct.gov/caes/lib/caes/Aquatics_Guide.pdf

http://www.quickr.org/Connecticut_coastline_length

http://www.ct.gov/dep/lib/dep/pesticide_certification/Supervisor/aweeds.pdf

http://www.ecy.wa.gov/Programs/wq/plants/weeds/aqua003.html

Inland Invasion: The Impact of Eurasian Watermilfoil on Water Habitats

by Emily Chang

The Eurasian watermilfoil, also called Myriophyllum spicatum or simply the milfoil, is an invasive plant species introduced to the United States from Europe in the 1940s, and it has spread to various places in North America from British Columbia to South Carolina. Its leaves, which are jade-green in color and consist of approximately twelve to twenty-one paired leaflets, are grouped into three to six whorls, or coils. The stems and small flowers of the milfoil are usually red-brown but have some variation in color. Because the Eurasian watermilfoil looks similar to certain other plant species, particularly the native northern watermilfoil and the native coontail, it requires close observation to identify this submersed plant. While the native northern watermilfoil (Myriophyllum sibiricum, or M. exalbescens) has fewer than twelve pairs of leaflets per leaf group, the Eurasian watermilfoil generally has twelve to twenty-one per leaf. Unlike Eurasian watermilfoil, the native coontail (Ceratophyllum demersum) has a rough texture and toothed leaves.

Although the Eurasian watermilfoil can spread to inland lakes and ponds via boats, boating equipment, and waterbirds, its primary means of dispersal occurs through plant fragmentation. The milfoil generally reproduces and spreads when parts of its stems break off and travel to other waterbodies, where they would take root and create new colonies. This plant fragmentation process often takes place in two ways: when the milfoil’s stems become brittle and easily broken around late summer to fall annually, and when motorboats sever the stems and disperse them to new locations. Horizontal plant segments called stolons contribute to the local colonization of water habitats by milfoils as well. These dispersal methods, coupled with the plant’s ability to withstand a wide range of temperatures, allow the milfoil to spread quickly; it can colonize a lake in less than two years’ time. Once a colony is established in a body of water, the milfoil could cause substantial harm to its environment. For one thing, it can grow into dense mats that cover the surface of a lake; this can crowd out other native plant species, obstruct waterways and water intake passages, and decrease the oxygen levels of the lake. Dense milfoil growth can also hinder human activity such as boating and fishing. A variety of methods have been employed to control the growth and spread of milfoil. Biocontrol methods include the use of pathogens, insects, and fish; aquatic herbicides and other chemical methods are somewhat effective but must be implemented every one to three years. Humans have also employed hand-pulling, rototilling, underwater vacuuming, and mechanical harvesting to keep milfoil populations under control. Although these means of control are effective, they have not managed to completely eliminate Eurasian watermilfoil colonies in bodies of water.

Because the spread of the milfoil can occur through human activities, notably boating, it is reasonable to question the ties between humans and this invasive plant species. As I read on some of these websites, aquatic wildlife and ecological organizations advise boaters and fishers to remove plant material from their boats and other equipment and discard this debris in a container or location reasonably far from lakes and ponds. Also, I saw information concerning aquatic gardening and how to choose, plant, and discard aquatic plants for a garden. Such notices and advice generate some doubts in my mind as to whether they are effective. When organizations put up helpful tips like these, people often do not heed them, which render them ineffective. An analogous situation would be putting recycle bins along trails to prevent littering while people still choose to throw their trash among the trees and other plant vegetation that could be potentially harmed. Since scientists and researchers have not achieved milfoil eradication, then it is reasonable to take a step back and reflect on the situation at hand. How could people effectively conquer and defeat this detrimental species? If scientists do find a way to control milfoil colonies, will this method harm other plant and animal species? Will it involve unreasonable measures for humans to take – in other words, will it ask too much of both the scientific community and recreational boaters alike to implement? Like I have said, the various control methods currently used to keep milfoil colonies under control are only successful to a certain extent, so I believe that scientists and conservationists should either look for alternative methods to eradicate milfoil populations or research new ways to eliminate them. The wildlife organizations also could impose inspections of boating equipment that could result in heavy fines for boaters who fail to clean their equipment well.

Sources:

http://www.iisgcp.org/exoticsp/watermilfoil.htm

http://plants.ifas.ufl.edu/node/278

http://plants.ifas.ufl.edu/node/90

http://www.ecy.wa.gov/Programs/wq/plants/weeds/milfoil.html

http://www.dnr.state.mn.us/invasives/aquaticplants/milfoil/index.html