Aquatic Invasive Species

Larson’s paper centers around the rhetoric of invasion biology. He argues that many biologists attempt to disseminate their findings by strategically using words that relate invasive species and human counter-measure efforts to invasion plans of foreign countries. By using such words, he feels that the wrong messages about invasive species are being sent to the public (i.e. the American public and U.S. Congress) and cause the general populace to consider control efforts in “a militaristic framework…” (Larson 2005). He also feels that their informality detracts from good science. Larson says such thinking is counter-productive, as a war-like approach will not succeed because human intervention is ultimately the main source of invasive species.

After sifting through our past class materials, I came across the article on mute swans. The title: Deeply Divided Panel Backs Eradication of Mute Swans. Immediately, the word “eradication” struck me as militaristic (Halsey 2009). Had the author wanted to just write an article about the declining swan population, a word such as removal or euthanization could be used. However, this word choice grabs the readers attention as an attack on the swans. The phrase “formidable threat” continues the description of the mute swan (Halsey 2009). Better yet, the article furthers its combative stance with this invader by stating a Maryland Dept. of Natural Resources panel convened to “review its eradication program” (Halsey 2009). Why does such a belligerent stance seem so commonplace? Whether we like it or not, humans hold a innate propensity for war. Since my birth, America has engaged in several armed conflicts, and has spent very little time at peace. It would seem as though these aggressive words (or more likely, this aggressive behavior) have made their way from the battlefield to the homefront, and by extension the classroom, laboratory, dorm room, and dinner table. The first things that grab our attention are usually sensational, emotion-provoking words and images. By casting a certain invasive species as the worst thing to ever happen to an area, a researcher or reporter is almost guaranteed to gain public recognition (and often funding to conduct more research or implement a control plan). In stark contrast, the odds of a scientist gaining public recognition outside his/her field of a paper or recommendation without using militaristic words are extremely low. We are too conditioned to think like soldiers (in this sense), and often ignore anything that we don’t perceive to be a threat.

Even though we hold a natural tendency to fight anything we consider detrimental, it is ultimately our own fault for the introduction of invasive species. While such metaphors are problematic when it comes to formality, they do bring a large, rapid response from the intended audience. During the Maryland snakehead scare, many of my friends and neighbors became incredibly frightened by this Chinese “superfish.” However, the public outcry allowed for the rapid approval of snakehead removal efforts. Thus, the response provoked by using militaristic references are almost always unparalleled.

Halsey, A. “Deeply divided panel backs eradication of mute swans.” 2009. The Washington Post. Retrieved 23 February 2010. http://www.washingtonpost.com/wp-dyn/content/article/2009/05/15/AR2009051501258.html

Larson, B. M. H. 2005. The war of the roses: demilitarizing invasion biology. Frontiers in Ecology and the Environment 3: 495-500.

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

Reading the four articles, especially the Mute Swans article, got me thinking about the definition of invasive species. While the ecological definition of invasive species is relatively well defined (“non-native species of plants or animals that out-compete native species in a specific habitat” from http://www.floridasprings.org/glossary.html), I feel that that the qualities that label a species as “invasive” and offensive by the public are much more vague.

The Mute Swans, for example, are scientifically an invasive species. The species was first introduced to the East Coast from Europe and Asia in the early 1900’s, when they were imported as decorative birds for parks and estates. Wild Mute Swan populations increased drastically in the Chesapeake Bay in the 1980’s and 90’s, as they out-competed native species for food and habitat. Legislation was passed in 2000 to control the swan population. There has, however, been public opposition to killing the mute swans. The article from class mentioned the “deeply divided” state panel, and the opposition from animal rights groups.

Mute swans pose just as great a threat to native species as snakeheads or didymo, but the opposition to swan population control in the Chesapeake made me wonder why there were no similar movements for these species. I guess the fact that swans are more aesthetically pleasing (as opposed to http://www.mountainmurmur.com/wp-content/uploads/2008/11/didymo-mararoa_s1.jpg) does influence public opinion on how comparatively “invasive” species seem, since noone wants didymo in their water. I’m sure there are many other invasive species that drastically disrupt native ecosystems and completely drive away certain species, but we don’t make a big deal about them because we are okay with having the invasive species around. There are factors (economic or aesthetic) other than endangering native ecosystems that the public takes into account when we decide whether a species is “invasive” and should be eliminated, or if nature should be allowed to run its course.

http://news.nationalgeographic.com/news/2003/06/0605_030605_muteswan.html

http://www.chesapeakebay.net/muteswan.aspx?menuitem=16930

With their elegant-shaped necks, and snowy white feathers, mute swans are arguably one of the most beautiful birds in America. Especially in the Chesapeake Bay, they have become a common vista for travelers and the inhabitants of that area. It is therefore surprising to find that the mute swans are an invasive species to the area and are on a warpath of destruction that is reaping havoc on the habitats of indigenous species. Mute swans were introduced to eastern United States when five “lawn-ornament” swans escaped from an estate. Since then, the population has bloomed from the original five to a peak of four thousand. The swans feed on shallow-root grasses that are the safe-haven for young crabs and fishes. Each swan can consume up to 8 pounds of bay grass each day, accumulating to 10.5 million pounds for the entire population. Also, mute swans are extremely territorial, and will trample over nests of endangered native bird species, e.g. least terns (Sterna antillarum) and black skimmers (Rynchops niger), etc.

Currently, measures are being taken to shoot down a quota of swans and addle their eggs with vegetable oil so that the eggs won’t be able to hatch. Though such dealings to appear to be a bit severe, they do appear to be necessary to control the mute swan’s exponentially expanding population. I think because of the extent to which muted swans have already disrupted the environment of native species, it is necessary to shoot down swans in attempts to control the population. However, because of how much mute swans have become part of the milieu in the Chesapeake Bay area, we should take caution from killing too many swans and from wiping them completely out of the area.

After all, what is an invasive species? All animals eventually will migrate from one place to another; the world is in a constant flux. Humans are merely facilitating the process. What difference is human-introduction of a species to a new area and natural migration? Over time, according to Darwin’s theory of evolution, the newly introduced will eventually adapt to the environment and become the indigenous. Therefore, though this isn’t what I actually believe, given Darwin’s theory of natural selection, is it even necessary to attempt to control the mute swans’ population? Maybe the endangered indigenous species are too evolutionarily weak and the swans are there to place a stressor on them so that they can evolve into a stronger species. But then that question doubts the concept that endangered species need saving.

http://news.nationalgeographic.com/news/2003/06/0605_030605_muteswan.html

http://www.njaudubon.org/SectionConservation/ThreatenedandEndangeredSpecies.aspx

http://www.washingtonpost.com/wp-dyn/content/article/2009/05/15/AR2009051501258.html

http://somd.com/news/headlines/2009/10085.shtml

Mute Swans and Trees of Heaven

Although many people see mute swans as majestic, beautiful creatures that add enjoyment to our lives, according to John R. Griffin, secretary of the Department of Natural Resources, they are “an environmental hazard to the Chesapeake Bay ecosystem.” Furthermore, other reports by Griffin’s appointees have continued to vividly depict the problem of mute swans by describing mute swans as “formidable threats.”

The mute swan or cygnus olor originated in north central Europe and north central Asia, and they spend their winters in North Africa, the Near East, and parts of India and Korea. The name, mute swan, comes from the fact that these swans are generally more silent than other swans. The mute swan was first introduced into North America in the late 1800s mostly for superficial reasons. Their population has grown dramatically over time not only in the Chesapeake Bay area but across North America including the Great Lakes region. Many environmentalists are worried because of their aggressive behavior towards other birds like Canada geese and even humans. Furthermore, they consume significant portions of vegetation in the areas in which they habitat, up to eight pounds of bay grass a day. In recent years, there have been many environmental actions concerning the mute swan both for decreasing the population as well as protecting them. There has been a significant amount of lethal action from 2000 on. The population of mute swans in the Chesapeake Bay went from about 4,000 in 2000 to only 500 in 2009. The Humane Society has spoken publicly against this awful treatment of animals on numerous occasions. Mute swans are protected in some areas of the country like Connecticut. I definitely do not think that anyone should be killing mute swans; I think that since we were the ones that brought them over here then we should find a way to deal with the problem efficiently in another manner. We should put them in wildlife reserves throughout the country or put them in areas that protect mute swans. If neither of these options work, then we should send them back to Europe or Asia. Maybe, we could give them as gifts to other countries and better political ties with other countries.

In Georgia, there are numerous types of invasive species such as mimosa, small carpgrass, honey bee mite, amber snail, as well as tree of heaven. A tree of heaven is usually a small tree that grows very rapidly. They are native to Asia and were first introduced to North America in 1748. They were typically planted in communities or cities due to the fact that they could easily grow in harsher conditions. Flowering happens in early summer, and they are very resilient growing in poor soil conditions as well as even in cracks in short structures or cement sidewalks. Trees of heaven typically do best in the edges of forests. The problem is that they displace native species and rapidly take over fields, meadows, and harvested forests. I am not sure what exactly has been done to help prevent these trees from continuing to populate, but once again like the mute swans, I think that humans must take responsibility for creating these situations for invasive species to cause environmental problems due to our introduction of foreign species into North America.

References

www.gainvasivespecies.org

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

http//:animaldiversity.ummz.umich.edu/site/accounts/information/Cygnus_olor.html

The Muting of the Swans (SW1)

By: David Lung

Cygnus olor, or commonly known as the mute swan, originally came from much of Europe and Asia, but was introduced into North America where it was presented for its ornamental value in parks, zoos and private estates. A few escaped in New Jersey and New York in 1916 and 1919 respectively. They can grow up from 4-5 feet tall and weigh up to 30 lbs. Adult swans are white with orange bills that have a characteristic black basal knob. They lay up to 10 eggs and guard their young vigorously. There are few natural predators of mute swans and only attack cygnets. They often avoid attacking when adults are present, leaving many mute swans to grow to adulthood. The mute swan can be seen from Southern Ontario all the way to North Carolina and has been a symbol of love, grace and beauty for many people in the United States. However, its aesthetic appearance does not coincide with the mute swan’s image. The mute swan feeds heavily on submerged aquatic vegetation (SAVs), which causes many problems for the survival of these SAVs as well as the survival of young animals such as crabs and fish that use the SAVs as shelters before they can live on their own., The Rhode Island Department of Environmental Management (RIDEM) and the University of Rhode Island have observed that areas where mute swans feed have a 95% decrease in the biomass of SAVs. The mute swan also is aggressive towards native species such as the loon and tundra swan, driving many of these birds away from their original nesting grounds, resulting in a decline in these native species’ breeding frequency and ultimately a decline in their population. The mute swans also affect humans. Mute swans also will attack humans who get close to their breeding grounds as well as potentially contaminate our drinking water supplies when they defecate into the water. The contamination will also add excess nutrients into the water, causing algal blooms which will result in problems for many organisms in that aquatic ecosystem such as a decline in the rate of photosynthesis and oxygen reduction in the water (suffocation of fish and other aquatic organisms).

There are many methods employed today to control the mute swan’s rapid population growth such as egg addling (coating eggs with oil to prevent their hatching), relocation, and killing of adult birds. Most states allow the mute swans to be hunted. Animal rights groups have tried to limit the killing of adult birds by trying to get state governments or the federal government to protect the birds, but they have not been successful because of a general agreement that mute swans have a deleterious effect on aquatic ecosystems that impact the organisms in them and also humans. In the article Maryland panel members John Grandy and Joseph Lamp asked for proof that the elimination of mute swans would help the recovery of SAVs, but with the RIDEM and University of Rhode Island’s findings on the effect of mute swans on the population of SAVs, it is clear that the mute swan population must be controlled.

The mute swans, despite my own personal admiration of swans, are detrimental to aquatic environments in North America. They disrupt the breeding patterns in these aquatic ecosystems by driving out native waterfowl, damaging their breeding grounds and leaving young organisms vulnerable by consuming large amounts of SAVs that provide shelter for them before they fully mature. They also might potentially disrupt the food chain of these ecosystems as they reduce the SAVs and other vegetation drastically and harm other organisms. Mute swans are also a danger to humans by contaminating our water supplies and attacking humans whenever we are around their breeding grounds. I support most measures to reduce the population of mute swans. The claims in the article concerning breaking the necks of mute swans is too drastic, but continuing to coat their eggs with oil and shooting them is acceptable since both are effective methods to managing the mute swan population. However, should the swans be completely eliminated or just be controlled? Humans brought the mute swans to North America, hence it is not natural for them to be here and natural selection does not apply since it only works in a population, not in an entire ecosystem. In the controlling of populations, why are animal rights groups not on board with the process? Although systematic elimination of mute swans is unfortunate, it is for the greater good since many other organisms would benefit from it. Animal rights groups seem to be more of a hindrance and blind to the fact that many organisms are also being harmed as long as the mute swans are present. Because there is so much admiration for the mute swans, should the federal government also get involved in the efforts to relocate the swans rather than killing them? Relocation is expensive, but the federal government could provide substantial aid in helping to reduce the costs, even though there may be opposition from voters who do not want to see their tax money being used for it.

Sources:

http://www.bioone.org/doi/abs/10.1656/1092-6194%282003%29010%5B0305%3AMSCOIO%5D2.0.CO%3B2

http://www.dem.ri.gov/programs/bnatres/fishwild/pdf/muteswan.pdf

http://www.mdsg.umd.edu/issues/restoration/non-natives/workshop/mute_swan.html

http://www.dnr.state.mn.us/invasives/terrestrialanimals/muteswan/index.html

http://www.washingtonpost.com/wp-dyn/content/article/2009/05/15/AR2009051501258.html