Elser from Arizona State University and his team conducted a study examining the distribution and competitive effects of the invasive zooplankton Daphnia lumholtzi in Arizona. First detected in Texas in 1990, this species indigenous to Africa, Australia, and India has spread throughout the midwestern and southern United States.
Elser conducted a field sampling of 12 reservoirs in central Arizona and a competition experiment involving water from Canyon Lake. The samplings demonstrated that D lumholtzi was dispersed across central Arizona in various watersheds, some with a greater percentage of the exotic zooplankton than others (ranging from none to more than the native species). This proves the persistence of this specie’s invasion in Arizona. The competition experiments found that the production of both species (D lumholtzi and native D pulex) decreased when both were present at the lake. Also, D lumholtzi reduced total zooplankton production. Therefore, communities dominated by D lumholtzi are expected to be less fertile and retain lower biomass.
Research on this detrimental species will continue because it impacts plankton communities and fish production since their spination renders them inedible.
Resource: Journal of the Arizona-Nevada Academy of Science Vol. 34(2): pp 89-94. (2002)
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The red swamp crayfish, P. clarkii, is one of the most ecologically damaging aquatic species. A native of Louisiana, this freshwater crustacean has invaded Mediterranean ecosystems in 5 of the 7 continents, imposing detrimental effects on each.
Scott Valentine of Duke University has proposed a study to determine the mechanisms by which P. clarkii reduces biodiversity in invaded ecosystems. Valentine hopes to find major differences in the food preferences of the native and invasive crawfish. He is confident that he will find sufficient support since many faculty members from the University of Florence and other universities throughout southern Europe have expressed interest and dedication to the study of P. clarkii.
Valentine believes the study will take approximately 15-36 months to complete. Field collections in two northern Italian streams, one dominated by P. clarkii and the other by A. italicus, will take about a year and may enlist supplementary assistance from citizen scientists. The bulk of the work, however, will take place in the lab as scientists analyze the stomach contents of the different species collected to determine the contrasting diets of the native and invasive crayfish species. Organic material found in the stomachs of each will likewise be scrutinized to ascertain the major ecosystem differences resulting from the P. clarkii invasion.
P. clarkii is a keystone species which further complicates the establishment of effective removal methods. This invasive species fills the niche originally held by the native crawfish species in each habitat but causes all sorts of problems because it is not a perfect match. “Ideally we would want to remove all P. clarkii and replace them with the native A. italicus species, but it is not that simple,” reports Valentine. The balance previously maintained in this ecosystem cannot be achieved because of the environmental alterations that have begun because of the P. clarkii introduction. On the whole, Valentine is referring to the “crawfish plague.” One of the most unfortunate consequences of P. clarkii invasion is its simultaneous transportation of the fungus A. astaci. When this fungus is brought in to foreign ecosystems that haven’t been acclimated to it, the local crawfish die.
“What we really are hoping to achieve is the reduced spread of invasive species, specifically the red swamp crayfish. This is a slippery slope, however, because native species are having difficulties reestablishing themselves due to the fungi transported via the invasive crayfish,” says Valentine. In addition to the stress placed on the environment by P. clarkii who dominate the native population and upset the natural balance of resource chains, the fungus serves as a major impediment. In order to return to the initial conditions before the invaders scientists would have to do more than just eliminate P. clarkii entirely, since the fungus spreads to the native species which in turn either die or subsequently serve as carriers for many years. Complete extermination of both the native and non-native invasive species as well as eradication of the fungi would all need to occur for a return to normalcy.
Biodiversity loss is a major factor contributing to the problem with this invasive species. Specifically, the loss of biodiversity after the invasion of P. clarkii caused a decrease in the freshwater volume of detritus, small fishes, and benthic organisms (all part of the P. clarkii diet), all of which contributed to a decrease in the water quality. P. clarkii burrow in the sides of streams where rice plantations are located and they caused a widespread decline in various countries’ rice production. Humans are inherently linked to the environment and thus also bear the repercussions of this invasive species.
In sum, Valentine’s study will enable scientists to learn how the P. clarkii changes an ecosystem by examining its food sources and the overall mechanisms by which it invades and dominates foreign habitats. More effective control methods can eventually be developed to end the invasion and continued eco-trauma delivered by the red swamp crayfish.
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The National Research Council (2002) conducted scientific investigations of genetically engineered organisms to assess their environmental risk. After evaluating harm, hazard, and risk, William Muir of Purdue University has singled out three forms of GE modification which include inducing male-based sex ratios, releasing inducible fatality genes, and introducing non-disposable genetic loads to decrease exotic species populations. Scientists are reluctant to engage in the first two methods because they demand continuous reintroductions for effectiveness since the genes won’t spread unassisted. One disadvantageous effect associated with GE organisms, specifically non-disposable genetic loads, is the Trojan gene effect whereby subsequent development in the target species makes it more susceptible to transformation by the transgene into an even greater threat. However, this side effect may prove beneficial for the control of invasive species who up to now have only been approached via chemical, mechanical, and biological methods. Currently, implementation of selfish genes appears to hold the most promise. This alternative technology creates the spread of a ‘super-Mendelian’ gene that destroys a crucial gene function. It has a specific host (in this case, the sought-after invasive species) and employs faster eradication methods. A possible concern with this technique is the elimination of non-target species that possess similar qualities and are thus correspondingly affected.
Aquatic Sciences. DOI 10.1007/s00027-004-0721-x
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I was thoroughly impressed by Paul Neal Jordan’s paper on religious satire in Hollywood. The integration of religion and pop culture that he analyzed via the movies Saved! and Borat was provoking and captivating. I couldn’t stop myself from reading through the entire paper in one swift sitting because it flowed so eloquently and held my constant attention. Initially, it starts off with a narrative-like description of a relevant SNL skit that immediately captures the reader and sets the general subject into play. Humor and sarcasm are two techniques not only discussed but also practiced in the paper. The writing is at times crude which mirrors the statements made concerning how non-news sources are more at leisure to employ literary techniques and relay information in relaxed and even demeaning ways. Satire in this way is proven even through Jordan’s own writing to be a safe medium to express feelings pertaining to religion and as an indirect route to allow the audience to scrutinize their own prejudices. I was surprised and impressed by his incorporation of classic literary works like Huck Finn and Voltaire to promote his point. I would not have immediately considered their connection to the topic at hand in that their points can be considered humorous because of where they are coming from. Likewise, they are condemning racial and religious attitudes by mocking them just as Borat ridicules Jews and as Hillary Faye and other characters from Saved! scorn non-Christians. The exaggerated satire throughout Saved! arouses reflection about stereotypes and biases and allows readers to conform their perceptions. Specifically, this movie parodies the harsh opinions fostered by some devout Christians against such things as gays and abortion. The strategy of proving one point by emphasizing another is similarly revealed in this movie. Hillary Faye, a “Christian Jewel” of the fundamentalist community, is in herself a polarized juxtaposition since her actions towards her friend who becomes pregnant (namely rejection) are in severe contrast with the ‘holier-than-thou’ attitude she continually proclaims to uphold. Jordan simply advocates, with confirmation from Saved!, that a religion cannot spread its values if it simultaneously preaches intolerance. The high school attitudes of the characters in the movie give an accessible and easily relatable example of how the actions of religious groups in fact deter others from complying with their beliefs because of their polarization and outcasting. Jordan summarizes and reconnects all entities of his analyzation in the end of the paper when he discusses the trick mirror theory. This metaphorical analogy is the perfect way to finish off the composition. Clearly, this Duke student did his duty in developing a literary work that utilized language, structure, and functions that emphasized and at times reflected the point he was addressing. His arguments were strong and well supported and I can only hope that my papers evoke such a great response from my readers.
It is difficult to compare my paper to Jordan’s paper because they are basically at opposite ends of the writing spectrum. Unlike my MWP1, this paper made us of more informal and conversational rhetoric. Jordan incorporates an almost chatty tone throughout and speaks to the reader in ways that force insightful considerations as one peruses his literary exploration. While reading the paper, I found myself chuckling at the structure that he employed and the humorous anecdotes that he included. The examples cited were pop culture literary works and TV episodes or movies as opposed to the scientific research articles and studies that I referenced. With respect to format, Jordan did follow a similar arrangement to my MWP1. He began with an introduction in which he stated a clear and organized thesis and followed with examinations of two examples that adequately prove the point he was attempting to address and solidify. He states the drawbacks or faux-pas associated with each of his examples as well and follows with a discussion-like conclusion that sums up the overall paper. In the papers that I have written for this Writing 20 I have frequently used militaristic literary terminology to relay my opinions. Jordan instead mirrors the satirical theme of his paper by writing in a similarly mocking and at times vulgar way. Overall, I think that academic writing must consist of a certain structure with a thesis, cited examples, and a conclusion, but the manner in which these are all expressed (in terms of language used and literary styles employed) can vary dramatically.
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The context through which invasive species are described often relies on aggressive and militaristic figures of speech and expression. Larson disagrees with this particular writing style, arguing that the language alters the way that readers view the species discussed and how they react toward them. He finds that terms such as bombardment, detonation, enemy release and strategy make it seem like humans are rivals to the natural world (Larson 2005). He argues that hostile writing influences conceptions of scientific, nationalistic, and social objectivity. He even goes as far as to propose that discussing invasive species in this fashion makes certain people think of actions against exotic raiders as class-based or race-based. Larson promotes that instead we look at invasive species as some sort of disease that weaken an ecosystem’s health, like pathogens do unto the body. This metaphor emphasizes the detrimental affects of invasive species and subtly implies militarism since that is the way some diseases are combatted in the mind (Larson 2005).
In my SW3 blog post I found several examples of militaristic rhetoric. “The water hyacinth, an invasive aquatic plant indigenous to South America, continues to lay siege on Lake Victoria in Kenya.” As the paper continued I also included such expressions as termination, deployed, control agent, and war. Looking back on this post, I consider this style and wording convincing in addressing my point and I don’t think that it overemphasizes the perilousness or voracity of invasive species, specifically the water hyacinth.
While I understand Larson’s point of view and can appreciate his outlook pertaining to militaristic language and metaphor use, I do not particularly agree with him. He seems to be taking things a little too personally and his exaggerated attempts to connect society, nationalism, and politics to these militaristic metaphors fails to tickle my fancy. Invasive species generate disastrous effects on native ecosystems and economies and I find the use of warlike expressions quite fitting. They impart an appropriate amount of concern since invasive species do pose severe risks to our natural environments and are difficult to control. I am fond of his invasive species-disease analogy and would agree that this parallel is more appropriate and applicable to environmental interaction. Taking Larson’s advice and applying terms of passivity that promote “quality of life” doesn’t seem effective or wise because it downplays the major harm looming behind continued invasion. In this way, I think that the “boomerang effect” serves as an effective method of detailing the urgency with which we need to deal with exotic invaders. Persuasion of this sort bolsters more support from local community members. In sum, militaristic rhetoric serves as a practical technique for scientific writers to advocate action against invasive species by instilling feelings of environmental patriotism and acknowledging their threatening influences. It’s mode of encouragement and enlightenment seems beneficial in association with exotic invasions.
Larson, B.M.H. 2005. The war of roses: demilitarizing invasion biology. Frontiers in Ecology and the Environment 3: 495-500
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The Brazilian peppertree, an invasive species from southern South America, intruded on Florida before the 1900s and spread to Texas and Hawaii soon after. Specifically in Florida, this weed plagues pine land, hammock, and mangrove dwellings as well as the Everglades National Park. In the 1980s, a search for Brazilian pepper’s natural enemies for use as biological controls began and several candidate agents were unearthed. The TAG advocated the release of P. ichini in May 2007. First examined in Brazil, these thrips proved effective in reducing the strength and reproductive rate of Brazilian pepper in both their larval and adult stages. Using snap cap vial quarantine experiments, researchers developed a mass-breeding technique to verify that ample healthy insects could be released as control agents. These trials proved successful and allowed the Entymology and Nematology Department to gain approval for conducting field releases of P. ichini against the Brazilian pepper in locations throughout Florida.
Cuda, J. P., Gillmore, J. L., Medal, J. C., & Macedo, J. H. P. (2008). Mass rearing of pseudophilothrips ichini (thysanoptera: Phlaeothripidae), an approved biological control agent for brazilian peppertree, schinus terebinthifolius (sapindales: Anacardiaceae). The Florida Entomologist, 91(2), 338. Retrieved from http://search.proquest.com/docview/219330109?accountid=10598
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The negative economic and environmental repercussions of non-native species invasion encourages citizen science assistance. Voluntary aid contributions and access to lands typically restricted from professional scientists serve as worthy advantages. However, there are many drawbacks including increased variability among data, misidentification, and oversimplified procedures yielding worthless information.
Crall et al. of the Nelson Institute for Environmental Studies at the University of Wisconsin-Madison advocates creating a worldwide database to share figures about invasive species. A survey was conducted with 249 citizen science groups regarding available resources, data collection, data management, and data assurance or control. Crall et al.’s results documented deviation between number of volunteers, available educational resources, and funding. In addition, new invasions could be missed by random sampling and small sample sizes. This justifies the reluctancy behind acknowledging data submitted by citizen scientists: their lack of scientific background prompts reliability and data quality concerns.
These surveys generated better understanding of citizen science programs and contributed to cyber resource designs, like NISS’s citisci.org, which integrate information while still protecting sensitive data.
The water hyacinth, an invasive aquatic plant indigenous to South America, continues to lay siege on Lake Victoria in Kenya. This pernicious, prolifically-spreading plant forms thick carpets on the lake that cause harm to other plant and animal species, including humans. In fact, the introduction of the water hyacinth reduced catch levels and lowered the income of local Ugandans, fouled drinking water with rotting vegetation, and even contributed to the spread of diseases like malaria by attracting mosquitoes to the stagnant pools. The water hyacinth can thus be deemed a destructive pest whose harm needed to be terminated. Bio-control efforts first began in the 1990s with weevils which were bred and deployed on the water hyacinth. This biological control appeared effective as the weed population was dramatically reduced. Wilson et al. (2007) argues that the importation of the Neochetina control agent served as the main source of water hyacinth elimination. He does, however, confirm that the blustery weather brought on by the El Niño event catalyzed the water hyacinth reduction. William et al. (2007), on the other hand, counters that El Niño weather conditions were the only true contenders in the war against the invasive plant.
The windy weather patterns generated by El Niño allowed for plant mat mobility to particular areas of the lake. According to Wilson et al. (2007) the MODIS satellite images depict some areas with high density growth and some with very little. This situation brings up much controversy in relying on the satellite images because severe improvement or deterioration could be conjectured based upon the particular location of a site or the specific time it was viewed. In other words, a shoreline area attracting many of the scattered remains of hyacinth would suggest a resurgence while an upstream area that lost many of its remains would appear to be cured of this weed infestation. The data pictures collected from the satellites, therefore, are undoubtedly misleading. Using the shots to evidence the degree of hyacinth magnitude is unreliable and cannot effectively prove the source of invasive species control.
Wilson et al. (2007) asserts that the landmark turnaround in water hyacinth population occurred at a convenient time in connection with the biocontrol effort. A halt to the rapid climbing of hyacinth growth occurred four years after the weevil was introduced, which conforms to typical biocontrol observations in other countries. Wilson et al. (2007) also brings up a good point pertaining to hyacinth resurgence. While strong currents and winds cause stress to the plants (which would seemingly contribute to their destruction), El Niño could have revived the water hyacinth problem. Breaking apart the hyacinth mats would promote the penetration of sunlight and would increase the levels of nitrates and phosphates because of the thick plant sheets’ decreased absorption of agricultural runoff. Both of these factors could stimulate germination and actually cause a proliferation of the hyacinth. The weevil populations would not effectively be able to help resist this resurgence because many of the eggs and larvae would drown when the mats sank. In this respect, Wilson et al (2007) claims that El Niño may even have counteracted attempts to reduce water hyacinth levels. Williams et al. (2007) relies on this same data to strengthen his argument that El Niño was the sole reason behind reduced volumes of hyacinth. It is funny that Williams et al. (2007) and Wilson et al. (2007) were able to fortify their different hypotheses using almost identical facts and figures.
Despite the facilitation provided by El Niño’s wet and cloudy weather conditions, the weevils did indeed contribute to the campaign against the water hyacinth. I find myself drawn more toward the opinions of Wilson et al. (2007) as his arguments suggest more multiplicity in causation of water hyacinth reduction (a multi-faceted control effort). He emphasizes the importance of continued reliance on weevils as a biological control effort. It is interesting to note that both Wilson et al. (2007) and Williams et al. (2007) comment on the lowered efficiency of this control on large bodies of water, like that of Lake Victoria. Nevertheless, I still believe that weevil usage proves effective and should continue to be employed against this invasive weed.
NASA Earth Observatory. 2007. Water Hyacinth Re-invades Lake Victoria. http://earthobservatory.nasa.gov/IOTD/view.php?i=7426. Viewed 24 Jan 2011
Williams, A. E., R. E. Hecky, and H. C. Duthie. 2007. Water hyacinth decline across Lake Victoria – Was it caused by climatic perturbation or biological control? A reply. Aquatic Botany 87: 94-96
Wilson, J. R. U, O. Ajuonu, T. D. Center, M. P. Hill M. H. Julien, F. F. Katagira, P. Neuenschwander, S. W. Njoka, J. Ogwang, R. H. Reeder, and T. Van. 2007. The decline of water hyacinth on Lake Victoria was due to biological control by Neochetina spp. Aquatic Botany 87:90-93
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Posted by: Nikki Rigl in SW2
Strange Days on Planet Earth gives movie viewers an up close and personal look into real-life alien invaders. Hosted by Edward Norton, this environmental documentary uses enrapturing images, graphic around-the-world examples, and trustworthy accounts from scientists to illustrate the impact of invasive species on our world.
I thought that the film was sophisticatedly captured. The soundtrack was intense and added an ominous overtone to the story line. The introductory snapshots of various invasive species were captivating, especially with the emphasis on bright colors. Throughout the film, the close up pictures were often frightening yet beautiful at the same time in terms of their expression of natural phenomena. I enjoyed how the idea of random ups and downs in the environment were mirrored by Mr. Norton’s sudden ‘appearance and disappearance’ act in the first scenes of the movie. Mystery was a common theme stressed by the musical and visual cues. The overall thesis of the film was also addressed out front so that the audience was aware that invasive species would dominate the overall action of the documentary.
I was impressed by the inclusion of examples and how well each was described. As Jim Carlton expressed, invasive species truly are playing a round of ‘Russian Roulette’ that directly effects our environment, economy, and society as a whole. This is particularly evident in the case of the foreign termite infestation in New Orleans. This invasive species swarms homes and is cleverly adapted to the hot and sticky Louisiana environment (they can live both above and below ground which keeps them from succumbing to pesticides like native termite species).
It’s interesting to consider that we are the ones often at fault for the negative aftereffects on our environment. After all, our own globalization of trade and expansion of transportation instigated an extensive spread of alien species around the world. The film showed us vivid snapshots of critters teeming in ship ballast water and termites looming within the wood of crates. The statistics concerning possible species extinction are quite startling: 2/3 of land mammals may vanish! In fact, Carlton reveals that 99% of marine life in San Francisco Bay comes from somewhere else. This means that only 1% of inhabitants are native species. Another surprising piece of information that was shared pertained to Hawaii. Did you know that species typically considered to be of Hawaiian origin, like pineapple, macadamia nuts, and lei flowers, are actually alien species?
Whether using extensive technological equipment (like Asner’s helicopter remote sensing scheme for mapping out infestations of Miconia) or taking a community-based approach (like the weed warriors in California), it is clear that bringing a species in is much more difficult than trying to eradicate it. This is adequately proven through the slightly disturbing figure the there are between two and three invasions in the world every day!
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The cane toad is an invasive aquatic species that was brought to Australia from Central and South America in an attempt to reduce the number of insect pests harming the sugar cane crops. These toads reproduced rapidly and overpowered native environments. Even local predators were dying after consuming the poison excreted by the toads. When I took AP environmental science in high school, I remember watching a video detailing the arrival and eventual harm caused by these cane toads. It is amazing that they have been negatively impacting our native environments since the 1930s!
Malakoff notifies us that recent studies by Sydney researchers have suggested the use of Australian frog tadpoles to diminish the intrusion by cane toads. A number of experiments were done in which cane toad tadpoles were placed in bins with a varied number of Australian frog tadpoles to see how this competition would impact the cane toads. Apparently, the presence of these native tadpoles prompted the cane toad tadpoles to become less reproductively fit, even causing a higher death rate. This biocontrol effort will hopefully prove to be as effective in the wild as it was in the ‘competition bins.’ I am both intrigued and impressed by this use of native species to combat the impact of the invasive cane toads.
Cane toads have been plaguing Australian natives for far too long. It is distressing that efforts to cease their negative impacts have not been successful. In fact, Professor Seebacher from the University of Sydney explained that cane toads may actually flourish under the conditions generated by global warming. This means that while other species (especially natives) suffer from the higher temperatures cane toads may actually become even more of a threat.
All in all, it seems as though scientists should have put a little more time and effort into reviewing the possible consequences of introducing this foreign species to Australia to solve their cane beetle woes.
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