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Driving in to work today, there was a discussion underway on the radio regarding the 'Snakehead Fish', native to Asia and Africa, captured by amateur video in Burnaby’s Central Park lagoon. Snakehead fish are voracious predators that can grow to more than a meter in length and reproduce rapidly.


Michael Russello, an associate professor of biology at UBC’s Okanagan campus, said the snakehead, were it to breed, would be a big threat to B.C. aquatic life. “It has a fantastic ability to reproduce and spread. They are an ambush predator,” he said. “They can completely decimate native fish populations.”




Snakeheads can become invasive species and cause ecological damage because they are top-level predators, meaning they have no natural enemies outside of their native environment. Not only can they breathe atmospheric air, but they can also survive on land for up to four days, provided they are wet, and are known to migrate up to 1/4 mile on wet land to other bodies of water by wriggling with their body and fins. National Geographic has referred to snakeheads as "Fishzilla"[2][3][4] and the National Geographic Channel reports that the "northern snakehead reaches sexual maturity by age 2 or 3. Each spawning-age female can release up to 15,000 eggs at once. Snakeheads can mate as often as five times a year. This means in just two years, a single female can release up to 150,000 eggs."




My purpose in starting this thread is to promote a broader discussion than this one fish, however, as it is but one example of many such concerns.


Wherever humans have ventured we have brought with us our plants and animals (and disease, but that can be another discussion). In our ongoing endeavors to shape the environment to better suit our purposes we have also introduced many species with the idea of 'natural control' of an existing plant, animal or insect and in many cases these introduced 'controls' have gotten out of control.


In a number of debates, humans have been touted as the most invasive species of all because of our ability to shape most environments to support our basic needs. Leaving that debate also for another thread, I would invite persons to share on this thread their knowledge and experience of any species that have been introduced into their own region, and whether these introductions have proven beneficial or have become problematic.

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My purpose in starting this thread is to promote a broader discussion than this one fish, however, as it is but one example of many such concerns.


Wherever humans have ventured we have brought with us our plants and animals (and disease, but that can be another discussion). In our ongoing endeavors to shape the environment to better suit our purposes we have also introduced many species with the idea of 'natural control' of an existing plant, animal or insect and in many cases these introduced 'controls' have gotten out of control.


In a number of debates, humans have been touted as the most invasive species of all because of our ability to shape most environments to support our basic needs. Leaving that debate also for another thread, I would invite persons to share on this thread their knowledge and experience of any species that have been introduced into their own region, and whether these introductions have proven beneficial or have become problematic.


where to begin!? the biggy that comes to mind first is English Ivy, which is blanketing much of the urban forestland in my county and making its way outside urban areas. due to budget cuts the county eliminated the weed control board and things are getting worse. many people don't know the damage it does, and many of those who do either don't care or can't afford to remove it.


the english ivy covers the ground & blocks light & takes water & nutrients that native ground plants would otherwise use. the climbing parts of the vines cover tree trunks which kills off the lichens & mosses while adding tremendous weight to trees as well as holding water (and ice and snow) and adding surface area that increases wind load on trees. when english ivy climbs high enough, the leaf shape changes and the plant starts producing seed which birds eat and spread the invasion further.


it's no less than a disaster in my humble view. :wilted: :(


here's a blurb from invasive.org. :read: English ivy


main page of invasive.org. >> Invasive and Exotic Species of North America


2,783 Invasive Species


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English Ivy, an invasive? That's quite fascinating to me. I recall, as a child, that mother always was busy 'training' the ivy to grow as she wanted in the parlor, hers being a potted indoor specimen for purely ornamental purpose. After a year or so, she would be busy with the shears, demanding that it grow in a shape and manner which pleased her senses. I seem to recall feeling sorry for the plant as a child but perhaps that was in response to my own reaction to scissors, lol. ( I used to want to grow my hair long but my mother would have no unkempt child either.)


I do not recall ever seeing ivy growing out of doors here in the Yukon and although it is frequently seen in the flower shops being sold as a cultivar, I rather expect that it hasn't got a snowball's chance of surviving a Yukon winter, as I note that the extent of it's range seems to be limited by the frost point, according to Wikipedia.



It ranges from Ireland northeast to southern Scandinavia, south to Spain, and east to Ukraine and northern Turkey.

The northern and eastern limits are at about the -2°C winter isotherm, while to the west and southwest, it is replaced by other species of ivy.



From various old movies set in the British Isles, my mind retains images of ivy-trimmed cottages in a small country village, nothing at all like this following image, which would make many claustrophobic to enter perchance, for fear that one might get sealed inside while they slept by such rampant growth.



Who would have surmised.....English Ivy?


Apparently not so quaint and adorable. :ohdear:


Thank you, Turtle, for starting this thread in action. When I return from work, I shall add an invasive that was introduced to the Yukon by those in authority, more's the irony. What's that saying about 'the road to hell is paved with good intentions', leaving out the debate on the existence of such a place, of course.



Now, we look at the rate of change in volume in hell. Boyle's Law states that in order for the temperature and pressure in hell to stay the same, the ratio of the mass of souls and volume needs to stay constant. Two options exist:


  1. If hell is expanding at a slower rate than the rate at which souls enter hell, then the temperature and pressure in hell will increase until all hell breaks loose.
  2. If hell is expanding at a rate faster than the increase of souls in hell, then the temperature and pressure will drop until hell freezes over.


Either way, I can't envision 'hell' as being suitable habitat for Hedera helix. :rolleyes:

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Thank you, Turtle, for starting this thread in action. When I return from work, I shall add an invasive that was introduced to the Yukon by those in authority, more's the irony. What's that saying about 'the road to hell is paved with good intentions', leaving out the debate on the existence of such a place, of course.


Either way, I can't envision 'hell' as being suitable habitat for Hedera helix. :rolleyes:


my pleasure. :) nothwithstanding that i'm no believer in heaven or hell, good intentions are a hell of a lot better than bad intentions. on to another good intention run amuck here; the invasive himalayan blackberry. these nogoodniks don't restrict themselves to forest and woodlot margins, though they'll get in there & give the ivy a run for the money. again, the problem is only getting worse in my county with the disbanding of the weed control board. i'm not sure if they took the laws off the books that require property owners to control invasive plants, but even if they remain there is no one to enforce them. rather hard to induce tourists to come see our unique ecosystem -and spend their money- when they can't see it for the weeds. wake up people!! :soapbox: ;)





The Himalayan blackberry is the largest and possibly most

invasive, non-native variety of blackberries in the Pacifi c

Northwest. It was fi rst introduced from Europe to the area as

a crop plant in the 1800’s. Since then, it has invaded large

areas throughout the west coast.



Himalayan blackberry grows very rapidly and can cover and replace native habitat that is important for plant and animal diversity. Onceestablished, it will out-compete native vegetation and cover more ground with each season. The fast growing thorny canes make removal difficult and often painful. The canes of Himalayan blackberry can grow ten feet tall and over twenty feet long in a single year.



i'll try and get some photos to give y'all some idea of the scope of the problems. :photos:

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White sweetclover appeared along our road allowances in the year immediately following highway improvements and reconstruction in the greater Whitehorse area. The crews could be observed hydro-seeding the road allowance with the aim of stabilizing and re-establishing vegetation. They used a green colorant in the process to make apparent where they had seeded and they did a most thorough job with the result that the soil disturbed by the work of much heavy machinery was soon covered with growth and pleasing to the eye.


For a few years, the roadside mix seemed to be doing a wonderful job of showcasing our excellent highways and the flowers mixed in with the grasses were a visual delight. Then a number of years with adequate moisture observed a change in the view as the white sweetclover began to out-compete the other varieties of seed that were in the original mix. Spring run-off and wind enabled the sweetclover to move beyond the highway, following the path of the drainage. While riding my horses, I observed that we had this plant now growing in our subdivision, a kilometer away from the highway. A few scattered plants soon became a hedgerow of of the stuff along each side of the road.


The sweet clover grew so tall that it was obstructing visibility along the highway where other roads intersected, requiring the highways department to contract people to mow the road allowance for safety reasons. This was not anticipated and has added considerable costs to the highways budget.


Interestingly, some people are suggesting that the sweetclover was NOT the result of seeding but rather that it has come up the highway with truckloads of hay for animal forage. I would dispute that suggestion because we have had horses and hay from many sources on this property since 1985 and hay has been coming up the highway for decades. (I travel the 13 miles between here and town regularly and there was no sweetclover to be seen. It's very distinctive scent is another give-away sign that was absent.)


The sweetclover did not appear until immediately after the hydro-seeding. Moreover, it is exceedingly uniform in where it is established which just happens to coincide with the reseeding efforts which took place alongside all of the highway improvements.


I'll grant that hay from outside the Yukon does bring in some new and unusual weed species which are also of concern but none as aggressive as the white sweetclover. Yellow, pink and purple varieties were intermingled but they have almost disappeared. The white variety is obviously the most competitive of the lot. It seems to require plenty of water to get well established and has not been a problem in my yard. Only a few plants have appeared in isolation and it shows so sign of the spreading behavior it exhibits along roadways.


On a positive note, it has a most delightful vanilla scent to it and the pollinating insects are quite wild for the stuff. In my own opinion, this introduced species, while aggressive, poses less of a threat than another which I will post here soon.




Common name: Sweetclover


Scientific name: Melilotus alba (white) or Melilotus officinalis (yellow)


Family: Fabaceae



Sweetclover is an annual or occasionally biennial plant in the pea family that can grow 2 m tall but is usually less than 1 m. It rapidly colonizes gravelly well-drained soils such as roadsides, waste areas and river banks and bars. A single plant can produce 300,000 seeds and the seeds remain viable in the soil or under water for many years (80% survival after 30 years). This is likely Yukon's most invasive and problematic species.





The CBC News did a piece on the sweetclover in August of last year. http://www.cbc.ca/ne...r-invasion.html

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When I lived in the Dallas-Fortworth area of Texas, Fire Ants were a big problem. You just can't keep them out of your yard, I even had a colony inside the wall of my house. It's very hard to avoid getting stung when doing yard work and if you have pets, you always worry about them getting hurt. It's easy to imagine people and animals dying because of fire ants swarming over them (a very bad way to go out of this life). The best way I found to kill them is to use Amdro (yellowish granules) gets rid of a colony in 3 or 4 days. But in Texas it's a never ending battle as they re-infest almost as fast as you can kill them. They don't seem to do well in the northern states yet, but I read where they are starting to adapt.


A typical fire ant colony produces large mounds in open areas, and feeds mostly on young plants, seeds, and sometimes crickets. Fire ants often attack small animals and can kill them. Unlike many other ants, which bite and then spray acid on the wound, fire ants bite only to get a grip and then sting (from the abdomen) and inject a toxic alkaloid venom called solenopsin, a compound from the class of piperidines. For humans, this is a painful sting, a sensation similar to what one feels when burned by fire—hence the name fire ant—and the after effects of the sting can be deadly to sensitive individuals. The venom is both insecticidal and antibiotic.


Fire ants nest in the soil, often near moist areas, such as river banks, pond shores, watered lawns and highway shoulder. Usually, the nest will not be visible, as it will be built under objects such as timber, logs, rocks, or bricks. If there is no cover for nesting, dome-shaped mounds will be constructed, but these are usually only found in open spaces, such as fields, parks and lawns. These mounds can reach heights of 40 cm (15.7 in), and can also be as deep as a metre and a half (five feet). Colonies are founded by small groups of queens or single queens. Even if only one queen survives, within a month or so, the colony can expand to thousands of individuals. Some colonies may be polygynous (having multiple queens per nest).


Although most fire ant species do not bother people and are not invasive due to biological factors, Solenopsis invicta, known in the United States as the red imported fire ant (or RIFA) is an invasive pest in many areas of the world, notably the United States, Australia, the Philippines, China and Taiwan. The RIFA was accidentally introduced into the United States aboard a South American cargo ship that docked at the port of Mobile, Alabama, in the 1930s, and came to infest the majority of the Southern and Southwestern United States.


In the US the FDA estimates more than US $5 billion is spent annually on medical treatment, damage, and control in RIFA-infested areas. Furthermore, the ants cause approximately $750 million in damage annually to agricultural assets, including veterinarian bills and livestock loss, as well as crop loss. Over 40 million people live in RIFA-infested areas in the southeastern United States. Between 30 and 60% of the people living in fire ant-infested areas are stung each year. Since September 2004 Taiwan has been seriously affected by the red fire ant. The US, Taiwan and Australia all have ongoing national programs to control or eradicate the species, but, other than Australia, none have been especially effective. In Australia, an intensive program costing A $175 million had by February 2007 eradicated 99% of fire ants from the sole infestation occurring in south-east Queensland.


In just seventy years, according to a study published in 2009, lizards in parts of the United States had developed longer legs and new behaviors to escape the ants, which can kill the lizard in under a minute


The venom of fire ants is composed of alkaloids such as piperidine (see Solenopsis saevissima). The sting swells into a bump, which can cause much pain and irritation at times, especially when caused by several stings in the same place. The bump often forms into a white pustule, which can become infected if scratched, but if left alone will usually flatten within a few days. The pustules are obtrusive and uncomfortable while active and, if they become infected, can cause scarring. Some people are allergic to the venom, and as with many allergies, may experience anaphylaxis, which requires emergency treatment. An antihistamine or topical corticosteroids may help reduce the itching[citation needed]. First aid for fire ant bites includes external treatments and oral medicines.

External treatments: a topical steroid cream (hydrocortisone), or one containing aloe vera.

Oral medicines: antihistamines


Severe allergic reactions to fire ant stings, including severe chest pain, nausea, severe sweating, loss of breath, serious swelling, and slurred speech, can be fatal if not treated.



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Fire ants are a problem in my area as well. Flathead catfish and blue catfish have been introduced to the Cape Fear River with less than pleasing results, sunfish and bullhead catfish populations have taken a big hit. European Carp, one of the most widely distributed fish in North America are introduced, they have competed with native fish and disturbed spawning grounds as well as over populating rivers and competing via sheer volume of biomass.


Pacu have been introduced to tropical areas in the Pacific islands near Java and resulted in fish that attack nude men in the river... not kidding, they have bitten off a couple appendages so far but for the most part they are driving out the native fishes and attacking wildlife. it seems there's not enough fruit falling into the river to satisfy them...


Spreading invasive species is what humans do, just one of those sweet things about humans and their animals, in this series by Harry Turtledove http://en.wikipedia.org/wiki/Worldwar the aliens invade earth and bring their own animals to Earth where they become invasive as well, he postulates that moving invasive animals around is what intelligent beings do... we end up doing it to them...

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I'm reasonably certain that we have no Fire Ants in the Yukon at the present time, and by what you have shared, arKane and Moontanman, I'm rather glad of this. Apparently we do have 19 different varieties of ants in the Yukon according to this paper done by Andre Francoeur. For those who may be interested in this information, I post the link:




Some years ago, I recall a piece done by BBC on Fire Ants, how they formed a living life-raft. Some amazing footage of Fire Ants in the Amazon.


I can across an interesting little time lapse piece of ants performing one of their most utilitarian services, clean-up of deceased biology set to the music of the popcorn song. Although the thought of ants may may your skin crawl, this short video is not particularly distressing, in my opinion.


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I watched a program about large Burmese pythons being introduced to South Florida and becoming a major top predator in the area. I was somewhat dismayed to see a map of their projected spreading out in the South U.S. states, and I thought rattle snakes were bad enough.


Python Snakes, An Invasive Species In Florida, Could Spread To One Third Of US





ScienceDaily (Feb. 23, 2008) — Burmese pythons—an invasive species in south Florida—could find comfortable climatic conditions in roughly a third of the United States according to new "climate maps" developed by the U.S. Geological Survey (USGS). Although other factors such as type of food available and suitable shelter also play a role, Burmese pythons and other giant constrictor snakes have shown themselves to be highly adaptable to new environments.


The just-released USGS maps can help natural resource agencies manage and possibly control the spread of non-native giant constrictor snakes, such as the Burmese python, now spreading from Everglades National Park in Florida. These "climate match" maps show where climate in the U.S. is similar to places in which Burmese pythons live naturally (from Pakistan to Indonesia).


A look at the map shows why biologists are concerned.


The maps show where climate alone would not limit these snakes. One map shows areas in the U.S. with current climatic conditions similar to those of the snakes' native ranges. A second map projects these "climate matches" at the end of this century based on global warming models, which significantly expands the potential habitat for these snakes.


Biologists with Everglades National Park confirmed a breeding population of Burmese python in the Florida Everglades in 2003, presumably the result of released pets. Python populations have since been discovered in Big Cypress National Preserve to the north, Miami's water management areas to the northeast, Key Largo to the southeast, and many state parks, municipalities, and public and private lands in the region.


"Wildlife managers are concerned that these snakes, which can grow to over 20 feet long and more than 250 pounds, pose a danger to state- and federally listed threatened and endangered species as well as to humans," said Bob Reed, a USGS wildlife biologist at the Fort Collins Science Center in Colorado, who helped develop the maps. "Several endangered species," he noted, "have already been found in the snakes' stomachs. Pythons could have even more significant environmental and economic consequences if they were to spread from Florida to other states."


Control of exotic species is often prohibitively expensive once they have become established. Therefore, prevention through screening and risk assessment is of great importance, especially when protecting continental areas from invasive reptiles, said USGS invasive snake expert Gordon Rodda, also of the Fort Collins center. USGS scientists and their partners are seeking to compile the scientific data necessary to guide management efforts to prevent further introductions, control existing populations of snakes, and contain their spread.


Burmese pythons have been found to eat endangered Key Largo woodrats and rare round-tailed muskrats. "This makes it that much more difficult to recover these dwindling populations and restore the Everglades," said park biologist Skip Snow, "and all the more important that pet owners be responsible in their choice of pet and dispose of it properly should they need to. Releasing them into the environment is bad for that pet, bad for native species, and also illegal."


Currently, scientists with the USGS and Everglades National Park are investigating the behavior and biology of these snakes - that is, what are their requirements for survival? This information will help refine predictions of where the snakes might go next and their likelihood of survival. USGS researchers are also conducting a risk assessment for nine species of giant constrictors (including boa constrictors and yellow anacondas) that are prevalent in the pet trade and as such, potential invaders in the United States.


Due to be completed by early 2009, the assessment evaluates the risk of invasion for these species and the potential for social, economic, and environmental impacts. The two agencies are also developing and testing tools to control invasive snake populations and prevent their spread, especially to the Florida Keys where several listed species would be threatened by the presence of pythons or other constrictors.

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When people ask my why I tolerate living in such an inhospitable climate, one of my replies is that we have no snakes in the Yukon. B)




Snakes (Suborder Serpentes)

Snakes are the best-represented group of reptiles in Canada, with 35 varieties in three families. They can be found in all provinces and territories except Yukon, Nunavut, and Newfoundland and Labrador.





There are relatively few reptiles in Canada, as only a limited number of species have been able to adapt to the diverse, generally colder Canadian climate. Most species are confined to the southernmost parts of the country. At higher latitudes, the harsh conditions, especially in winter, make it impossible for these cold-blooded animals to survive. Canadian reptiles are represented by the orders Squamata and Testudines; there are no crocodilians or sphenodonts native to Canada.








The fossil record of snakes, however, is patchy and incomplete, with large gaps. Newer techniques using molecular biology may give us a more complete picture of snake evolution. Using methods such as immunological responses and DNA-DNA hybridization, the precise genetic "distance" between living species can be determined, and a rough picture of when and in what order they evolved can be drawn. The study of snakes using DNA techniques is still in its infancy, but has already revealed a few surprises. Preliminary results indicate that the vipers are not, as was formerly thought, the most recent of the snakes, but instead diverged from the ancestral boid stock before both the elapids and the colubrids.


If this finding is confirmed, it means that we have to completely re-think our view of how snakes evolved. It appears that the snakes underwent a rapid radiation in their initial burst of evolution, with a number of different lifestyles appearing at once and then developing independently and in parallel afterwards. Much work remains to be done on the evolution of snakes.




There are a few people who keep snakes as pets in the Yukon but escapement of this species is not a concern at this time.

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Foxtail Barley is a native grass throughout most of North America, including Yukon, yet it has an 'invasive' nature. It fares particularly well in our poor soil and when it is immature it makes very decent forage for grazing animals. It is when it goes to seed that it can be problematical, as the feathery awns are barbed and can become lodged in throat, gums, eyes and nose of many species, both domestic and wild. Many of my friends have incurred significant veterinary expense to relieve the discomfort of their pets, mostly dogs, that have ingested these seeds.


Horses, also, can get the awns caught in their mouth and throat and these large animals are both difficult and expensive to treat. I have been fortunate to date in not having any of my horses injured by the grass but it is always a concern when purchasing hay as this perennial grass can invade the fields of our agricultural growers and when dry and hard the awns are even more sharp and persistent than when the grass is still in it's green state. By the use of fertilizer and reseeding, the foxtail barley can be combated as it does not stand up to the competition of the better grasses but this poses additional expense for the grower and the costs get passed on to the end user.


Every year, I wage war with the crop which has established itself in my clearing and gradually we are gaining ground. I pull the vexing seed heads by hand and put them in plastic bags and then burn them in the autumn. One does not want to put this weed into their compost pile because our season is too short to generate sufficient composting heat to kill this tenacious seed. My other strategy is to graze the horses on their lead ropes on this grass when it is young and this also reduces the amount of energy it has for growing seed heads.


It is not an unattractive species and many seed catalogs sell the seed in their ornamental grass section although I rather doubt anyone in these parts buys it as we have plenty of that also growing in our highway road allowances. <_<









Ecological Impact

Foxtail barley is distinguished from cultivated barley (Hordeum vulgare L.) and Meadow barley (Hordeum brachyantherum) by lemma awn length. H. brachyantherum has awn lengths of ½ an inch; Foxtail barley has lengths of ½-3 inches; and cultivated barley of 10–15 cm in length. Once Foxtail barley is established, it becomes extremely difficult to eradicate. Its extensive root systems and aggressive habit, as well as its ability to tolerate saline soils make it a resilient competitor. It is considered a weed because of this competitive ability and the dangers it poses to wildlife and livestock. While Foxtail barley may be palatable for animals in early spring before it flowers, its seed heads, when dry, are very harmful to grazing animals. The awns with upward-pointing barbs become easily attached and embedded in the animal's mouth and face, causing severe irritation, abscesses, and even blindness. Foxtail barley is also host to a number of viruses, and because it harbours wheat rust and blackstem rust, can indirectly affect the development of field crops. Since Foxtail barley accumulates high amounts of salt in its leaves and roots, it has the potential of reducing soil salinity. Given Foxtail barley's ability to withstand saline soils, it has been identified as having potential for the revegetation of saline mine spoils to reduce erosion. It has also been recommended as a species suitable for wildlife habitat rehabilitation on disturbed lands, but given its other less desirable traits, other natural grass species would be more beneficial.




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  • 2 months later...

invasive species can also effects the natural resources. Because they are because they disrupt natural communities and ecological processes. They also consume same resources & life requirements as native species..


Japanese Knotweed Specialist


I looked at the gallery of pictures and that Knotweed looks like a cool plant. But I guess the fact that it is so successful at growing anywhere makes it a real nuisance.

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