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INVASIVE SPECIES ASSIGNMENT
Transcript of INVASIVE SPECIES ASSIGNMENT
Northern Snakeheads have no natural predators, but are hunted by humans for food, medicinal purposes, and pleasure. They may also carry harmful diseases.
Northern Snakeheads are aggressive top-level predators. They are very protective of their young, but are shy towards humans. They are highly adaptable to their environment and have a very wide tolerance range. Northern Snakeheads are native to northern China, eastern Russia, and parts of Korea. They were brought to North America to be sold in fish markets and pet stores. Northern Snakeheads were brought to North America to sell in fish markets and pet stores as pets, and for food, and medicinal purposes. They were most likely released into lakes by people who bought them as young fish, and didn’t realize how big they would become, or how much they would eat. Once the fish became too big for them, or too hard to handle, they got rid of them.
In 2002, Crofton lake, Maryland was found to be full of Northern Snakeheads, along with several other small lakes in the area, but all Northern Snakeheads were successfully removed. Several years later, however, established breeding sites were found throughout the Potomac River in Virginia, and are spreading down the river. They can be found from Washington DC to Chesapeake Bay. There are also large populations of Northern Snakeheads in Michigan, Arkansas, Florida, New York and California. These sites have large bodies of water, and the Northern Snakeheads cannot be removed. They are expected to continue to spread throughout North America. Northern Snakeheads are highly adaptable, very reproductive, and have no natural predators here in North America. Their diet consists of a wide variety of marine organisms. They can survive on land in moist conditions for 4 days, and possibly longer if they burrow themselves in mud. This, along with their ability to wriggle their body and move short distances across land allows them to enter various bodies of water, invading a greater area. Although many species of Snakehead have a reputation of being invasive, Northern Snakeheads haven’t really had a big effect on North America in any way. Their population is still relatively small, and the regions they are currently inhabiting are very large and diverse, making it hard for one species to have a big impact. They also contain other non-native species who have learned to coexist. In the future, if the population of Northern Snakeheads continues to increase, they may take over the bodies of water they have entered, and have devastating effects in the ecosystem. Their diet, which is similar to those of native fish such as largemouth bass, could lead to competition, and cause the extirpation of various small fish species. This would cause species in higher trophic levels to decline, effectively destroying the ecosystem. Northern Snakeheads also carry a disease called Red Spot Disease, or EUS, which could be harmful if transferred to native species and their young.
Northern Snakeheads could also be effecting the economy slightly, as natives and tourists are paying large amounts of money to fish for them. Also, their removal from small bodies of water is very costly. Northern Snakeheads have been found in small numbers across the United States and Canada. Large populations of them have been found in the temperate deciduous biome, specifically Virginia, New York, Arkansas, Pennsylvania, and Maryland, and are spreading down the Potomac River as far as Washington D.C. , and Chesapeake Bay. There are established breeding areas in California and Florida as well. Northern Snakeheads are predicted to enter the Hudson Drainage area and Great Lakes watershed, and would also thrive in the temperate rainforest biome, near Vancouver Island. The prefer eutrophic water, but can be found in oligotrophic, and even semi-marine habitats as well. They can also survive in waters covered in ice for part of the year. Northern Snakeheads have been banned in many states and provinces, and have been put on the Injurious List by the American government. They cannot be sold, imported, or transported within the States. In Ontario and Saskatchewan, among others, they are illegal to sell or possess. In Virginia and New York, among others, anglers have been instructed to cut off their heads if any Northern Snakeheads are found. The American government is also considering closing several canals that link Canada to the United States through the Great Lakes.
In Crofton Lake, Maryland, two herbicides, Diquat Dibromide and Glyphosate, were used to lower oxygen levels, killing most of the aquatic life. A piscicide, Rotenone, was then used to kill any remaining fish. The water returned to normal eventually, and all surrounding lakes were inspected. All Northern Snakeheads were gone. This method was very effective for a small, contained area, like the lake, but would be impractical and expensive for larger bodies of water, as the pesticides used are broad-spectrum, and affect many non-target species. Also, Northern Snakeheads have the ability to travel overland into close bodies of water, allowing them to escape. Small populations of Northern Snakeheads that are found in lakes are removed by draining the lakes. In 2004, established breeding populations of Northern Snakeheads were found in the Potomac River, Virginia, where they have access to many other bodies of water. Other states with large populations of Northern Snakeheads include California, Arkansas, Florida and New York. As of yet, no effective plan for removal has been developed, and the Northern Snakeheads are continuing to spread.
As Northern Snakeheads are top-level predators, there is no way of removing them through biological means. Through the arrival of Northern Snakeheads in North America, we have learned that when buying pets, it is important to research them, ensure that you are prepared to care for them, and have a suitable place for them to live and grow. We have also learned that when you no longer want your pet, it should be returned to the pet store, or given to someone who will care for it, and not released into the wild.
Invasive species in general have taught us about the fragility of our natural ecosystems, and the importance of preserving them. We need to be more aware of the species that we are importing, and the harm they may cause.
Situations like that of Northern Snakeheads can be avoided easily by not releasing non-native species into the wild. To help stop the spread of Northern Snakeheads, they have been banned throughout much of North America, however we still need to be aware of their growing population, as they continue to spread throughout North America. We also need to try to prevent other non-native species from becoming invasive. http://www.invadingspecies.com/invaders/fish/northern-snakehead/
http://www.environment.gov.sk.ca/adx/aspx/adxGetMedia.aspx?DocID=849ca5c2-6be0-46ff-9d1d-cc6799db4aea&MediaID=4601&Filename=Northern+Snakehead+Media+Advisory.pdf&l=English At the moment, the equilibrium of the ecosystem has not been largely affected. For example, the Potomac river in Virginia, which has been invaded by Northern Snakeheads, is large and diverse, and full of non-native species that have learned to coexist. As Northern Snakeheads like slow-moving eutrophic water, it’s possible they may stay in the shallows and feed off of the smaller fish without ever effecting the ecosystem. If, however, their population grows, they may cause problems, and make the ecosystem unsustainable by preying on and competing with native species. They also carry a disease called EUS that could be transferred to native species and harm them. Northern Snakeheads are incredibly adaptable. If they find their way into open water, where smaller fish have nowhere to hide, the effect could be devastating. As their population continues to grow, we will soon see if it takes over, or if their population levels out and equilibrium remains. http://whyfiles.org/160invasive_spec/2.html (Channa argus) http://allthingsfish.blogspot.ca/2010/08/snakeheads-here-to-stay.html THE END CHARACTERISTICS APPEARANCE BEHAVIOUR
TOLERANCE RANGE FEEDING HABITS LIFE CYCLE http://www.csa.com/discoveryguides/snakehead/overview.php ECOLOGICAL NICHE ARRIVAL IN NORTH AMERICA EFFECT ON ECOSYSTEM EFFECT ON EQUILIBRIUM WHERE ARE THEY NOW? NATIVE RANGE REMOVAL OF NORTHERN SNAKEHEADS from NORTH AMERICA CONCLUSION BIBLIOGRAPHY
Northern Snakeheads are generally tan in colour, but they get darker as they age. They have flat heads that are covered in snake-like scales and large mouths full of long sharp teeth. Their bodies are cylindrical and narrow, and they have a long dorsal fin. They are covered in a thick layer of slime. They can be up to 100 cm long and weigh 7 kilos. Northern Snakeheads breathe through gills, but also have a lung-like organ that allows them to gulp oxygen above water.
Northern Snakeheads are aggressive towards other fish, but shy of people. They are also very protective of their young. They prefer regions with slow-moving eutrophic water, and hunt early in the morning or late at night. When hunting, they lie near the bottom of the water and wait for their prey to swim by.
Northern Snakeheads have a very wide tolerance range, and are highly adaptable. They like to live in slow-moving eutrophic bodies of water. They can survive water temperatures between 0 and 30°C. Their ability to gulp oxygen above water allows them to live in bodies of water with a variety of oxygen levels, as they can supplement the amount of oxygen in the water based on their needs. Although Northern Snakeheads prefer freshwater, they can live in water with much higher salt concentrations as well. They can also survive roughly half a year of frost days, and live in frozen water by burrowing in the mud and hibernating. WHAT ARE THEY? Northern Snakeheads are a species of freshwater fish native to Asia. Dubbed "Frankenfish" and "Fishzilla" by the media, they have invaded parts of the U.S.A., and are predicted to thrive in Canada as well. http://www.msnbc.msn.com/id/6254302/ns/us_news/t/frankenfish-rears-its-ugly-head-lake-michigan/ Juvenile Northern Snakehead http://en.wikipedia.org/wiki/File:Northern_snakehead.jpg http://www.csa.com/discoveryguides/snakehead/overview.php Adult Northern Snakehead http://www.dfo-mpo.gc.ca/science/publications/article/2009/01-06-09-eng.htm Map of North America, showing regions suitable for Northern Snakeheads MECHANICAL
BIOLOGICAL http://www.iiseagrant.org/NabInvader/Atlantic/suspects/suspect_norm.html http://www.monsterfishkeepers.com/forums/showthread.php?75290-CHANNA-SPECIES-GUIDE-UPDATE-IN-PROGRESSION/page2 Native Range of Northern Snakeheads (shown in yellow) http://www.eoearth.org/article/Northern_snakehead?topic=49540 Regions Currently Invaded by Northern Snakeheads (shown in red)