All throughout the world invasive species are making a devastating impact to ecosystems and the way of life of entire populations who significantly dependent on native species to survive, and consequently disrupting countries’ economies around the world. They are called invasive since they are non-native species that thrive, spread, or harms native species. They broadly range of microorganisms to any kind of animal, insect, or plant harming native organisms.
Several occurrences of invasive species that have made an impact in the United States are the Zebra Mussels as well as the Asian Langhorne Beetle. There are also plants that have made the invasive species list in the United States like the Old World Climbing fern and the Kudzu. But invasive species are not only a problem of the United States, but also worldwide. The Cane Toad and the weed Lantana Camara are some of the invasive species that are creating problems in Australia, and in Europe, the Sacred Ibis and the common ragweed.
Invasive Species in the United States
Zebra Mussels (Dreissena polymorpha)
The Zebra Mussels are native of the Caspian and Black Sea region and have found their way to the United States and Canada as the international commerce increased. The Zebra Mussels are causing many problems for the country’s fishery and mollusk’s diversity, therefore affecting ecosystems (McNeely, 2004). Contrasting native mussel larvae, which disperse themselves by fastening on fish, zebra mussel larvae have tiny hair like fibers that enable them to suspend themselves in water. These features allow zebra mussel larvae to spread with extraordinary swiftness in a current, therefore considerably spreading throughout North America’s waters. Zebra Mussels are driving out the native North American mussels, which could have terrible effects on local ecosystems. These mussels are also depleting phytoplankton by filtering them along with other contaminants from the water, but there are other species that eat on the phytoplankton. Once the phytoplankton is depleted, then those species would not be able to feed on that resource, therefore creating a gap in their natural food chain (McKinney, Schoch, & Yonavjak, 2013).
Asian Long-horned Beetle (Anoplophora glabripennis)
According to (McNeely, 2004) the Long-horned Beetle found its way to the United States by packing crates made of low quality timber originated from Asia. There were some reports of outbreaks around Chicago in 1992, Brooklyn in 1996, California in 1997, and in New England as recent as 2013. This specie of beetle finds suitable native trees like maples, elders, and elms, amongst others. Like other invasive species, the Asian Long-horned Beetle has no natural predator making it easy to spread from tree to tree. It can also spread by transporting the infected bark to a new place infecting the new ecosystem once again. They particularly like maple trees; “females deposit eggs in pits they dig in tree bark, once the eggs hatch the beetle larvae penetrates into the part of the bark that carries the trees’ nutrients, and kill the tree within two years”(Alien Attack, 2009 pp. 4-5).
Old World Climbing Fern (Lygodium microphyllum)
The world climbing fern “is a climbing fern that is becoming one of the worst non-indigenous invasive plant species in the greater Everglades ecosystems of south Florida” (Volin, J. C., Lott, M. S., Muss, J. D., & Owen, D. (2004). Hurricanes and fires are natural occurrences that deliver the ideal opportunities for this fern to spread and establish itself. Furthermore the isolated location and the subtropical climate of the Everglades made the old world climbing fern flourish and spread throughout the area subsequently suffocating native trees, like Cypress trees, and vegetation along the way (Volin, J. C., et al., 2004). According to (McKinney et al., 2013) the old climbing fern’s origins are from East Asia and Australia and it was transported to the United States deliberately to use as a landscape decorative plant.
The old world climbing fern reproduces in all possible ways like several distinctive ferns, by alternating between vegetative and sexual reproductive forms in uninterrupted generations. Additionally, unlike other invasive plants like Kudzu, the old world climbing fern has a copious nature and combined with the lack of natural insect or disease controls, it is unrelenting. “The fern’s coverage is greatest in a low-light understory environment, where it has been shown to establish and eventually dominate” (Volin, J. C., et al., 2004).
Alligator Weed (Alternanathera philoxeroides)
According to (Alternanthera philoxeroides, 2016), the alligator weed is native of South America; in specific places like Argentina, Brazil, and Paraguay and first reported in the southern part of the United States in 1987. It has been recorded that this invasive plant was introduced to the United States through ballast water and spread throughout fifteen southern states as of 2008. The alligator weed is an aquatic and terrestrial weed. It grows and spreads between the aquatic and terrestrial environments. “Spread is predominant vegetative, from axillary buds at each node in the warm summer” (Alternanthera philoxeroides, 2016).
The stems are hallow therefore allowing the weed to float on water and to cover not only the shore, but also streams or other bodies of water. There is no known natural enemy, therefore detriment of native species to survive because the alligator weed would cover and smother the native specie until they disappear. Alligator weed is known to “impact agriculture in North Carolina where it was invading over 4,000 ha of agriculture land” (Alternanthera philoxeroides, 2016).
Invasive Species in Australia
Cane Toads (Rhinella marina)
According to (White, 2007) in an effort to save the sugarcane industry from beetles, the state brought cane toads to Queensland, Australia. They thought it was a good idea at the time, because cane beetles did not have a known predator, and they were spreading effortlessly throughout Queensland, and the surrounding areas. Not without opposition, the state of Queensland officials thought of bringing cane toads to the state because they were effective on exterminating or reducing sugar cane predation, predominantly in West Indies, Philippines, Hawaii, and Puerto Rica.
The decision to bring the cane toads to Australia was the best decision at the time to get rid of cane beetles, but forty years after their release, cane toads multiplied in exponential numbers and expanded their territory beyond the sugar cane plantations. Cane toads could be found in great numbers where the area had predominant species like the grey back beetles and the armyworms making the competition for natural resources fierce. Furthermore, they kill native predators and scavengers through the ingestion of their skin toxins, tadpoles or eggs as well as killing native animals by water borne skin secretions (White, 2007). In recent years, there have been local and regional initiatives to keep the toads from spreading further more with no avail.
Lantana Camara (Verbenaceae)
Reference
- Alien Attack (Cover story). (2009). Current Events, 109(11), p. 4-5
- Alternanthera philoxeroides (Mart.) Griseb. (2016). EPPO Bulletin, 46(1), 8-13 doi:10.1111/epp.12275
- Bhagwat, S. A., Breman, E., Thekaekara, T., Thornton, T. F., & Willis, K. J. (2012). A Battle Lost? Report on Two Centuries of Invasion and Management of Lantana camara L. in Australia, India and South Africa. Plos ONE, 7(3), 1-10. doi:10.1371/journal.pone.0032407
- McNeely, J. A. (2004). Strangers in Our Midst: The Problem of Invasive Alien Species. (Cover Story). Environment, 46 (6), 16
- McKinney, M. L., Schoch, R. M., Yonavjak, L., & Zell, S. (2013). Environmental Science Systems and Solutions. Boston, MA: Jones and Barlett Learning
- Volin, J. C., Lott, M. S., Muss, J. D., & Owen, D. (2004). Predicting rapid invasion of the Florida Everglades by Old World Climbing Fern (Lygodium microphyllum). Diversity & Distributions, 10(5/6), 439-446. doi:10.1111/j.1366-9516.2004.00091.x
- White, A. W. (2007). Living with Bufo. Royal Zoological Society Of New South Wales Forum Proceedings – Pest & Guest, 16-29