Found at: http://www.anguillaguide.com/article/articleprint/6195/-1/140/
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CONSERVATION EDUCATION & AWARENESS SUPPORTING ENHANCED CAPACITY FOR ENVIRONMENTAL MANA. IN ANGUILLA
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The term invasive Alien species generally refers to organisms (plants, animals, pathogens) that are non-native to the environment which they are in and are likely to cause economic, social, and/or environmental harm. Invasive species (or introduced species or non-native species as they are sometimes called) have been deliberately or unintentionally introduced to countries.
One of the most common ways by which an invasive species enters a country is through the trade industry. These species can be transported from one environment to another by concealing themselves in cargo or containers. For example, imported goods and material that are not checked thoroughly before and after transportation can result in the introduction of undetected species. Additionally, yachts, cargo ships, and other boats that move between different bodies of water can transport marine organisms from one body or water to another in their ballast water and even on the boat itself.
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Cuban Tree Frog
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People also directly aid in the spread of invasive species by bringing them into the country to harvest as a source of food or as pets. These organisms, however, can also spread by natural means through storms, currents, and the dispersal of seeds by migratory birds.
Regardless of the method of introduction and regardless of whether it is intentional or accidental, Anguilla can be – and has been – affected by invasive plants and animals. Although some of these species have been on the island for a significant amount of time and while they may not pose an immediate threat to the environment, they are still considered invasive and efforts must be made to monitor and control those that are most threatening to our natural habitats, native organisms, and the survival of our people.
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Coral Vine
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Invasive Species Potential impacts
Some of the most well-known examples of invasive species in Anguilla include: the Giant African Snail; the Cuban Tree Frog; the Pink Mealy Bug; the Black Rat; the Corn Snake; Casuarina (plant); and Yellow dada (plant).
Many people might wonder or ask “what’s the big deal about invasive species”? Well, invasive species are considered to be a problem as some of them have the potential to threaten a country’s native species and may completely replace the local plants and animals that have been used by persons in a particular society for cultural or medicinal purposes. Additionally, invasive species are major competitors with native species for food and habitat (shelter). It should also be pointed out that some types of introduced species may be carriers of disease or equipped with toxic chemicals which are capable of contaminating other organisms as well as our food and water supply. This, in turn, may cause the plants/animals to die or even become extinct. This scenario can also pose a health factor because as humans consume the affected food/water or come into contact with the said affected species, the possibility exists for them to also be vulnerable to the diseases those species carry.
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Giant African Snail
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Another reason why invasive species are considered to be a problem is related to their ability to interact sexually with similar native species. Once this happens, the offspring is considered to be a hybrid, and therefore it will be sterile, that is, unable to reproduce. The end result of this phenomenon is that the introduced species can actually cause the extinction of the native species.
Apart from the aforementioned impacts, the greatest effects of invasive species, however, are often felt in the economic sector of countries and islands. Control costs and environmental damages caused by invasive species can add up to billions of dollars each year. Studies have shown that in the USA alone, invasive species contribute to approximately $120 billion in losses on an annual basis.
Brief Case Studies on the Impact of Invasive Species
Around the year 2000, the Giant African Snail was introduced to Anguilla. Since
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Black Rat
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then, it has caused significant damage to crops and plants and is considered to be a nuisance to residents on the island. Being an unsightly species, it discards slimy residue and faeces on houses and buildings. According to records from the Department of Agriculture, efforts to control this invasive over the past five years have valued anything in excess of US $100,000. This same snail caused Florida over US$1 million in an eradication campaign in the 1970’s, and it is currently causing the government of Barbados significant funds to monitor and control its spread.
In the island of Hawaii, the Rosy Wolf Snail was introduced as a predator to control the spread of the invasive Giant African Snail. As it turned out, the Rosy Wolf species had little impact on the intended victims, but rather attacked and caused the extinction of nine different species of Hawaii’s native and endemic snails.
The Pacific island of Guam is known for a wide variety of bird species including 22 native species. However,
the Brown Tree Snake, an invasive species, was introduced and caused the extinction of four of those native bird species. Now, in Guam, the ratio of snakes to birds is four to one.
The Nile Perch, a species of fish which can weigh up to 530 pounds, was introduced to Lake Victoria (Africa) in the late 1950’s to be used by fishermen as a source of food. Within a short period, the invasive Nile Perch adapted to its new environment. Once fully established, the Nile Perch became a major predator, attacking and causing the extinction of native chichlid fish species.
Controlling Invasive Species
Although the introduction of some types of invasive species can be devastating, several methods can be used to control their spread. Such methods require the integration of efforts from the government as well as local communities and include:
• Physical control which involves removing of the invading species by (among other methods) pulling plants by machine or by hand, tilling the land, burning the area that they have invaded, and trapping and/or killing the unwanted animals, insects, and organisms.
• Chemical control which involves using pesticides, herbicides, fungicides, and other chemicals to kill alien species on contact or indirectly by preventing them from reproducing. Since chemical control can negatively affect non-target species (including humans) it is no longer as widely used.
• Biological control involves using living organisms (such as predators, parasites, and disease) to control the population growth of invasive species. Many organisms used to control invasive species are also alien themselves and this can lead to additional problems. Biological control methods need to be carefully researched and administered.
• Integrated control involves using a combination of control methods and preventative measures to both control invasive species and their re-colonisation of an area.
Clearly, invasive species are a great threat to Anguillia’s biodiversity, and can only be controlled with the knowledge and efforts of our communities. Therefore, as concerned and responsible citizens, we should ensure that we are educated about their impacts and put mechanisms in place to safeguard Anguilla from unwanted pests.