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Friend turned foe
INTRODUCTION | ||||
The articles in the Sunday Perspective section of the Bangkok Post are often long and usually serious. That section is dedicated to analysis and discussion of current issues some local, some of international concern. The section also contains articles expressing the opinions of readers, often academics. That makes it a bit of a heavy section for most second-language readers. However, every once in a while an article comes along about an interesting local issue, one that is important for all of us to know more about. In feature focus this week, you will find the introduction and the first part of just such a long article. A little review Before you read today’s excerpts, here’s a quick review of some of the basics you’ll need to know. The story is about plants and animals that have been brought to Thailand for a variety of reasons. They were not native to Thailand, that means they did not originate or grow here naturally. One problem with non-native (or "non-indigenous") species is that they often have no natural enemies in the new environment. Natural enemies check populations, that is, keep them under control. That balance of nature is an important part of the relationships in a place. The relationship of organisms (any living things) to each other and to the place they live in is the ecology of their environment The total number of different species in a location (habitat) is called its bio-diversity. Who are those aliens The title of today’s article refers to non-native species as "aliens". The writer explains what those aliens are, how they affect their new environment, and in some cases how they got here. In technical or scientific articles like this one, writers know they have to define certain terms which are not commonly understood. As you read, you will find two definitions: 1) alien or non-indigenous species, and 2) invasive alien species. Highlight those definitions in the text when you find them. The writer tells us that alien species fall into two categories. Some are completely beneficial while others seem to be very destructive, they are called invasive. However, some have desirable characteristics that led to them being imported, but they turned out to be damaging.
What can be done? One of the problems that the writer points out is the lack of awareness on the part of the public about the dangers of alien organisms. In addition to the species mentioned in today’s story, there have been news stories about giant cockroaches being sold as pets. Do you know of other potentially damaging species? Work with a group in your class or with study group friends to make a poster warning people against buying alien creatures as pets. You will no doubt want to illustrate your poster. Will you give reasons for avoiding such a purchase? How will you make your message dramatic so that people will notice and pay attention? TIP Hopefully this lesson will show you that you can read part of a longer and quite difficult article, improve your knowledge of an interesting subject and build your reading skills as well.
OUR STORY FROM THE BANGKOK POST |
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Thirty million baht a year of taxpayer's money has been spent by the Thai government over the past ten years to rid Thailand of the hoi cherry (apple snail) from rice fields, to no avail. The Amazon species of the snail was first imported as a protein food source. Today, rice farmers fear crop damages and loss of money every year from the alien species, which can grow to the size of a softball. Furthermore, the large snails have driven local snail species such as the hoi khong to extinction. The story brings to mind the long-standing battle against the non-native water hyacinth, which continues to block canals and river passages. Various state ministries use up large amounts of the national budget every year and farmers spend much time and effort to control the spread of alien species which adapt all too well in Thailand, choking out native species. The invasion of apple snails and water hyacinths seems permanent, even as new species are brought into the country, usually due to a lack of awareness among state agencies which have failed to come up with control measures. The public largely remains unaware of the continuing and potential damages these alien species inflict on the national ecology and economy. The terms alien or non-indigenous species may refer to plants, animals or micro-organisms that grow outside of their habitats of origin. Many cannot survive in the new environment, but others thrive, and even push out native species. Alien species are considered either beneficial or invasive.
Invasive alien species successfully reproduce to form a sustained population in a new territory. These species typically have high reproductive rates, good means of dispersal, and the ability to survive adverse conditions. Native species generally are not invasive because they have evolved with the system in which they are found, having natural predators or other variables that help check their populations. Certain species can be both beneficial and at the same time damage native species. The common African walking catfish has some desirable qualities over local varieties, but it has practically wiped out local catfish species. Generally, species which bring economic or other benefits become accepted by Thais to the point that they are not considered alien anymore. The plaa nil or Nile Tilapia fish from Africa, the plaa yisoktes or Rohu fish from India, and the plaa duk oy or African walking catfish, are but a few examples. Alien plants such as saranae(mint) and phak krashed (water mimosa) are included in many Thai traditional dishes. TIP OF THE ICEBERG The World Conservation Union (IUCN) has a list of the 100 top invasive species in the world. There are 36 plants, 56 animals and eight micro-organisms on the list. According to Niphon Iamsupasit of the National Center for Genetic Engineering and Biotechnology: At least three have greatly damaged the national economy and ecology of Thailand for a long time now, with no end in sight. These are the water hyacinth, the golden apple snail and the giant sensitive plant, which is a type of mimosa that establishes dense prickly thickets along watercourses and on floodplains. The thickets inhibit access to waterways, smother pastures and alter the natural ecology in conservation areas. But says Director Jarujin Napeetapat of the National Science Museum Organisation's Natural Science Division, "These three are just the tip of the iceberg." Many species which have adapted to Thailand have been raised as pets and released into the wilds. Some were imported for economic reasons. Some of these have led local species to extinction. He points to a survey which shows that at least one alien species, a turtle from Japan, has already taken over the habitat of Thailand's native turtles. "This Japanese turtle is prospering throughout the country's waterways, whereas the native species are now rarely found. These Japanese turtles are very hardy and are able to multiply in virtually any type water, even polluted water," said Jarujin. The turtles were imported from Japan as pets because they look attractive when young. But the colourful stripes disappear when they grow and the hard shell turns dark. The fully-grown turtle, which can grow up to 12 inches, is often released into the wild. The South American species known as sucker fish, imported to clean up waste in aquariums, is now invading natural waterways. Jarujin, a researcher surveying fish and animal populations in public waterways, has found an increasing number of sucker fish in the canals, particularly in nonpolluted areas of the Prawes Canal in the eastern suburbs of Bangkok. "We have no idea what they eat, or how they breed. Just like the Japanese turtle, they are released into the waterways when they grow and become ugly. We do not know how they affect other animals or plants in waterways," he said. He has noted other alien species which cause trouble in waterways. These include the zebra mussel, which once infested the Cheiw Larn dam in the south. According to records of the Royal Forest Department, up to 10,000 iguanas are imported as pets — legally and illegally — each year. When they grow, owners give them to zoos or release them. Jarujin said that some have been found dead in the forests because they could not survive on their own. |
predator adverse to no avail extinction brings to mind choke out inflict thrive sustained reproductive dispersal evolved wiped out tip of the iceberg prickly thicket smother virtually |
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maureen@bangkokpost.co.th |
On a separate sheet of paper create a graphic organiser like the one below. In the left circle write the beneficial species mentioned in the story; in the right circle add those that are completely destructive according to the article. In the overlapping area, write the names of those species that at first seemed desirable, but have turned out to be damaging to the environment. You will find eleven species mentioned.
Rice farmers are at high risk from the golden apple snail, which damages their crop