Coral reefs areunderwater structures made from calcium carbonate secreted by corals.Coral reefs are colonies of tiny living animals found in marine waters thatcontain few nutrients. Most coral reefs are built from stony corals, which inturn consist of polyps that cluster in groups. Coral reefs
A
Coral reefs areestimated to cover 284,300 km2 just under 0.1% of the oceans' surface area,about half the area of France. The Indo-Pacific region accounts for 91.9% ofthis total area.Southeast Asia accounts for 32.3% of that figure, while thePacific including Australia accounts for 40.8%. Atlantic and Caribbean coralreefs account for 7.6%. Yet often called “rainforests of the sea", coral reefsform some of the most diverse ecosystems on Earth. They provide a home for 25%of all marine species, including fish, mollusks (软体动物), worms, crustaceans(甲壳类动物),echinoderms(棘皮动物),sponges, tunicates and other cnidarians. Paradoxically, coral reefsflourish even though they are surrounded by ocean waters that provide fewnutrients. They are most commonly found at shallow depths in tropical waters,but deep water and cold water corals also exist on smaller scales in otherareas. Although corals exist both in temperate and tropical waters,shallow-water reefs form only in a zone extending from 30° N to 30° S of theequator. Deep water coral can exist at greater depths and colder temperaturesat much higher latitudes, as far north as Norway. Coral reefs are rare alongthe American and African west coasts. This is due primarily to upwelling andstrong cold coastal currents that reduce water temperatures in these areas(respectively the Peru, Benguela and Canary streams). Corals are seldom foundalong the coastline of South Asia from the eastern tip of India (Madras) to theBangladesh(孟加拉国)and Myanmar borders. They are also rare along the coast aroundnortheastern South America and Bangladesh due to the freshwater release fromthe Amazon and Ganges Rivers(恒河), respectively.
B
Coral reefs deliverecosystem services to tourism, fisheries and coastline protection. Theglobal economic value of coral reefs has been estimated at asmuch as $US375 billion per year. Coral reefs protect shorelines by absorbingwave energy(潮汐能), and many small islands would not exist without their reef to protectthem. C
The value of reefsin biodiverse (生物多样的) regions can be even higher. In parts of Indonesia and the Caribbean wheretourism is the main use, reefs are estimated to be worth US$1 million persquare kilometer, based on the cost of maintaining sandy beaches and the valueof attracting snorkelers (浮潜者)and scuba divers (水肺潜水).Meanwhile, a recent study of the Great Barrier Reef in Australia found that thereef is worth more to the country as an intact ecosystem than an extractivereserve for fishing. Each year more than 1.8 million tourists visit the reef,spending an estimated AU$4.3 billion (Australian dollars) on reef-relatedindustries from diving to boat rental to posh island resort stays. In theCaribbean, says UNEP, the net annual benefits from diver tourism was US$2billion in 2000 with US$625 million spent directly on diving on reefs. Further,reef tourism is important source of employment, especially for some of theworld's poorest people. UNEP says that of the estimated 30 million small-scalefishers in the developing world, most are dependent to a greater or lesserextent on coral reefs. In the Philippines, for example, more than one millionsmall-scale fishers depend directly on coral reefs for their livelihoods. Thereport estimates that reef fisheries (渔场) were worth between $15,000 and $150,000per square kilometer a year, while fish caught for aquariums (水族馆) wereworth $500 a kilogram against $6 for fish caught as food. The aquarium fishexport industry supports around 50,000 people and generates some US$5.5 milliona year in Sri Lanka along.
D
Unfortunately,coral reefs are dying around the world. In particular, coral mining,agricultural and urban runoff(入水), pollution (organic and inorganic),disease, and the digging of canals and access into islands and bays arelocalized threats to coral ecosystems(生态系统). Broader threats are sea temperature rise,sea level rise and pH changes from ocean acidification (酸化) , allassociated with greenhouse gas emissions. Some current fishing practices aredestructive and unsustainable. These include cyanide fishing, overfishing andblast fishing. Although cyanide (氰化物毒)fishing supplies live reef fish for thetropical aquarium market, most fish caught using this method are sold inrestaurants, primarily in Asia, where live fish are prized for their freshness.To catch fish with cyanide, fishers dive down to the reef and squirt cyanide incoral crevices and on the fast-moving fish, to stun the fish making them easyto catch. Overfishing is another leading cause for coral reef degradation.Often, too many fish are taken from one reef to sustain a population in that area.Poor fishing practices, such as banging on the reef with sticks (muro-ami),destroy coral formations that normally function as fish habitat. In someinstances, people fish with explosives (爆炸物) (blast fishing), which blast apart thesurrounding coral.
E
Tourist resortsthat empty their sewage directly into the water surrounding coral reefscontribute to coral reef degradation. Wastes kept in poorly maintained septictanks can also leak into surrounding ground water, eventually seeping out tothe reefs. Careless boating, diving, snorkeling and fishing can also damagecoral reefs. Whenever people grab, kick, and walk on, or stir up sediment (沉淀物) in thereefs, they contribute to coral reef destruction. Corals are also harmed orkilled when people drop anchors on them or when people collect coral.
F
To find answers forthese problems, scientists and researchers study the various factors thatimpact reefs. The list includes the ocean's role as a carbon dioxide sink,atmospheric changes, ultraviolet light (紫外线光) , ocean acidification, viruses, impacts ofdust storms carrying agents to far flung reefs, pollutants, algal blooms andothers. Reefs are threatened well beyond coastal areas. General estimates showapproximately 10% of the world’s coral reefs are dead. About 60% of theworld's reefs are at risk due to destructive, human-related activities. Thethreat to the health of reefs is particularly strong in Southeast Asia, where80% of reefs are endangered.
G
In Australia,the Great Barrier Reef(大堡礁) is protected by the Great Barrier ReefMarine Park Authority, and is the subject of much legislation, including abiodiversity action plan. Inhabitants of Ahus Island, Manus Province, Papua NewGuinea, have followed a generations-old practice of restricting fishing in sixareas of their reef lagoon(环礁湖). Their cultural traditions allow linefishing, but not net or spear fishing. The result is both the biomass andindividual fish sizes are significantly larger than in places where fishing isunrestricted.
Questions 14-19
Reading Passage 1has seven paragraphs A-G.
Write the correctletter A-G, in boxes 14-19 on your answer sheet.
NB You may use anyletter more than once.
14 Geographicallocation of world’s coral reef
15 How does coralreef benefit economy locally
16 The statisticsof coral reefs economic significance
17 The listedreasons for declining number of coral reef
18 Physical approach tocoral reef by people 19 Unsustainablefishing methods are applied in regions of the world
Questions 20-25
Do the followingstatement agree with the information given in Reading Passage 2?
TRUE if thestatement is true
FALSE if thestatement is false
NOT GIVEN if theinformation is not given in the passage
20 Coral reefsprovide habitat to variety of marine life.
21 Coral reefdistribute around the ocean disproportionally.
22 Coral reef isincreasingly important for scientific purpose.
23 Coral reefs aregreatly exchanged among and exported to other counties.
24 Reef tourism isof economic essence generally for some poor people.
25 As with otherfishing business, coral fishery is not suitable to women and
children
Questions 26
Choose the correctletter. A, B, C or D.
Write your answersin boxes 26 on your answer sheet.
What is the mainpurpose of the this passage
A Demonstrate howcoral reef grow in the ocean
B To tell thatcoral reef is widely used as a scientific project
C Present thegeneral benefits and an alarming situation of coral reef
D To show the vitalefforts made to protect coral reef in Australia
答案：
|Archiver|手机版|小黑屋|雅思托福英语全球网
( 闽ICP备14014910号 )
|
闽公网安备 35020302034732号
发表于 2020-11-16 19:55:47
