Thứ Năm, 13 tháng 9, 2012

Creating Artificial Reefs (Academic Reading)

READING  PASSAGE  1
You should spend about 20 minutes on Questions 1-13 which are based on Readme
Passage below.

                   Creating Artificial Reefs

In the coastal waters of the US, a nation's leftovers have been  discarded.  Derelict ships, concrete  blocks, scrapped  cars, army tanks,tyres filled with concrete and redundant planes litter the sea floor. However, this is not waste disposal, but part of a coordinated, state-run programme. To recently arrived fish, plants and other sea organisms, these artificial reefs are an ideal home, offering food and shelter.
Sea-dumping incites widespread condemnation. Little surprise when oceans are seen as 'convenient' dumping grounds for the rubbish we have created but would rather forget. However, scientific  evidence  suggests that if we dump the right things, sea life can actually be enhanced. And more recently, purpose-built structures of steel or concrete have been employed - some the size of small apartment blocks - principally to increase fish harvests. The choice of design and materials for an artificial reef depends on where it is going to be placed. In areas of strong currents, for example,
a solid concrete structure will be  more appropriate than ballasted tyres. It also depends on what species are to be attracted. It is pointless creating high-rise structures for fish that prefer flat or low-relief habitat. But the  most important consideration is the  purpose of the reef.
In the US, where there is a national reef plan  using cleaned up rigs and tanks, artificial reefs have mainly been  used to attract fish for recreational fishing or sport-diving.  But there are many other ways in which they can be used to  manage the marine habitat.  For as well as protecting existing habitat, providing purpose-built accommodation for commercial species (such as lobsters and octupi) and acting as sea defences, they can be an effective way of improving fish harvests.
Japan, for example, has created vast areas of artificial habitat - rather than  isolated reefs - to increase  its fish stocks. In fact, the cultural and  historical importance of seafood in Japan is reflected by the fact that it is a worldleader in reef technology; what's  more, those who construct and deploy reefs have sole rights to the harvest.
In Europe, artificial reefs have been mainly employed to  protect habitat. Particularly so in the Mediterranean where reefs have been sunk as  physical  obstacles to stop illegal trawling, which is destroying sea grass beds and the marine  life that depends on them. If you want to protect areas of the seabed, you need something that will stop trawlers dead in their tracks,' says Dr Antony Jensen of the Southampton Oceanography Centre.
Italy boasts considerable artificial  reef activity. It deployed  its first scientifically planned reef using concrete cubes assembled in pyramid forms in 1974 to enhance fisheries and stop trawling.
And Spain has built nearly 50 reefs in its waters, mainly to discourage trawling and enhance the  productivity of fisheries. Meanwhile, Britain established  its first quarried rock  artificial  reef in 1984 off the  Scottish coast, to assess its  potential  for  attracting commercial species.
But while  the  scientific study of these  structures  is  a little  over a  quarter of a century old, artificial  reefs made out of readily available materials such as bamboo and coconuts  have  been used by fishermen for centuries. And the benefits have  been  enormous. By placing reefs close to  home, fishermen  can save time and fuel. But unless they are carefully  managed, these areas can become over-fished. In the  Philippines, for example, where artificial reef programmes have been instigated in response to declining fish  populations, catches are often allowed  to exceed the maximum potential new production of the artificial reef because there  is  no  proper management control.
There is no doubt that artificial  reefs have lots to offer. And while purpose-built structures are effective, the real  challenge now is to develop environmentally safe ways of using recycled waste to increase marine diversity. This will  require more scientific research. For example, the leachates from one  of the  most  commonly used reef materials, tyres, could  potentially be harmful to  the  creatures  and  plants that they are supposed to attract. Yet few extensive studies have been undertaken into the  long-term effects of disposing of tyres at sea. And at the moment, there is little consensus about what is environmentally acceptable to dump at sea, especially when it comes to oil and gas rigs. Clearly, the challenge isto develop environmentally acceptable ways of disposing of our rubbish while enhancing marine life too. What we must never be allowed to do is have an excuse for dumping anything we like at sea.

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