填空题
Something weird is happening in the wilderness. The animals are becoming restless. Polar bears and penguins, dolphins and dingoes, even birds in the rainforest are becoming stressed. They are losing weight, with some dying as a result. The cause is a pursuit intended to have the opposite effect: ecotourism.
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Ecotourism has clear benefits. Poor countries that are rich in biodiversity benefit from the money tourists bring in, supposedly without damaging the environment. "Ecotourism is an alternative activity to overuse of natural resources," says Geoffrey Howard of the East Africa office of IUCN (the World Conservation Union) in Nairobi, Kenya.
"Many of our projects encourage ecotourism so that rural people can make a living out of something apart from using too much of the forests or fisheries or wetlands."
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What is not considered are less obvious impacts. "Transmission of disease to wildlife, or subtle changes to wildlife health through disturbance of daily routines or increased stress levels, while not apparent to a casual observer, may translate to lowered survival and breeding," says Philip Seddon of the University of Otago in Dunedin, New Zealand.
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Such changes in behaviour "are potentially serious for the population", says Gordon Hastie, a marine mammal expert at the University of British Columbia in Vancouver, Canada.
Hastie and his team have found that dolphins in the Moray Firth in Scotland spend significantly more time surfacing synchronously in the presence of boats than they do otherwise. This could lead to the animals resting more at night, possibly reducing the time they spend socialising and foraging.
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Markus Dyck and Richard Baydack of the University of Manitoba, Winnipeg, have found that signs of vigilance among male bears increased nearly sevenfold when vehicles were around. Just one vehicle could disturb the bears.
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Such effects are seen among yellow-eyed penguins in the Otago peninsula in New Zealand. Observations by Seddon"s team, also to be published in Biological Conservation, show that chicks in areas frequently visited by tourists weigh on average 0.76 kilograms less than chicks in an area not visited, a fall of over 10 per cent.
This could be a result of parents taking longer to reach the chicks after they finish foraging at sea. "Yellow-eyed penguins tend to delay landing if people are clearly visible at their beach landing sites," says Seddon. "Penguins will run back into the sea if approached on the beach, and will wait beyond the breakers until a beach is clear."
Such delays could mean that the birds digest some of the food that they would otherwise regurgitate to feed their chicks. Seddon found that the lighter chicks were less likely to survive, and he fears that heavy tourist traffic could ultimately spark the failure of a colony.
A For instance, Rochelle Constantine of the University of Auckland, New Zealand, and her colleagues have been monitoring schools of bottlenose dolphins along the country"s north-eastern coast since 1996. In an upcoming paper in Biological Conservation, they report that the dolphins become increasingly frenetic when tourist boats are present. They rest for as little as 0.5 per cent of the time when three or more boats are close, compared with 68 per cent of the time in the presence of a single research boat.
B Like dolphins, the bears may pay a heavy price for such altered behaviour. The tourist visits could be increasing the animals" heart rates and metabolism when they ought to be conserving their energy, and this could be reducing their body fat and individual fitness, the researchers argue. "For slow-breeding animals the effects could take years to detect, by which time it may be too late to reverse the damage," says Constantine.
C The massive growth of the ecotourist industry has biologists worried. Evidence is growing that many animals do not react well to tourists in their backyard. The immediate effects can be subtle -- changes to an animal"s heart rate, physiology, stress hormone levels and social behaviour, for example -- but in the long term the impact tourists are having could endanger the survival of the very wildlife they want to see.
D Ecotourism can have an even more detrimental effect in the wilderness regions of Africa and South America. "In more remote places such as the Amazon, there"s not much control," says ecologist Martin Wikelski of Princeton University in New Jersey.
E Land animals are affected too. Since the early 1980s, specialised vehicles have been taking people to watch polar bears during October and November in Manitoba, Canada, a time when the animals should be resting and waiting for Hudson Bay to freeze over so they can start hunting seals. But often the bears are not resting as they should.
F But while the IUCN and other organisations, and governments of nations such as New Zealand and Australia, try to ensure that their projects are ecologically feasible, many ecotourist projects are unaudited, unaccredited and merely hint they are based on environmentally friendly policies and operations. The guidelines that do exist mostly address the obvious issues such as changes in land use, cutting down trees, making tracks, or scaring wildlife.