Few Remaining River Dolphins Indicators of River, Human Health

雪儿 · 发表于: 2011-7-14 16:26:16

freshwater-dolphins-threatened-indus-river_25652_600x450.jpg 保存到相册

River Rescue

Photograph by François Xavier Pelletier, WWF-Canon

This gallery is part of a special National Geographic news series on global water issues.

Local men rescue an Indus river dolphin in Sind Province, Pakistan.

The endangered Indus dolphin is the only river dolphin species on the rise, with populations estimated at around 1,700 in 2006, up from 1,200 in 2001.

While this species treads water, the decline and near extinction of several other species of river dolphins is an indication of the deterioration of water quality and quantity, as well as human health, around the globe, according to a new WWF report released yesterday during World Water Week in Stockholm.

One species—the Yangtze river dolphin or baiji—has already been declared extinct.

The environmental nonprofit WWF profiles the seven remaining known species, many of which are facing significant survival threats from water pollution, competition with fisheries, and habitat fragmentation through dams and other water infrastructure.

—Tasha Eichenseher, reporting from World Water Week in Stockholm, Sweden

Published September 8, 2010

雪儿 · 发表于: 2011-7-14 16:26:37

freshwater-dolphins-threatened-yangtze-finless-porpoise_25655_600x450.jpg 保存到相册

Yangzte Finless Porpoise

Photograph by Jean-Pierre Sylvestre, Bios/Photolibrary

The Yangtze finless porpoise is one of two large marine mammals that used to ply China's longest river.

It has outlived the now extinct Yangtze river dolphin, which was last seen in 2007.

Just 1,600 to 1,800 of the finless porpoises were counted in 2006 along the middle Yangtze and in two lakes. A population of the porpoise that has been protected in one of the Yangtze's oxbow lakes—remnants of where the river used to run—has grown by three or four calves a year.

To help the animals, local governments open sluice gates at 40 lakes along the Yangtze, returning, to some degree, the seasonal flow of the river and the dolphin to a larger stretch of its original habitat, said Lifeng Li, director of freshwater programs at WWF.

River dolphins, many elusive, are the canaries in the coal mine of the planet’s freshwater ecosystems, according to WWF. The threats facing dolphins are the same threats facing people, the environmental nonprofit's new report states.

“Unsustainable fishing practices both harm dolphins and erode the basis of fishermen’s livelihoods; toxic chemicals used in agriculture and mining affect the health of people and dolphins alike; and loss of natural river flows and habitats decreases the productivity of the freshwater ecosystems that sustain both human societies and river dolphins.”

Published September 8, 2010

雪儿 · 发表于: 2011-7-14 16:26:50

freshwater-dolphins-threatened-bolivian-river_25650_600x450.jpg 保存到相册

Baby Bolivian Dolphin

Photograph by Dado Galdieri, Associated Press

The Bolivian river dolphin comes equipped with a flexible body that allows it to make its way through the tree roots of flooded forests.

All three South American river dolphin species compete for habitat with fishers who sometimes use the dolphin as bait, according to WWF. But, the new report goes on to state that the primary threat to the Bolivian dolphin is mercury pollution from small-scale gold mines.

This baby was rescued in the summer of 2010 in the Pailas River, a tributary of the Rio Grande, when drought led to lower-than-usual water levels.

Published September 8, 2010

雪儿 · 发表于: 2011-7-14 16:27:02

freshwater-dolphins-threatened-tucuxi_25654_600x450.jpg 保存到相册

Tucuxi River Dolphin

Photograph by Mark Bowler, Amazon-Images/Alamy

A dorsal fin skims the surface of the Yavari River in Peru.

Tucuxi look like bottlenose dolphins but have longer noses and broader flippers. The species is found throughout the Amazon region, with the exception of Bolivia.

Both Tucuxi and Irrawaddy dolphins are distinct from the other five species in that they are part of the Delphinidae family of mostly ocean-dwelling dolphins. Both species have marine populations, as well as freshwater populations.

雪儿 · 发表于: 2011-7-14 16:27:15

freshwater-dolphins-threatened-ganges-river_25651_600x450.jpg 保存到相册

Ganges River Dolphin

Photograph courtesy François Xavier Pelletier, WWF-Canon

A Ganges river dolphin, or Susu as it is known locally, waits at the surface of the Karnaphuli River in Bangladesh, where it comes up to breathe every minute or so. WWF estimates that there are fewer than 2,000 of the endangered species left in the river system made up of the Ganges, Brahmaputra, Meghna, and Karnali Rivers in Bangladesh, India, and Nepal.

雪儿 · 发表于: 2011-7-14 16:27:28

freshwater-dolphins-threatened-irrawaddy_25653_600x450.jpg 保存到相册

Irrawaddy River Dolphin

Photograph courtesy David Dove, WWF Greater Mekong

An Irrawaddy dolphin breaches the Mekong River in Cambodia. According to WWF, fishers in Myanmar's Irrawaddy River work in cooperation with Irrawaddy dolphins. The dolphins herd fish along side boats as they feed. The Irrawaddy dolphin's range has been limited to a 120-mile (190-kilometer) stretch of the Mekong, and small sections of the Irrawaddy and Mahakam Rivers, each subpopulation reduced to the critically endangered number of less than 75.

雪儿 · 发表于: 2011-7-14 16:27:42

freshwater-dolphins-threatened-amazon-river_25649_600x450.jpg 保存到相册

Amazon Feeding Time

Photograph courtesy François Xavier Pelletier, WWF-Canon

A man feeds an Amazon river dolphin in Brazil's Tocantins state. Legends around river dolphins abound. Amazon river dolphins are said to be shape shifters, changing into handsome men at night.

Often known as pink dolphins or "boto," Amazon river dolphins face the same risks as the other two South American species, including the habitat fragmentation that comes with dam building along the Amazon and its tributaries.

The species is widely distributed along the Orinoco and Amazon River Basins, in Venezuela, Colombia, Ecuador, Peru, Brazil, Suriname, and Guyana.

雪儿 · 发表于: 2011-7-14 16:27:56

freshwater-dolphins-threatened-yangtze-river_25656_600x450.jpg 保存到相册

Yangtze River Dolphin

Photograph by Mark Carwardine, Photolibrary

Photographed in 1988 in captivity at the Institute of Hydrobiology in Wuhan, China, this male Yangtze River dolphin, or baiji, may have been the last of its kind. The species was officially declared extinct in 2007.

The marine mammal could not compete with a barrage of threats that included rapid development along the Yangtze River Basin, increased pollution, fishing practices that hooked and electrified the species, shipping traffic, and altered river flows due to dams and sluice gates.

帐号		自动登录	找回密码
密码			免费注册

[其他] Few Remaining River Dolphins Indicators of River, Human Health

相关帖子 » 标签

浏览过的版块