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Warming threatens aquatic resources

By Li Jing (China Daily)
Updated: 2009-09-14 07:37

Tuotuo River is one of the source regions of the Yangtze River that a new study shows is suffering threats to its aquatic life from the effects of global warming. [China Daily]

Global warming might endanger aquatic life in the source regions of the Yangtze River, a recent research report on fishery resources found.

Although the ecological environment and fish resources remain in good condition at the source regions of the Yangtze, a group of leading Chinese scientists on aquatic animals found that global warming has forced some fish species upstream, which can have damaging implications.

The Yangtze, the country's longest river, originates from glaciers at the foot of Mount Geladandong on Qinghai-Tibet Plateau in Qinghai province.

Extending over some 159,000 sq km, the Yangtze sources comprise Tuotuo, Dangqu and Qumar rivers. The average altitude is between 4,400 m and 4,700 m.

Near the Tuotuo River Bridge, the research team caught several Bilobed-lip schizothoracins, with the largest weighing more than 750 grams, which historically have not been found in that area.

It is a stark contrast with other fish species, which usually measure only about 10 cm, living in the Yangtze sources "These small fish are endemic species on the Qinghai-Tibet Plateau," said Tang Wenjia, an engineer with the Qinghai Provincial Fishery Environmental Monitoring Center.

"As an adaptation to the extreme weather conditions and high altitude here, they grow at a very slow pace, only about 1 cm per year," he said.

The larger Bilobed-lip schizothoracin originally lived in Jinshan River on the upper reaches of the Yangtze, according to Chen Yifeng, a researcher with the Institute of Hydro Biology (IHB) under the Chinese Academy of Sciences (CAS).

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"Usually, this species is rarely seen at an altitude higher than 4,000 m," Chen said. "Perhaps it is the rising water temperature incurred by global warming that has forced them here."

The research team caught another batch of Bilobed-lip schizothoracins in Qumalai county in southwestern Qinghai province. Most weighed more than 500 g.

"This means the species has already moved upstream in a relatively large quantity," Chen said.

Hard-hit plateau

The Qinghai-Tibet Plateau is among the regions hit hardest by global warming, which will have direct and long-term effects on the aquatic animals living in this area, said Wang Ding, a veteran expert from IHB.

Statistics show that the temperature in the Tibet autonomous region rose by an average of 0.32 C every 10 years between 1961 and 2008.

That rate of warming was much faster than the average across China, where temperatures rose by between 0.05 C and 0.08 C every 10 years during that period.

The situation is similar in neighboring Qinghai province.

The rising temperatures have led to the continuous melting of glaciers, scientists have found.

After the Arctic and Antarctic, the Qinghai-Tibet Plateau has the third-largest number of glaciers.

But 82 percent of glacier surfaces on the plateau have retreated, and the glacier area itself has decreased by 4.5 percent during the past 20 years, according to Qin Dahe from CAS.

Qin is the former head of the China Meteorological Administration, and he is former co-chair of a working group for the Intergovernmental Panel on Climate Change.

"Due to global warming, glaciers on the Qinghai-Tibet Plateau are retreating extensively at a speed faster than in any other part of the world," Qin said.

"In the short term, this will cause lakes to expand and bring floods and mudflows," Qin said.

Another threat from warming is the degradation of permafrost, or perennially frozen ground, Qin said.

"Permafrost plays a vital role in protecting the ecological environment and hydrological cycles. But it has been breaking down during the past 50 years," Qin said.

All these events could mean catastrophic changes for the aquatic animals in the Qinghai-Tibet plateau, as they are very fragile to any slight alteration of habitats, according to Chen of IHB.

Upsetting the balance

"Changes of topography and river directions are common in the Qinghai-Tibet plateau," Chen said.

"But the wetland degradation as a result of warming may threaten the fate of aquatic life," he said.

Introducing new species forced upstream also might lead to upsetting the ecological balance in the river sources.

"The result is still hard to predict at the moment," Chen said.

The survey was jointly conducted by the World Wildlife Fund, IHB, Yangtze River Fishery Resources Management Committee and the Qinghai Provincial Fishery Environment Monitoring Center.

This is the first time that Chinese scientists have conducted a thorough survey of fish resources in the source regions of the Yangtze, said Wang Limin, deputy conservation director of the World Wildlife Fund.

"This survey will help to give us a panoramic view of the fishery resources in the source regions of the Yangtze, and help us understand the impact of climate change on aquatic life in the river," Wang said.

"The Yangtze River is facing different challenges posed by global warming at different river sections," she said. "Knowing what is happening in the source regions will help us better mitigate and adapt to the changes."