Yangtze River & Lakes - A Global Ecoregion
Perhaps the first or second richest of temperate rivers
Snapshot: Ecoregion 149
Size:
1,613,378 sq. km (622,925 sq. miles)
Habitat type:
Large Rivers
Asia - flowing west to east through China
Conservation Status:
Critical/Endangered
Quiz Time!
What is special about the Chinese river dolphin?
Answer:
The Chinese river dolphin is not able to see very well, but it can hear with incredible sensitivity. It detects its prey by listening to sound waves in shallow water, a rare ability known as "echolocation". The Yangtze River is the only place on Earth where this severely endangered creature lives.
About the Area
From an elevation of 4,900 meters (about 16,000 feet), the third longest river in the world - Yangtze, descends rapidly as it crosses gorges and runs past limestone hills. Today, the Yangtze (known locally as Chang Jiang, or "Long River") is a centre for agriculture, industry, and tourism.
The river and the lakes that it feeds are also where diverse species of fish, birds, and mammals have lived for centuries. During the summer rainy season, swollen waters of the Yangtze River flood into the surrounding lake basins; during winter and spring when river levels are low, the lakes drain back into the river.The flora and fauna are adapted to these cycles as fish mix freely between lakes during flooding and terrestrial mammals swim to seek high ground. Poyang Lake, one of the largest lakes, serves as winter habitat for numerous waterfowl species.
Local Species
Two species of aquatic mammals - the Chinese river dolphin (Lipotes vexillifer), and Yangtze finless porpoise (Neophocaena phocaenoides) are of special concern as they are threatened by pollution, habitat destruction, and fishing operations.
The river dolphin, restricted to freshwater habitats of the Yangtze and its adjoining lakes, is considered the most endangered dolphin species in the world. The finless porpoise is also imperiled but is a more widespread marine species, visiting river mouths throughout the Indian Ocean and the Western Pacific.
Among the numerous threatened fish species are the Yangtze sturgeon (Acipenser dabryanus), Chinese sturgeon (A. sinensis), and the Chinese swordfish (Psephurus gladius). Other vertebrates include the largest salamander in the world, Audrias davidianus, Red-crowned crane (Grus japonensis), and the highly endangered Yangtze alligator (Alligator sinensis).
Threats
Fish farming, deforestation, cultivation of surrounding land for farming and grazing, pollution, oil drilling, industrialisation, urbanisation, and introduced diseases from domestic waterfowl pose widespread threats to this ecoregion. The most pressing and severe threat is construction of dams and dykes on the Yangtze and its tributaries, which alter the natural flow regime, block migratory routes, and sever the connection between the rivers and their floodplain habitats.
The most notorious of these projects is the Three Gorges Dam, which when complete will be 185 meters high and will store 40 x 109 m3 of water. Interbasin water transfers also threaten to upset water levels and create opportunities for the introduction of species. If completed, the controversial dam will stretch two kilometers across the Yangtze River, create a reservoir more than 600 kilometers long, cause the forcible resettlement of more than 1.3 million people, destroy the habitat for a number of endangered aquatic species, and flood over 1,200 cultural antiquities and archaeological sites. The dam could cost over US$70 billion.
Resources
• NationalGeographic.com
