Yang:【4】Species Disruption

Not only would the aquatic population become affected but the invaluable animal species inhabiting the land areas and large forests would also become affected. Huge reservoirs by their nature alter the ecosystem and threaten some habitats while helping other habitats. Most of the lands and forests would become submerged due to the flooding of the riverbeds. These large areas of land and forests host thousands of invaluable animal species. Most of the existing endangered species would have the possibility of becoming extinct.

With the disruption of the species habitat, the discussion on how the TGP would affect the fish species in the upper and middle reaches of the Yangtze River would be the next concern. The naturally free flowing Yangtze River will be transformed into a slow moving reservoir, which will further deteriorate water pollution. Since siltation elevates the riverbeds and water levels, the toxic substances and pollutants will be slowly released from the land into the river system. The substances and pollution would drastically change the biological activity in the river. With a temperature change and an increased light penetration due to stratification, it would produce plankton blooms, which triggers the start of eutrophication (Brower,1990). The total productivity of the river increases until the nutrients are depleted. Since the biological activity would become dependent on nutrient flow, the existing species would overtake the habitat. The new exotic species could decline the existing fish population depending on whether the fishes can find another suitable habitat.

Within the Yangtze River, there are about 196 fish species in the upper reach, among which 90 belong to special species. The fish species in the middle reach of the Yangtze River breeds in the Middle River during the flooding season. The breeding of these native species requires a certain rise of the water level as well as water temperature. However, since the TGP will drastically reduce the down stream water temperature and the rise of water level during the flooding season, it will delay the breeding period by several days. Consequently, some of theses species may disappear. In addition, the TGP may speed up the extinction rate of the rare species, such as the Chinese Sturgeon and the Chinese Paddlefish. The survival of these two species requires the middle and upper habitat of the Yangtze River. In addition to the rare Chinese Sturgeon and the Chinese Paddlefish, there is also the endangered Yangtze River dolphin (Lipotes vexillifer). The Yangtze River dolphin is one of the world's most endangered cetaceans an estimated 300 individuals remain. With the alteration to the Yangtze River due to the TGP, the extinction rate of the Yangtze River dolphin will increase. Because of the dam, fish species are unable to reach their upstream spawning habitats, affecting their natural biological cycles. Other affected species include the Chinese Sturgeon, Chinese Tiger, Chinese Alligator, Siberian Crane, and the Giant Panda. Of the 3,000 to 4,000 remaining critically endangered Siberian Crane, approximately 95% currently winter in wetlands that will be destroyed by the Three Gorges Dam.

Reference:

"All About the Three Gorges Dam." Sherwood Institute

            <http://www.sherwoodinstitute.org/all-about-the-three-gorges-dam/>.

"Chinese Dam Projects Criticized for Their Human Cost." International Rivers <http://www.internationalrivers.org/resources/chinese-dam-projects-criticized-for-their-human-cost-2978>.