These shoals and the submerged land surrounding them to a depth of 6 meters (20 ft) form theJiuduansha Wetland Nature Reserve.[2] The entire area stretches roughly 46.3 kilometers (28.8 mi) east to west and 25.9 kilometers (16.1 mi) north to south, covering an area of 423.5 square kilometers (163.5 sq mi),[2] although only 114.6 square kilometers (44.2 sq mi) of this is abovesea level.[3] The area is considered one of thenational urban wetland parks ofChina and forms part of theChina Biosphere Reserve Network. A 1996 field study found that, for seven bird species investigated, the number present at Jiuduansha exceeded 1% of the world's total for the species, establishing it as a Wetland of International Importance.[4]
Although Jiuduansha literally translates as "Nine-Part Sands", the number nine is here being used in a colloquial way similar to Englishseveral.[5] In fact, the group consists of four mainshoals. These are sometimes given theirMandarin names ofShangsha,Zhongsha,Xiasha, andJiangyanansha[6] and sometimes translated asUpper,Middle,Lower, andSouth Jiuduansha.[2] South Jiuduansha is known as Jiangya Nansha in Chinese after thepinyinromanization of theSSKiangya, the passenger steamer which exploded nearby (probably owing to amine from theSecond World War or theChinese Civil War) in 1948.
Jiuduansha originally formed part of theWaitongsha shoal, but frequentfloods of theYangtze in 1949 and 1954 connected a series oftroughs and separated Jiuduansha from theTongsha shoal.[2] Shanghai's universities have studied Jiuduansha since the 1990s and, in 1995, introducedcordgrass in order to speed the shoal's stabilization,[7] particularly in light of roughly 71% reduction insedimentation caused by the manydams erected along the course of the Yangtze during the 20th century.[8] In March 2003,[9] the Shanghai municipal government established thenature reserve. The cordgrass and environmental protection were intended to accommodate birds then living at the site being developed asPudong International Airport.[5] From October 2002 to January 2003,Fudan University and the reserve's administration conducted four joint surveys[2] and, in 2005, the wetland was finally upgraded to a national nature reserve.[5] In the time since its introduction, the cordgrass has been found to have becomeinvasive,[5] aggressively crowding out the nativereeds andbulrushes[7][8] and degrading parts of the wetlands.[5] A wetland museum, as well as a Science Popularization Park on about 5 square kilometers (1.9 sq mi) of the island, are planned to increase public awareness and support.[5]
Jiuduansha is the spawning ground for thehairy crab, one of the most important products of theChinese fishing industry[10] and a delicacy of thecuisine of Shanghai and eastern China.[11][12] The shoals also host large communities ofCipango andSiberian prawn andswimming crabs.[10] They are known to host 5protected species offish[13] and 14 protected species ofbirds, including theblack-faced spoonbill.[4] All 14 observed species ofaquatic mammals are protected and Jiuduansha is thought to be the most important habitat in China for thefinless porpoise, thebottlenose dolphin, and thespotted seal.[14]Many birds live on Jiuduansha, including wintering birds from Australia to Siberia, some of which are endangered species. Jiuduansha is an important transit station for these birds, since there are many fish for them to prey on, and the reeds are a good place for resting during the long journey. Most of the birds in Jiuduansha are first and second levels in protected animals in China. For example: Swan Goose; Oriental Stork; Spotted Greenshark; Platalea minor.
