These shoals and the submerged land surrounding them to a depth of 6 meters (20 ft) form the Jiuduansha 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 above sea level.[3] The area is considered one of the national urban wetland parks of China and forms part of the China 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]
^But here using the number nine in its colloquial Chinese sense of "some" or "several".
