Is the polar port a coastal port?

That's right. See the following introduction for details.

Yancheng Biosphere Reserve:

Located in the middle of Subei Plain, east of the Yellow Sea, it is said that it was reclaimed from the sea by Jingwei. Yancheng Biosphere Reserve is located along the coast of the North Yellow Sea in Jiangsu Province, spanning Dongtai, Dafeng, Sheyang, Binhai and Xiangshui counties along the beach, with a total length of 582 kilometers. It covers an area of 243,000 hectares. It is the first and largest marine wetland nature reserve in China. 1983 established a nature reserve, and 1992 listed it as a biosphere reserve. 1996 was accepted as a member of Northeast Asia Crane Reserve Network.

The water sources of the reserve are mainly land water and ocean water. Terrestrial water mainly includes two types of water systems and precipitation: Huaihe River Basin and Yishu Sihe River Basin. There are dozens of coastal estuaries, and more than ten large rivers, such as Guanhe, Zhongshanhe, Biandan Port, Sheyang River, Huangshahe, Xinyang Port, Doulong Port, Wanggang, Chuandonggang and Dongtai River, pass through the territory, and the water entering the sea accounts for about 90% of the total water entering the sea in the province. The water sources in this area are mainly beaches in land waters, mainly (1 128~ 1855) a large amount of sediment that entered the sea when the Yellow River seized the Huaihe River, sediment released by rivers such as the Yangtze River, and some sediment on the seabed, which were deposited into a vast muddy coastal plain under the action of ocean dynamics such as tidal current. From 65438 to 0855, the beaches in the south of Sheyang, the core area of the reserve, Dafeng and Dongtai still extend to the sea at speeds ranging from 50 to 200 meters.