China's Jiuduansha Wetlands is located at the mouth of Yangtze River. The estuary is formed where fresh and salt waters meet land. China designated the wetlands a protected area back in 2000. It has become a national natural reserve. Due to its special location, law enforcement officers help ensure its protection. Patrol work at the wetlands is anything but easy. More than two hundred patrols have been carried out so far. They have helped co the number of animal and plant species in the wetlands, including many nationally protected animals and plants. Some residents and fishermen have also volunteered to join conservation efforts.