Expert Practice – Leave 20% of Rations for Migratory Birds | Caofeidian’s Local Ecological Conservation Experiment Has Realized the “Double Cycle” of Wetlands (I)
2020/4/4 15:27:00 本站

In March 2019, entrusted by the Management Office of Caofeidian Wetland and Birds Provincial Nature Reserve (hereinafter referred to as the Reserve), Wang Yingeng, researcher of Yellow Sea Fisheries Research Institute of China Academy of Fishery Sciences, led the team to undertake the planning and implementation scheme design of the project “Trial Scheme for Wetland Ecological Conservation System and Waterfowl Habitat Creation”.

 

"The purpose of this project is very clear, there are three main objectives:1). to protect the wetland ecological attributes of the region, improve the stability and biodiversity of the wetland water system; 2). to create a fish and bird symbiotic environment such as bird island, protect the bird habitat such as Oriental Storks; 3). to do a better job in ecological breeding after removing the breeding ponds, and realize the harmonious symbiotic development of local people's production and life and wetland maintenance", Wang Yingeng also said that although in recent years, there has been plenty of breeding industry on the 18,000 km coastline of China, Caofeidian wetland has its own distinct ecological background.

 

Caofeidian wetland, with a total area of 540 square kilometers, is a large salt and alkali beach around Bohai Bay. In the past, Chinese people used to call the salt and alkali beaches as "smooth land" or "salt and alkali land". The ancients of China described this land as follows, "in winter, there is a vast expanse of whiteness; in summer, there is a vast expanse of water; almost no grass, and it is difficult for human beings to stand on their feet." According to the local chronicle records, since the Northern Wei Dynasty (526 A.D.), the local people lived by boiling salt, and the Ming and Qing Dynasties became famous for drying salt. In the 1950s, China called for reclamation, and the Ministry of Reclamation of the People's Republic of China established Bogezhuang farm, which mobilized 100,000 people from Henan, Hebei, Shandong and other provinces, including volunteers from Korean War fields, to develop state-owned farms and transform the saline-alkali land for around ten years. Volunteers at that time developed aquaculture by diverting water, planting reeds and cultivating rice fields. In 2005, the People's Government of Hebei Province approved its 100 square kilometers as a provincial nature reserve.

 

Caofeidian wetland is located at the seaside, with strong wind and high evaporation throughout the year, which is also an important factor in its long-term use as a natural salt field. According to the monitoring data, the annual average evaporation here is 2,078 mm, which is 4 times the local annual average precipitation; the wetland water system is also underdeveloped, and the natural freshwater source within the wetland range mainly relies on a Shuanglong river with small water volume. “In fact, Caofeidian wetland is seriously short of water. It has been dry here several times before, and after drying, the land turned to be salinity immediately.” Wang Yingeng said that in view of the problem of water shortage in Caofeidian wetland, the solution that their research team came up with was to establish a water circulation system and basically achieve zero discharge within the 14,000 Mu experimental area located in Laoyemiao area of Caofeidian, that is - to make full use of local freshwater, seawater, brine, and other water sources, so that the whole water source system can be recycled with Brine Shrimp breeding as the core element.

 

We design make-up pumps and settling and biological purification channels to collect farmland wastewater, domestic wastewater, rainwater, and river water. Through the natural productivity and purification of plankton and micro-ecological agents such as algae, the ecological culture of shrimp and fish was carried out. Then, fish and shrimp excrement and other organic matters are introduced into the brine shrimp breeding area to feed and purify them, and then the subsequent growth of brine shrimp is fed to fish and shrimp for feeding, so as to realize no feeding in the system and form a multi nutrition level food chain cycle. At the same time, let the water circulate in the system. With the evaporation of water and the increase of salinity, the brine will be formed to increase brine shrimp culture and realize the circulation purification and zero discharge of wetland water system. In this system, there will be rich biodiversity, such as unicellular algae, Cladocera, brine shrimp, shrimp, and fish, which provide rich food sources for different kinds of birds. Wang Yingeng called this system as “Wetland Ecosystem Maintenance System with Brine Shrimp as the Core” (also known as ABC System). At the same time, in order to protect the water quality of the wetland, Wang Yingeng’s team improved the high-density culture here to the low-density culture on the large water surface, realizing no bait and no medicine. After nearly a year’s practice, his team found that this combined system, under the premise of water shortage in Caofeidian wetland, really played a role in maintaining the water conservation and water quality stability of the wetland, kept the characteristics of the constructed wetland and avoided the threat of drying up, swamping and salinization.

 

If the water environment of the wetland is preserved, the habitat of birds will be basically preserved. Then, how to protect the birds? In terms of bird protection, Wang Yingeng’s research team thought of the way to combine several small ponds in the former breeding area into large ponds, and then build artificial bird islands in the large ponds, and build them at a slope of 1:10 to create high earth dams, shoals, deep water and other habitats for all kinds of birds. In this way, in the experimental scheme designed by Wang Yingeng, the research group used brine shrimp and 20% of the fish and shrimp left in advance every year to solve the food problem for the resident birds and a large number of migratory birds; at the same time, to create an artificial bird island is to provide an undisturbed breeding environment for those birds.

 

The most important innovation of our project is to realize two cycles: one is the water cycle, zero discharge, and full conservation of wetland; the other is the food chain cycle, that is, from basic biological brine shrimp → fish and shrimp → to bird's food chain cycle." Wang Yingeng introduced that in the process of making these two-cycle systems work normally, the project team members monitored the water quality in real-time, and regulate the water level of bird island so that birds can easily get enough food.

 

For example, for water level regulation, basically according to the rhythm of spring - shallow, summer - deep, autumn - lower and winter - shallow, when a large number of migratory birds are about to migrate to Caofeidian wetland in autumn and winter, the water level in the experimental area will be lowered so that waders will not be unable to find food; or, if food appears insufficient, it is necessary to feed shrimp, barracuda, Gobiidae, sea goldfish to birds. The whole experimental area is under closed management. Control of human activities: strictly implement the wintering and spring migration period of birds from the beginning of January to the end of February, and forbid the entry of personnel; the maintenance workers can enter the winter and spring migration period at the end of March and April for maintenance; the breeding period of birds from the beginning of May to the middle of June, forbid the entry of personnel again; until the breeding period of birds ends in the middle of June, the maintenance personnel can enter the closed experimental area again; and finally, the maintenance staff left in early October of that year, leaving the space for birds migrating in autumn and winter.


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(Photo credit: CBCGDF volunteers)


Original Chinese article:

http://www.cbcgdf.org/NewsShow/4854/11828.html


By / Tongtong Modified / Maggie