Study Of Different Sea-water Aquaculture Models Of Environmental Nitrogen And Phosphorus Loading Of Eastern Guangdong

Eastern Guangdong is one of the main seawater aquaculture areas of China. In the present study, the nitrogen and phosphorus loading of fish marine cages, intensive farming of shrimp, and intensive farming of shellfish in Zhelin Bay, the nitrogen and phosphorus loading of fish pond culture-extensive breeding, semi-intensive monoculture of shrimp, and semi-intensive polyculture of shrimp with crabs in Haifeng Dongguan Lian'anwei wetland areas, and nitrogen and phosphorus of seawater and sediments in Haifeng Dongguan Lian'anwei wetland mariculture areas were examed, aiming to reveal the environmental effects of mariculture in eastern Guangdong. The main findings were showed as follows:1) Fish cage culture in Zhelin Bay produced environmental nitrogen loading of 1370.37 tons, environmental phosphorus loading of 413.08 tons, if the fish were fed with artificial feed; environmental nitrogen loading of 2760.39 tons and environmental phosphorus loading of 679.11 tons when fish were fed with trash fish. In the condition of using trash fish, the major of environmental nitrogen loading is the unconsumed diet, accounting for 61.41%; the major of environmental phosphorus loading is the unconsumed diet, accounting for 65.00%; the main components of nitrogen in the unconsumed diet stored in soft tissues, about 768.62 t; the main component of phosphorus in the unconsumed diet stored in bones, about 241.73 tons.2) Environmental nitrogen loading and phosphorus loading of shrimp farming in Zhelin Bay were 210.21 tons and 45.45 tons, respectively. Environmental nitrogen loading mainly come from excretion, accounting for 74.74%, and environmental phosphorus loading mainly come from feces, accounting for 54.72%.3) Environment nitrogen loading and environment phosphorus loading of shellfish farming in Zhelin Bay were-108.93 tons and-7.48 tons, respectively.4) In the three mariculture methods in Haifeng wetland, semi-intensive monoculture of shrimp produced most of nutrient release-environmental nitrogen loading of 93.77 Kg/ha and phosphorus loading of 18.83 Kg/ha, semi-intensive polyculture of shrimp with crabs released environmental nitrogen loading of 10.11 Kg/ha and environmental phosphorus loading of 2.72 Kg/ha, and fish pond culture did not discharged but reduced 7.90 Kg/ha nitrogen and 1.04Kg/h phosphorus from seawater.5) According to the measurement of nitrate, nitrite, ammonia, total nitrogen, phosphate, and total phosphorus in seawater and Kjeldahl nitrogen and total phosphorus in sediments in aquaculture areas of Haifeng wetland, fish pond culture was environmental friendliness, semi-intensive polyculture of shrimp with crabs somewhat caused environmental pollution, and the quality of seawater received the nutrients produced by semi-intensive monoculture of shrimp was worst.