Abstract:
Based on field data of nutrients observed in coastal aquaculture area in Shandong province, 2018, using the methods of nutrient limitation, the distribution characteristics of nitrogen、phosphorus and silicate were analyzed and discussed. The results showed that the average annual concentrations of DIN, PO
4-P and SiO
3-Si in Shandong coastal culture areas were (0.253±0.048) mg/L、(0.00743±0.00238) mg/L and (0.269±0.089) mg/L, respectively. The concentrations of DIN and SiO
3-Si in Bohai aquaculture area were generally higher than those in Yellow Sea aquaculture area, and the high-value stations were mostly distributed in the semi-closed bay, such as Laizhou Bay, Dingzi Bay. The concentration of PO
4-P was generally low. The annual mean ratios of N/P, Si/N and Si/P were 131±47、0.92±0.47 and 90±60, respectively. The areas with high N/P ratio were mainly distributed in Bohai and Haiyang-Laiyang area. Most Si/N、Si/P high-value stations were distributed in Muping area in the east of Shandong Peninsula and Weifang, Longkou and Laizhou-Zhaoyuan area. The analysis of the nutrient structure showed that the nutrient structure of Shandong coastal culture area was obviously limited by phosphorus and limited by silicon in dry season. The phosphorus limitation was obviously in four seasons, and the silicon limitation was obviously during dry season. It is suggested that the reasonable planning of stocking density can not only effectively increase the amount of shellfish resources, but also make full use of marine primary productivity to purify water quality. It should actively promote the simultaneous cultivation and rotation of shellfish and algae in raft aquaculture shellfish and algae aquaculture areas, adjust the structure of culture products, and improve the poor nutritional status caused by the change of nutritional structure.