Abstract: Based on the monitoring data in the Sanmen Bay in August 1997 and October 2011, the distribution features of nitrogen, phosphorus and the changes of the nutrient salts at this section in the past 15 years were analyzed.The results show that the concentration of nitrogen and phosphorus have doubled since 1997 and the degree of eutrophication in the Sanmen Bay is from mild to serious. According to the nutrient structure, phosphorus still is the limitation factor of phytoplankton growth in the Sanmen Bay. It is also found that the excessive development of mariculture has improved the concentration of the nutrient salts directly. And it is suggested that the scale of marine aquaculture and adjusting the structure of mariculture as well as strengthening the pollution control should be performed in order to control the intensifying eutrophication level in the Sanmen Bay. It is needed to obtain the effective coordination of aquaculture economic and ecological environment, and the sustainable development is recommended.

Key words: Sanmen Bay, nitrogen, phosphorus, eutrophication, comparison analysis