Abstract: Sipunculus nudus is a special species distributed in the Beihai Gulf, and it is also a kind of precious sea food. In order to exploit its economic value, the content of amino acids of S. nudus was measured. Nutritional values of amino acids were evaluated according to amino acids grade standard mode of FAO/WHO. The investigation was conducted in February, May, August and November 2013 in five sea areas including Shankou, Beimu, Yingpan, Daguansha and Zhulin. Then the amino acids content and composition were analyzed. The result showed that the average content of amino acids of S. nudus in Beimu was highest, being 68.02%±0.50%. The contents of amino acids, essential amino acids and nonessential amino acids presented a trend of increase first and decrease later over seasons in the five sea areas. 16 kinds of amino acids were detected in S. nudus, and the content of glutamic acid was highest, which could reach 17.34%±0.61%. The ratio of essential amino acids to total amino acids and the ratio of essential amino acids to nonessential amino acids approached the FAO/WHO standard. Our results provided theoretical basis and technical support for the development of S. nudus with high edible and medicinal values.

Key words: leaf, soil water content, carbon isotope, water use efficiency, alpine meadow