中文摘要：

在实验室条件下，研究了赤潮异弯藻（Heterosigrnaakashiwo）对不同溶解性有机氮（DON）的响应，以揭示赤潮异弯藻种群增殖和赤潮发生的环境背景。结果表明，赤潮异弯藻可以利用多种DON，不同N源下生长优劣程度分别为苏氨酸〉尿素〉丙氨酸〉谷氨酸〉NO^3〉甘氨酸。在苏氨酸、尿素、丙氨酸、谷氨酸组的最大细胞数量和最大比生长率甚至明显高于无机营养盐组（NO^3），最大细胞数量为无机营养盐组的125％～253％，但赤潮异弯藻不能有效利用丝氨酸和尿酸两种N源。赤潮异弯藻不能耐受营养盐缺乏条件，在N或P缺乏以及N、P同时缺乏的条件下，无法生长。研究结果说明，赤潮异弯藻对DON具有较强的利用能力，可使之在激烈的种群竞争中占据优势，而近岸海域的富营养化及有机污染为其赤潮的发生提供了物质基础。

英文摘要：

In order to understand the environmental conditions of the bloom occurrence of Heterosigma akashiwo growth responses of H. akashiwo to various dissoved organic nitrogen （ DON ） sources were assayed in laboratory experi- ments. H. akashiwo could utilize several kinds of DON, rank order of maximum cell number was ： threonine 〉 urea 〉 alanine 〉 glutamic acid 〉 NO3- 〉 glycine. The maximum cell number and the maximum specific growth rate （μ_max ） in the medium of threonine, urea, alanine, and glutamic acid were superior to those in NO3- medium, with the relative maximum cell number of 125% -253% compared to NO3- medium. However, H. akashiwo could not maitain effective growth in serine and uric acid medium. H. akashiwo could not endure N-free or P-free or both nutrient free conditions. The results suggested that the high capasity of H. akashiwo to utilize DON made it predominance in phyto- planton competition, and eutrophication and orginc pollution in coastal areas provide basic nutrient demands for its bloom occurrence.