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在实验室条件下,研究了赤潮异弯藻(Heterosigma akashiwo)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。
Under laboratory conditions, the response of Heterosigma akashiwo to different dissolved organic nitrogen (DON) was studied to reveal the environmental background of population proliferation and red tide occurrence in Heterosigma akashiwo. The results showed that DON could utilize a variety of DON. The growth and development of different heterotrophic fungi were threonine> urea> alanine> glutamic acid> NO-3> glycine. In the group of threonine, urea, alanine and glutamic acid, the maximum number of cells and the maximum specific growth rate were even higher than that of the inorganic nutrient group (NO-3). The maximum cell number was 125% 253%, but Heterosigma akashiwo can not effectively utilize two N sources of serine and uric acid. Heterosigma akashiwo can not tolerate nutrient-deficient conditions and is unable to grow in the absence of N or P and the absence of N and P at the same time. The results showed that A. henryi had a strong DON utilization ability, which could make it dominant in the fierce competition of the population. However, the eutrophication and organic pollution in coastal waters provided the material basis for the occurrence of red tide.