室内培养硏究硝酸盐对中肋骨条藻生长的影响

中肋骨条藻是一种广温、广盐性的浮游硅藻，并且多次在长江口及其他海域形成赤潮，对海洋生态环境造成严重危害，因此引起国内、外赤潮研究者的广泛关注。不少学者对中肋骨条藻种群的生态、生理特点展开研究(刘东艳等，2002；黄文祥等，1989；邹景忠等，1989；李铁，1990，2000)。营养盐是海洋浮游植物所必需的成分，海水中某种营养盐含量过低往往对浮游植物生长形成限制(Myers et al.，1981；Brian，1986；胡明辉等，1989)。海水营养盐含量过高则易形成富营养化，可进一步引发赤潮(周名江，2001)。硝酸盐是海洋浮游植物所必需的营养物质之一，它直接影响着浮游植物的生长、繁殖等生物活动(李铁，2000；Ryther et al.，1971)。研究海水中硝酸盐浓度和N/P对浮游藻类生长的影响将有助于我们了解高营养化与赤潮发生之间的关系。本文对在不同营养结构条件下，中肋骨条藻的生长速率、培养介质中的pH和溶解有机碳(DOC)进行了研究。

Effect of Nitrate on the Growth of Skeletonema costatum by Indoor Culture Experiment

Skeletonema costatum is the dominant phytoplankton in Changjiang Estuary. Blooming of Skeletonema costatum arose several times in Changjiang Estuary in recent years. In order to study the relationship between concentration of nitrate and the Skeletonema costatum blooming. We studied the growth of Skeletonema costatum in different concentration of nitrate. Growth rate, PH, dissolved organic carbon (DOC) and maximal uptake rates of nutrients were educed through the experiment. The results showed that low nitrate concentration limited the growth of Skeletonema costatum although the concentration of phosphate was high. The optimum N/P ratio was 15.7 among different N/P ratios tested in the experiment. The closer the N/P ratio was to the Redfield ratio 16:1, the higher was the growth rate of phytoplankton. The growth rate and concentration of cell, when N/P ratio was over 15.7 were much higher those when N/P ratio was under 15.7. Under condition of low nitrate concentration, the dependence of Skeletonema costatum growth on nitrate was increased. The release of DOC was promoted obviously by enrichment of nutrient.