海水养殖与生态环境关系的研究——Ⅰ.无机氮对浮游植物生长的影响

STUDIES ON THE RELATIONSHIP BETWEEN SEAWATER CULTURE AND ECOLOGICAL ENVIRONMENT——Ⅰ . THE EFFECT OF INORGANIC NITROGEN ON THE GROWTH OF PHYTOPLANKTON

采用中尺度受控生态实验、小型混养实验和虾池取样测定,研究海水中无机氮、N/P比值和藻类光合作用速率的变化规律,分析了无机氮和溶解有机氮(DON)的相互转化,比较了钙质角毛藻对不同形式无机氮的吸收,探讨了人工养殖海水中无机氮对浮游植物生长的影响。

Inorganic nitrogen. N/P and the photosynthctic rate of phytoplankton were determined by means of experiments with the mesocosms. small mixed cultivating experiments and the investigations on shrimp pools. The optimum N/P was ca. 16 : 1 for the growth of algae. The uptake of NH4-N by algae was significant with the coexistence of NO3-N,NO2~N and NII4-N. The maximum velocity of NH4-N uptake by Chaetoceros calcitrons was 4. 48 ×107 μg atN/ (cell· h), and the half-saturation constant was 34. 29 μg at N/L. In the seawatcr of cultivation, inorganic nitrogen could be transferred to DON, and vice versa. Increase of NH4-N and DON indicated that seawater became reductive. Too much NH4-N was. not beneficial to the growth of algae, and might induce the decrease of PR. The results of the small mixed cultivating experiments suggested that PR of phytoplankton was negatively correlated with NH4-N and DON, and positively correlated with NO3-N and NO2-N.