Effects Of Nitrogen Resources On The Growth Of Prorocentrum Donghaiense Lu

HABs, caused by Prorocentrum donghaiense Lu, frequently occurred in the East China Sea. The role of nutrients in blooming are still under researching. Therefore, several experiments were carried out: 1.the effects of eight different nitrogen resources on the growth of P. donghaiense under different concentrations; 2. starvation experiment: the growth of P. donghaiense with and without nutrient enrichment after different period of starvation; 3. the uptake of several main inorganic nitrogens by P. donghaiense: nitrate, ammonium and nitrite. The results are as follows:1. NaNO₃,NH₄Cl,NaNO₂ and urea can be utilized by P. donghaiense. The growth rate was the fastest when N/P ratios were close to Redfield ratio (N/P=16). When glycin, L-alanine and L-threonine as the nitrogen sources, the growth rate were lower compared to those of controls. However, when N source was 1 , 4-tetramethylene-diamine hydrochloride, a small quantity absorbtion was recorded under low concentration(N/P=1 and 8).2. After stationary phase with no additional nutrition, every group experiences a sharp reduction of cells concentration, after the continuance of low cells concentration, the quantity of the cells rise, and then drops again. After uptake of different N resources, P. donghaiense can transfer the nitrogen to organic substance and deposit in cells. When there is lower ambient nutrient oncentrations, the deposited organic substance in algal cells can be utilized to support algal growth. The transfer and deposit ability of P. donghaiense was greater when cultured in inorganic nitrogen than those in the organic nitrogen.3. After starvation for about 70-140 days of cultivation, a new growth cycle has been recorded after a new nitrogen enrichment. The group of N/P=16 and 32 with higher N concentration showed higher ability of depositing nitrogen than those of the lower N concentration (group of N/P=0 and 8).After 160 days of cultivation without any nutrient addition, the ability of movement and propagation of the algae was almost lost. After starvation for about 30-60 days when the nitrogen resource was urea,...