Polyamines Change Of Harmful Algae Blooms Succession In The East China Sea And Regulatory Role To Resistance To Nutrient Limit Stresses Of Harmful Alga

Harmful algae blooms frequently occurred in the East China Sea, and harmful alge blooms succession has attracted wide attention. The composition, content, and distribution of predominant free polyamines were studied in seawater of the area of frequent red-tide occurrence of the East China Sea in spring 2011. The effects of different nutrients on the concentration of polymines were investigated by mesocosm experiment, to prove relationship between polyamines and harmful algae blooms succession. In addition, polyamines response to nutrient limit stress and their physiological roles in Skeletonema costatum and Prorocentrum donghaiense were studied. Meanwhile, the regulatory roles were studied on Skeletonema costatum and Prorocentrum donghaiense under nutrient limit stress by adding polyamine. The results are as follows:Putrescine, spermidine and spermine ranged between 0~48, 3~11 and 2~17nmol/L respectively in the survey area. The average concentration of putrescine was the highest, followed by spermidine and spermine. During diatom bloom that dominated by Skeletonema costatum and dinoflagellate bloom that dominated by Prorocentrum donghaiense, polyamine concentration was relatively higher in area where algae bloom occurred. Polyamine concentration varied with process of algae bloom outbreak, and showed correlation with organic carbon, particulate organic carbon, organic nitrogen and carbon-nitrogen ratio.The effects of different nutrients on the concentration of polymines were investigated by mesocosm experiment. Obvious species succession occurred from Skeletonema costatum to Prorocentrum donghaiense in all mesocosms that of water from where Skeletonema costatum bloom broke up in 2011. In every mesocosm, putrescine concentration was the highest. In early growth stage of Skeletonema costatum the level of putrescine turned down, turned up with Skeletonema costatum growth, and fell with Prorocentrum donghaiense growth in the later stage of the experiment. In every mesocom, spemine concentration was lower and presented a large fluctuation during the succession. In every mesocom, the level of spermidine was much lower and had no obvious change in the process of succession. Variation of nutrient affected polyamines by means of influencing phytoplankton.Under nutrient limit stress, the relative growth rate of Skeletonema costatum decreased, particularly under the lower condition of Si and P. Under nutrient limit stress, SOD activity and MDA content in the Skeletonema costatum all increased, compared with control group. DAO and PAO activity in the Skeletonema costatum were all higher than the control. Changes of polymines were complicated. All putrescine, free and total spermidine, and total spermine were higher the control. Under nutrient limit stress, physiology index of Skeletonema costatum might promote algae cells resist nutrient limit stress.Under nutrient limit stress, the growth of Skeletonema costatum was restrained. Adding exogenous spermidine and spermine, the relative growth rate of Skeletonema costatum increased. Under nutrient limitation stress, MDA content in the Skeletonema costatum were higher than the control. After adding exogenous spermidine and spermine, MDA content in the Skeletonema costatum declined, and SOD activities were higher than the nutrient limit groups. After adding exogenous spermidine and spermine, DAO and PAO activities in the Skeletonema costatum changed to regulate content of endogenous polyamines and reduce damage from nutrient limit stress. After adding exogenous spermidine and spermine,bound polymines increased to enhance cell stability and resist the nutrient limit stress.Under nutrient limit stress, the relative growth rate of Prorocentrum donghaiense decreased. Under nutrient limit stress, MDA contents in the Prorocentrum donghaiense were higher than the control. SOD activity in the Prorocentrum donghaiense declined particularly in lower N and P concentration. PAO and DAO activity in the Prorocentrum donghaiense were all higher than the control. Bound and total Put, free, bound and total Spd, and free, bound and total Spm were all higher than the control, and played the important role in resisting nutrient limit stress.Under nutrient limit stress, the growth of Prorocentrum donghaiense was restrained. Adding exogenous polyamines, the relative growth rate of Prorocentrum donghaiense increased. Under nutrient limit stress, SOD activities in the Prorocentrum donghaiense of all groups declined. SOD activities increased and MDA content declined in all groups. PAO and DAO activies changed under nutrient limit stress, which could regulate polyamines content of algal cells, and ptotect the cell integrity. Endogenous polyamine content changed under nutrient limit stress, which could enhance cell stability, and resist the harm nutrient limit stress caused.Polyamines contents and distribution during harmful algae blooms succession were concerned with harmful algae blooms biomass, polyamines variation in mesocosm were affected by algal changed. Under nutrient limit, growth of Skeletonema costatum and Prorocentrum donghaiense were restrained. Adding exogenous polyamines could enhance Skeletonema costatum and Prorocentrum donghaiense resistance to nutrient limit stress.