6种赤潮甲藻对荧光标记藻类的吞噬行为研究

STUDY ON PHAGOTROPHIC BEHAVIOR OF SIX HARMFUL DINOFLAGELLATES ON FLUORESCENT LABELED ALGAE

选取6种在中国沿海广泛分布的赤潮甲藻米氏凯伦藻(Karenia mikimotoi)、链状亚历山大藻(Alexandrium catenella)、东海原甲藻(Prorocentrum donghaiense)、海洋原甲藻(Prorocentrum micans)、微小原甲藻(Prorocentrum minimum)和锥状斯氏藻(Scrippsiella trochoidea),采用经5-(4,6-二氯三嗪基)氨基荧光素(DTAF)标记灭活的荧光饵料藻进行投喂,观察目标甲藻是否存在吞噬行为,研究光照、营养盐条件对目标甲藻的吞噬行为的影响。结果发现,链状亚历山大藻能吞噬旋转海链藻(Thalassiosira curviseriata),东海原甲藻能摄食球等鞭金藻(Isochrysis galbana),但其摄食概率非常低,且不受光照和营养盐条件的影响。实验中,未观测到米氏凯伦藻、海洋原甲藻、微小原甲藻和锥状斯氏藻的吞噬行为。在黑暗中培养48-72h后,目标甲藻均出现不同程度的死亡,尤其是东海原甲藻和链状亚历山大藻。虽然东海原甲藻和链状亚历山大藻具吞噬行为属于混合营养生物,但光合自养是目标甲藻获取营养、维持生长最主要的方式。

Six dinoflagellates species Karenia mikimotoi, Alexandrium catenella, Prorocentrum donghaiense, Proro- centrum micans, Prorocentrum minimum and Scrippsiella trochoidea were chosen as the target species. The preys which were labeled with 5-（4,6-Dichlorotriazinyl） aminofluorescein （DTAF） as the fluorescent labeled algae （FLA） were added to investigate whether the six dinoflagellates had the capability of phagotrophy and to analyze the influence of light and nutrients on their phagotrophic behavior. Results showed that A. catenella could ingest the fluorescent labeled Thalassiosira curviseriata and P donghaiense could ingest the fluorescent labeled lsochrysis galbana. These two species had the capa- bility of phagotrophy and thus belonged to the mixotrophic organisms. However, for both species, the grazing frequencies were so low and the phagotrophic behavior was not influenced by the variation of light and nutrient concentrations. No phagotrophic behavior was detected for the species of K. mikimotoi, P. micans, P minimum and S. trochoidea. After inocu- lation in the dark for 48--72h, the dinoflagellates died in different extent, especially P minimum and A. catenella. All these results support that phototrophy was the major mode in gaining nutrition and sustaining the growth for the target dinoflag- ellates.