STUDY ON PHAGOTROPHIC BEHAVIOR OFSIX HARMFUL DINOFLAGELLATES ON FLUORESCENT LABELED ALGAE
6种赤潮甲藻对荧光标记藻类的吞噬行为研究

Six dinoflagellates species Karenia mikimotoi,Alexandrium catenella,Prorocentrum donghaiense,Prorocentrum 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 Isochrysis galbana.These two species had the capability 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 inoculation 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 dinoflagellates.