光照及营养盐对3种赤潮甲藻吞噬营养行为的影响

Effects of light and nutrients on the phagotrophic behaviors of three harmful dinoflagellates

通过在室内批量培养实验中添加活体藻类及荧光标记藻类(Fluorescent Labled Algae,FLA)的方式,研究不同光照及营养盐条件下3种赤潮甲藻米氏凯伦藻(Karenia mikimotoi)、链状亚历山大藻(Alexandrium catenella)及东海原甲藻(Prorocentrum donghaiense)的吞噬营养行为;通过现场船基围隔实验,研究2010年春季,东海原甲藻赤潮发生时其对荧光标记的球等鞭金藻(Fluorescent Labled Isochrysis galbana,FLIg)和骨条藻(Fluorescent Labled Skeletonema sp.,FLS)的摄食行为。结果表明,米氏凯伦藻、链状亚历山大藻和东海原甲藻均具有吞噬营养行为,属混合营养甲藻。米氏凯伦藻能摄食活体球等鞭金藻;链状亚历山大藻摄食荧光标记的旋转海链藻(Fluorescent Labled Thalassiosira curvis-eriata,FLTc)。在围隔实验前期,东海原甲藻可对FLIg、FLS进行摄食,但该摄食行为随培养时间的延长近乎消失。无论是在黑暗或是在营养盐胁迫的条件下,仅发现极个别目标甲藻存在摄食行为,发生摄食的概率极低;在围隔现场,东海原甲藻对FLA的摄食概率仅为0.4%～1.4%,表明吞噬营养并非3种目标甲藻的主要营养方式,它们属于主要依赖光合自养获取营养的种类。

The effects of light and nutrients on the phagotrophic behaviors of three red-tide dinoflagellates （Karenia mikimotoi, Alexandrium catenella, and Prorocentrurn donghaiense） were studied by adding live algae and fluorescent labeled algae （FLA） in the batch culture experiments. During the bloom period in the spring of 2010, the phagotrophic behavior of R donghaiense on fluorescent labeled Isochrysis galbana （FLIg） and Skeletonerna sp. （FLS） was inspected in the mesocosm experiment on board. Results showed that K. mikimotoi, ,4. catenella, and P. donghaiense could ingest cells, belonging to the mixotrophic organisms. K. mikimotoi could ingest live I. galbana and A. catenella could ingest fluorescent labeled Thalassiosira curviseriata （FLTc）. In the prophase of the mesocosta experiment, R donghaiense could ingest FLIg and FLS, but the behavior disappeared along with time. However, in the darkness or under the nutrient-deficient conditions, only little amount of dinoflagellates were found to ingest cells. The ingestion frequencies of P. donghaiense on FLA were only 0.4%-1.4 % in the mesocosm experiment in situ. These results indicate that although these three species are mixotrophic dinoflagellates, autotrophy rather than phagotrophy might play an important role in acquiring nutrients.