Emiliania Huxleyi: Role of the Scaled Flagellate in the Life Cycle and Bloom Dynamics

自其起源于晚更新世以来，在世界海洋中已变得无处不在。它是最丰富的生物体，也是将大气中的二氧化碳转移到海洋沉积物中最重要的生物。形态包括球粒、结球和裸露的球状细胞，以及鳞片鞭毛。只有球石的形态模式在自然样本中很容易识别，到目前为止关于该物种的分布和丰度的所有研究都只对这种形态模式进行了研究。与其他球藻的比较表明，运动型是一个交替的生活史阶段，但它的生活史仍然知之甚少，它在水华动态中的作用也是未知的。最近开发的技术可以识别和跟踪自然种群中的裸露和鞭毛细胞，并简化培养细胞倍性的测定。本研究的目的是(1)比较鞭毛型和球型在自然种群开花前、开花期间和开花后的丰度和分布；(2)建立倍性和生活史；(3)确定鞭毛型和有性重组在开花动态中的作用。

Since its origin in the late Pleistocene, >Emiliania huxleyi> has become ubiquitous in the world's oceans. It is the most abundant living coccolithophore and the most important organism in the transfer of atmospheric carbon dioxide to the ocean sediments. Morphological forms include coccolith.bearing and naked coccoid cells, and scaled flagellates. Only the coccolith.bearing morphotype is readily identifiable in natural samples, and all studies to date on the distribution and abundance of the species have been studies of only this morphotype. Comparison to other coccolithophores suggests the motile form is an alternate life cycle stage, but the life cycle of >Emiliania hyxleyi> remains poorly understood, and its role in bloom dynamics is unknown. Recently developed techniques permit identification and tracking of naked and flagellated >Emliliania huyxleyi> cells in natural populations and simplify determination of ploidy in cultured cells. The objectives of this research are (1) to compare the abundances and distributions of the flagellated form to that of the coccoid forms in natural populations before, during and after blooms, (2) to establish ploidy and the life history, and thus (3) to determine the role of the flagellated form, and of sexual recombination, in bloom dynamics.