Diatom Aggregation as a Significant Source of Marine Snow inthe Ocean

尽管许多表面衍生的物质以被称为海洋雪的宏观集合体的形式流入海洋内部和海底，但人们对海洋中这些大颗粒的产生过程知之甚少。具有潜在全球意义的海洋雪的一个来源是硅藻开花后活着的硅藻大量凝聚和定居。虽然这种现象只能从沉积物捕捉器研究中推断出来，而且还没有发表过关于自然界中硅藻形成海洋雪的经验描述，但PI经常使用水肺观察到，在南加州海湾，活的硅藻形成了直径几厘米的丰富的海洋雪聚集体。她对这些絮体的种类组成和沉降率进行了初步调查。这项研究继续沿着这些思路进行。这项建议的目的是：1)记录硅藻絮凝事件的持续时间、时间、絮体丰度和特征，以及对垂直通量的影响；2)确定与自然界中硅藻形成海洋雪有关的状态、物种组成和丰度；以及3)调查硅藻碰撞和粘连形成聚集体的物理和生物机制。这项研究将首次提供硅藻聚集作为海洋雪的重要来源的经验数据。这将进一步加深我们对海洋中大颗粒形成机制的理解，这是充分理解和预测海洋通量所必需的。

Although much of surface-derived matter fluxes to the ocean interior and the sea floor in the form of macroscopic aggregates known as marine snow, little is known about the processes governing the production of these large particles in the ocean. One source of marine snow of potential global significance is the mass flocculation and settlement of living diatoms following diatom blooms. While this phenomenon is known only inferentially from sediment trap studies and no published empirical accounts of marine snow formation by diatoms in nature yet exist, the PI has regularly observed, using scuba, living diatoms forming abundant aggregates of marine snow centimeters in diameter in the Southern California Bight. She has conducted preliminary investigations of the species composition and sinking rates of these flocs. This research continues along those lines. The objectives of this proposal are to: 1) document the duration, timing, floc abundance and characteristics, and impact on vertical flux of diatom flocculation events; 2) determine the state, and species composition and abundance, associated with marine snow formation by diatoms in nature; and 3) investigate the physical and biological mechanisms by which diatoms collide and stick to form aggregates. This research will provide the first empirical data on diatom aggregation as a significant source of marine snow. It will further our understanding of the mechanisms of large particle formation in the ocean necessary to fully understand and predict ocean flux .