Diatom Aggregation as a Significant Source of Marine Snow inthe Ocean

虽然许多来自表面的物质以被称为海洋雪的宏观聚集体的形式流入海洋内部和海底，但人们对控制海洋中这些大颗粒产生的过程知之甚少。具有潜在全球意义的海洋雪的一个来源是硅藻华后生活硅藻的大量絮凝和沉降。虽然这种现象只是从沉积物陷阱研究中推断出来的，而且还没有发表过关于硅藻在自然界中形成海洋雪的实证报告，但PI经常使用水肺观察到，活硅藻在南加州海域形成了大量直径为几厘米的海洋雪。她对这些絮凝体的种类组成和下沉速率进行了初步调查。这项研究沿着这些思路继续进行。本提案的目标是：1)记录硅藻絮凝事件的持续时间、时间、絮凝丰度和特征，以及对垂直通量的影响；2)确定自然界中硅藻形成海洋雪的状态、种类组成和丰度；3)研究硅藻碰撞和粘聚形成聚集体的物理和生物机制。本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。它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 .