RUI: Influences of Benthic Boundary-Layer Flow on Distributions and Feeding Rates of Protists in Subtidal Near-Bottom Water and Surficial Sediments

沉积物-水界面（SWI）和近底层水中的微生物过程对于包括沿海沃茨、大陆架和深海在内的许多潮下带海洋环境中的底栖生物生产力、营养物循环和底栖生物-浮游生物耦合至关重要。 然而，原生生物在底栖-浮游过渡带微生物食物网中的作用却知之甚少。 该提案描述了一项结合实地采样和实验室实验的研究，以阐明底栖边界层（BBL）流对原生生物生态的影响。 该项目旨在回答以下问题：（1）在西南湾和近底层水中原生生物的垂直分布和丰度是什么，（2）BBL流在多大程度上和通过什么机制影响这些分布，（3）在多大程度上和通过什么机制，BBL流量的变化是否会影响SWI和近底层水中异养原生生物的摄食率？ 为了回答这些问题，本研究的目的是：（1）描述布扎德湾沿岸潮下带生境近底层水和表层沉积物中原生生物的垂直分布特征，并将这些分布与流速的潮汐变化联系起来：（2）在实验室水槽中调查野外观察到的水流影响细胞垂直分布的机制;（3）在水槽中，在与野外相似的条件下，测定BBL水流对异养原生生物摄食率的影响。 这项工作的结果将为底栖微生物生态学中的物理-生物相互作用和沿海生境中的底栖-中上层耦合提供新的见解。 通过这些过程，在潮下带沿海栖息地的物理能量水平的流动可能有深远的影响，微生物营养动力学，次级生产，以及近底和表层沉积带的生物地球化学过程。

Microbial processes at the sediment-water interface (SWI) and in near-bottom water are critical for benthic productivity, nutrient cycling, and benthic-pelagic coupling in numerous subtidal marine environments, including coastal waters, continental shelves, and the deep sea. The roles of protists in the microbial food webs of the benthic-planktonic transition zone, however, are poorly understood. This proposal describes a study of combined field sampling and laboratory experiments to elucidate influences of benthic boundary-layer (BBL) flow on protistan ecology. The project is designed to answer the following questions: (1) what are the vertical distributions and abundances of protists at the SWI and in near-bottom water, (2) to what extent, and by what mechanisms, does BBL flow influence these distributions, and (3) to what extent, and by what mechanisms, do variations in BBL flow affect feeding rates of heterotrophic protists at the SWI and in near-bottom water? To answer these questions, the objectives of the research are: (1) to characterize the vertical distributions of protists in the near-bottom water and surficial sediment of a coastal subtidal habitat, Buzzards Bay, MA, and to relate these distributions to tidal variations in flow speed; (2) to investigate in a laboratory flume the mechanisms by which flow influences vertical distributions of cells as seen in the field; and (3) to measure in a flume the influences of BBL flow on feeding rates of heterotrophic protists under conditions similar to the field. The results of this work will provide novel insights into physical-biological interactions in benthic microbial ecology and benthic-pelagic coupling in coastal habitats. Through these processes, the physical energy level of flow in subtidal coastal habitats may have far-reaching influences on microbial trophic dynamics, secondary production, and biogeochemical processes in the near-bottom and surficial-sedimentary zone.