Application of a Cooled CCD Imaging System to the Study of Microorganisms and Non-Living Particles in the Picoplankton Size Range

海洋浮游生物系统中的亚微米颗粒在系统的基础化学和生物学、种群和食物网动态以及生物地球化学循环中发挥着重要作用。微浮游生物大小范围内的颗粒包括活微生物、病毒和无生命碎屑颗粒。这些不同颗粒的丰度、大小光谱和荧光性质可以用图像分析的荧光显微镜来测量。在美国联合全球海洋通量研究“长期开发计划”的资助下，基于冷却CCD相机开发了一种灵敏、准确的图像分析系统，以自动测量自然样品。该奖项是对过去奖项的更新，旨在升级系统的空间分辨率，以提高这些颗粒尺寸测量的精度。该仪器将用于小颗粒在种群丰度，大小光谱和荧光染色方面的表征。该系统将使用已知的病毒浓缩物进行校准，以确定是否可以根据其大小和荧光特性将其与小细菌区分开来。该仪器将用于确定JGOFS百慕大时间序列站和当地河口水域的粒子种群特征。样品也将通过电子显微镜以及碳和氮组成进行分析，特别是一些尺寸分馏样品。这种不同的测量方法将有助于更好地了解这些颗粒的性质及其在海洋生物地球化学循环中的潜在作用。

Sub-Micrometer particles in marine plankton systems may play important roles in the basic chemistry and biology of the system, in population and food web dynamics and in biogeochemical cycling. Particles in the picoplankton size range include living microorganisms, viruses and non-living detrital particles. The abundance, size spectra and fluorescent nature of these various particles can be measured using image analyzed epifluorescence microscopy. With funding from the "Long-Lead Time Development Program" of the US Joint Global Ocean Flux Study, a sensitive, accurate image analysis system, has been developed, based on a cooled CCD camera, to automate these measurements of natural samples. This award which constitutes a renewal of the past award is to upgrade the spatial resolution of the system to increase the precision of the size measurements of these particles. The instrument will than be used for the characterization of small particles in terms of population abundances, size spectra, and fluorochrome staining. The system will be calibrated using known virus concentrates to determine if they can be distinguished from small bacteria based on their size and fluorescence characteristics. The instrument will be used to characterize particle populations at the JGOFS Bermuda Time Series station and in local estuarine waters. Samples will also be analyzed by electron microscopy as well as for carbon and nitrogen composition, particularly some of the size-fractionated samples. This variety of measurements should lead to a better understanding of the nature of these particles and their potential roles in marine biogeochemical cycles.