Renewal of essential flow cytometry instrumentation for the study of marine microbes

Marine microbes provide essential ecosystem services, including the vast majority of marine primary productivity and the addition of huge quantities of new nitrogen to the ocean. In order to understand how marine microbes support these ecosystem services, and how that might change in the future, high-quality measurements of the abundance and physical characteristics of marine microbes are required. Flow cytometry enables counting and characterization of cells by flowing them through a beam of focused light. That light is scattered and fluorescence is emitted in a manner that is specific to the characteristics of each cell. This enables researchers to determine the abundance, size and pigment content of marine microbes at the single cell level. Here we request funds to replace a discontinued flow cytometer, which was used heavily by two research groups in the last 7 years. A new model of this sensitive, robust, user-friendly instrument will enable these two large research groups to continue studies that (1) determine the responses of marine microbes to changes in temperature, in the laboratory and in the field, (2) examine who the important nitrogen cycling marine microbes are and what controls their growth and abundance, and (3) determine the role of micronutrients and microbial interactions in controlling the growth of marine primary producers. The results of these studies will enhance our understanding of how productivity in the ocean may change in the future, as the Earth's climate warms. This is important for Canadians because this ocean productivity is directly related to both the production of fisheries resources and to the movement of carbon dioxide from the atmosphere to the deep ocean.