usefulness of the data, and allow us to better interpret the results of bulk water FRR 

 measurements. The main limitations of the pump/probe flow cytometer are those of sensitivity, 

 in that at present we are able to measure only the larger phytoplankton cells. In addition, we are 

 not planning to try to make in situ measurements, so we will obtain potential rates rather than 

 real-time information such as is obtained by FRR fluorometry. The measurements will be more 

 limited in scope, but more highly resolved in terms of organisms, than the FRR measurements. 



STATUS OF RESEARCH 



We are still in the early stages of development of the instrument, and in fact we are now 

 trying a new approach (photon counting) to increase sensitivity so we can measure small as well 

 as large cells, so actual construction has not yet begun. We still plan, however, to have a 

 working instrument in the next year (even if it only works for large cells), to participate in the 

 field year. 



Keywords: phytoplankton, flow cytometer, nutritional status, fluorescence 



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