The filter-transfer-freeze method for quantitative phytoplankton analysis

Allan.Cembella [ at ]


Although the filter-transfer-freeze (FTF) technique is considered among the classical approaches for cell counting and identification, it is not specifically a cell enumeration method, but rather a means of cell concentration, collection, and transfer for counting by alternative means. When applied correctly, the accuracy and reproducibility of cell counts performed by the FTF technique is more a function of the subsequent counting and identification methods than of the FTF procedure itself. The FTF method was introduced more than two decades ago (Hewes and Holm-Hansen 1983), but in spite of its simplicity and proven effectiveness, the method has not been widely employed. This is regrettable because the FTF method can be applied for both critical taxonomy (with some caveats) and for rapid but superficial analysis of phytoplankton samples. The original method was designed with respect to nanoplankton and indeed appears to work best for taxa in the size range of ca. 5 – 200 μm diameter. Smaller cells tend to get lost to the filter and larger organisms do not transfer well. Nevertheless, this size-range embraces most of the diatoms and nanoflagellates of interest and chain-formation does not markedly decrease transfer efficiency from the filter to slide.

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Cembella, A. and Rafuse, C. (2010): The filter-transfer-freeze method for quantitative phytoplankton analysis / B. Karlson , C. Cusak and E. Bresnan (editors) , In: Microscopic and molecular methods for quantitative phytoplankton analysis, IOC Manuals and Guides, no. 55, Microscopic and Molecular Methods for Quantitative Phytoplankton Analysis, Paris, IOC-UNESCO, 6 p. .

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