Microbe abundance and biomass at station SEPT-1999-K6 in the Northeastern Aegean Sea

Borax-buffered formalin (final concentration 2% formaldehyde). Slides for nanoflagellates counting were stored at -20°C. Subsamples (10-30 ml) were concentrated on 25mm black polycarbonate filters of porosity 0.6µm for nanoflagellates, stained with DAPI for 10 min (Porter & Feig 1980) and filtered. Heterotrophic (HF) and photototrophic (PF) nanoflagellates were distinguished using UV and blue excitation and enumerated. Nanoflagellates were classified in size categories and the biovolume was calculated.