In vivo chlorophyll fluorescence measurements : comparing the YSI 6025 sensor with the standardized NEN 6520 analyses

The aim of this study is a comparison between an in situ chlorophyll sensor (YSI 6025) and the spectrophotometric method for chlorophyll (NEN6520:2006) and to find explanations for possible deviations. The YSI 6025 sensor seems a promising tool which can be used complementary to standardized spectrophotometric analyses. To find out what the unexplained variation is between the YSI and NEN, Deltares advices to include CDOM and algal composition (and concentration) in the field monitoring program. The YSI 6025 chlorophyll sensor should be calibrated with the phytoplankton assemblage of the location of interest to obtain correct chlorophyll readings.