Variable chlorophyll a fluorescence techniques to determine photosynthetic activity of marine phytoplankton

Photosynthesis is the basis of biological survival. Traditional methods are complicated, time consuming and destruction of the sample. Variable chlorophyll a fluorescence techniques provide a rapid, sensitive and non-invasive measurement of the photosynthetic physiology of algae. Based on this technique, an in situ measurement system of photosynthetic activity (F _v /F _m ) was established, using blue LEDs and detecting the main emission peak of chlorophyll fluorescence around 685 nm. Both the laboratory cultures of Skeletonema costatum and Prorocentrum minimum and field experiment in the coastal sea of Qingdao showed a significant correlation between F _v /F _m values measured by our newly developed system and those analyzed by commercial Water-PAM fluorometer, indicating that our measuring system could be used to analyze photosynthetic activity of marine algae in natural waters.