The rates of light and dark 14CO2 fixation by natural phytoplankton communities in Lake Kinneret were studied in situ and in vivo in the laboratory. Dark fixation (DF) contributed an important part of the total primary productivity in Lake Kinneret.
In addition, it was found that during the dark period the relative amount of fixed inorganic carbon depends upon the sampling depth and season.
The DF contribution of the dominant phytoplankton species in Lake Kinneret (Peridinium gatunense) was found to be between 3-30% of the total light carbon fixation (LF). Carbon uptake was dependent on the light history of the cells. DF and LF in photosynthetic bacteria was found to be equivalent. A time course of carbon uptake by Peridinium showed that DF increased with time.