Intensive outdoor algal cultures: How mixing enhances the photosynthetic production rate

Experiments were carried out to define the effect of mixing upon primary productivity. The method compares the production of a water column with ¹⁴C-labelled samples (i) along a classic vertical profile and (ii) with a rotating system moving between the surface and the bottom of the pond, which was 0·5 m deep. In all the experiments, photosynthesis was best in the moving flask. The effect of mixing is particularly important at sunrise and sunset hours: the vertical photosynthetic budget may be over 2·5 times that of homogeneous non-turbulent water. These results have clear implications for monitoring intensive outdoor algal cultures.