Effects of light intensity and artificial aeration on growth and photosynthetic physiology of marine invasive green alga Codium fragile from Bohai Sea, China

Abstract

Codium fragile has attracted much attention due to its high economic and nutritional values. The light intensity and artificial aeration affect its growth and photosynthetic activity, which in turn affect its economic and nutritional values. The light intensities (30µmol·m− 2·s− 1, 60µmol·m− 2·s− 1, 90 µmol·m− 2·s− 1) and aeration regulation are investigated to the effect on the growth and photosynthetic physiology of C. fragile collected from the Bohai Sea, China. The results show that different light intensities have a highly significant effect on the maximal photochemical efficiency of PSII(Fv/Fm), photochemical quenching coefficient (qP), and a significant effect on the non-photochemical quenching coefficient (NPQ). They all decreased the least under 60µmol·m− 2·s− 1. The increase in the relative growth rate(RGR) of C. fragile during aeration was greater than that of the non-aeration group. At the same time, the Fv/Fm and qP decreased less than those of the non-aeration group. It shows that the aeration regulation had a highly significant effect on the wet weight, Fv/Fm and qP of C. fragile. Among the six groups, only aeration and light intensities of 60 and 90µmol·m− 2·s− 1 were suitable for the growth of C. fragile, because the Fv/Fm decreased less and the qP increased. The result shows that the interaction of the two environmental factors had a significant effect on the Fv/Fm and qP of C. fragile, while there was no significant effect on the wet weight and NPQ.