Light spectrum matters: Interactive effects of light and nutrients on phytoplankton communities and trophic transfer

Phytoplankton is highly sensitive to both the quantity (intensity) and quality (spectrum) of available light, due to a large range of light-absorbing pigments. While light is considered as a main driver for trophic energy transfer, focus has been primarily on the intensity of light. This study investigated the role of different light spectra on the community structure and biochemical composition of natural phytoplankton. We found that light spectrum affects the species composition and biochemistry of phytoplankton communities with these effects being highly dependent on light intensity and nutrients. Additionally, we tested for potential nutritional constraints for the zooplankton species Daphnia pulex in response to changes in the phytoplankton community and found different growth responses of D. pulex as a result of changing mineral and biochemical growth contraints for the Daphnia species. We conclude that, beyond nutrients and light intensity, also the light spectrum influences plankton dynamics and trophic transfer in aquatic systems.