The distribution of life on Earth is critically linked to environmental conditions suitable for photosynthesis. In the ocean, photosynthesis can only occur in the uppermost (euphotic) layer where sufficient light is available. Yet, a new study, showed that Arctic microalgae can photosynthesise at extremely low light levels at the end of the polar night. The microalgae only had about one hundred thousandth of the amount of light of a sunny day on the Earth’s surface available for their growth.

The researchers explain, that at this time, the sun is barely above the horizon, with the microalgae’s habitat obscured from light by the snow and ice cover on the Arctic Ocean. The results of the study; Photosynthetic light requirement near the theoretical minimum detected in Arctic microalgae (Hoppe, C.J.M., Fuchs, N., Notz, D. et al.) revealed that photosynthesis in the ocean is possible under much lower light conditions – able to take place at much greater depths than previously assumed. The study shows that the build-up of biomass can actually take place with a quantity of light that is close to this minimum.

Even though the research is specific to the Arctic Ocean, it shows the incredible capabilities of photosynthesis and may provide answers to boosting photosynthesis in crop plants by extending growing seasons, growing in higher latitudes, or growing more efficiently indoors by using less (artificial) lighting.

The study was led by Dr. Clara Hoppe from the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI) and focused on studying phytoplankton and ice algae. Along with close collaboration with sea ice researchers Dr. Niels Fuchs and Prof Dirk Notz from the Institute of Marine Research at the University of Hamburg, whom were responsible for combining measurements of the light field with the biological measurements.