Photosynthesis in near darkness

The study was made possible by the close collaboration of researchers from various disciplines. Sea ice researchers Dr Niels Fuchs and Prof Dirk Notz from the Institute of Marine Research at the University of Hamburg were responsible for combining measurements of the light field with the biological measurements. "To measure such low light levels under the harsh conditions of the Arctic winter, we had to freeze special, newly developed instruments into the ice in the middle of the polar night," explains Niels Fuchs. His colleague Dirk Notz adds that it was particularly difficult to take into account irregularities in the light field under the ice due to variations in ice thickness and snow: "But in the end we could be sure: There was just not more light."

The results of the now published study are important for the entire planet. "Even though our results are specific to the Arctic Ocean, they show what photosynthesis is capable of. If it is so efficient under the challenging conditions of the Arctic, we can assume that organisms in other regions of the oceans have also adapted so well," says Clara Hoppe, contextualising the results. This means that there could also be enough light to produce usable energy and oxygen through photosynthesis in deeper areas of the oceans, which would then be available for fish, for example. The corresponding photosynthetic habitat in the global ocean could therefore be significantly larger than previously assumed.