Original version of This story Appears in Quanta Magazine.
Most of the engines of life run in sunlight. Photons filter the atmosphere and are eagerly absorbed by light-loaded organisms such as plants and algae. Through photosynthesis, particles of light are cellular reactions that produce chemical energy (in the form of sugars), passed around the food web in complex dances of herbivores, predators, scavengers, decompositioners, and more.
On bright, sunny days, there is a wealth of photons. But what happens in low light? Biologists have long been interested in how little photosynthesis is, or how quickly the cellular photosynthetic machines need to arrive, and how quickly they need to arrive, to process carbon dioxide into oxygen and energy. The calculations suggest that the theoretical minimum is approximately 0.01 micromolar photons per square meter per second, or less than 10,000 of a photon on a sunny day.
For decades, this calculation has been theoretical, and given the difficulty of studying photosynthesis under low light, it has been theoretical. There are many places on the planet that hardly reach them, but no one could see them in the field. For example, like the sun hidden by the tilt of the earth, the Arctic winter disappears for months each year. A meter of snow covers the sea ice, blocks incoming light, and darkens the cold sea like inside the grave. So, biologists envisioned photosynthetic microalgae that lived in the power of water and ice for the seasons, waiting for warmth and light to return.
“People thought that these desert conditions with little life, and that everything would sleep and hibernate, waiting for the next spring.” Clara Hoppea biogeochemist at the Alfred Wegener Institute in Germany. “But really, people never really saw it.”
In winter 2020, Hoppe lived on a ship stained with ice streams throughout polar nights, studying the limits of photosynthesis in the dark. Her team’s recent study in natural communication reported microalgae Growth and recreation At theoretical minimum or nearby light levels, it is lower than previously observed.
This study shows that life blooms with the most hairy amount of light in some of the coldest and darkest places on Earth. “At least some phytoplankton may be able to do something very useful under some conditions with very low light,” he said. Douglas Campbellwas an aquatic photosynthesis expert at Mount Allison University in Canada and was not involved in the research. “That’s an important job.”
The power of the dark side
Scientists traditionally understood that the Arctic Circle was a place of stagnation for most of the year. In winter, creatures that can escape from the extremely cold seas do so. Those who continue to live from a preserved sanctuary will either be stored or fall asleep in quiet sleep. Then, when the sun returns, the place comes back to life. During spring flowers, photosynthetic algae and other microorganisms kickstart the Arctic ecosystem, fueling annual levels with annual crustaceans, fish, seals, birds, polar bears, whales and more.
Phytoplankton seemed to expect to get an earlier start than the competition could have had a more successful summer. This made her wonder when, precisely, the creature could react to the returning light.
