New Extremophiles: through Arctic night period. (Introduction)

by David Turell , Wednesday, January 29, 2025, 18:12 (1 day, 3 hours, 56 min. ago) @ David Turell

Under the ice:

https://www.quantamagazine.org/how-does-life-happen-when-theres-barely-any-light-20250129/

"In early 2020, Hoppe found herself testing the limits of photosynthesis directly, camped aboard an icebreaker ship that had been deliberately rammed into an ice floe and allowed to drift with its engines off through the polar night. A rotating crew of scientists with the expedition Mosaic (Multidisciplinary Drifting Observatory for the Study of Arctic Climate) occupied RV Polarstern on its journey to gather as much data about the Arctic winter as possible.

"Hoppe and her colleagues worked in the darkness of 24-hour night, amid expanses of glittering ice and wind chills down to minus 76 degrees Fahrenheit. Cracks and ridges in the ice constantly shifted the route to a permanent hole in the ice, named Ocean City, from which Hoppe and her team gathered hundreds of liters of seawater samples and hauled them back to the ship for analysis.

***

"In February, the darkness of the polar night was nearly absolute, and not even photons from a bright moon or fleeting twilight could reach the dark waters below. Then, in late March, the sun briefly surfaced over the horizon. Beneath that ice, the light sensors recorded an astronomically small number of photons: an upper range of 0.04 micromoles per square meter per second, a number very close to the theoretical minimum amount of light that photosynthesis can run on. The actual amount of light was probably lower.

***
'Pairing Fuchs’ light data with Hoppe’s microalgae observations clinched it: At the end of March, right when the barest amount of sunlight returned, the microalgae not only had their photosynthetic machinery up and running but were also growing and building biomass. Her team concluded that they’d made the first-ever field observation of photosynthesis at just around the theoretical minimum — where the amount of light was an order of magnitude lower than what had been observed in nature before.

"Her team found that during the darkest periods of polar night, the microalgae didn’t show a measurable uptick in carbon uptake — they were neither growing nor photosynthesizing. Yet they weren’t totally dormant either. The cells kept running on low power. Then, as soon as the light levels rose enough to support active carbon fixation in late March, the algae were ready to explode into action."

Comment: another study of extreme life demonstrating how pliable life is, covering the Earth in every place possible.