Antarctica is a world of ice and snow, not the place we expected to be full of life. But a new study has found evidence of abundant phytoplankton blooms beneath the Southern Ocean sea ice, which seem to thrive in the cold waters regardless of light conditions.
The sea ice in the Southern Ocean is dense, and sunlight cannot penetrate the ice layer, but underwater phytoplankton need light for photosynthesis.
Therefore, scientists originally thought that there would be no thriving plant ecology under the Antarctic ice sheet in winter.
Only when the sea ice recedes in spring can we start to see phytoplankton appear in the upper ocean.
However, the team of Brown University in the United States and the University of Auckland in New Zealand used buoys to sample the water column and floating objects under the sea ice in Antarctica from 2014 to 2021.
The number of chlorophyll molecules is detected and compared with the sea ice coverage measured by NASA satellites.
They found that phytoplankton increased in 88% of floaters before sea ice receded, and subglacial algal blooms in 26%.
The team say, this could indicate an unaccounted-for hidden ecosystem lurking beneath the ice.
And if the phytoplankton that form the basis of the food web hide under the ice, then we may underestimate the amount of life hidden under the ice.
The study was limited, though, because the buoys the team used couldn’t precisely track where the samples were taken under the ice (but the researchers felt the evidence was strong enough).
It’s also too early to draw conclusions, as some early Arctic research is beginning to suggest that human-driven warming may be affecting algal blooms under Arctic sea ice.
The new paper was published in the journal Frontiers in Marine Science.