Scientists find out what grows under arctic sea ice

A team of scientists has conducted extensive research to study the Arctic marine ecosystem in more detail. They reported their findings in an article for the journal Frontiers in Marine Science.

Small photosynthetic algae are a key component of the Arctic marine ecosystem. However, their role in the ecology of the Arctic Ocean has been underestimated for decades. This is the conclusion reached by a group of scientists, combining research over the past 50 years and their observations in order to study the emergence, extent and composition of phytoplankton blooms under the Arctic sea ice.

Phytoplankton are free-floating microscopic organisms, most of which are unicellular algae. Like land plants, they use photosynthesis to turn light into energy by consuming carbon dioxide and nutrients from the water. Phytoplankton form the backbone of the marine food web and play a vital role in the carbon cycle by absorbing CO₂ from the atmosphere.

Around ten years ago, most scientists assumed that phytoplankton remained in stasis (stagnation) throughout the winter and spring, right up until the sea ice broke up. There is now growing evidence that phytoplankton blooms can occur in low light conditions under sea ice.

Thus, phytoplankton production in some regions of the Arctic Ocean may be an order of magnitude higher than originally projected. This discovery is crucial for the creation of climate models. To do this, you need to know exactly how much atmospheric carbon is absorbed by these algae.

Few places on Earth are transforming as quickly as the Arctic due to climate change. Unsurprisingly, the resulting thinning of the ice sheet allowed phytoplankton, which needs light to photosynthesize, to thrive. However, it turned out that the bloom was also happening as climate change changed the Arctic sea ice. Research from the 1950s and earlier shows that blooms, although not very large, still took place under thick ice in the central Arctic.

The authors note that further observations of phytoplankton blooms under sea ice are key to better predicting future changes in the Arctic carbon cycle.

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