The massive melting of polar ice has led to a sharp decline in the level of a key nutrient in seawater, negatively impacting populations of plankton, fish, seabirds, and mammals.
The amount of Arctic sea ice melting is increasing
The amount of Arctic sea ice melting is increasing
Recent studies have shown that the melting of sea ice in the Arctic Ocean, which was expected to lead to increased phytoplankton growth as a result of increased sunlight, may have a different effect than expected.
According to an analysis by researchers at the University of Edinburgh, increased exposure of shallow areas in the Arctic Ocean to sunlight after ice melt accelerates the breakdown and removal of nitrates from seawater. Nitrates are essential for the growth of phytoplankton, which form the base of the food web in the region.
Lower nitrate levels have negative effects on biodiversity and may limit the Arctic Ocean's ability to store carbon, given the role of phytoplankton in absorbing it through photosynthesis.
Analysis of samples collected over 20 years from the Fram Strait, the main outlet for Arctic waters into the Atlantic Ocean, showed a gradual decline in nitrate levels since 2009, coinciding with a sharp decline in sea ice extent.
Researchers point out that widespread ice loss has accelerated the conversion of nitrates to nitrogen gas in the shallow continental shelves that cover about half of the Arctic Ocean, making the marine environment more nutrient-poor.
According to the study, this shift towards nitrate-limited conditions may reduce the ecosystem's ability to support only smaller types of plankton in the future, with the system finding it difficult to return to its previous state even if ice loss slows down.
Scientists emphasize the need for more research to track these changes in other areas of the oceans, including the North Atlantic.
