According to new research released on July 4, the Arctic Ocean is being deprived of essential nutrients due to climate change, with its six main rivers providing much less of the nitrogen form that marine ecosystems depend on. According to the study, which was headed by Bridger J. Ruyle of the Tandon School of Engineering at New York University, rising temperatures are altering the chemistry of rivers in ways that may deprive coastal food webs of inorganic nitrogen, a nutrient that is crucial for primary production. The study was chosen as an Editor’s Choice and published in “Global Biogeochemical Cycles”. Ruyle declared, “This is a red flag for the Arctic.”

“The way these marine ecosystems function could be drastically altered by rapid changes in river nitrogen chemistry.” Twenty years’ worth of water chemical data from the Yenisey, Lena, Ob, Mackenzie, Yukon, and Kolyma rivers were examined by the researchers. Together, these streams provide nitrogen that sustains up to 66 per cent of primary output in coastal Arctic regions and drain roughly two-thirds of the land area that flows into the Arctic Ocean. While dissolved organic nitrogen, which is much less accessible to marine life, rose between 2003 and 2023, inorganic nitrogen levels decreased in four of the six rivers. Because of these modifications, nitrogen is still getting into the ocean, but it is doing so in a form that is more difficult for phytoplankton and other creatures to utilise. The study concluded that the change is due to climate change-induced increases in precipitation and air temperatures, which affect permafrost thawing and river discharge.

Permafrost loss was identified by sophisticated statistical modelling as the primary cause of the divergent trends in organic and inorganic nitrogen. Organic material is locked away for millennia by permafrost, which is frozen soil and sediment. That substance breaks down as it thaws, releasing organic forms of nitrogen. On the other hand, inorganic nitrogen usually originates from mineralised sources, which are diminishing due to changes in hydrological channels and landscapes. A consistent supply of bioavailable nutrients is essential to the coastal Arctic food webs that have supported Indigenous people for thousands of years.

These systems might be upset by a prolonged decrease in inorganic nitrogen, which would have an impact on fish, seabirds, marine mammals, and plankton higher up the food chain. Ruyle stated that this investigation shows why water quality and climate change are issues that are inextricably intertwined. The results, he continued, are a component of his larger research on the interplay between natural processes, climate change, and human activity that impacts water quality. Environmental change can exacerbate water quality issues, as demonstrated by Ruyle’s previous research on toxins, including pharmaceuticals and per- and polyfluoroalkyl compounds, also known as “forever chemicals”, in wastewater.

For instance, less river flow during a drought results in less pollution dilution. He claimed that another illustration of how climate-driven changes ripple across intricate biogeochemical systems is the Arctic nitrogen shift. Researchers from Florida State University, the University of Alberta, the Carnegie Institution for Science, the University of Canterbury in New Zealand, and the Marine Biological Laboratory in Woods Hole are among the study’s co-authors. Funding was provided by the Arctic Great Rivers Observatory initiative of the National Science Foundation. Ruyle cautioned that more postponements in tackling the causes of Arctic change may make recovery more difficult and stated that the results should guide ecosystem management and climate adaptation plans.