Global warming continues to reshape the Arctic, with melting sea ice altering the underwater light environment and impacting marine life [2, 5]. A recent study led by Monika Soja-Woźniak and Jef Huisman from the University of Amsterdam, published in Nature Communications, reveals how these changes affect the base of the Arctic food web [2, 3].
As sea ice diminishes, the light that penetrates the ocean shifts from a broad spectrum to one dominated by blue light [2, 3]. Sea ice reflects most sunlight, allowing a small amount of light with a full range of wavelengths to pass through [2, 3]. Open seawater, however, absorbs much of the red and green light, allowing only blue light to travel deeper [2, 3].
This spectral shift poses challenges for algae and phytoplankton adapted to the diverse colors found under the ice [2, 4]. These organisms, which form the base of the Arctic food chain, may struggle to photosynthesize efficiently in the blue-dominated environment [2, 5]. Changes in algae productivity or species composition can have cascading effects on fish, seabirds, and marine mammals, and also impact the ocean's ability to absorb CO2 [2, 5].