Antarctic sea ice plays critical role in marine ecosystems – new study

The ice ringing Antarctica’s coast forms an essential part of marine food webs in the Southern Ocean, a new study confirms.

Landfast sea ice - ice that remains attached to the coastline – serves as a unique habitat for a variety of marine life, particularly ice algae. Landfast algae account for about 12% of all algae produced in the Southern Ocean's sea ice and thereby provide a key food source for krill and fish, researchers found.

The study notes that the growth of ice algae in landfast sea ice is influenced by factors such as snow cover, light availability, and nutrient levels.

Landfast sea ice off Antarctica. Credit: Sebastien Moreau

Climate change is leading to a decline in both the duration and thickness of this ice. The authors warn that this could limit the future growth of ice algae and have far-reaching consequences for the entire marine ecosystem.

The predicted decline of landfast sea ice also disrupts nutrient cycling and other natural processes in the Southern Ocean, where ice algae play a crucial role in capturing atmospheric carbon dioxide. Changes in their growth could therefore influence global carbon cycles, further exacerbating climate change. 

“Our findings contribute to a growing body of evidence emphasizing the importance of sea ice ecosystems in the context of climate change,” said Sebastien Moreau from the iC3 Polar Research Hub, who participated in the study.

“Protecting Antarctica’s ice is not just about preserving a remote environment, it is crucial for maintaining life in the oceans and a stable global climate. We hope that our work will provide useful data that can inform conservation efforts and policy decisions.”

Sebastien Moreau and a colleague coring sea ice. Credit: Delphine Lannuzel

iC3 drives global efforts to quantify how ice sheets influence Earth’s carbon cycle, climate and ocean ecosystems in the past, present and future. The research centre in Tromsø, the capital of Arctic Norway, is currently inviting expressions of interest from potential postdoctoral candidates from all nationalities.

The study “Gross Primary Production of Antarctic Landfast Sea Ice: A Model‐Based Estimate” was published in JGR Oceans and is available open access.