Researchers were able to trace biomarkers that are unique to algae growing within sea ice to connect marine mammals with a food source that is rapidly diminishing in the face of climate change.
“This study builds on work we have been doing in the Bering and Chukchi Seas to show that these tracers of ice algae and phytoplankton can be used to monitor the ecosystem response to disappearing sea ice,” said lead study author Chelsea Koch of the University of Maryland Center for Environmental Science.” “Ongoing monitoring of these sea ice biomarkers in walruses and even other organism tissues in the region will potentially help us to identify how the system is responding to changing food sources at the base of the food web as a result of climate change.”
The marine ecosystem of the Pacific Arctic near Alaska is adapted to utilizing fat-rich foods derived from biological production in sea ice. Ice algae blooms lead to a pulse of high-quality food to the sea floor. This in turn supports high abundances of clams and other benthic organisms throughout the Bering and Chukchi Seas – and lots of food for walruses to eat.
However, the loss of seasonal sea ice poses a threat to Pacific walruses, particularly how they use sea ice for rest and to access and forage on these dense offshore clam beds. With the disappearance of sea ice in many recent years near Alaska, thousands of walruses are coming ashore on coastal beaches in the late summer that are distant from the most productive clam beds. Stampedes are also likely to occur with these massive gatherings, leading to additional mortalities.
