The frigid waters encircling Antarctica are home to a unique and fragile ecosystem that experiences dramatic seasonal changes. A new study from the University of Washington sheds light on how single-celled organisms, such as sea-ice algae, adapt to these extreme shifts, providing insights into the future of this ecosystem under the influence of climate change.
During the Antarctic winter (from March to October), the region experiences near-constant darkness as the sun barely rises. During this time, seawater freezes, expelling salts and creating pockets of super-salty brine where microbes thrive. In the summer, constant daylight causes the sea ice to melt, producing warmer, fresher surface water.
This remote ecosystem houses much of the Southern Ocean’s photosynthetic life and plays a crucial role in global ocean currents and marine ecosystems. However, it remains poorly understood due to its extreme conditions and inaccessibility.
The recent study, published in the ISME Journal, offers some of the first measurements of how sea-ice microbes adapt to changing conditions in this environment.
The research, led by Hannah Dawson, a UW postdoctoral researcher, and senior author Jodi Young, a UW assistant professor of oceanography, examined how these microscopic organisms respond to fluctuations in temperature and salinity.
The study also investigated the molecules produced and used by these microbes to survive, which are vital for supporting higher organisms in the ecosystem and have implications for climate processes like carbon storage and cloud formation.
The researchers conducted experiments at the U.S. research station on the West Antarctic Peninsula, Palmer Station. They sampled seawater and sea ice, then manipulated temperature and salinity in tanks to mimic sea-ice formation and melt. Genetic and metabolite analyses were performed on the samples in Seattle.
The results showed that sea-ice algae adapt to their changing environment by producing cryoprotectants, similar to antifreeze, to prevent their cellular fluid from freezing. They also adjust the concentration of salt-like organic molecules to maintain water balance when salinity changes. Notably, different microbe species displayed consistent responses to changing conditions, simplifying predictions of future responses to climate change.
The study also suggested that lower-salinity environments might lead to reduced production of omega-3 fatty acids, impacting consumers of krill oil supplements and the marine ecosystem that relies on these algae-derived nutrients.
The research highlights the importance of understanding how sea-ice algae cope with environmental changes, both under normal conditions and in the context of climate change, which is altering the landscape in terms of sea ice formation and freshwater input from melting ice.
This study was funded by the National Science Foundation, the Simons Foundation, and the Alfred P. Sloan Foundation and involved collaboration with researchers from Scripps Institution of Oceanography and Arizona State University.
Read Now:Cosmic Whodunit: Clues to Alien Life on Exoplanet K2-18b?
Reference: https://www.sciencedaily.com/releases/2023/09/230914224040.htm
