Antarctic land-fast sea ice is an integral component of coastal ecosystems supporting bottom ice algal communities that are some of the most productive marine habitats on Earth. As Antarctic climate forecasts predict an increase in snow precipitation coupled with a reduction in shortwave radiation, there’s a pressing need to evaluate how these communities will respond to shifting light regimes.
We explore the in-situ response of fast-ice bottom communities under both natural and artificially manipulated light regimes altering both intensity and spectral quality. Five 5x5 m translucent Perspex panels (red, green, blue, black, and grey) were positioned on the ice surface 29 days prior to sampling over the 2019 spring season at Cape Evans, Antarctica.
By combining pigment analyses, species composition and imaging spectroscopy of different ice core sections, we observed ice algal biomass rising towards the surface under altered light regimes, accompanied by a significant shift in its vertical photophysiological structure.
The wide range of induced community adaptations further allowed to refine statistical bio-optical models to non-invasively predict algal biomass and photophysiology. By applying these models to in-situ under-ice data, the study showcases the capability to monitor shifts in ice algae photophysiological traits and their broader ecological and biogeochemical implications.