Collaborative Research: Sea ice as a driver of Antarctic benthic macroalgal community composition and nearshore trophic connectivity

Sea ice cover, light levels, and other environmental parameters on community structure will be modelled to determine which factors have the largest influence. Impacts on community structure, food webs, and carbon flow will be assessed through a mixture of SCUBA diving and video surveys. Broader impacts include the training of graduate students and a postdoctoral researcher, as well as numerous informal public education activities including lectures, presentations to K-12 groups, and a variety of social media-based outreach.

Macroalgal communities are more abundance and diverse to the north along the Western Antarctic Peninsula, perhaps due to the greater light availability that is associated with shorter period of sea-ice cover. This project will determine the causes and community level consequence of this variation in algal community structure. First, satellite data on sea ice extent and water turbidity will be used to select study sites between 64 S and 69 S where the extent of annual sea ice cover is the primary factor influencing subsurface light levels.

Then, variations in macroalgal cover across these study sites will be determined by video line-transect surveys conducted by SCUBA divers. The health, growth, and physiological status of species found at the different sites will be determined by quadrat sampling. The relative importance of macroalgal-derived carbon to the common invertebrate consumers in the foodweb will be assessed with stable isotope and fatty acid biomarker techniques.

This will reveal how variation in macroalgal abundance and species composition across the sea ice cover gradient impacts sea floor community composition and carbon flow throughout the food web. In combination, this work will facilitate predictions of how the ongoing reductions in extent and duration of sea ice cover that is occurring in the region as a result of global climate change will impact the structure of nearshore benthic communities.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.