LIA: Collaborative Research: Biogeography, Population Genetics, and Ecology of two Common Species of Fleshy Red Algae in McMurdo Sound

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Climate change is changing the number of sea-ice free days in coastal polar environments, which is impacting Antarctic communities. This study will evaluate the change in macroalgae (seaweed) communities to increased light availability in order to predict if macroalgae will be able to spread to newly ice-free locations faster than invertebrates (e.g., sponges, bryozoans, tunicates, and polychaetes) in shallow underwater rocky habitats. Study sites will include multiple locations in McMurdo Sound, Ross Sea, Antarctica. This study will establish patterns in plant properties, genetic diversity and reproductive characteristics of two species of seaweeds, Phyllophora antarctica and Iridaea cordata in relation to depth and light. Long-term changes will be assesed by comparing to results from a survey in 1980. This will be the first study in the region to estimate the potential effects of climate, in particular reductions in annual sea ice cover and resulting increase in light intensity and duration, on shifts in macroalgal communities in McMurdo Sound. Three-dimensional photogrammetry will also be used to evaluate benthic community structure on the newly discovered offshore Dellbridge Seamount. Visualization from the video footage will be shared with web-based interactive applications to engage and educate the public in polar ecology and factors causing changes in marine community ecosystem structure in this important region.This project is evaluating macroalgae biogeography in Antarctic coastal waters near McMurdo Sound, a relatively understudied region that is experiencing large changes in fast sea ice coverage. The population ecology and genetic diversity of nearshore shallow and deeper offshore benthic macroalgal communities of Phyllophora antarctica and Iridaea cordata will be assessed for percentage cover, biomass, blade length, and reproductive characteristics at seven locations: Cape Royds, Cape Evans, Little Razorback Islands, Turtle Rock, Arrival Heights, Granite Harbor, and Dellbridge Seamount in McMurdo Sound, Antarctica. The team is also assessing differential reproductive successes at different depths and comparing results to populations surveyed in 1980. The genetic diversity of the two species is being estimated using a combination of whole genome sequencing and species-specific microsatellite genetic markers. Samples from this study will be compared to samples collected from other regions in Antarctica such as the South Shetland Islands and Antarctic Peninsula. In addition, a macroalgal assemblage and 3D models of the community structure will be generated using photogrammetry from the newly discovered Dellbridge Seamount that is located 2 km offshore in McMurdo Sound. With the addition of photogrammetry and 3D visualization to this research, web-based applications will be used to engage and educate the public in subtidal polar ecology, population genetics, and the importance of Antarctic science to their lives.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.