Abstract
Global models predict that Antarctica has little suitable habitat for
macroalgae and that Antarctic macroalgae therefore make a negligible
contribution to global carbon fixation. However, coastal surveys are rare
at southern polar latitudes (beyond 71° S), and here we report diverse and
abundant macroalgal assemblages in un-navigated coastal habitats of the
Ross Sea from 71.5˚ – 74.5˚ S. We found extensive macroalgal assemblages
living at depths >70 m and specimens of crustose coralline algae as
deep as 125 m. Using global light modelling and published photosynthetic
rates we estimate that Antarctic macroalgae may contribute between 0.9 –
2.8 % of global macroalgal carbon fixation. Combined, this suggests that
Antarctic macroalgae may be a greater contributor to global carbon
fixation and possibly sequestration than previously thought. The
vulnerability of these coastal environments to climate change, especially
shifting sea ice extent and persistence, could influence Southern Ocean
carbon fixation and rates of long-term sequestration.