A research team led by the Australian National University (ANU) has discovered the first definitive proof that Antarctica is not isolated from the rest of the Earth, after uncovering a raft of foreign kelp that drifted some 20,000 km before reaching the continent.
Lead researcher Dr Crid Fraser from ANU’s Fenner School of Environment and Society said DNA analysis revealed one kelp specimen drifted all the way from the Kerguelen Islands in the southern Indian Ocean, while another originated in South Georgia.
Scientists previously believed that Antarctic plants and animals were wholly distinct from others around the world because of their isolation. However, the new findings suggest that these differences result from environmental extremes rather than distance.
"This is an unequivocal demonstration that marine species from the north can reach Antarctica," Fraser says. "To get there, the kelp had to pass through barriers created by polar winds and currents that were, until now, thought to be impenetrable."
Using advanced modelling techniques, the team was able to see how large waves that arise during storms could push kelp rafts toward Antarctica. Powerful westerly winds and surface currents are expected to drive floating material northward, but this changes once the disruptive influence of Antarctic storms is factored in.
"Once we incorporated wave-driven surface motion, which is especially pronounced during storms, suddenly some of these biological rafts were able to fetch up on the Antarctic coastline," explains co-researcher Dr Adele Morrison from ANU. “If plants and animals get to Antarctica fairly frequently by floating across the ocean, they will be able to establish themselves as soon as the local environment becomes hospitable enough."
The kelp’s journey is the longest-known biological rafting event ever recorded. Its discovery has helped scientists to revaluate the science of ocean drift that is used to track plastic, aeroplane crash debris and other floating objects across global oceans.