Globe-trotting kelp set new world record

by Mary Caperton Morton
Friday, October 12, 2018

Kelp grows in underwater forests in shallow regions of temperate, tropical and polar oceans. Air bladders in the leaves enable the seaweed to travel vast distances on currents across oceans. Credit: public domain.

When marine biologist Erasmo Macaya, from University of ConcepciĆ³n in Chile, found a piece of kelp washed up on a beach in Antarctica, he suspected the scrap of seaweed had come a long way.

“Kelp does not grow in Antarctica, but we know it can float and can act as a raft, carrying many other intertidal plants and animals with it across oceans,” he said in a statement released with a new study in Nature Climate Change. DNA testing revealed the kelp had traveled more than 20,000 kilometers, in the longest-known marine rafting event ever recorded.

Previously, scientists had thought that Antarctica’s flora and fauna were effectively isolated from the rest of the world due to its remote location, but the new study suggests that influxes of new biota are limited more by the icy continent’s environmental extremes than by geographic isolation.

“This is an unequivocal demonstration that marine species from the north can reach Antarctica,” said lead author Ceridwen Fraser of the Australian National University in Canberra. Modeling by Fraser and colleagues demonstrated how the kelp could have reached Antarctica from the Kerguelen Islands in the southern Indian Ocean. Another scrap of kelp was traced to South Georgia Island in the South Atlantic.

“Our findings also indicate that plants and animals living on Antarctica could be more vulnerable to climate change than we had suspected,” Fraser said, as living conditions become milder, allowing more invasive species to gain a foothold on the extreme landscape.

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