Warming oceans to aid spread of invasive species in Antarctica

Kelp rafts seen pathways for non-native worms, snails

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For now, humans are the main invasive species in Antarctica, but that could change as the surrounding ocean warms. @bberwyn photo.

Staff Report

Parts of Antarctica could soon face an invasion by exotic species floating southward on kelp rafts, Australian researchers found in a new study published in the journal Ecography.

While the Antarctic circumpolar current has long formed a barrier to invasive species, the research found that the kelp rafts often cross that Antarctic Polar Front, carrying with them crustaceans, worms, snails and other seaweeds across hundreds of kilometres of open ocean.

“So far, the northern species don’t seem to be surviving long in the cold, icy Antarctic. But with climate change and warming oceans, many non-Antarctic species could soon colonize the region,” said lead researcher Dr. Ceridwen Fraser, from the Australian National University Fenner School of Environment and Society.

The evidence was collected by surveys of floating kelp. On three different ship voyages in 2008, 2013 and 2014, researchers counted drifting seaweed species in both sub-Antarctic and Antarctic water.

“Although we saw more seaweed north of the Polar Front, we still found lots of kelp in Antarctic water, especially just south of the Front,” said co-author Professor Peter Ryan, from the University of Cape Town.

Dr Fraser said the study will help scientists to plan strategies for conserving Antarctica’s unique marine life.

“We’ve been focusing a lot on minimizing plants and animals being accidentally carried into the Antarctic by humans, for example with ship ballast water,” Dr Fraser said. “This research shows that some species can also get into the region without our help.”

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