A beautiful pest: Invasive marine worm spotted in Sydney

Marine scientists at the Australian Museum have sounded the alarm over an invasive underwater worm discovered in Sydney's Botany Bay—the farthest north the pest has ever been spotted in NSW.

The European Fanworm (Sabella spallanzanii), a sea-dwelling relative of the earthworm, is native to the Mediterranean Sea and the European Atlantic but has already invaded much of southern coastal Australia. It was first spotted in Australia in 1965.

The worm, which can approach 50cm long, lives in a tube that attaches to rocks and boats and uses its elaborate, fan-shaped head to filter water for food. It reproduces rapidly, and can quickly crowd out native species.

"It does affect the overall food chain, and if you took it to the extreme it could impact on native commercial species or recreational species of fish," said Stephen Keable, Collection Manager, Marine Invertebrates at Australian Museum.

Dr Keable, who was among the scientists who found European Fanworms during a routine dive to collect specimens in Botany Bay in March, said trying to stop the pest by picking them off was an uphill battle.

"One individual can have up to 50,000 eggs. You can imagine that, like the Crown of Thorns star fish, they can reproduce incredibly rapidly. It's a needle in a haystack to try and find them. It only takes a few mature worms to survive and establish the population all over again," he said.

The Australian Museum alerted the NSW Department of Primary Industries to their disconcerting find, and experts from both agencies are working on a plan to determine the extent of the pest's spread.

Dense carpets of worms

Pat Hutchings, Senior Principal Research Scientist at Australian Museum and an expert on marine worms, said the European Fanworms in other parts of Australia have formed a dense carpet across stretches of sea bed, completely changing the marine ecology and leaving no food for other species.

"They have really large feeding crowns and they basically just filter the entire water column. Nothing gets past them. Underneath them, it's like a desert," she said.

"The worms we found in Botany Bay weren't big, so we are quite certain we have not found the main population of those worms in Sydney."

European Fanworms are likely to have hitched a ride to Australia on the hulls of ships that have sailed from Europe, she said.

"What this highlights on Botany Bay is that we need to be more diligent about the cleaning of boats, including all the nooks and crannies and chains," said Dr Hutchings.

"It's not very easy getting rid of marine pests. Think of the amount of money spent on trying to eradicate cane toads or rabbits. Well, at least you can see them on land. It's not so easy underwater."

The scientists will discuss their findings and other invasive species at the 11th International Polychaete Conference, to be held in Sydney from August 4 and at an invasive pest workshop being held at the Australian Museum on August 1 and 2.

This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).