Sex life of toxic sea slugs to be studied

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The sex life of toxic sea slugs which have killed several dogs on Auckland beaches is about to go under the microscope in a $250,000, three-year study.

Massey University said the research would investigate if their sex life held the key to why the creatures were washing up in increasing numbers on Auckland beaches around the Hauraki Gulf.

Last year the Auckland Regional Council (ARC) put up signs warning people to closely supervise children and pets after a number of dogs ate the slugs and died.

Project head evolutionary geneticist Professor Paul Rainey said there was a concern that the toxin the slugs produced, tetrodotoxin, could be dangerous to humans as well as potential harming seafood sources and aquaculture industries.

The study would look at how far the slugs moved and mutations.

"We want to find out who the slugs are having sex with. Is it with their neighbours, or out-of-towners?"

Prof Rainey is based at the New Zealand Institute for Advanced Study at Massey's Albany campus in Auckland.

He will be working with the ARC, and the Cawthron Institute in Nelson to establish genetic similarities and compare concentrations of the lethal toxin in different sea slug populations in the Hauraki Gulf and elsewhere in New Zealand coastal waters.

Before the dogs died sea slugs were not known to be toxic.

"We want to find out if sea slug populations are increasing and what is causing them to increase."

DNA samples would be taken to provide clues to the bio-geography of sea slug populations and show any variations in the levels of toxin they produced.

Prof Rainey said recent research suggested the apparent rise in sea slug numbers may be linked to the proliferation of Asian date mussels in Auckland coastal waters.

Divers collecting sea slug samples had noted anecdotally that slugs fed on the mussels, an invasive marine species introduced to New Zealand in the 1970s which have spread throughout the Waitemata Harbour.

Earlier this month beachgoers were warned to supervise their children and pets after toxic sea slugs were reported across Auckland's eastern bays beaches from Okahu Bay to Kohimarama.

Sea slugs were found earlier this winter near Long Bay, Browns Bay, Narrow Neck Beach, Cheltenham, Bayswater on the North Shore and Illiomama Rock near Rangitoto Island.

Last month, they were also found at Kohimarama Beach, about 8km east of downtown Auckland.

- NZPA