In late March 1999, divers surveying the Port of Darwin for potential marine pests discovered dense colonies of an unidentified shellfish on piers and other surfaces in Cullen Bay Marina.
Within two days, specimens collected from the marina were identified by Richard Willan, a mollusc taxonomist at the Museum and Art Gallery of the Northern Territory, as the invasive black-striped false mussel (Mytilopsis sallei).
Native to tropical South and Central America, Mytilopsis sallei is a world-wide pest in harbours and other inshore marine environments, where it fouls pylons, jetties, boat hulls, mooring ropes and mangroves. It poses a serious threat to aquaculture, including pearl farms and commercial and recreational fisheries throughout tropical and warm-temperate parts of the world.
Economic losses from two closely related invasive species in the Great Lakes of North America currently exceed US$500 million per year.
Although the black-striped false mussels had almost certainly been in Darwin Harbour for less than six months, it was found to be spreading rapidly on the hulls of ships and small boats. Within a week of its detection, the Northern Territory Government declared a State of Natural Disaster, closed and quarantined all Port of Darwin marinas, and instigated an eradication campaign. The first option - chlorine treatment - failed because wet-season rains diluted the chlorine, but a second option - dropping 30 tonnes of copper sulphate into the marinas - worked. Within a few weeks, the last-known living individual of Mytilopsis sallei in the Port of Darwin, and hence in Australia, was dead. The marinas were re-opened, and the species has not been seen in Australian waters since.
This is one of very few examples of successful eradication of a marine pest anywhere in the world. A potential marine economic and environmental disaster was averted. If the species had not been identified there and then and eradicated immediately afterwards, it would have spread uncontrollably along inshore northern Australian waters, causing massive economic losses and incalculable environmental damage. One estimate suggests that costs from a failure to eradicate the black-striped false mussel would have been at least 200 million dollars.
Rapid identification was instrumental in the successful response to the black-striped false mussel in the Port of Darwin. If there had not been an expert taxonomist in Darwin, if it had been necessary to send the specimens elsewhere, if it had taken a few days or weeks longer to identify them, the story may have had a very different ending.
How many people do you know who have saved the country $200 million?
