Sea’s bio-soup studied for clues to invaders

An innovative Western Australian biosecurity warning system based on DNA “soup” has piqued the interest of ports in NSW, Victoria and particularly Queensland, where a trial is planned for later this year.

The bio-soup is made from a slush of organic materials – cells, growths, sediments – that have grown on or adhered to PVC plates the size of beer coasters. Attached to a metal frame, these plates are submerged for two months at a time, twice a year, at various port locations along the 11,000 kilometre length of Western Australia’s coast.

The material from each of the plates is turned into a liquid mix, or soup, which  is analysed for DNA tell-tale markers that would signal the appearance of invasive species in WA waters. Invasive marine pests, such as sea-squirts or Asian green mussels, could hitch a ride on or in ships into Australian ports and then multiply and spread, to the detriment of the local environment and industry.

Australia has a long and sorry history of feral invasive species wreaking havoc with native wildlife, so an early warning system is considered essential to sound the alarm if there are are trespassers in Australian waters.

The detection in an Australian port of an invasive organism, such as the invasive Asian bag mussel – already well-established in waters around Fremantle and in the Swan River – would trigger rapid action to prevent the alien species taking hold in Australia.

“The State Wide Array Surveillance Program (or SWASP), as a collaborative marine biosecurity surveillance network, is unique to this program”, says Dan Pedersen, environment and heritage manager at the Pilbara Ports Authority in WA, referring to the plates and bio-soup program. The SWASP program is now in use in 11 ports in WA, all working with the WA Department of Primary Industries and Regional Development.

The SWASP program, Pedersen adds, is cost-efficient, reliable and robust. And it’s voluntary. “As ports we don’t need to do this, but we do it as part of being environmental stewards in our ports environment”, he points out.

The plates have shown a huge diversity of marine life in Western Australia’s port waters, says marine biologist Dr Justin McDonald, manager of aquatic pest biosecurity at the WA department (of primary industries etc). The positive detection of a range of Australian species, he says, along with exotic species such as the Asian bag mussel, has proved the system’s efficacy.

Scientists are now working on the detection of small strings of DNA in the soup, which signal the “high likelihood” rather than the absolute certainty of a species’ presence in the ports, he says, but a project now underway to reinforce the SWASP program includes cataloguing and sequencing as many marine species’ genomes as possible.

“If we had an encyclopedia of every marine species, and we had all their references, we could identify anything in that water column”, he says. “Plants, molluscs, fish, crabs. You name it”.

Meanwhile, federal authorities say ports continue to be monitored for six invasive marine species that have been detected in Australian ports, but have yet to “reach their full range”, a spokesperson for the federal Department of Agriculture and Water Resources in a statement.

These alien species, according to the statement, include the Northern Pacific seastar, the Asian date mussel, the European green crab, wakame – a type of edible algae, the European fan worm and the Pacific oyster.

Targeted diseases include white spot disease (which hits prawns and other crustaceans). Land-based pests on the ports watch-list include the varroa mite – the scourge of honeybees in Europe, the red fire ant, the khapra beetle and the brown marmorated stink bug.

The department refuses to say how many detections of invasive species have occurred in Australia’s sea ports, and declines to specify the type of pests discovered at each site and how the incursions were dealt with. The spokesperson simply noted preventative measures taken by dedicated biosecurity staff include physical inspections, treatment requirements, traps and monitoring.

Invasive Species Council chief executive officer Andrew Cox says Australia’s invasive pest management at ports was “very patchy”.

“The fact that we’re still getting detections at the border for the things we’re looking for shows that we could be doing a lot better”, he says, adding that prevention was the best way to deal with potentially invasive pests and diseases. “Even before the goods are sent to Australia, we should be trying to make sure there are no pests, diseases or bugs in the ship, inside the containers or outside the containers.”

Scientists, he explains, have identified about 240 insect species that would damage the environment if they took hold in Australia. One is the harlequin ladybird, a fierce predator that has already become established in New Zealand and is now being detected at Australian borders.

“We should really be striving for clean pathways, clean trade, clean cargo, and clean goods”, he says. “We should be getting better at making sure things are properly fumigated when (authorities abroad) say they are. We should be making sure we’re only bringing things into the country which are low risk.”

New pests and diseases are arriving and becoming established in Australia every year, he warns, adding that red fire ants and yellow crazy ants have regularly been found at ports. A disease called virtual rust arrived in 2010 and it has now spread through much of the country and Cox expects it will eventually cause extinctions in native eucalypts and myrtles.

The Asian black spined toad, which looks like a smaller cane toad and breeds just as prolifically, has been found near containers every so often in Australia. Now invading Madagascar, worryingly this toad has a better tolerance for cool climates than the cane toad.

Cox fears worse is yet to come on the invasive species front, partly because trade is inexorably and inevitably increasing. “Australia’s volumes of imports will increase”, he says, “and so, of course, the risks will increase”.