Introduced marine species a major threat

Introduced marine species were one of the major threats to the world’s oceans, Australia’s ASP Ship Management Group Training Manager Ben Brooksby told last month’s Biosecurity Summit in Christchurch.

He said Australia was particularly vulnerable. For example, Port Phillip Bay in Victoria was now home to more than 160 non-indigenous species, including:

Northern Pacific seastar (Asterias amurensis) – a native to the coasts of China, Korea, Russia and Japan, introduced to Tasmania and then Port Phillip Bay, possibly in its larval stage in ballast water, though adults have also been found in seachests. Within five years of its first discovery in Port Phillip Bay in 1995, the population had grown to nearly 100 million. Northern Pacific seastar is a voracious predator, preying on native shellfish, and with potential to impact on shellfish farming.

Mediterranean fanworm (Sabella spallanzanii) – a native of the Mediterranean and East Atlantic Coasts from North West France to Morocco, the species was possibly introduced in its planktonic form in ballast water or as vessel fouling. It is found in densities of approximately 1,000 per square metre on jetty piles and 300 per square metre on the bay floor of Port Phillip. It is also found in parts of Western Australia, South Australia, Tasmania, New South Wales and Victoria. Mediterranean fanworm is regarded as a pest because of its ability to densely colonise hard surfaces and form dense beds, impacting on commercial shellfish operations and likely to out-compete native species.

Japanese kelp (Undaria pinnatifida) – native to the Japan Sea and northwest Pacific coasts of Japan and Korea. It is known as “Wakame” and extensively cultivated for food in Japan. It is likely to have been introduced via vessel fouling but possibly ballast water as well. It was first reported in Tasmania in 1988, and was found in Port Phillip in 1996. Japanese Kelp is highly invasive, grows rapidly and can exclude native species. This is particularly problematic if the native algal eaters will not feed on the species in areas where it has become dominant, as their normal food source will no longer be readily available.

Page last updated: 8 January 2009