Science topics

Introduced marine pests - Caroline Sutton

The Scientist

I work as a marine biologist with CSIRO’s Centre for Research on Introduced Marine Pests (CRIMP). I studied zoology at University of New South Wales and completed my honours in 1992. I started work with CSIRO in 1993 to work on larval fish and began working on introduced pests shortly after the northern Pacific seastar, Asterias amurensis was identified to be a major pest in the Derwent Estuary, Hobart. Since then I have worked on a variety of introduced marine pest projects including; the larval biology and ecology of Asterias, evaluating the best methods to sample ballast water, assessing and modeling the survival of zooplankton in ballast water and most recently a project to develop a community monitoring program for detecting marine pests.

Caroline's collaboration is with artist Anne Morrison.

The Research

In the ocean, like on land introduced species can become a problem in their new environment because they no longer have the natural predators and diseases that normally keep their populations in balance. There are hundreds of introduced species in Australia, but not all of them are considered pests. An introduced marine species is considered a pest when it poses a serious ecological or economic risk to the marine environment or marine resources, for example, if it contributes to habitat destruction for critically endangered species like the spotted handfish or threatens wild fisheries or aquaculture industries. Australia has identified 12 marine pests *(Northern Pacific seastar, European green crab, Giant fanworm, Asian mussel, European clam, Black-striped mussel, Toxic dinoflagellates, Japanese seaweed, Aquarium Caulerpa, Broccoli weed, Hydroides sanctaecrucis and the Asian green mussel) species that are of serious concern. *More information available on these species as PDF information sheets.

Species can be introduced in a number of ways including; the ballast water of ships, attached to the hulls of boats (hull-fouling), inadvertently through the live aquarium trade and aquaculture, adults being used as live bait, attached to marine debris or on fouled ropes, traps or any submersed equipment that has been moved form place to place. The research at CRIMP has focused on developing strategies to manage the marine pests problem, the approach is three pronged — prevention, incursion response and long-term management.

Prevention is better than the cure…

Much of the research has focused on how to keep marine pests from being introduced in the first place. For example, ballast water research undertaken at CRIMP has allowed us to identify which ships are likely to contain pest species. This is called Risk Assessment. By identifying high-risk ships, managers have the opportunity to ensure that measures are taken to treat the ballast water before it is released in Australian waters. More information available on ballast water as PDF information sheets.

Incursion response…

Once an introduced species has been identified, action must be taken fast to remove it and contain its spread. CRIMP has developed a rapid response framework to help managers respond to incursions quickly. The community can help by reporting suspected marine pests or by getting involved in community monitoring programs. CRIMP was involved in the first successful eradication of a marine pest; the black striped mussel was permanently removed from marinas in Darwin by physically chlorinating three marinas. Although it seemed to be a very destructive exercise, the potential damage the mussel could have caused to the pearl and wild fisheries in the Northern Territory warranted dramatic action.

Long-term management…

Once a marine pest has become established there are no quick fixes to the problem. They are best managed using an integrated approach that combines a number of methods of containment. Research on biological controls (parasites and genetics) for long-term management of pests is being explored as well as modeling to understand the dynamics of invading populations to develop the best way to implement these techniques once they have been developed. CRIMP and the University of Tasmania assessed the effect of physical removal on the Hobart population of the northern Pacific seastar, Asterias amurensis, as currently physical removal is the only management option we have for the seastar.

Community Detection Kits

The most recent project I have been involved in is the development a community detection kit for marine pests. The project involved assessing beach walks, trapping, fouling plates and spat-collectors for use as monitoring devices for marine pests. Community involvement is important because in many cases scientists have been alerted to marine pests incursions by members of the public, the community detection kit provides a formal means for the community to take a real role in the monitoring and therefore management of the marine pest problem.

Beach walks are easy and all they require is that the general community is aware of marine pest issues and notice an unfamiliar species that could be an introduced species. To help the public identify marine pests CRIMP has information sheets on the CRIMP website and has recently developed an online database for marine pests called NIMPIS (National Introduced Marine Pest Information System).

Trapping is best suited to introduced crabs like the European green crab, Carcinus maenus. Although the traps do catch seastars, the seastars don’t tend to enter the traps if they have a plentiful food source, which is generally the case in an area they have recently invaded.

Spat-collectors are excellent for monitoring for the northern Pacific seastar, Asterias amurensis. Asterias has what we call planktonic larvae that float around in the ocean currents. If the larvae settle in the spat collectors then it indicates that they could also potentially settle in the surrounding environment. Larval densities up the east coast of Tasmania have reached such high numbers that they are causing serious damage to the scallop industry as the same bags that are used to collect scallops also collect the seastar larvae and the juvenile seastars eat the juvenile scallops!

Settlement plates are excellent means of monitoring as they sample fouling community and therefore they give an indication of the suite of species that are likely to be on the nearby boats, jetties and moorings. We have found that a deployment of three months allows an adequate length of time to sample the resident fouling community and allow enough time to let them grow to a size large enough for species identification.

Additional links for more information:

• CSIRO Centre for Research on Introduced Marine Pests (CRIMP)
• Northern Pacific Seastar (information sheet)
• Introduced Marine Pests (information sheet)
• Black striped mussel in Darwin's Cullen Bay (feature article)
• Information on recent and fossil bryozoa