Marine pest invasions

What are marine pest species?

Introduced marine species (‘exotic’, ‘invasive’ or ‘alien’ species) are species moved to locations outside their natural range by human-mediated dispersal1. Such species are considered ‘marine pests’ if they threaten human health or environmental and economic values1. Introduced pests and diseases may pose the most important long-term threat to coastal ecosystems2. Therefore, pest incursions into coastal waterways were used as an indicator of ecosystem integrity during the National Land and Water Resources Audit.

The number (and identity) of documented marine pests in coastal waterways is also an indicator for State of the Environment (SOE) reporting (e.g. Indicator 3.11 in the Estuaries and the Sea volume)3.

How are marine pest species introduced to Australian coastal waters?

Biological invasions can be either accidental or intentional introductions, and can arise from a wide variety of private and commercial practices4.

  • Ballast water is water (and associated sediment) used to control the trim and draft of a vessel1, and is a significant source of marine pests in Australia56. It has been estimated that at any given moment, some 10,000 different species are being transported across biogeographic regions in ballast tanks1. These organisms may be released at a distant port when cargo is unloaded. Some organisms can also be transported via the water in other internal seawater systems, such as engine cooling systems, toilet/bathroom systems (if they use saltwater) and on-board aquarium systems.
  • Transport of encrusting organisms via fouling of vessels (e.g. hulls, propellers, intake grates and cavities) and other gear (e.g. nets, cages, lines, floats and anchors) was the most important vector in the past7. Fouling as a vector has increased in importance in recent years due to an increase in international small boat traffic, and because the use of the anti-fouling biocide tributyltin is being out-phased due to its detrimental effects on aquatic organisms (e.g. imposex8 ). Fouling organisms can also be transported via attachment to floating debris. Risks imposed to coastal waterways from shipping activities can be assessed using the shipping, boating & yachting pressure indicator.
  • Other transport vectors include accidental or intentional releases from the aquarium industry, aquaculture activities (e.g. intentional releases, stock, gear or food movement, discarded packing materials) and movement of species through canals14.
  • Little work has been done to assess the extent to which sea chests (water intakes) and propeller shaft housings provide havens for exotic species although the results of a recent study suggest a wide variety of species are capable of surviving in sea chests9.

Waterways susceptible to introduced marine pests

Introduced species have been found throughout the salinity gradient, from fresh water through to marine conditions. An important factor in the establishment of exotic species is the number of visits by international ships (i.e. import opportunities). Australia has 78 ports, and receives more than 6000 ship visits per year in which ballast water is released6. Shoreline habitats such as salt marshes, mangroves and beach and dune10 areas can also be invaded by exotic species2.

Environmental significance

Introduced pests differ from most other marine issues in three important ways:

  • pests may spread widely to the limits of their physiological tolerances2 – this is apparently because introduced species escape from their natural enemies and are less parasitised11.
  • prospects for the complete eradication of pests are poor2; and
  • the ecological impacts of invasive species can only be partially predicted2.

Some known impacts of invasive species include:

  • Direct predation of native species e.g. Northern Pacific Seastar (Asterias amurensis) and Green Crab (Carcinus maenuas)1.
  • Competition for space and food, in some cases resulting in competitive exclusion of native species and changes in habitat structure e.g. Seastar (Patiriella regularis). Local modifications to seagrass areas have also been reported2.
  • Nuisance fouling species e.g. barnacles1.
  • Harmful blooms and the bioaccumulation of toxins in shellfish, fish, molluscs and other species e.g. toxic dinoflagellates Gymnodium and Alexandrium sp.1.
  • Disruptions to aspects of nutrient cycling. These may include alterations to benthic denitrification (e.g. by fanworms) and changes in the patterns of organic matter settling2.

Considerations for the detection and reporting of marine pests

Early detection of marine pests is imperative for effective management. However, determining whether a species is a pest can be difficult. Criteria for determining as to whether an anomalous or unidentified species is native or exotic have been developed, and are listed in Table 3.5 (p. 99) in the Development of a Regional Risk Management Framework for APEC Economies for Use in the Control and Prevention of Introduced Marine Pests1. The National Introduced Marine Pest Information System (NIMPIS12 ) contains detailed descriptions, photos and illustrations for over 80 exotic species found in Australian waters. Limited information is also provided for another 35 species not currently found in Australia, but thought to pose a significant threat. Marine pest identification guides/pamphlets can also help with local pest identifications, and are available from relevant state government agencies. If an invasive species is identified, it is recommended that it be reported as soon as possible to the relevant state agency. Accompanying information should include the extent of the infestation (e.g. numbers of pests per m2), and the location and attributes of the site (e.g. habitat type, subtidal vs. intertidal and sediment type). Pest sightings can be reported to state authorities and to the Centre for Research on Introduced Marine Pests (CRIMP) via the web using the ‘Report a Pest’ procedure in NIMPIS12. Phone numbers for the relevant state authorities are also provided in the ‘Report a Pest’ module in NIMPIS. Marine pests are hard to detect in turbid ecosystems13. Tide-dominated coastal waterways which occur frequently in tropical regions (e.g. deltas, estuaries and tidal creeks) are naturally turbid because strong tidal currents cause fine sediment to resuspend14.

Existing information and data

Various data pertaining to invasive species can be obtained from state agencies, Commonwealth institutions and universities. More information on marine pests as an SOE indicator (e.g. reporting scales, outputs, analysis and interpretation and data sources) can be found in the Estuaries and the Sea volume of Environmental Indicators for National State of the Environment Reporting3. The Introduced Marine Pests Program at the Department of Environment, Water, Heritage and the Arts is the key platform in the Federal Government’s response to invasive species. The National Taskforce on the Prevention and Management of Marine Pest Incursions at the Department of Environment, Water, Heritage and the Arts submitted a report15 with recommendations for actions to establish three important components of the national system.

These components include:
(i) the prevention of new marine pest incursions and translocations;
(ii) the coordination of emergency response actions to new marine pest incursions & outbreaks; and
(iii) the undertaking of longer term mitigation and control measures to combat established marine pests.

The Ballast Water Decision Support System is a tool that enables vessel masters the opportunity to provide ballast uptake and discharge information before entering Australian waters.

CSIRO’s Centre for Research on Introduced Marine Pests (CRIMP) is the national research centre for impacts and management of introduced species. The CRIMP website contains information about marine pests, technical reports, information on community projects, publications, and links to other web-based information sources. CRIMP also developed NIMPIS 12 which provides managers, students, researchers and the general public with access to accurate and up to date information on the ecology, biology, and distribution of known and potential introduced marine species, and control options for those considered pests. Tidal ranges, depths and maximum and minimum values for salinity, temperature and pH where different introduced species occur are also included in NIMPIS. A comprehensive literature review on Australian ports16 documents the availability of water temperature, bathymetry & layout, surficial sediment, dredging activity, stratigraphy, habitat, water quality, current and wave, and introduced pest data for 66 Australian ports, and can be used in conjunction with NIMPIS to help in risk assessment.

NLWRA 2008: Estuarine, coastal and marine habitat condition, indicator guideline

Pest species

More information on pest (plant, animal) species.


Regina Counihan, Cooperative Research Center for Coastal Zone, Estuary and Waterway Management
David Ryan, Geoscience Australia

  1. Williamson, A.T., Bax, N.J., Gonzalez, E. & Geeves, W. (2002) Development of a Regional Risk Management Framework for APEC Economies for Use in the Control and Prevention of Introduced Marine Pests. APEC MRC-WG Final Report, 208 pp.                  
  2. Cappo, M., Alongi, D.M., Williams, D, and N. Duke. 1995. A review and synthesis of Australian Fisheries Habitat Research: Major threats, issues and gaps in knowledge of coastal and marine fisheries habitats. Fisheries Research and Development Corporation.              
  3. Ward, T., Butler, E. and Hill, B. 1998. Environmental Indicators for National State of the Environment Reporting, Estuaries and the Sea, Commonwealth of Australia, pp. 81.    
  4. Carlton, J.T. 2001. Introduced species in U.S. Coastal Waters: Environmental Impacts and Management Priorities. Pew Oceans Commission, Arlington, Virginia.    
  5. Coastal and Marine Pollution at the Department of Environment, Water, Heritage and the Arts.  
  6. Australian Ballast Water Management Requirements    
  7. National biofouling management guidelines for commercial vessels.  
  8. Birchenough, A.C., Barnes, N., Evans, S.M., Hinz, H., Kronke, I., and Moss, C. 2002. A review and assessment of tributyltin contamination in the North sea, based on survey of butyltin tissue burdens and imposex/intersex in four species of neogastropods. Marine Pollution Bulletin 44, 534-543.  
  9. Coutts, A. amd Dodgshun, T. 2007. Ships sea chests: an overlooked mechanism for species transfers. Australian Marine Sciences Association Marine Science in a Changing World conference, Melbourne, Australia, 9-13 July.  
  10. Hilton, M. 2002. Management implications of exotic dune grasses on the Sir Richard Peninsula, South Australia. Proceedings of Coast to Coast 2002 – “Source to Sea”, Tweed Heads, pp. 186-189.  
  11. Torchin, M.E., Lafferty, K.D., Dobson, A.P., McKenzie, V.J. and Kuris, A.M. 2003. Introduced species and their missing parasites. Nature 421, 628-630.  
  12. Hewitt C.L., Martin R.B., Sliwa C., McEnnulty, F.R., Murphy, N.E., Jones T. & Cooper, S. 2002. Editors. National Introduced Marine Pest Information System, Date of access.      
  13. Neil, K.M. 2002. The detection, response and challenges of a pest detection. Proceedings of the annual conference of the Australian Marine Sciences Association, 10-12 July 2002, Fremantle WA.  
  14. Heap, A., Bryce, S., Ryan, D., Radke, L., Smith, C., Smith, R., Harris, P. and D. Heggie. 2001. AGSO Record 2001/07, pp. 118, [PDF 17 Mb].  
  15. Joint SCC/SCFA National Taskforce on the Prevention and Management of Marine Pest Incursions Report of the Taskforce.  
  16. Harris, P. and P. O’Brien. 1998. Australian Ports Environmental Data & Risk Analysis Phase 1: Literature Review, A Report Prepared for Australian Quarantine Inspection Service (AQIS), pp.201, [PDF 1.2 Mb].