Advice to the Minister for Environment and Heritage from the Threatened Species Scientific Committee on a public nomination of a Key Threatening Process under the Environment Protection and Biodiversity Conservation Act 1999
1. Name and description of the threatening process
The nomination is titled 'Introduction of Marine Pests to the Australian Environment via Shipping'. The nominator also states that the name of the process is 'The introduction of marine pests into the Australian marine environment via the discharge of ballast water and/or hull fouling'.
Information on the impacts of exotic marine species introduced to the Australian Environment via ships' ballast water and hull fouling is included, including the impacts of predation on native species, competition with native species, and habitat change. The term 'hull fouling' and how it introduces exotic organisms is not defined in the nomination.
The following description is based on that provided in the nomination:
Ballast water consists of water that is taken on board a ship for the enhancement of the ship's stability at sea. Ballast water may contain sediment if it is taken on whilst the ship is in shallow or turbid water. These sediments and the water can contain a wide range of live marine and estuarine flora and fauna. These are then transported away from their original source and discharged into the destination port as the ship is loaded with cargo. The larvae and spores of some marine animals and plants can survive this journey. Australia is particularly vulnerable as many cargo ships arrive here without cargo and therefore with a large quantity of ballast water.
If the organisms survive the transport and discharge process they may become established in the new community and populations may flourish. There are now more than 250 exotic species known to be present in the Australian marine environment. The introduced organisms can affect local marine life in a number of ways, by competing with native species for food or space, preying on native species, crossbreeding with native species or by changing the habitat.
The term 'pest' is not defined in the nomination. Generally if the effects of introduced organisms are sufficiently severe they are referred to as 'pests'. About one in six introduced marine species become pests.
The process relating to hull fouling is not defined by the nomination, however when specifically asked, many experts consider that introduction of pests via hull fouling and by ballast water should be considered a single threatening process. One expert considers that further discussions are necessary to determine this.
2. How judged by TSSC in relation to the Environment Protection and Biodiversity Conservation Act 1999 criteria
In general, and as the nomination notes, there have been few studies on the impacts of introduced marine species on native communities, and the full impact of pest species on these communities has yet to be established.
A. Could the threatening process cause a native species or an ecological community to become eligible for listing in any category, other than conservation dependant?
The nomination states that the Dampier Archipelago, the Barrow Islands, the Montebello Islands, Ningaloo Marine Park and Shark Bay regions are risk areas for the introduction of exotic marine organisms, but indicates that there are no reported cases of native species decline or community disturbance or species decline.
The shallow water fauna in Port Davey and Bathurst Harbour are also stated by the nomination to be potentially under threat from organisms that could arrive in ballast water, and literature is cited in relation to the introduced European Shore Crab Carcinus maenas which is already present in Tasmania. One expert opinion confirms that the European Shore Crab and the Northern Pacific Seastar (Asterias Amurensis) pose a significant threat to the south west Tasmanian shallow-water fauna. However, no evidence is available of the process changing the conservation status of this fauna.
The nomination states that two species of goby may have impacts on native species of gobies but no definite impacts are described.
The nomination states that there are impacts from the Northern Pacific Seastar and the New Zealand Seastar on native seastars, but this has not been substantiated. It is possible that the Northern Pacific Seastar is having more significant effects now than when the nomination was prepared. The nomination states that Northern Pacific Seastar had by April 1999 spread to Port Phillip Bay and other Victorian bays and inlets. It has now expanded its presence in those areas, and it is estimated that 90 million of these animals now populate Port Phillip Bay. However, there is no evidence of impacts that would cause a species to become listed.
Conclusion: Based on the information provided and summarised above TSSC considers the evidence insufficient at this point to indicate that the threatening process could cause a native species or an ecological community to become eligible for listing in any category, other than conservation dependant. The threatening process is therefore not eligible under this criterion.
B. Could the threatening process cause a native species or an ecological community to become eligible to be listed in another category representing a higher degree of endangerment?
The nomination names one listed species, the Spotted Handfish, Brachionichthys hirsutus (Endangered) as adversely affected by the exotic Northern Pacific Seastar (believed to have been introduced to Australia via ballast water during the 1980s). One expert considers that predation by the seastar on ascidians and other benthic biota that serve as spawning sites for the Spotted Handfish is a plausible mechanism for their decline. However that expert and the Recovery Plan for the Spotted Handfish state that the role of Northern Pacific Seastar in the decline has not yet been established. TSSC considers that there is no evidence that the process could cause listing in a more endangered category at this stage.
Conclusion: Based on the information provided and summarised above TSSC considers that the process is unlikely to cause a native species or an ecological community to become eligible for listing in a higher category of endangerment. The threatening process is therefore not eligible under this criterion.
C. Does the threatening process adversely affect 2 or more listed threatened species (other than conservation dependent species) or 2 or more listed threatened ecological communities?
As described above, the Spotted Handfish may be adversely affected by the Northern Pacific Seastar, however there is insufficient evidence of current adverse effect.
Conclusion: Based on the information provided and summarised above TSSC considers that although the process may be adversely affecting the listed Spotted Handfish, there is as yet no evidence of an effect, nor evidence of the process currently adversely affecting any other listed species or ecological community. The threatening process is therefore not eligible under this criterion.
The TSSC believes that the threatening process as named and described in the nomination:
- is not likely to cause a native species or an ecological community to become eligible for listing in any category, other than conservation dependant;
- is not likely to cause a listed threatened species or a listed threatened ecological community to become eligible to be listed in another category representing a higher degree of endangerment; and
- does not adversely affect 2 or more listed threatened species (other than conservation dependant) or 2 or more listed threatened ecological communities.
The threatening process does not meet s188(4)(a), s188(4)(b), or s188(4)(c ) of the EPBC Act.
- TSSC recommends that "The introduction of marine pests to the Australian environment via shipping", as named and described in the nomination, is not eligible for inclusion as a Key Threatening Process in the list referred to in section 183 of the EPBC Act;
- TSSC note that "Introduced Novel Biota" is a major threat to Australian biota, and they will correspond with BDAC and AQIS on this issue; and
- TSSC recommend further research be conducted on the Northern Pacific Seastar to determine it's distribution and impact on Australian biota.