Advice to the Minister for Sustainability, Environment, Water, Population
from the Threatened Species Scientific Committee (the Committee) on Amendments to the List of Key Threatening Processes under the
Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)
Name and description of the threatening process
1.1 Title of the process
Novel biota and their impact on biodiversity
The term ‘novel biota’ refers to organisms that are new to an ecosystem whether by natural or human introduction, the latter being the primary focus of this KTP. There are a large number of terms in common use that fall within the term but the use of ‘novel biota’ is intended as an all-encompassing term.
1.2 Name Changes
The original title of the nomination was ‘The introduction of novel biota and its impact on biodiversity’. The Committee changed the name of the nomination to ‘Novel biota and their impact on biodiversity’ to reflect that the threatening process is not restricted to only the introduction of novel biota.
1.3 Description of the process
Since the arrival of the first non-Indigenous people to Australia, introduced novel biota have posed an ongoing threat to Australia’s unique environment and biodiversity. Invasive species are considered by biologists to have the second most destructive impact on native species and ecological communities after habitat destruction (Sanderlund et al., 1999, p 2; Coutts-Smith and Downey, 2006). Recognising the environmental impact of introduced species, the Convention on Biological Diversity, of which Australia is a signatory, aims in Article 8 (h) to ‘Prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species’ (Convention on Biological Diversity, 1993).
This key threatening process (KTP) ‘Novel biota and their impact on biodiversity’, includes six major groups of novel biota that are impacting on biodiversity, as detailed below.
Novel biota and their impact on biodiversity, including:
Competition, predation or herbivory and habitat degradation by vertebrate pests.
Competition, predation or herbivory and habitat degradation by invertebrate pests.
Competition, habitat loss and degradation caused by terrestrial weeds.
Competition, habitat loss and degradation caused by aquatic weeds and algae.
Competition, predation or herbivory and habitat degradation by marine pests.
Mortality, habitat loss and degradation caused by pathogens.
This KTP does not include species in domestic, agricultural and commercial forestry situations where these species remain appropriately managed. These species would only be included in this KTP if they escape or are released from managed situations and become invasive, threatening biodiversity.
This KTP does include further introductions of new genetic material of invasive species that are already present in Australia, such as buffel grass (Cenchrus ciliaris). Buffel grass is an important agricultural pasture species in northern Australia, however the species has escaped into the environment and is considered a major environmental weed in areas where it has established and displaces native species. Similarly, further introduction of leucaena (Leucaena leucocephala) a small shrub introduced for fodder and widely planted in tropical and sub tropical Australia, is covered by this KTP. Unless appropriately managed and heavily grazed it escapes into the surrounding environment and becomes an invasive weed, forming dense thickets that restrict and out-compete native species.
The KTP also includes the introduction or further cultivation of potentially weedy species for the biofuel industry. Many species promoted as quality source biofuel plants have specific qualities such as hardiness, ability to outcompete other species, need for limited water and resistance to pests and disease, qualities that also make them excellent weed species (Low and Booth, 2007). Many of the best biofuel plants such as giant reed (Arundo donax) and spartina (Spartina sp.) are listed by the World Conservation Union in the top 100 of the World’s Worst Invaders (Lowe et al., 2000; Low and Booth, 2007). If these weedy species are widely planted in Australia it is expected that they will thrive as invasive weed species.
Novel biota have an impact directly or indirectly on all of society. Economic losses and control costs to agriculture, fisheries and forestry enterprises are well documented (Pimentel, 2002; McLeod, 2004). In 2009, it was estimated that the loss from invasive vertebrate species alone was around $750 million (Gong et al., 2009) and Sinden et al., (2004) estimated the economic impact from weeds to be around $4 billion. Novel biota impact significantly on recreational values in the community, for example fire ants in Queensland potentially severely disrupt gardening and outdoor activities, and weeds prevent access to recreational areas. They also have social impacts such as effects on health and Indigenous people’s way of life. While these very important impacts are acknowledged, the purpose of the KTP is to assess the impact of invasive species on the environment and biodiversity.
This overarching KTP includes novel biota which are currently not present in Australia but that may be introduced in the future, and species already in Australia that currently are not invasive but have the potential to become so. Any current or future novel biota that fit into the six broad categories outlined in the description above are considered to be included. A flowchart representing how species are included in the KTP is at Figure 1 below.
The purpose of this KTP is to recognise the threat that all novel biota pose to the Australian environment and to highlight the vast array of different novel biota and the threats they pose. Novel biota, from introduced vertebrate species and deadly pathogens to smothering weeds both on land and in the sea, all have varying impacts on native ecosystems, but ultimately they all threaten the continued survival of the native species and ecological communities upon which they impact.
Figure 1: Flow diagram
Species entering via natural pathways
Species not currently present in Australia
New threat abatement measures
Specific single invasive taxa KTPs e.g. rabbits, foxes
Existing threat abatement measures
Novel biota and their impact on biodiversity KTP
Potentially invasive ‘sleeper’ species in Australia
Invasive species that are established in Australia that do not have a specific KTP
1.4 The use of the term novel biota
Not all introduced species that fit into the six categories (A—F) included in this KTP pose a threat to the environment; many introduced species have become naturalised (survives naturally through reproduction) in Australia and it is only a small subset of these that become invasive (Williamson, 1996, p 2; Phillips et al., 2010 and references therein). Such species are recognised as novel to the habitat however this KTP includes introduced species that are not only novel but also significantly impacting on biodiversity. These species are referred to as invasive (species whose introduction and spread threatens ecosystems, habitats or species with economic or environmental harm) and are a threat to native biodiversity. For the purpose of this document, the term ‘novel biota’ refers to non-native or non-Indigenous invasive species that have been introduced and naturalised in a new habitat and have a significant detrimental impact on the environment.
This KTP does not consider native species that, due to changing climate conditions or natural evolutionary change, extend their ranges into areas where they are not currently present. The extension of ranges may result in new combinations of native species that could result in changes to ecosystem functioning (Hobbs et al., 2006). This new combination of native species, while novel, is considered to be a natural change.
This KTP includes native species translocated outside their range (except where translocation was for conservation purposes), that have become invasive and are adversely impacting on the environment. The Cootamundra wattle (Acacia baileyana) is an example of a native species that is now considered to be invasive after being translocated outside its range. The Cootamundra wattle is native to southern New South Wales but has been very widely planted as an ornamental. It is now naturalised in many parts of Australia and hybridises with other wattles (Morgan et al., 2002). The seeds of this small tree are spread by the spring-loaded action of its pods, and also by ants and birds. When it invades native bushland the Cootamundra wattle can replace local native shrubs and shade out native grasses and wildflowers.
1.5 Currently nationally listed KTPs
There are currently 19 KTPs listed under the EPBC Act. Fourteen1 of these describe decline in native species and/or ecological communities caused by one or more invasive taxa including cats, foxes, feral pigs, gamba grass and fire ants (DEWHA, 2009a). This KTP encompasses the 14 currently listed specific invasive taxa KTPs, as well as other novel biota that are already established in Australia and species with the potential to become invasive in the future.
There are a significant number of novel biota currently present in Australia, and of these only a very small proportion (14) are nationally listed as KTPs. Novel biota that are currently nationally listed as KTPs are considered to be some of the most detrimental species introduced into Australia and warranted being listed as a specific KTP. These 14 listed KTP species are also captured by this overarching KTP as they are considered to be invasive species and fit within the categories defined for this KTP, as detailed above. However, it is not intended that this overarching novel biota KTP will replace the existing species-specific KTPs.
It is anticipated individual novel biota KTPs will continue to be listed as stand-alone KTPs, as the novel biota they cover have a very significant detrimental impact on the Australian environment. Maintaining individual KTPs remains an effective mechanism for drawing attention to and addressing the impact of particular invasive taxa, particularly as threat abatement action is already well developed for these threatening processes.
1.6 Listing status under state and territory legislation
There are a number of KTPs listed under state legislation that recognise threats posed by one or more novel biota. These are listed below:
New South Wales
The following are listed as potentially threatening processes under the New South Wales Threatened Species Conservation Act 1995:
Competition and grazing by the feral European rabbit
Competition and habitat degradation by feral goats
Herbivory and environmental degradation caused by feral deer
Invasion and establishment of the cane toad
Predation and hybridisation by feral dogs (Canis lupus familiaris)
Predation by feral cats
Predation by the European red fox
Predation by the plague minnow (Gambusia holbrooki)
Predation by the ship rat (Rattus rattus) on Lord Howe Island
Predation, habitat degradation, competition and disease transmission by feral pigs (Sus scrofa)
Introduction and establishment of exotic rust fungi of the order Pucciniales pathogenic on plants of the family Myrtaceae
Invasion and establishment of exotic vines and scramblers
Invasion of native plant communities by bitou bush & boneseed
Invasion of native plant communities by exotic perennial grasses
Invasion, establishment and spread of Lantana camara
Invasion of native plant communities by African olive Olea europaea L. subsp. cuspidata
Invasion and establishment of escaped exotic garden plants as a key threatening process
Importation of red imported fire ants into NSW
Introduction of the large earth bumblebee (Bombus terrestris)
Competition from feral honeybees
Invasion of the yellow crazy ant (Anoplolepis gracilipes)
Infection by psittacine circoviral (beak & feather) disease affecting endangered psittacine species
Infection of frogs by amphibian chytrid fungus causing the disease chytridiomycosis
Infection of native plants by Phytophthora cinnamomi.
The following is listed as potentially threatening process under the New South Wales Fisheries Management Act, 1994:
The introduction of fish to fresh waters within a river catchment outside their natural range
The following are listed as potentially threatening processes under the Victorian Flora and Fauna Guarantee Act 1988:
Introduction of live fish into waters outside their natural range within a Victorian river catchment after 1770
Predation of native wildlife by the cat (Felis catus)
Predation of native wildlife by the introduced red fox (Vulpes vulpes)
Reduction in biodiversity of native vegetation by sambar (Cervus unicolor)
Reduction in biomass and biodiversity of native vegetation through grazing by the rabbit (Oryctolagus cuniculus)
Invasion of native vegetation by blackberry (Rubus fruticosus L. agg)
Invasion of native vegetation by ‘environmental weeds
Introduction and spread of Spartina to Victorian estuarine environments
Spread of Pittosporum undulatum in areas outside its natural distribution
Loss of biodiversity in native ant populations and potential ecosystem integrity following invasion by Argentine ants (Linepithema humile)
The introduction and spread of the large earth bumblebee (Bombus terrestris) into Victorian terrestrial environments
Infection of amphibians with chytrid fungus, resulting in chytridiomycosis
The spread of Phytophthora cinnamomi from infected sites into parks and reserves, including roadsides, under the control of a state or local government authority
Use of Phytophthora-infected gravel in construction of roads, bridges and reservoirs
Threats to native flora and fauna arising from the use by the feral honeybee (Apis mellifera) of nesting hollows and floral resources
The introduction of exotic organisms into Victorian marine waters.
1.7 Impacts of invasive novel biota
There are many documented environmental impacts from invasive novel biota including: predation by feral animals; soil erosion and water pollution; habitat loss; changes to hydrology; and clogging and deoxygenation of waterways.
The impact of vertebrate pests on Australian species and biodiversity is well documented (Dickman, 1996; May and Norton, 1996; Pultridge et al., 1997; Banks, 1999; Pultridge, 2002; Glen and Dickman, 2005; McKenzie et al., 2006; Fitzsimons et al., 2010; Phillips et al., 2010). Vertebrate pest species in Australia have few natural predators or disease and can reproduce rapidly. Species such as cats and foxes prey on native birds, mammals, reptiles and insects. Feral livestock, such as pigs and goats, directly and indirectly impact threatened species and ecological communities in a variety of ways such as by grazing native species, fouling waterways and damaging native vegetation. Rabbits graze heavily on native vegetation, which results in many species failing to produce seed and a loss of food source and habitat for native fauna species.
Invasive invertebrates introduced to Australia, particularly invasive ant species such as the big-headed ant (Pheidole megacephala) and Argentine ant (Linepithema humile), have had various impacts on native species such as the displacement of native ants, and potential effects on the ecological processes undertaken by the native ants (Lach and Thomas, 2008; Callan and Majer, 2009). On Christmas Island the yellow crazy ant (Anoplolepis gracilipes) is linked with the displacement of native ants and is having a major impact on the endemic Gecarcoidea natalis (red land crab) that is resulting in changes to the structure and composition of the rainforest (O’Dowd et al., 2001; Lach and Thomas, 2008). Similarly, giant centipedes (Scolopendra sp.) introduced to Christmas Island have been recorded as a possible reason for the dramatic decline in the population of Pipistrellus murrayi (Christmas Island pipistrelle) (DEWHA, 2009b).
Invasive weed species in Australia have altered the environment by changing fire regimes, as is seen with gamba grass in the Northern Territory (Rossiter et al., 2004; Fitzsimons et al., 2010). Invasive weed species have also changed hydrology by altering drainage into rivers and lakes (Levine et al., 2003), and affecting nutrient cycling (Wittenberg and Cock, 2001, p 4). Invasive weeds degrade catchment areas (Wittenberg and Cock, 2001, p 4), degrade habitats (Smith et al., 2007), and invade National Parks (Cowie and Werner, 1993; Stephens et al., 2008).
Aquatic weeds and algae impact on near-shore marine systems and freshwater ecosystems (Finlayson and Rea, 1999; Wittenberg and Cock, 2001, p 4). Aquatic weed species, including salvinia (Salvinia molesta) and water hyacinth (Eichhornia crassipes), clog water ways (resulting in fouling of the water, reduction in flow, and deoxygenation of water), kill and restrict access by native species and act as breeding grounds for mosquitoes (Gopal, 1987, p 471; WoNS, 2003a). The semi-aquatic upper tidal weed common cordgrass or rice grass (Spartina anglica) clogs many Tasmanian estuaries (Kriwoken and Hedge, 2000).
Marine pests invade the habitat of native species, compete for food, and in some cases feed on native species (Buttermore et al., 1994). Invasion by marine pests, such as Asterias amurensis (Northern Pacific seastar) and Patiriella regularis (New Zealand seastar), has resulted in native species being displaced (Buttermore et al., 1994). Other species, such as European fan worm (Sabella spallanzani), can become so prolific that they smother the native species and act like a carpet which transforms the seabed, altering the marine habitat (Marine Pests, 2009).
Native species are also being impacted on by pathogens. Three pathogens are currently listed as KTPs under the EPBC Act, including: ‘Psittacine Circoviral (beak and feather) Disease affecting endangered psittacine species’; ‘Dieback caused by the root-rot fungus (Phytophthora cinnamomi)’; and ‘Infection of amphibians with chytrid fungus resulting in chytridiomycosis’. Endemic pathogens such as hydatids caused by the tapeworm Echinococcus granulosus and carried by wild dogs, foxes and feral pigs, threaten small macropodids such as the vulnerable Petrogale penicillata (brush-tailed rock wallaby) (Barnes et al., 2010). Similarly, toxoplasmos,a parasitic disease caused by the protozoan Toxoplasma gondii and carried by feral cats (Felis catus), threatens native species including Perameles gunnii (eastern barred bandicoot) and Isoodon obesulus (southern brown bandicoot) (Henderson, 2009 and references therein).
1.8 Invasion pathways
Introduced species primarily arrive in Australia in two ways, either via accidental introduction or by deliberate introduction. Accidental introduction can be as a result of species inadvertently being transported on ships or aeroplanes. Deliberate introduction may be as a result of approved import for biological control, smuggling by people wanting to import a prohibited species, or by the escape of approved imported species into the natural environment. Figure 2 below illustrates the main invasion pathways for introduced species. Species can also enter Australia without human assistance, for example insects, seeds or spores aided by wind and vagrant birds, and weed species in the gut and on feathers of migratory birds.
Figure 2: Invasion pathways of introduced species (Wittenberg and Cock, 2001, p 2).
Accidental or unintentional introduction means introduction of a species outside its natural range unwittingly by humans or human delivery systems. The increase in globalisation, including world trade, tourism and migration, has resulted in greater opportunities for introductions of alien species on an international scale (Sanderlund et al., 1999, p 5). Accidental introductions include introduced species entering the country in a variety of unintentional ways. Some examples of the pathways for accidental introductions are outlined below.
Contaminants of agricultural products and livestock
Many species that have arrived in Australia have been introduced unintentionally as a contaminant of agricultural products or livestock. African lovegrass (Eragrostis curvula) was thought to have been introduced to Australia accidentally as a contaminant of pasture seed (Parsons and Cuthbertson, 2001a, p 107) and is now a declared noxious weed in many states (Cook, 2008). Bathurst burr (Xanthium spinosum), a plant native to South America, is reported to have been introduced to Australia in the 1840s by arriving in the tails of horses imported from Chile (Hocking and Liddle, 1995, p 250 and references therein) and is now a widely distributed weed in Australia.
Contaminated seed crops, nursery plants and cut flower trade
Siam weed (Chromolaena odorata) is thought to have been introduced into the Tully region in Queensland in 1994 in contaminated seed from Brazil (CRC Weed Management, 2003a). Seeds of Siam weed are spread by wind and water; further spread can occur by movement of stem and root fragments. Seeds may be blown long distances and also moved in mud on machinery and recreational vehicles. Siam weed smothers native species, changing the environment and reducing habitat for native species.
Machinery, equipment, vehicles, military etc
Machinery, equipment and vehicles imported into Australia or returning from military activities overseas can hide novel biota as weed seeds. Under today’s standards, military equipment returning from service overseas is required to comply with detailed decontamination processes to remove any foreign species that may have attached to the equipment that could potentially invade Australia (Wittenberg and Cock, 2001, p 88). Historically, parthenium weed (Parthenium hysterophorus), a two metre tall herb, was accidentally introduced into Australia on military equipment during World War II (Calvert, 1998). Parthenium weed can grow very rapidly, potentially maturing and setting seed in 28 days in ideal conditions (WoNS, 2009). Parthenium weed is currently found in Queensland, and the Northern Territory, where it smothers native plants, particularly native grassland ecological communities such as the endangered ‘Natural grasslands of the Queensland Central Highlands and the northern Fitzroy Basin’ (DEWHA, 2008a). The species can tolerate a wide variety of soil types and has the potential to spread widely.
Similarly, alligator weed (Alternanthera philoxeroides) was thought to have been unintentionally transported to Australia from South America in the ballast of two post World War II cargo ships (EPA/MAV, 2001). It was first noticed growing on ballast dumped in the Newcastle area in the 1940s (Julien, 1995, p 2), and can either grow on land or as a floating mass on fresh water (WoNS, 2009). It can spread to new areas in small pieces of soil in machinery and smothers native vegetation, deoxygenates waterways and degrades habitat of native species.
Many species arrive as hitchhikers on ships, planes and in shipping containers. Exotic rats, the black rat (Rattus rattus), the brown rat (Rattus norvegicus) and the Pacific rat (Rattus exulans), were common on ships in the 1800s and would have colonised Australia along with the first European settlers (Rolls, 1969, p 410; Frith, 1973, p 150). Exotic rats have had a particularly devastating impact on Australia’s offshore islands, and are listed as a KTP (DEWHA, 2006a). Exotic rats are opportunistic feeders, with their diet at any one time generally reflecting the availability of food in their environment. They eat both plant and animal matter all year round and are able to utilise a diverse range of food sources to facilitate colonisation of different environments. They are known to prey primarily on birds, small mammals, tortoises, lizards, large insects, land molluscs, plant seeds and seedlings. Exotic rats impact on threatened Australian native bird species including Cyanoramphus cookii (Norfolk Island green parrot) and Gallirallus sylvestris (Lord Howe woodhen), by preying on their eggs and young chicks (DEWHA, 2006a).
Ship ballast and hull fouling
Marine species have been spread around the world inadvertently in the ballast of ships. Ballast is used to stabilise ships while at sea and is then discarded in port before taking on new cargo (Mack, 2003, pp 11–14). In the 1800s and early 1900s ballast mainly consisted of rubble, gravel and stones found around the port of departure. This ballast often contained plants, invertebrates and pathogens that were dispersed when the ballast was discarded in the new port (Mack, 2003, pp 11–14). More recently, ships have used water as ballast and this resulted in different species being introduced as larvae of the many species that are easily sucked up into the ship hulls, with the water before being pumped out in another port (Carlton and Geller, 1993).
Hull fouling is another method of introduction of novel biota. Black striped mussel (Mytilopsis sp.) discovered in Darwin’s marina in 1999 was thought to have arrived on the hull of a boat that had not been treated with anti-foulant. Black striped mussel can grow in significant abundance on boat hulls, mooring ropes, chains and other surfaces, causing native species to be displaced (DAFF, 2007).