the species is found in Odemira, in the Algarve (EPPO, 2016). In Germany it is reported as a casual from the Rhineland-Palatinate (GEFD, 2016). It is not clear whether older localities, such as that noted by Margot (1983) in Belgium still persist (Verloove, 2006). See Appendix 4, Figure 6 for the distribution of the species in Europe. Oceania Salvinia molesta was introduced into Papua New Guinea in 1972, where a few plants were introduced into the Sepik River floodplain. Eight years later, the infestation had reached over 250 km2 (Oliver, 1993). Sundaresan & Reddy (1979) reported on two large infestations in Fiji (the Rewa delta and the Waidalice River), noting impacts on rice fields. In Australia, S. molesta was first recorded in 1952. By 1976 the species had spread to many rivers and lakes overtaking the occurrence of other aquatic plant pests like Eichhornia crassipes (Cronk and Fuller, 2001; but cf. the reports of Chauhan & Gopal 2005 for India). See Appendix 4, Figure 7 for the distribution of the species in Australia and New Zealand. 7. Habitats and their distribution in the PRA area Habitats EUNIS habitat types Status of habitat (eg threatened or protected) Present in PRA area (Yes/No) Comments (e.g. major/minor habitats in the PRA area) Reference(s)
Freshwater bodies (e.g. canals, ponds, rivers streams, canals, ditches, irrigation channels, estuaries, reservoirs, and lakes) C1: Surface standing waters C2: Surface running waters Protected pro parte: e.g. Annex 1 Standing freshwater habitats: 22.11 x 22.31, 22.11 x 22.34, 22.12 x ( 22.31 and 22.32), 22.12 x 22.44, 22.13, 22.14, 22.34. Running freshwater habitats: 24.225, 24.4, 24.52, 24.53 (see PDF for definitions). Parts of estuaries and lagoons (Annex 1 habitat codes 13.2 and 21) may also be at risk if the salinity is relatively low) Yes Major habitats within the PRA area Garbari et al. (2000); Giardini (2004); Margot (1983); Paradis & Miniconi (2011) Wetlands C3: Littoral zone of inland surface waterbodies None known. Yes Major habitats within the PRA area None known, but marginal habitats – e.g. C3.5 Periodically inundated shores with pioneer and ephemeral vegetation – seem likely to be affected. The presence of the species in rice paddies in other parts of the world also attests to the potential of S. molesta to invade tall helophyte communities (e.g. Sundaresan & Reddy, 1979). Many freshwater bodies and wetland are protected within the EPPO region. Freshwater habitats are detailed within the Habitats Directive 1992 and the Water Framework Directive 2000. Such habitats often harbour rare or endangered species. 8. Pathways for Possible pathways (in order of importance) Pathway: Plants for planting Short description explaining why it is considered as a pathway Salvinia molesta is used in aquaria, and as an ornamental plant for outdoor ponds (where it may be mislabelled as Salvinia natans (L.) All.; Brunel 2009 considered this ‘likely’). The species is also traded informally between aquatic plant enthusiasts.
What is the most likely stage associated with the pathway? All three growth forms of the plant would be associated with this pathway. What are the important factors for association with the pathway? Aquatic plants are produced in locations multiple species are being produced and handled therefore contamination may occur. Is the pest likely to survive transport and storage in this pathway? Yes, survival is an inherent part of the pathway. Can the pest transfer from this pathway to a suitable habitat? Yes, through agency (i.e. intentional introductions or the unintentional disposal of plants into wild habitats). The species could be misused and introduced directly into freshwater bodies and ecosystems (e.g. stream, lakes, dams). The unintended habitats are freshwater bodies and ecosystems (semi-natural and natural waterbodies). Plants used in confined waterbodies could spread to unintended habitats very easily through human activities as well as through natural spread by floods downstream. Improper disposal of aquarium contents has been a source of introduction of aquatic plants in some countries, even if it is considered as an accidental pathway of introduction (e.g. Cabomba caroliniana in the Netherlands, see the EPPO PRA on the species; Hydrilla verticillata in the USA; Langeland, 1996). Will the volume of movement the pathway support entry? No. The volume of movement as a contaminant this pathway would be low. Will the frequency of movement along the pathway support entry? No. The frequency of movement as a contaminant be low. Likelihood of entry Low Moderate High Rating of uncertainty Low Moderate High Possible pathways (in order of importance) Pathway: Leisure equipment Short description explaining why it is considered as a pathway It is possible that the use of recreational equipment (e.g. fishing or canoeing gear) could spread the species, particularly in its primary form, although this is not likely to be significant pathway. Is the pathway prohibited in the PRA area? No. However, there are awareness campaigns within the EU to raise awareness of the movement of invasive alien plants by this pathway. For example, the “Check, Clean and Dry” campaign in Great Britain highlights the need to inspect and treat recreational material following use.
Biological control According to McFarland et al. (2004), the weevil Cyrtobagus salviniae Calder and is “recognized throughout the world as the method of choice for S. molesta management”. The insect has been released in 22 countries around the world including: Australia, Fiji, India, Kenya, Namibia, South Africa, Sri Lanka, USA, Zambia and Zimbabwe (Doeleman, 1990). The impacts of C. salviniae on S. molesta are overviewed by Julien et al., 2009) with Coetzee et al., (2011) giving a case study example for South Africa. Other species considered as biological control agents include the aquatic grasshopper Paulinia acuminata De Geer, the pyralid moth Samea multiplicalis Guenee, the weevil Cyrtobagus singularis Hustache and the grass carp Ctenopharyngodon idella Val., although none of these has been found to be as effective as C. salviniae (Oliver, 1993). A thorough review of the topic is also provided by Julien et al. (2009). “Moderate” uncertainty has been given because, in general, it is not possible to know that historical impacts described in the literature are still being felt in any particular geographical area. Rating of the magnitude of impact in the current area of distribution Low ☐ Moderate ☐ High X Rating of uncertainty Low ☐ Moderate X High ☐ 12.02. Impacts on ecosystem services Ecosystem service Does the IAS impact on this Ecosystem service? Yes/No Short description of impact Reference Provisioning Yes Mat formation by, and decomposition of, S. molesta can affect quality and availability (and so potentially fish abundance). Food production may also be affected by the increased risk of Mitchell (1969); Sundaresan & (1979); Hattingh (1961); McFarland et al. (2004)
13.03 Socio-economic impact of the species See above Overall assessment 14. Identification of the endangered area Salvinia molesta is a frost-sensitive free-floating species. The southern countries within the EPPO region provide suitable climatic conditions for the plant. This includes regions in which the water bodies are not enclosed in ice during the winter months. Furthermore, thermal waters in other EPPO countries provide potential habitats for Salvinia molesta. Salvinia molesta is capable of establishing in the Mediterranean biogeographical region. The species is capable of limited establishment in small areas of the Black Sea and Atlantic biogeographical regions. Additionally, areas around the Adriatic Sea have the potential for establishment (see appendix 1). Significant impact be expected in man-made water bodies. Habitats within the endangered area include slow moving rivers, canals, irrigation and drainage systems, lakes and reservoirs which are widespread within the EPPO region. 15. Climate change 15.01. Define which climate projection you are using from 2050 to 2100* Climate projection RCP 8.5: 2070, 2070 15.02 Which component of climate change do you think is most relevant for this organism? Delete (yes/no) as appropriate Temperature (yes) Precipitation (no) C02 levels (no) Sea rise (no) Salinity (no) Nitrogen deposition (no) Acidification (yes) Land use change (no) Other (please specify)
Are the introduction pathways likely to change due to climate change? (If yes, provide a new risk and uncertainty score) Reference The introduction pathways are unlikely to change as a result of climatic change as the species enters the EPPO region as a result of the horticultural trade. The overall rating for introduction will not change. (Personal Communication J. van Valkenburg, 2016). Is the risk of establishment likely to change due to climate change? (If yes, provide a new risk and uncertainty score) Reference The risk of establishment will increase with increasing temperature in some countries, in which frost events currently hinder establishment of S. molesta. With projected climate change it is predicted (using the scenario RCP 8.5: 2070) that the species will be capable of establishing throughout the Atlantic zone, Western Continental Europe (as far east as the western borders of Poland and Romania), and is likely to increase its potential distribution around the Black Sea (see Appendix 1). The overall rating given in section 9 will not change. See appendix 1 Is the risk of spread likely to change due to climate change? (If yes, provide a new risk and uncertainty score) Reference The risk of spread into countries from interconnecting water bodies, in which frost events currently hinder the establishment of S. molesta will increase with increasing temperature. Increased flood events resulting from climate change could facilitate the spread of the species into new regions (see Appendix 1). The risk of spread will remain as moderate but the level of uncertainty could be reduced from moderate to low. See appendix 1 Will impacts change due to climate change? (If yes, provide a new risk and uncertainty score) Reference With increasing temperature the impacts of Salvinia molesta will be more profound than under the current climatic conditions. As the species spreads, impacts will manifest across a larger part of the PRA area. More rapid growth and biomass accumulation will result in higher impacts to native species. The ratings given in section 12 will not change. See appendix 1 16. Overall assessment of risk The overall likelihood of Salvinia molesta entering into the EPPO region is high. The plant is imported into the EPPO region and is sold for aquarium and garden ponds. In addition, it is grown and traded within the EPPO region. In view of the risk of entry, establishment and spread, it is surprising that despite the long history of trade as an ornamental and the climatic match with the Mediterranean, it is not yet widely established.