Study on Invasive Alien Species – Development of Risk Assessments to Tackle Priority Species and Enhance Prevention" Contract No 07.0202/2018/788519/ETU/ENV.D.21

Home , Cheilostomatida, Cryptosula pallasiana, Flustrina, Schizoporella, Schizoporella unicornis, Schizoporellidae

Risk assessment template developed under the "Study on Invasive Alien Species – Development of risk assessments to tackle priority species and enhance prevention" Contract No 07.0202/2018/788519/ETU/ENV.D.21

Name of organism: Schizoporella japonica

Author(s) of the assessment:

Jack Sewell & Christine A. Wood, The Marine Biological Association, UK

Risk Assessment Area: The risk assessment area is the territory of the European Union (excluding the outermost regions) and the United Kingdom.

Peer review 1: Marika Galanidi, Dr, Dokuz Eylul University, Institute of Marine Sciences and Technology, Izmir, Turkey

Peer review 2: Argyro Zenetos, Dr, Research Director, Hellenic Centre for Marine Research, Greece

Date of completion: 31/10/19

Date of revision: 01/09/2020

Positive opinion by the Scientific Forum: 17/11/2020

1 This template is based on the Great Britain non-native species risk assessment scheme (GBNNRA). A number of amendments have been introduced to ensure compliance with Regulation (EU) 1143/2014 on IAS and relevant legislation, including the Delegated Regulation (EU) 2018/968 of 30 April 2018, supplementing Regulation (EU) No 1143/2014 of the European Parliament and of the Council with regard to risk assessments in relation to invasive alien species (see https://eur- lex.europa.eu/legal-content/en/TXT/?uri=CELEX%3A32018R0968 ). 1

Contents

SECTION A – Organism Information and Screening ...... 3

SECTION B – Detailed assessment ...... 12

1 PROBABILITY OF INTRODUCTION ...... 12

2 PROBABILITY OF ENTRY ...... 20

3 PROBABILITY OF ESTABLISHMENT ...... 28

4 PROBABILITY OF SPREAD ...... 36

5 MAGNITUDE OF IMPACT ...... 53

Biodiversity and ecosystem impacts ...... 53

Ecosystem Services impacts ...... 57

Economic impacts ...... 59

Social and human health impacts ...... 61

Other impacts ...... 62

RISK SUMMARIES ...... 65

Appendix 1: Climatic variables maps ...... 69

Distribution Summary ...... 74

ANNEX I Scoring of Likelihoods of Events ...... 76

ANNEX II Scoring of Magnitude of Impacts ...... 77

ANNEX III Scoring of Confidence Levels ...... 78

ANNEX IV Ecosystem services classification (CICES V5.1, simplified) and examples ...... 79

ANNEX V EU Biogeographic Regions and MSFD Subregions ...... 83

ANNEX VI Delegated Regulation (EU) 2018/968 of 30 April 2018 ...... 84

SECTION A – Organism Information and Screening A1. Identify the organism. Is it clearly a single taxonomic entity and can it be adequately distinguished from other entities of the same rank?

Response: The taxonomic family, order and class to which the species belongs: Bryozoa (Phylum); Gymnolaemata (Class); Cheilostomatida (Order); Flustrina (Suborder); Schizoporelloidea (Superfamily); Schizoporellidae (Family); Schizoporella (Genus)

The scientific name and author of the species, as well as a list of the most common synonym names: Schizoporella japonica Ortmann, 1890

Synonyms: Schizoporella unicornis var. japonica Ortmann, 1890 Although not officially listed as a synonym in the World Online Register of Marine Species (WORMS), the name was used to describe the species when first identified in Japan. It has also been used in some papers describing distribution in North America. It was later elevated to separate species status as Schizoporella japonica (Bock 2015). Records of S. unicornis from Australia are considered as likely to be S. japonica also (Ryland et al 2014).

Names used in commerce (if any): None known

A list of the most common subspecies, lower taxa, varieties, breeds or hybrids: None known

Developed, encrusting colony on marina equipment, Bilaminar, orange growth Photo: Christine Wood, showing unilaminar and bilaminar growths Photo: MBA John Bishop, MBA

Close up of zooids, showing white ovicells, perforated frontal wall, orifice and sinus shape, and avicularia. Photo: John Bishop, MBA

A2. Provide information on the existence of other species that look very similar [that may be detected in the risk assessment area, either in the environment, in confinement or associated with a pathway of introduction] Include both native and non-native species that could be confused with the species being assessed, including the following elements:  other alien species with similar invasive characteristics, to be avoided as substitute species (in this case preparing a risk assessment for more than one species together may be considered);  other alien species without similar invasive characteristics, potential substitute species; native species, potential misidentification and mis-targeting

Response: It is possible that colonies may bear a superficial, passing resemblance to encrusting sponges, colonial ascidians or encrusting algal growths, however the presence of uniformly-sized, regularly, continuously arranged zooid ‘cells’ (visible with the naked eye) make bryozoan colonies distinctive from any of these. There are a large number of orange encrusting bryozoan species, which occur in the risk assessment area, both native and introduced, that, to the naked eye, show similarities to S. japonica e.g. Cryptosula pallasiana, Oshurkovia littoralis, Escharoides coccinea, Schizobrachiella sanguinea, Smittina spp.,Turbicellepora magnicostata (all native to the North-East Atlantic). S. japonica has a distinctive bright orange colouration, although this may be more or less apparent depending on the age and condition of colonies. Use of a hand lens to look at the shape of the zooidal structures will eliminate many of these confusion species. However, microscopic investigation will be required in most cases, and for a conclusive identification of a suspected new introduction SEM imaging or DNA analysis will be necessary. The most difficult to distinguish are other species within the genus Schizoporella, all members of the genus have rectangular or polygonal zooids, regular perforations in the frontal wall, a D-shaped orifice with a U or V- shaped sinus, prominent globular ovicells, and single or paired avicularia to the side of the orifice (see figure in A-1). However, there is ‘extensive confusion in identifying species within the genus Schizoporella (IUCN 2019, Dick et al, 2005; Porter, 2012), which has led to the historic misidentification and reporting of species in the genus. Special care should therefore be taken in observing and identifying specimens, with reference to relevant keys and scientific papers e.g. Hayward & Ryland (1995); Ryland et al 2014. The following species are the most likely to cause identification confusion: S. unicornis (Johnston in Wood, 1844) (Native to North-East Atlantic) S. dunkeri (Reuss, 1848) (Native to North-East Atlantic) S. errata (Waters, 1878) (Native to East Atlantic, from Iberian coast and Mediterranean, Invasive in Australasia) S. pseudoerrata (Soule & Chaney, 1995) (Distribution uncertain not native to North-East Atlantic)

A3. Does a relevant earlier risk assessment exist? Give details of any previous risk assessment, including the final scores and its validity in relation to the risk assessment area.

Response: A risk assessment has been undertaken for Norway and it has been considered a High risk, with high chance of invasiveness, with a small ecological impact and high level of uncertainty (Oug et al 2019).

A4. Where is the organism native? including the following elements:  an indication of the continent or part of a continent, climatic zone and habitat where the species is naturally occurring  if applicable, indicate whether the species could naturally spread into the risk assessment area

Response: The north-west Pacific from China to Japan. It is considered very unlikely that S. japonica will spread naturally into the risk assessment area from its native range.

A5. What is the global non-native distribution of the organism outside the risk assessment area?

Response: Schizoporella japonica (described as S. unicornis) (Dick et al 2005) was introduced to the north- eastern Pacific on oysters from Japan (Powell, 1970). It has been reported along the Pacific coast of North America from Alaska to California. It is likely also be present in Australia where S. unicornis (possibly S. japonica) was reported in 1975 following imports of Pacific oysters (Dick et al 2005). The precise introduced range is currently unknown, as it is commonly misidentified as S. unicornis or S. errata (Dick et al 2005; Treibergs 2012). Reproducing, introduced populations have been identified in Malaysia (Taylor & Tan 2015).

Current suspected distribution of Schizoporella japonica based on information taken from: Ocean Biographic Information System (OBIS); Global Biodiversity Information Facility (GBIF); Loxton et al (2017); Dick et al (2005); Gittenberger et al. (2019) (from Reviewer pers comm February 2020) .

A6. In which biogeographic region(s) or marine subregion(s) in the risk assessment area has the species been recorded and where is it established? The information needs be given separately for recorded and established occurrences.

Response (6a) Recorded: Marine regions: North-east Atlantic Ocean Marine subregions: Greater North Sea, Celtic Seas

Response (6b) Established: Marine regions: North-east Atlantic Ocean Marine subregions: Greater North Sea; Celtic Seas

Assertion is based on data collated from the Global Biodiversity Information Facility (GBIF) and the Ocean Biogeographic Information System, as well as the literature studied in the preparation of this report, particularly Loxton et al (2017), which provides a comprehensive and recent overview. Also observations of Celtic Seas populations made by the authors (unpublished). Due to historic misidentification, there is a possibility that the range may be greater than currently known.

A7. In which biogeographic region(s) or marine subregion(s) in the risk assessment area could the species establish in the future under current climate and under foreseeable climate change? The information needs be given separately for current climate and under foreseeable climate change conditions. A7a. Current climate: List regions A7b. Future climate: List regions With regard to EU biogeographic and marine (sub)regions, see above. With regard to climate change, provide information on  the applied timeframe (e.g. 2050/2070)  the applied scenario (e.g. RCP 4.5)  what aspects of climate change are most likely to affect the risk assessment (e.g. increase in average winter temperature, increase in drought periods) The assessment does not have to include a full range of simulations on the basis of different climate change scenarios, as long as an assessment with a clear explanation of the assumptions is provided. However, if new, original models are executed for this risk assessment, the following RCP pathways shall be applied: RCP 2.6 (likely range of 0.4-1.6°C global warming increase by 2065) and RCP 4.5 (likely range of 0.9-2.0°C global warming increase by 2065). Otherwise, the choice of the assessed scenario has to be explained.

Response (A7a): Regarding S. japonica, temperature and salinity are considered the most important climatic variables in limiting establishment for the species. Based on current conditions, salinity is within the known tolerance range of 15-36ppt (Powell 1970, Loxton 2014) throughout the Greater North Sea, Celtic Seas, Bay of Biscay and northern Iberian Coast and Bay of Biscay, as well as parts of the Black Sea, (see Map Appendix 1). Salinity in most of the Mediterranean and the southern Iberian Coast is considered to be too high and in the Baltic Sea, and north-west Black Sea salinity is considered to be below the level which the species is known to tolerate. In areas of the Mediterranean with lower levels of salinity – for example the Thau Lagoon, France and Venice Lagoon, Italy –as well as the lower Iberian coast, salinity levels reach a maximum of 37ppt, which is only marginally higher than the known survivable level of 36ppt and seasonally, temporarily drops to tolerable levels. Given the adaptability of the species and lack of detailed research into the tolerances of the species and regional variants, introduction and establishment in these areas should not be completely discounted. Temperature range in which the species is known to reproduce is wide and records from Malaysia (Taylor and Tan 2015) suggest a highest temperature tolerance of 30oC, whilst records from Alaska and elsewhere suggest a lowest temperature tolerance of -1.4 oC (CABI 2019). With this in mind, February and August sea temperatures throughout the EU are within the tolerable range for the species, suggesting salinity may play the most important role in restricting the spread of the species to The Greater North Sea, Celtic Seas, and Bay of Biscay and (northern part of) Iberian Coast (see Appendix 1). 8

Response (A7b): Based on future air temperature warming scenarios RCP 2.6 (likely range of 0.4- 1.6°C global warming increase by 2065) and RCP 4.5 (likely range of 0.9-2.0°C global warming increase by 2065).). Bruno et al (2018) predict temperate marine areas will experience a maximum SST increase of 2.6°C under BAU (Business as usual) RCP 8.5 scenario. In the event that this occurs, the maximum temperature for survival will be exceeded in some parts of the Mediterranean (southern Italy, areas around the Balearics and areas outside the RAA). As presence in these areas is likely to already be limited by salinity levels in the area, this does not represent a significant change of potential habitable area under these scenarios.

Projections of sea surface salinity (SSS) under future climate conditions can be much more variable, depending largely on the model used for predictions (Pushpadas et al 2015; Schrum et al 2016; Thiébault & Moatti 2016). In the Mediterranean Sea, a progressively higher SSS is however generally projected with values ranging from 0.06 psu to 1 psu over the next 100 years, depending on the scenario employed (Thiébault & Moatti 2016), while freshening of the North Sea, the Baltic Sea as well as the Iberian coast (Jordà et al 2017) in the order of -0.1 to -0.6 psu may be anticipated under different scenarios. Thus, in the two regions where salinity was acting as a limiting factor for establishment, the direction of change will further limit the potential for S. japonica to become established, (i.e. even higher salinities in the Mediterranean and even lower salinities in the Baltic Sea). A projected freshening of the Iberian coast may result in a higher likelihood of establishment along the entire Iberian coast. (see maps in Appendix 1)

A8. In which EU Member States has the species been recorded and in which EU Member States has it established? List them with an indication of the timeline of observations. The information needs be given separately for recorded and established occurrences.

A8a. Recorded: List Member States

A8b. Established: List Member States

Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden,

The description of the invasion history of the species shall include information on countries invaded and an indication of the timeline of the first observations, establishment and spread.

Response (8a): United Kingdom, Ireland. UK - First record Plymouth 2009; Holyhead, Wales 2010; Orkney, Scotland 2011; Scottish coast 2013; Blyth, NE England 2016. Ireland - Greystones Marina 2015. Netherlands, Dutch Wadden Sea, first recorded 2018 (Gittenberger et al.2019)

Response (8b): United Kingdom. First established population noted in Holyhead, Wales 2010. Netherlands. Records from oyster beds in the Wadden Sea suggest establishment in this region (Reviewer pers comm after Gittenberger et al. 2019).

A9. In which EU Member States could the species establish in the future under current climate and under foreseeable climate change? The information needs be given separately for current climate and under foreseeable climate change conditions. A9a. Current climate: List Member States A9b. Future climate: List Member States With regard to EU Member States, see above. With regard to climate change, provide information on  the applied timeframe (e.g. 2050/2070)  the applied scenario (e.g. RCP 4.5)  what aspects of climate change are most likely to affect the risk assessment (e.g. increase in average winter temperature, increase in drought periods) The assessment does not have to include a full range of simulations on the basis of different climate change scenarios, as long as an assessment with a clear explanation of the assumptions is provided. However, if new, original models are executed for this risk assessment, the following RCP pathways shall be applied: RCP 2.6 (likely range of 0.4-1.6°C global warming increase by 2065) and RCP 4.5 (likely range of 0.9-2.0°C global warming increase by 2065). Otherwise, the choice of the assessed scenario has to be explained.

Response (9a): For full explanation of expected potential range for establishment see 7a. Member states are: Belgium, France, Ireland, Portugal, Spain, UK, Denmark, Germany, Sweden.

Response (9b): Predicted warming scenarios will not cause an increase that is likely to exceed the tolerable temperature at a member state scale. Nor will states not currently considered suitable become suitable as sea temperature increases. It is not anticipated that predicted warming scenarios will alter the member states in which the species might be able to become established.

A10. Is the organism known to be invasive (i.e. to threaten or adversely impact upon biodiversity and related ecosystem services) anywhere outside the risk assessment area?

Response: S. japonica is a competitor for space and is known to inhibit the growth of adjacent species. It has proved very capable of colonising and dominating natural and man-made habitat and competitively excluding or overgrowing native species, in particular where it has invaded through its North American range (Dick et al 2005). However it is suggested that it may be a poor invader of previously occupied space (Sutherland, 1978).

A11. In which biogeographic region(s) or marine subregion(s) in the risk assessment area has the species shown signs of invasiveness? Indicate the area endangered by the organism as detailed as possible.

Response: North-east Atlantic Ocean - Greater North Sea and, Celtic Seas.

Populations in the Northern Isles of Scotland have become a dominant member of fouling communities on artificial structures and have started to colonize natural substrate in the wild, competing for space with native species (Nall et al 2015, Loxton et al 2017). In Anglesey, North Wales, the species dominated fouling communities in Holyhead marina, appearing to competitively exclude other species following clearance of the invasive tunicate Didemnum vexillum (Ryland et al 2014). In Plymouth, England it similarly initially dominated the fouling in a newly constructed marina and spread to two further nearby marinas (unpublished observations by authors).

A12. In which EU Member States has the species shown signs of invasiveness? Indicate the area endangered by the organism as detailed as possible.

Response: United Kingdom – Scottish Northern Isles; Anglesey, North Wales; Plymouth, England.

A13. Describe any known socio-economic benefits of the organism. including the following elements:  Description of known uses for the species, including a list and description of known uses in the Union and third countries, if relevant.  Description of social and economic benefits deriving from those uses, including a description of the environmental, social and economic relevance of each of those uses and an indication of associated beneficiaries, quantitatively and/or qualitatively depending on what information is available. If the information available is not sufficient to provide a description of those benefits for the entire risk assessment area, qualitative data or different case studies from across the Union or third countries shall be used, if available.

Response: No information has been found.

SECTION B – Detailed assessment Important instructions:  In the case of lack of information the assessors are requested to use a standardized answer: “No information has been found.”  With regard to the scoring of the likelihood of events or the magnitude of impacts see Annexes I and II.  With regard to the confidence levels, see Annex III.  Highlight the selected response score and confidence level in bold but keep the other scores in normal text (so that the selected score is evident in the final document).

1 PROBABILITY OF INTRODUCTION Important instructions:  Introduction is the movement of the species into the risk assessment area (it may be either in captive conditions and/or in the environment, depending on the relevant pathways).  Entry is the release/escape/arrival in the environment, i.e. occurrence in the wild and is treated in the next section (N.B. introduction and entry may coincide for species entering through pathways such as “corridor” or “unaided)”.  The classification of pathways developed by the Convention of Biological Diversity (CBD) should be used. For detailed explanations of the CBD pathway classification scheme consult the IUCN/CEH guidance document2 and the provided key to pathways3.  For organisms which are already present in the risk assessment area, only complete this section for current active pathways and, if relevant, potential future pathways.

Qu. 1.1. List relevant pathways through which the organism could be introduced. Where possible give details about the specific origins and end points of the pathways as well as a description of any associated commodities. For each pathway answer questions 1.2 to 1.7 (copy and paste additional rows at the end of this section as necessary). Please attribute unique identifiers to each question if you consider more than one pathway, e.g. 1.2a, 1.3a, etc. and then 1.2b, 1.3b etc. for the next pathway. In this context a pathway is the route or mechanism of introduction of the species. The description of commodities with which the introduction of the species is generally associated shall include a list and description of commodities with an indication of associated risks (e.g. the volume of trade; the likelihood of a commodity being contaminated or acting as vector). If there are no active pathways or potential future pathways this should be stated explicitly here, and there is no need to answer the questions 1.2-1.9

2 https://circabc.europa.eu/sd/a/738e82a8-f0a6-47c6-8f3b-aeddb535b83b/TSSR-2016- 010%20CBD%20categories%%20pathways%20Final.pdf 3 https://circabc.europa.eu/sd/a/0aeba7f1-c8c2-45a1-9ba3-bcb91a9f039d/TSSR-2016- 010%20CBD%20pathways%20key%20full%20only.pdf 12

Pathway name: Transport: Contaminant - Contaminant on animals

Qu. 1.2a. Is introduction along this pathway intentional (e.g. the organism is imported for trade) or unintentional (e.g. the organism is a contaminant of imported goods)?

RESPONSE unintentional CONFIDENCE High

Response: The primary introduction of S. japonica outside its native range is believed to have been as a result of accidental transportation with the commercially grown Pacific oyster Magallana (was Crassostrea) gigas when the species was exported during the early twentieth century from Japan to the west coast of North America (Loxton et al 2017) . Records of S. unicornis (considered likely to be S. japonica) from Australia were reported following the introduction of Pacific oysters (Dick et al 2005). Although bivalve introductions are now carefully regulated to minimize the risk of importation of contaminated stock, introduction to member states via movements of shellfish from outside the RAA is possible. Additionally, introduction of contaminated stock to neighboring countries with different levels of control in place is feasible.

Qu. 1.3a. How likely is it that large numbers of the organism will be introduced through this pathway from the point(s) of origin over the course of one year?

including the following elements:

 discuss how likely the organism is to get onto the pathway in the first place. Also comment on the volume of movement along this pathway.  an indication of the propagule pressure (e.g. estimated volume or number of individuals / propagules, or frequency of passage through pathway), including the likelihood of reinvasion after eradication  if relevant, comment on the likelihood of introduction based on propagule pressure (i.e. for some species low propagule pressure (1-2 individuals) could result in introduction whereas for others high propagule pressure (many thousands of individuals) may not.

RESPONSE unlikely CONFIDENCE medium

Response: Schizoporella japonica is known to attach to a wide range of substrates and structures likely to occur in close proximity to bivalves in culture (e.g. aquaculture equipment, maintenance vessels and structures, and natural seabed) (Collin et al 2015). This represents a source of propagules which might be transported into the RAA. There is substantial evidence to suggest that the species will attach and grow readily on living bivalves and empty shells, including oysters (see examples in Loxton et al 2017). The species is hermaphroditic and reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement (Ryland et al 2014). These traits make contamination of shellfish stored in close proximity to colonies of S. japonica likely. Once 13

settlement takes place, individuals reproduce and spread by budding asexually to form encrusting sheets. Therefore, the successful settlement, development and growth of an individual on a transporting organism can result in a high level of propagule potential. However, EC regulation 708/2007 (EC 2007) aims to reduce the impact of introduced alien species from aquaculture and requires processes to be undertaken to ameliorate the potential environmental damage caused by such introductions. This should theoretically include measures to reduce the potential for ‘hitchhiking’ species to be introduced and may require careful treatment, quarantine and other processes before stock can be released into the wild. It is however unlikely that such stringent measures will be applied to movements of stock within member states and where species, normally native to or established in a member state are introduced. Where this is the case, it is difficult to evaluate whether or not management practices will be utilized that would effectively reduce the likelihood of introduction. It is considered that the measures currently in place mean that large numbers will not be introduced over the course of a year.

Qu. 1.4a. How likely is the organism to survive, reproduce, or increase during transport and storage along the pathway (excluding management practices that would kill the organism)?

RESPONSE very likely CONFIDENCE high

Response: Based on previous introductions, S. japonica has a very high potential to survive transportation attached to live shellfish (Dick et al 2005; Loxton et al 2017; Powell 1970; Ryland et al 2014)). The survivable temperature range is high (-1.4 - 30oC) (Loxton et al 2017, CABI 2019). Reproduction through asexual budding and colony growth is likely provided conditions are favourable and sexual reproduction (which takes place year round) is also likely.

Qu. 1.5a. How likely is the organism to survive existing management practices during transport and storage along the pathway?

RESPONSE moderately likely CONFIDENCE medium

Response: EC regulation 708/2007 (EC 2007) aims to reduce the impact of introduced alien species for aquaculture and requires processes to be undertaken to ameliorate the potential environmental damage caused by such introductions. This should theoretically include measures to reduce the potential for ‘hitchhiking’ species to be introduced and may require careful treatment, quarantine and other processes before stock can be released into the wild. It is however unlikely that such stringent measures will be applied to movements of stock where species, normally native to or established in a member state are introduced. For example, exemptions exist regarding the introduction of the Pacific oyster Magallana gigas (listed as Crassostrea) which has been implicated as a potential pathway of introduction of S. japonica in North America and Australia. Where this is the case, it is difficult to

evaluate whether or not management practices will be utilized that would effectively reduce the likelihood of introduction.

Qu. 1.6a. How likely is the organism to be introduced into the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

Response: Ancestrula (first colonising zooid) measure 350-400 x ~300 μm (Ryland et al 2014) and at this stage are extremely difficult to detect. A single ancestrula can develop and reproduce asexually to form colonies of hermaphroditic, reproductive individuals. Developed colonies are easier to detect measuring several centimetres across and being bright orange. However, confusions over identification and the large number of taxonomically similar native species reduce the likelihood that the species will be identified and intercepted except by experts. Regular eDNA monitoring of aquaculture sites has the potential to improve detection of the species, however to-date, the method does not appear to have been trialled for this particular species and it is impossible at present to provide the environmental conditions and population density that would be required at a site in order for this to be effective.

Qu. 1.7a. Estimate the overall likelihood of introduction into the risk assessment area based on this pathway?

RESPONSE Unlikely CONFIDENCE medium

Response: Based on the biological traits of the species and past examples of introductions globally by this particular pathway, introduction is considered possible. Legislation restricting the import and release of alien species for aquaculture (EC 2007) mean the likelihood of introduction by this pathway is reduced significantly by non-species specific management measures. The risk of introduction when attached to species already native to or established or species illegally introduced in the RAA is less certain and for this reason, the score ‘unlikely’ has been allocated.

End of pathway assessment, repeat Qu. 1.2 to 1.7 as necessary using separate identifier.

Pathway name: Transport: Stowaway - Ship/boat hull fouling

Qu. 1.2b. Is introduction along this pathway intentional (e.g. the organism is imported for trade) or unintentional (e.g. the organism is a contaminant of imported goods)?

RESPONSE unintentional CONFIDENCE high

Response: Schizoporella japonica is known to attach to and colonize a range of man-made structures including the hulls of commercial vessels, ferries and recreational vessels (Collin et al 2015; Ryland et al 2014; Bishop et al 2015). It is also known to colonize marina pontoons, fenders and other structures likely to occur in the vicinity of vessels. Global shipping and recreational boat travel takes place between areas from which the species is known and ports, harbours and marinas within the RAA. Hull fouling has been implicated in the spread of the species globally and to the UK, Ireland and Norway (Ashton et al 2014; Loxton et al 2017). The discontinuous UK distribution and the current concentration of records in and in close proximity to structures associated with recreational and commercial shipping, coupled with the species’ low natural dispersal potential is further evidence to suggest that hull fouling is a primary vector.

Qu. 1.3b. How likely is it that large numbers of the organism will be introduced through this pathway from the point(s) of origin over the course of one year?

including the following elements:

RESPONSE likely CONFIDENCE high

Response: Schizoporella japonica is known to attach to and colonize a range of man-made structures including the hulls of commercial vessels, ferries and recreational vessels (Collin et al 2015; Ryland et al 2014; Bishop et al 2015). It is also known to colonize marina pontoons, fenders and other structures likely to occur in the vicinity of vessels. Populations are therefore likely to exist in proximity to and therefore may spread to vessels which may travel to the RAA. Global shipping and recreational boat travel takes place between areas from which the species is known and ports, harbours and marinas within the RAA on a regular basis.

The species is hermaphroditic and sexual reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement, (Ryland et al 2014) giving time for the ciliated larvae to move between structures and moored vessels. These traits make attachment to the hulls of vessels moored in close proximity to colonies of S. japonica likely. Once settlement takes place, individuals reproduce and spread by budding asexually to form sheets. Therefore, the successful settlement, development and growth of an individual on man-made objects such as a vessel hull can result in a high level of propagule potential. 16

Qu. 1.4b. How likely is the organism to survive, reproduce, or increase during transport and storage along the pathway (excluding management practices that would kill the organism)?

RESPONSE very likely CONFIDENCE high

Response: Based on previous introductions, S. japonica has a very high potential to survive transportation attached to vessel hulls (Ashton et al. 2014; Loxton et al. 2017). The survivable temperature range is high (-1.4 - -30oC ) (Loxton et al 2017, CABI 2019). Reproduction through asexual budding and colony growth is likely provided conditions are favourable and sexual reproduction (which takes place year round) is also likely.

Qu. 1.5b. How likely is the organism to survive existing management practices during transport and storage along the pathway?

RESPONSE likely CONFIDENCE Medium

Response: Hull cleaning is an often practiced method of defouling ship and boat hulls and has the potential to physically remove colonies of S. japonica (although colony fragments are likely to remain), which would in turn reduce the risk of introduction. However the practice is not legally required before vessels enter the RAA and can be financially costly making it very likely that vessels traveling between contaminated and uncontaminated marinas and ports will not have been treated.

The authors were unable to find information about the ability of S. japonica to resist antifouling treatments, however it should be noted that in the congener S. errata, Cu (copper) based antifouling coatings on boat hulls can prevent growth of S. errata and stop its spread to new locations (Piola and Johnston 2006). Although (as with physical hull cleaning), antifouling is not currently a legal requirement, there is potential that treatments with biocidal compounds may prove an effective method of controlling fouling and reduce the likelihood of spread.

Qu. 1.6b. How likely is the organism to be introduced into the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

centimetres across and being bright orange. However, confusions over identification and the large number of taxonomically similar native species reduce the likelihood that the species will be identified and intercepted except by experts.

Qu. 1.7b. Estimate the overall likelihood of introduction into the risk assessment area based on this pathway?

RESPONSE very likely CONFIDENCE high

Response: Introduction to the RAA (UK and Ireland) has already taken place within in the last 10 years, presumably via this pathway. Introduced populations currently exist in the neighboring state of Norway. From here commercial and recreational shipping, as well as passenger ferries travel regularly to destinations within the RAA. The various biological traits described in previous sections, as well as the nature of the currently colonized sites mean that transfer to these vessels and those travelling from other sites internationally is highly likely.

Qu. 1.8. Estimate the overall likelihood of introduction into the risk assessment area based on all pathways and specify if different in relevant biogeographical regions in current conditions.

Provide a thorough assessment of the risk of introduction in relevant biogeographical regions in current conditions: providing insight in to the risk of introduction into the Union.

RESPONSE Very likely CONFIDENCE High

Response: Introductions have occurred to the UK and Ireland within the last 10 years. Most records were from locations associated with shipping and recreational boating activity suggesting shipping is a major vector (Loxton et al 2017; Ryland et al 2014). It has not yet been possible to ascertain the source population of these invasions, it is therefore difficult to say with certainty whether the route by which the species arrived in the UK would be likely to reoccur or that it would be a potential route that would impact other member states. The population now present in Norway (Porter et al 2015) does represent a potential source population with a high likelihood of transportation into the European Union.

Introductions via shellfish is considered less likely due to relevant legislation and restrictions in place regarding the movement of shellfish from outside the EU. This may be possible for species already present in the union for example Mytilus edulis and Magallana gigas (listed as Crassostrea).

Qu. 1.9. Estimate the overall likelihood of introduction into the risk assessment area based on all pathways in foreseeable climate change conditions?

Thorough assessment of the risk of introduction in relevant biogeographical regions in foreseeable climate change conditions: explaining how foreseeable climate change conditions will influence this risk.

With regard to climate change, provide information on

 the applied timeframe (e.g. 2050/2070)  the applied scenario (e.g. RCP 4.5)  what aspects of climate change are most likely to affect the likelihood of introduction (e.g. change in trade or user preferences) The thorough assessment does not have to include a full range of simulations on the basis of different climate change scenarios, as long as an assessment of likely introduction within a medium timeframe scenario (e.g. 30-50 years) with a clear explanation of the assumptions is provided. However, if new, original models are executed for this risk assessment, the following RCP pathways shall be applied: RCP 2.6 (likely range of 0.4-1.6°C global warming increase by 2065) and RCP 4.5 (likely range of 0.9-2.0°C global warming increase by 2065). Otherwise, the choice of the assessed scenario has to be explained.

RESPONSE likely CONFIDENCE medium

Response: S. japonica is primarily considered to be a cold-water species (Loxton et al 2017) however records of reproducing populations from Malaysia (Taylor and Tan 2015) suggest a far higher temperature tolerance with temperatures of up to 30 0C being suitable for growth and reproduction. It is therefore considered likely that temperature increases predicted under both RCP 2.6 and RCP 4.5 would be unlikely to change the potential for the species to be introduced by the pathways described.

It is possible that with melting sea ice caused by increasing temperatures, new Arctic trade routes may open up, increasing the likelihood that non-native species might be introduced by shipping (Miller & Ruiz 2014). If this were to happen, the established, non-native Alaskan population of S. japonica, present in and around harbours but also in wild habitats – might become a source population, being transported by commercial vessels. Such change would certainly increase the likelihood of introduction to the North Sea and Celtic Seas in particular, but additional regions may be vulnerable, depending on the nature of novel shipping routes.

2 PROBABILITY OF ENTRY Important instructions:  Entry is the release/escape/arrival in the environment, i.e. occurrence in the wild. Entry is not to be confused with spread, the movement of an organism within the risk assessment area.  The classification of pathways developed by the Convention of Biological Diversity (CBD) should be used. For detailed explanations of the CBD pathway classification scheme consult the IUCN/CEH guidance document4 and the provided key to pathways5.  For organisms which are already present in the risk assessment area, only complete this section for current active or if relevant potential future pathways. This section need not be completed for organisms which have entered in the past and have no current pathway of entry.

Qu. 2.1. List relevant pathways through which the organism could enter into the environment.

For each pathway answer questions 2.2 to 2.7 (copy and paste additional rows at the end of this section as necessary). Please attribute unique identifiers to each question if you consider more than one pathway, e.g. 2.2a, 2.3a, etc. and then 2.2b, 2.3b etc. for the next pathway.

In this context a pathway is the route or mechanism of entry of the species into the environment.

If there are no active pathways or potential future pathways this should be stated explicitly here, and there is no need to answer the questions 2.2-2.8

Pathway name: Transport: Contaminant - Contaminant on animals

Qu. 2.2a. Is entry into the environment intentional (e.g. the organism is released for a specific purpose) or unintentional (e.g. the organism escapes from a confinement)?

RESPONSE unintentional CONFIDENCE high

Response: For introduction summary see 1.2a. If infected bivalves are grown in open systems or laid in wild growing sites, the invading, hitchhiking species will have ‘entered into the environment’.

Qu. 2.3a. How likely is it that large numbers of the organism will enter into the environment along this pathway from the point(s) of origin over the course of one year?

4 https://circabc.europa.eu/sd/a/738e82a8-f0a6-47c6-8f3b-aeddb535b83b/TSSR-2016- 010%20CBD%20categories%20on%20pathways%20Final.pdf 5 https://circabc.europa.eu/sd/a/0aeba7f1-c8c2-45a1-9ba3-bcb91a9f039d/TSSR-2016- 010%20CBD%20pathways%20key%20full%20only.pdf 20

including the following elements:  discuss how likely the organism is to get onto the pathway in the first place. Also comment on the volume of movement along this pathway.  an indication of the propagule pressure (e.g. estimated volume or number of individuals / propagules, or frequency of passage through pathway), including the likelihood of reinvasion after eradication  if relevant, comment on the likelihood of entry into the environment based on propagule pressure (i.e. for some species low propagule pressure (1-2 individuals) could result in entry whereas for others high propagule pressure (many thousands of individuals) may not).

RESPONSE moderately likely CONFIDENCE medium

Response: Schizoporella japonica is known to attach to a wide range of substrates, including shellfish and finfish aquaculture equipment as well as a range of other structures (Collin et al 2015). This has the potential to place a source of propagules in close proximity to bivalves in culture, which might be transported into the RAA. There is substantial evidence to suggest that the species will attach and grow readily on living bivalves, including oysters (see examples in Loxton et al 2017). The species is hermaphroditic and reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement (Ryland et al 2014). These traits make contamination of shellfish stored in close proximity to colonies of S. japonica likely. Once settlement takes place, individuals reproduce and spread by budding asexually to form sheets Therefore, the successful settlement, development and growth of an individual on a transporting organism can result in a high level of propagule potential.

Qu. 2.4a. How likely is the organism to enter into the environment within the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

Qu. 2.5a. How likely is the organism to enter into the environment during the months of the year most appropriate for establishment?

RESPONSE very likely CONFIDENCE high

Response: S. japonica reproduces year round (Ryland et al 2014; Loxton et al. 2017; Treiburgs 2012) and therefore has the potential to spread and become established at any time of the year. It has been suggested that the ability of S. japonica to reproduce and remain active during colder periods may provide a competitive edge over some species, which become dormant over winter, suggesting this might be the most appropriate time for establishment (Loxton et al 2017; Ryland et al 2014).

Qu. 2.6a. How likely is the organism to be able to transfer from the pathway to a suitable habitat or host in the environment?

RESPONSE very likely CONFIDENCE high

Qu. 2.7a. Estimate the overall likelihood of entry into the environment within the risk assessment area based on this pathway?

RESPONSE likely CONFIDENCE high

Response: although transport to the RAA via this pathway is consider unlikely due to legal constraints, if transportation does occur, arrival would be very likely due to the nature of bivalve culture operations, which usually occur in open systems or in wild settings, providing a proliferation of suitable habitat within natural dispersal distance. As discussed, the year-round reproductive potential of S. japonica gives it the potential to become established at any time of the year through release of propagules.

End of pathway assessment, repeat Qu. 2.2 to 2.7. as necessary using separate identifier.

Pathway name: Transport: Stowaway - Ship/boat hull fouling

Qu. 2.2b. Is entry into the environment intentional (e.g. the organism is released for a specific purpose) or unintentional (e.g. the organism escapes from a confinement)?

RESPONSE unintentional CONFIDENCE high

Response: Schizoporella japonica is known to attach to and colonize a range of man-made structures including the hulls of commercial vessels, ferries and recreational vessels (Collin et al 2015; Ryland et al 2014; Bishop et al 2015). The apparently wide, discontinuous distribution around the UK, with records primarily from within marinas (Bishop et al 2015) suggests a connection with recreational vessels and may represent multiple introductions via this pathway or, more likely multiple examples of human mediated spread from sites within the RAA. It is also known to colonize marina pontoons, fenders and other structures likely to occur in the vicinity of vessels. Global shipping and recreational boat travel takes place between areas from which the species is known and ports, harbours and marinas within the RAA. Hull fouling has been implicated in the spread of the species globally and to the UK, Ireland and Norway (Ashton et al 2014; Loxton et al 2017). The current concentration of records in and in close proximity to structures associated with recreational and commercial shipping, coupled with the species’ low natural dispersal potential is further evidence to suggest that hull fouling is a primary vector.

Qu. 2.3b. How likely is it that large numbers of the organism will enter into the environment along this pathway from the point(s) of origin over the course of one year? including the following elements:  discuss how likely the organism is to get onto the pathway in the first place. Also comment on the volume of movement along this pathway.  an indication of the propagule pressure (e.g. estimated volume or number of individuals / propagules, or frequency of passage through pathway), including the likelihood of reinvasion after eradication  if relevant, comment on the likelihood of entry into the environment based on propagule pressure (i.e. for some species low propagule pressure (1-2 individuals) could result in entry whereas for others high propagule pressure (many thousands of individuals) may not).

RESPONSE moderately likely CONFIDENCE medium

Response: Schizoporella japonica is known to attach to and colonize a range of man-made structures including the hulls of commercial vessels, ferries and recreational vessels (Collin et al 2015; Ryland et al 2014; Bishop et al 2015). It is also known to colonize marina pontoons, fenders and other structures likely to occur in the vicinity of vessels, Global shipping and recreational boat travel takes place

between areas from which the species is known and ports, harbours and marinas within the RAA on a regular basis.

The current concentration of records in and in close proximity to structures associated with recreational and commercial shipping (Loxton et al 2017), suggest a potential source of propagules. The species is hermaphroditic and reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement, (Ryland et al 2014) giving time for the ciliated larvae to move between structures and moored vessels. These traits make attachment to the hulls of vessels moored in close proximity to colonies of S. japonica likely. Once settlement takes place, individuals reproduce and spread by budding asexually to form sheets. Therefore, the successful settlement, development and growth of an individual on man-made object such as a vessel hull can result in a high level of propagule potential.

Qu. 2.4b. How likely is the organism to enter into the environment within the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

Response: Ancestrula measure 350-400 x ~300 μm (Ryland et al 2014) and at this stage are extremely difficult to detect. A single ancestrula can develop and reproduce asexually to form colonies of hermaphroditic, reproductive individuals. Developed colonies are easier to detect measuring several centimetres across and being bright orange. However, confusions over identification and the large number of taxonomically similar native species reduce the likelihood that the species will be identified and intercepted except by experts. Mobile larvae are microscopic and therefore very unlikely to be detected without specialist sampling, equipment and expertise.

Qu. 2.5b. How likely is the organism to enter into the environment during the months of the year most appropriate for establishment?

RESPONSE likely CONFIDENCE high

Response: Response: S. japonica reproduces year round (Ryland et al 2014; Loxton 2017; Treiburgs 2012) and therefore has the potential to spread and become established at any time of the year. It has been suggested that the ability of S. japonica to reproduce and remain active during colder periods may provide a competitive edge over some species, which become dormant over winter, suggesting this might be the optimal time for establishment (Loxton et al 2017; Ryland et al 2014). Conversely this is the time of year when recreational boat users are less active and the likelihood of arrival by this particular pathway might be slightly reduced.

Qu. 2.6b. How likely is the organism to be able to transfer from the pathway to a suitable habitat or host in the environment?

RESPONSE very likely CONFIDENCE high

Response: Non-feeding ciliated larvae are brooded and released from ovicells, these larvae persist for only a few hours (Loxton et al 2017), but during this time are able to transfer from vessel hull to an adjacent surface. Multiple hard substrates have proved a suitable habitat for settlement and growth, including equipment and structures associated with commercial and recreational shipping and natural hard substrate, such as shell, rock and boulders (see review in Loxton et al 2017), which are all likely to be found in the vicinity of many marinas and ports. In some instances recreational vessels might moor in natural areas, adjacent to suitable natural substrate or a secondary structure such as a chain, rope or buoy, where propagules might be deposited leading to growth of new colonies.

Qu. 2.7b. Estimate the overall likelihood of entry into the environment within the risk assessment area based on this pathway?

RESPONSE very likely CONFIDENCE high

Response: Once transported into the RAA via this pathway, the nature of recreational and commercial shipping activities means that arrival in the natural environment is very likely. Shipping takes place in open systems, putting fouling colonies of S. japonica in close proximity to suitable habitat. Once in a suitable place propagules are able to travel the short distance to nearby suitable habitat. Such habitat might be a fully natural substrate or man-made object, which might provide a ‘stepping stone’ for the species to colonize adjacent natural habitat.

End of pathway assessment, repeat Qu. 2.2 to 2.7. as necessary using separate identifier.

Qu. 2.8. Estimate the overall likelihood of entry into the environment within the risk assessment area based on all pathways in current conditions and specify if different in relevant biogeographical regions.

Provide a thorough assessment of the risk of entry into the environment in relevant biogeographical regions in current conditions.

RESPONSE Very likely (North-East CONFIDENCE High (North-East Atlantic) Atlantic)

Likely (Black Sea) Medium (Black Sea) Unlikely (Iberian coast, Medium (Iberian coast, Mediterranean) Mediterranean)

Response: Schizoporella japonica is known to attach to and colonize a range of man-made structures including the hulls of commercial vessels, ferries and recreational vessels (Collin et al 2015; Ryland et al 2014; Bishop et al 2015). It is also known to colonize marina pontoons, fenders and other structures likely to occur in the vicinity of vessels. Global shipping and recreational boat travel takes place between areas from which the species is known and ports, harbours and marinas within the RAA.

Hull fouling has been implicated in the spread of the species globally and to the UK, Ireland and Norway (Ashton et al. 2014; Loxton et al. 2017). The current concentration of records in and in close proximity to structures associated with recreational and commercial shipping, coupled with the species’ low natural dispersal potential is further evidence to suggest that is a primary vector. The potential for S. japonica to enter the environment from imported shellfish once transported is considered very likely. However the likelihood of introduction via this particular pathway is not clear due to the legal barriers described in section 2.2.

An additional consideration is that, due to the sessile nature of adults, in order for entry to take place after introduction via the pathways discussed, conditions must be suitable for reproduction. This would mean that Entry might be unlikely in the Mediterranean and along the southern Iberian coastline, which are currently outside the known tolerable salinity range and at the top end of the temperature tolerance for the species. Hull-fouling colonies would need to survive travel across the Mediterranean basin – which would expose colonies to unfavourable conditions - in order to arrive in the Black Sea via the hull fouling pathway. It is therefore considered less likely that entry will take place in the Black Sea, although the ability of the species to survive these less favourable conditions for short periods of time is not well studied and confidence is therefore considered to be medium.

Qu. 2.9. Estimate the overall likelihood of entry into the environment within the risk assessment area based on all pathways in foreseeable climate change conditions and specify if different in relevant biogeographical regions.

Thorough assessment of the risk of entry in relevant biogeographical regions in foreseeable climate change conditions: explaining how foreseeable climate change conditions will influence this risk, specifically if likelihood of entry is likely to increase or decrease for specific pathways.

RESPONSE Very likely (North-East CONFIDENCE High (North-East Atlantic) Atlantic)

Likely (Black Sea) Low (Black Sea) Unlikely Low (Mediterranean) (Mediterranean)

Response: Based on future warming scenarios RCP 2.6 (likely range of 0.4-1.6°C global warming increase by 2065) and RCP 4.5 (likely range of 0.9-2.0°C global warming increase by 2065). The maximum temperature for survival is likely to be exceeded in some parts of the Mediterranean (southern Italy, areas around the Balearics and areas outside the RAA). As entry potential in these areas is likely to already be limited by salinity levels in the area, this does not represent a significant change under these scenarios (see maps in Appendix 1). There is potential that these changes may increase the likelihood of mortality during transport through the Mediterranean, however the extent to which this will reduce the risk of entry further in the Black Sea cannot be predicted with certainty based on current available knowledge. The potential reduced salinity in the Iberian oast region (see A7b) suggests that this region may become habitable under future scenarios.

Other than the differences described above, the likelihood of entry and confidence are the same for future scenarios as described in 2.8.

3 PROBABILITY OF ESTABLISHMENT Important instructions:  For organisms which are already established in parts of the risk assessment area, answer the questions with regard to those areas, where the species is not yet established.

Qu. 3.1. How likely is it that the organism will be able to establish in the risk assessment area based on the history of invasion by this organism elsewhere in the world (including similarity between other abiotic conditions within it and the organism’s current distribution)?

RESPONSE very likely CONFIDENCE High (northern)- Medium (southern)

Response: It is considered very likely that S. japonica will be able to become established if introduced throughout the Greater North Sea region, Celtic Seas, Bay of Biscay and the northern Iberian coast. It is also possible that establishment may occur in the Black Sea although introduction is considered far less likely. Salinity is within the 15 – 36ppt range, in which S. japonica is able to survive and reproduce (Loxton et al 2017) throughout this area, whilst the southern Iberian coast and Mediterranean exhibit higher salinities than this, reducing the likelihood of establishment if introduced. Levels of salinity in the Baltic region fall below those currently known to support the species, making establishment in this region unlikely.

Temperatures throughout the RAA are within the known tolerable range for S. japonica to survive and reproduce, considered to be -1.4 to 30oC (Loxton et al 2017, CABI 2019). This suggests that temperature is unlikely to be a factor limiting the establishment of the species. It has been observed that reproduction takes place throughout the year under colder conditions (7-15oC) (Treibergs 2012; Ryland et al 2014; Loxton 2014) and establishment patterns seem to show a faster rate of establishment in colder regions of the UK as opposed to warmer ones (Loxton et al 2017). The authors were unable to find information about reproductive rates under warmer conditions, but it is possible, based on evidence from the UK that establishment may be slower in southern, warmer regions and that temperature may play a role.

Qu. 3.2. How widespread are habitats or species necessary for the survival, development and multiplication of the organism in the risk assessment area?

RESPONSE ubiquitous CONFIDENCE high

Response: Schizoporella japonica is able to grow successfully on a range of hard substrates, including man-made objects - such as sea defences, pontoons, jetties and vessels – as well as natural hard substrates - such as shell, loose rock and bed rock (Loxton et al 2017). It is able to colonies 28

floating objects as well as shallow subtidal and intertidal habitat. Suitable habitat is therefore considered ubiquitous throughout the RAA.

Qu. 3.3. If the organism requires another species for critical stages in its life cycle then how likely is the organism to become associated with such species in the risk assessment area?

RESPONSE N/A CONFIDENCE high

Response: S. japonica is not dependent on any other organism at any stage of its lifecycle.

Qu. 3.4. How likely is it that establishment will occur despite competition from existing species in the risk assessment area?

RESPONSE likely CONFIDENCE medium

Response: S. japonica displays a number of traits, which makes it a highly competitive species, capable of colonizing areas quickly once introduced. It broods larvae (Dick et al 2005) providing protection during early stages in development. Once released, larvae travel only a short distance before settlement occurs and individuals reproduce asexually by budding, forming extensive colonies enabling rapid colonization of areas. The species has been shown to outcompete native bryozoan species in Alaska (Dick et al 2005). It is capable of overgrowing a number of native species, including mussels and other bryozoan species, causing mortality in some cases (Treibergs 2012; Macleod et al 2016). It has also been suggested that the ability of S. japonica to reproduce and develop colonies in cold conditions may provide a competitive edge against species which become dormant over winter, enabling space to be occupied. Efforts to clear pontoons in Holyhead Marina, Wales, UK led to colonization of cleared substrate by the species (Ryland et al 2014) demonstrating its ability to competitively colonize newly cleared areas. Colonies persisted in these areas beyond 18 months (Christine Wood and John Bishop observation reported in Loxton et al 2017) further illustrating the potential for the species to persist once settled and become established. Similarly a new marina in Plymouth was rapidly colonized in 2012 and the population is still present in 2019 (personal observation by author).

Qu. 3.5. How likely is it that establishment will occur despite predators, parasites or pathogens already present in the risk assessment area?

RESPONSE likely CONFIDENCE Low

Response: Little information could be found to suggest that establishment by S. japonica would be limited by predators, parasites or pathogens. However, new recruits may be vulnerable to predation by predatory and grazing invertebrates immediately after metamorphosis and attachment to the substrate. For example, predation by flatworms of embryos and larvae still in ovicells has been observed in the field (Gordon 1972; Treibergs 2012). The extent to which this might impact establishment is not clear, but patterns of previous successful establishments (for example Loxton et al 2017; Ryland et al 2014 and Treibergs 2012) suggest that at least in some areas, this is not likely to be a factor preventing establishment throughout the whole RAA.

Qu. 3.6. How likely is the organism to establish despite existing management practices in the risk assessment area?

RESPONSE very likely CONFIDENCE high

Response: At present, no or little legislation exists, which requires marina or harbour structures or equipment to be cleared of fouling or treated to prevent fouling taking place. Whilst some vessel owners do carry out cleaning and treatment of vessels, which may reduce introduction, establishment is unlikely to be impaired. Moreover, management efforts to eradicate another fouling, invasive species Didemnum vexillum in Holyhead Marine, Wales, UK actually seemed to promote the settlement and establishment of S. japonica (Ryland et al 2014) suggesting other measures to manage fouling species may have the unintended impact of increasing likelihood of establishment.

Establishment within aquaculture sites is less likely due to the legislation previously mentioned in 1.5a.

Qu. 3.7. How likely are existing management practices in the risk assessment area to facilitate establishment?

RESPONSE moderately likely CONFIDENCE medium

Response: Management efforts to eradicate another fouling, invasive species Didemnum vexillum in Holyhead Marine, Wales, UK actually seemed to promote the settlement and establishment of S. japonica (Ryland et al 2014) suggesting other measures to manage fouling species may have the unintended impact of increasing likelihood of establishment.

Qu. 3.8. How likely is it that biological properties of the organism would allow it to survive eradication campaigns in the risk assessment area?

RESPONSE likely CONFIDENCE High

Response: The difficulties distinguishing the species from other bryozoans and the small size at settlement – S. japonica ancestrula measure 350-400 x ~300 μm (Ryland et al 2014) – make it highly likely that targeted physical removal measures will be of limited success. Physical removal of colonies by scraping would probably fragment the brittle encrustations, which could lead to increased spread as any fragments not captured could be dispersed, potentially releasing larvae elsewhere. Moreover, the ability of S. japonica to rapidly colonize newly cleared areas, as demonstrated, following the removal of the invasive ascidian Didemnum vexillum from a marina in North Wales (Ryland et al 2014) means that more general clearance might actually benefit the settlement and competitive dominance of the species.

Qu. 3.9. How likely are the biological characteristics of the organism to facilitate its establishment in the risk assessment area? including the following elements:  a list and description of the reproduction mechanisms of the species in relation to the environmental conditions in the Union  an indication of the propagule pressure of the species (e.g. number of gametes, seeds, eggs or propagules, number of reproductive cycles per year) of each of those reproduction mechanisms in relation to the environmental conditions in the Union. If relevant, comment on the likelihood of establishment based on propagule pressure (i.e. for some species low propagule pressure (1-2 individuals) could result in establishment whereas for others high propagule pressure (many thousands of individuals) may not.

RESPONSE very likely CONFIDENCE high

Response: Once introduced in the RAA and entry in the environment have taken place, the biological characteristics of the species make establishment very likely, particularly in colder regions where reproduction is known to be continuous throughout the year, resulting in a regular flow of propagules from colonized areas.

Colonies begin with a single, sexually produced zooid, which buds asexually to produce sheets - which may be unilamellar or bilamellar depending on conditions and substrate – of hermaphroditic individuals ( Loxton et al 2017). Larvae are brooded in external brood chambers (ovicells) and non- feeding, ciliated (swimming) larvae are released. Once released, larvae have a short dispersal period of a few hours, after which attachment and metamorphosis occurs. This adaptation facilitates colonization locally and explains the rapid appearance of dense colonies, but limits the range of dispersal unless mediated by an additional vector (likely human) once settled. When settlement does

not occur after 24 hours (due to lack of available substrate), laboratory studies have shown that settlement does not take place and larvae are prone to die (Treibergs 2012).

Suitable habitat for settlement is ubiquitous throughout the RAA and a diverse range of solid substrates are suitable for the growth of colonies (Collin et al 2015), meaning that habitat availability is unlikely to be a limiting factor in the establishment of the species. The ability of the species to colonise intertidal hard substrate (Treibergs 2012; Macleod et al 2016)) suggests it would be well adapted to make use of oyster beds (naturalized and maintained), prevalent through much of the RAA but particularly the North Sea region. Records from oysters in the Dutch Wadden Sea (Gittenberger et al., 2019) also support this theory

The wide range of temperatures (-1.4 - 30oC) under which reproduction has been observed in wild colonies (Loxton 2014; Taylor and Tan 2015, CABI 2019) suggests that settlement and establishment would be possible throughout the RAA, however salinity in the Mediterranean, Baltic and southern Iberian coastline falls outside the currently known tolerance window of 15-36ppt. Malaysian records (Taylor and Tan 2015) suggests a maximum tolerance of 30oC based on average ambient sea water temperature locally. However, the majority of information regarding the reproductive ability of the species is from cooler areas and the authors could not find further details of reproductive ability in conditions exceeding 19oC. The ability of the species to become established in warmer areas is therefore less certain.

Studies have shown that S. japonica is sensitive to high levels of turbidity, with presence showing a negative correlation with turbidity in colonization studies and with a zero probability of colonization at values exceeding 30 NTU (Treibergs 2012) which may further restrict colonization in some areas.

Qu. 3.10. How likely is the adaptability of the organism to facilitate its establishment?

RESPONSE moderately likely CONFIDENCE high

Response: Schizoporella japonica is very unusual among the bryozoa in its ability to generate multiple ovicells on an individual zooid. It has been proposed that this may be an aberration caused by pollution (Powell 1970) or a naturally occurring modification (Loxton et al 2017), which may enhance reproductive output in less favourable conditions or in founding populations.

The wide temperature range (-1.4 - 30oC) which can be tolerated by the species (Loxton et al 2017; Loxton 2014; Taylor and Tan 2015, CABI 2019) and ability to colonize a wide variety of biotic, abiotic and man-made substrates (Loxton et al 2017) demonstrates adaptability to extremely variable conditions. As does its demonstrated ability to rapidly colonize newly cleared areas (Ryland et al 2014) .

Qu. 3.11. How likely is it that the organism could establish despite low genetic diversity in the founder population?

RESPONSE likely CONFIDENCE medium

Response: There is no reason to suppose that low genetic diversity would inhibit the ability of the species to become established. S. japonica is characterized as being hermaphroditic and having brooded, ciliated, coronate larva, which do not spend long in the water column and therefore travel only short distances before attachment and metamorphosis (Loxton et al 2017). Other species of bryozoan sharing this liffe-history trait (as opposed to releasing cyphonautes larvae, which spend a greater amount of time in the plankton and disperse over greater distances) tend to exhibit low genetic differentiation (Watts and Thorpe 2006). Its ability to reproduce asexually by budding means that individual animals can grow to cover large areas, and potentially spread to other areas via fragmentation.

Qu. 3.12. If the organism does not establish, then how likely is it that casual populations will continue to occur? Consider, for example, a species which cannot reproduce in the risk assessment area, because of unsuitable climatic conditions or host plants, but is present because of recurring introduction, entry and release events. This may also apply for long-living organisms.

RESPONSE likely CONFIDENCE high

Response: Considering that S. japonica is able to produce propagules year round (Loxton et al 2017) and that there is regular movement of recreational and commercial vessels between sites populated and other areas within the RAA, it is likely that introductions will continue to be transported into new areas within the RAA or to be re-introduced in areas multiple times. The pattern of records in Plymouth, UK suggests multiple introductions following an initial record from 2009 (Loxton et al 2017 and author observations).

Qu. 3.13. Estimate the overall likelihood of establishment in the risk assessment area based on the similarity between climatic conditions within it and the organism’s current distribution under current climatic conditions. In addition, details of the likelihood of establishment in relevant biogeographical regions under current climatic conditions should be provided. Thorough assessment of the risk of establishment in relevant biogeographical regions in current conditions: providing insight in the risk of establishment in (new areas in) the Union.

RESPONSE very likely CONFIDENCE high

Response: Schizoporella japonica has become established within northern parts of the RAA (North of Scotland, North Wales, South-West England) and neighboring Norway (Loxton et al 2017), there are large parts of the RAA with very similar climatic conditions and habitat to these areas, throughout the Greater North Sea and Celtic Seas regions. Sea temperature and habitat availability are extremely similar in the known range of S. japonica on the west coast of the America (Alaska to California) (Dick et al 2005), to the Celtic Seas, Greater North Sea, Iberian Coast and Bay of Biscay. Salinity is also similar, although south of Bilbao, Spain and into the Mediterranean region levels exceed those in the current known USA range and known tolerances of the species, suggesting that establishment would be less likely in these areas. It is important to note however that given uncertainty over the taxonomy of the species, the full native and introduced range of the species globally may not be completely known. The more recent records from Malaysia (Taylor and Tan 2015) illustrate this well, as the records were from an area where the known ambient water temperature exceeded that known from the current introduced range by approximately 10oC. Illustrating the need for caution when predicting the potential range of a species that is so little known and apparently tolerant of such a wide range of conditions.

Qu. 3.14 Estimate the overall likelihood of establishment in the risk assessment area under foreseeable climate change conditions. In addition, details of the likelihood of establishment in relevant biogeographical regions under foreseeable climate change conditions should be provided. Thorough assessment of the risk of establishment in relevant biogeographical regions in foreseeable climate change conditions: explaining how foreseeable climate change conditions will influence this risk. With regard to climate change, provide information on  the applied timeframe (e.g. 2050/2070)  the applied scenario (e.g. RCP 4.5)  what aspects of climate change are most likely to affect the likelihood of establishment (e.g. increase in average winter temperature, increase in drought periods) The thorough assessment does not have to include a full range of simulations on the basis of different climate change scenarios, as long as an assessment of likely establishment within a medium timeframe scenario (e.g. 30-50 years) with a clear explanation of the assumptions is provided. However, if new, original models are executed for this risk assessment, the following RCP pathways shall be applied: RCP 2.6 (likely range of 0.4-1.6°C global warming increase by 2065) and RCP 4.5 (likely range of 0.9-2.0°C global warming increase by 2065). Otherwise, the choice of the assessed scenario has to be explained.

RESPONSE likely CONFIDENCE low

Response: Based on known range and tolerances, it is likely that the area in which S. japonica might become established will be limited primarily by salinity, which is higher south of Bilbao, Spain than the salinity levels in the known current distributional range. The entire RAA is currently within the known tolerable temperature window for the species and will remain so even under future climate change scenarios (RCP 2.6 and RCP 4.5). However, as discussed in 3.13, patterns of establishment so far in the RAA suggest that colder conditions are preferable, possibly due to an increased competitive 34

advantage over ‘winter dormant’ species (Loxton et al 2017). If this is the case, warming seas may decrease the range at which this competitive edge is attained. However, not enough is understood about the parameters under which this might operate to make any accurate estimates.

4 PROBABILITY OF SPREAD Important instructions:

 Spread is defined as the expansion of the geographical distribution of an alien species within the risk assessment area.  Repeated releases at separate locations do not represent continuous spread and should be considered in the probability of entry section. In other words, intentional anthropogenic “spread” via release or escape (“jump-dispersal”), should be dealt within the entry section. However, as repeated releases contribute to the spread of the target organism in the risk assessment area, the relevant pathway(s) should be briefly discussed here too, with an explicit reference to the entry section for additional details.

Qu. 4.1. How important is the expected spread of this organism within the risk assessment area by natural means? (List and comment on each of the mechanisms for natural spread.) including the following elements:  a list and description of the natural spread mechanisms of the species in relation to the environmental conditions in the risk assessment area.  an indication of the rate of each of those spread mechanisms in relation to the environmental conditions in the Union. The description of spread patterns should include elements of the species life history and behavioural traits able to explain its ability to spread, including: reproduction or growth strategy, dispersal capacity, longevity, dietary requirements, environmental and climatic requirements, specialist or generalist characteristics.

RESPONSE Moderate CONFIDENCE medium

Response:

Natural larval dispersal

S. japonica is hermaphroditic and produces brooded, ciliated, coronate larva, which do not spend long in the water column and therefore travel only short distances before attachment and metamorphosis (Loxton et al 2017). It is therefore likely that natural spread throughout the RAA will be slow and may be restricted by ‘barriers’ such as stretches of unsuitable habitat or unfavourable current flows (Watts & Thorpe 2006).

Rafting

Schizporella japonica is known to attach to debris and flotsam and to travel long distances by this method. For example, following the Japanese Tsunami in 2011, colonies of living S. japonica (alive with embryos) were identified on objects originating in Japan and found on the Hawaiian Islands and North American coast after traversing the Pacific Ocean (and Carlton 2018 ). It is therefor possible that colonies may develop on natural objects which may become flotsam, providing a pathway of spread.

Hitchhiking on mobile species

No examples could be found of S. japonica colonizing mobile fauna specifically, however similar species are known to grow on the exoskeletons of crabs (e.g. Hyas areneus, Maja squinado, Cancer pagurus), many species of which exist in the RAA and move or migrate significant distances throughout the RAA. The ability of S. japonica to colonies such a wide range of substrates, including shellfish, suggests that spread by this vector is possible.

Qu. 4.2. How important is the expected spread of this organism within the risk assessment area by human assistance? (List and comment on each of the mechanisms for human-assisted spread and provide a description of the associated commodities.) including the following elements:  a list and description of the anthropogenic spread mechanisms of the species in relation to the environmental conditions in the Union.  an indication of the rate of each of those spread mechanisms in relation to the environmental conditions in the Union.

RESPONSE major CONFIDENCE medium

Response: Due to the limited natural dispersal potential of the species, it is believed that spread will be largely dependent on human facilitation. Many of these methods are described by Loxton et al (2017).

Transport: Stowaway - Ship/boat hull fouling (Movement of recreational vessels, ferries and commercial vessels)

Many of the existing Atlantic records of S. japonica are in or around recreational and commercial boating facilities (Loxton et al 2017), suggesting that the likelihood of propagules settling on vessels visiting these areas is high. There are many well used sailing routes connecting colonized and not-yet- colonized sites around the RAA (Loxton et al 2017), and given the year-round larval release exhibited by the species, the chances of settlement during busy times of the year is very high. Additionally, there are numerous passenger ferry and shipping routes connecting Scotland with the rest of the RAA providing additional modes of spread.

Transport: Stowaway Machinery/ Equipment (Movement of equipment associated with aquaculture and renewable energy structures)

As the demand for renewable energy increases, there are increasing numbers of marine structures associated with the industry, particularly on the Scottish coast. Nall (2015) studied such structures and found that they provided an ideal habitat for colonization by S. japonica. It was also discovered that many structures associated with offshore renewables are stored for significant periods of time in ports known to hold populations of S. japonica before being transported elsewhere for deployment (Loxton et al 2017). Such practices present a clear potential vector for spreading fouling species such as S. japonica.

Transport: Contaminant - Contaminant on animals (Transfer of live shellfish)

The primary introduction of S. japonica outside its native range is believed to have been as a result of accidental transportation with the commercially grown oyster Magallana (was Crassostrea) gigas when the species was exported during the early twentieth century from Japan to the west coast of North America (Loxton et al 2017) . Records of S. unicornis (considered likely to be) from Australia were reported following the introduction of Pacific oysters (Dick et al 2005). Although bivalve introductions are now carefully regulated to minimize the risk of importation of contaminated stock, introduction to member states via movements of shellfish between sites is possible. Additionally, introduction of contaminated stock to neighboring countries with different levels of control in place is feasible.

Shellfish, such as oysters mussels, scallops, cockles and clams are grown in open systems and transported between sites for on-growing throughout the RAA, currently movement within and between states is possible in most cases and there is certainly potential for colonized shellfish to become a vector of spread for organisms like S. japonica. Many operations notably take place on the coast of Scotland and North Wales.

Stowaway: Attachment to floating debris

It is known to attach to debris and flotsam and to travel long distances by this method, for example following the Japanese Tsunami in 2011, colonies of living (alive with embryos) were identified on objects originating in Japan and found on the Hawaiian Islands and North America after traversing the Pacific Ocean (McCuller and Carlton 2018 ). It is therefore possible that colonies may develop on drifting plastic, lost fishing equipment and other man-made objects which may become flotsam, providing a pathway of spread within the RAA. With an increase in drifting marine litter, this potential vector is becoming increasingly prevalent.

Qu. 4.2a. List and describe relevant pathways of spread. Where possible give detail about the specific origins and end points of the pathways. For each pathway answer questions 4.3 to 4.9 (copy and paste additional rows at the end of this section as necessary). Please attribute unique identifiers to each question if you consider more than one pathway, e.g. 4.3a, 4.4a, etc. and then 4.3b, 4.4b etc. for the next pathway. including the following elements:  a list and description of pathways with an indication of their importance and associated risks (e.g. the likelihood of spread in the Union, based on these pathways; likelihood of survival, or reproduction, or increase during transport and storage; ability and likelihood of transfer from the pathway to a suitable habitat or host). Where possible details about the specific origins and end points of the pathways shall be included.  an indication of the propagule pressure (e.g. estimated volume or number of specimens, or frequency of passage through pathway), including the likelihood of reinvasion after eradication.  All relevant pathways should be considered. The classification of pathways developed by the Convention of Biological Diversity shall be used.

Pathway name: Transport: Stowaway - Ship/boat hull fouling (Movement of recreational vessels, ferries and commercial vessels)

Qu. 4.3a. Is spread along this pathway intentional or unintentional (e.g. the organism is a contaminant of translocated goods within the risk assessment area)?

RESPONSE unintentional CONFIDENCE high

Response: Many of the existing Atlantic records of S. japonica are in or around recreational and commercial boating facilities (Loxton et al 2017), suggesting that the likelihood of propagules settling on vessels visiting these areas is high. There are many well used sailing routes connecting colonized and not-yet-colonized sites around the RAA (Loxton et al 2017) and given the year-round larval release exhibited by the species, the chances of settlement during busy times of the year is very high. Additionally, there are numerous passenger ferry and shipping routes connecting Scotland with the rest of the RAA providing additional modes of spread.

Qu. 4.4a. How likely is it that a number of individuals sufficient to originate a viable population will spread along this pathway from the point(s) of origin over the course of one year? including the following elements:  an indication of the propagule pressure (e.g. estimated volume or number of specimens, or frequency of passage through pathway), including the likelihood of reinvasion after eradication  if appropriate, indicate the rate of spread along this pathway  if appropriate, include an explanation of the relevance of the number of individuals for spread with regard to the biology of species (e.g. some species may not necessarily rely on large numbers of individuals).

RESPONSE very likely CONFIDENCE high

Response: Schizoporella japonica is known to attach to and colonize a range of man-made structures including the hulls of commercial vessels, ferries and recreational vessels (Collin et al 2015; Ryland et al 2014; Bishop et al 2015). It is also known to colonize marina pontoons, fenders and other structures likely to occur in the vicinity of vessels. Global shipping and recreational boat travel takes place between areas from which the species is known and ports, harbours and marinas within the RAA on a regular basis.

The species is present in a number of busy port and marina areas (Scottish Northern Isles, wider Scotland and northern England, North Wales, Plymouth and East coast of Ireland) (Loxton et al. 2017), which host passenger ferries, commercial vessels and recreational vessels travelling throughout the RAA on a regular basis. These movements provide ample opportunity for transportation within the RAA from existing invaded populations.

The species is hermaphroditic and reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement, (Ryland et al 2014) giving time for the ciliated larvae to move between structures and moored vessels, these traits make attachment to the hulls of vessels moored in close proximity to colonies of S. japonica likely. Once settlement takes place, individuals reproduce and spread by budding asexually to form sheets..

Qu. 4.5a. How likely is the organism to survive, reproduce, or increase during transport and storage along the pathway (excluding management practices that would kill the organism)?

RESPONSE very likely CONFIDENCE high

Response: Based on previous introductions, S. japonica has a very high potential to survive transportation attached to vessel hulls (Ashton et al 2014; Loxton et al 2017). The survivable temperature range is high (-1.4 - 30oC ) (Loxton et al 2017, CABI 2019). Reproduction through asexual budding and colony growth is likely provided conditions are favourable and sexual reproduction (which takes place year round) is also likely.

Qu. 4.6a. How likely is the organism to survive existing management practices during spread?

RESPONSE likely CONFIDENCE Medium

Response: Hull cleaning is an often practiced method of defouling ship hulls and has the potential to physically remove colonies of S. japonica, which would in turn reduce the risk of spread. However the practice is not legally required, particularly for vessels moving within the RAA and can be financially costly making it very likely that vessels traveling between contaminated and uncontaminated marinas and ports will not have been treated. In addition, complete removal of colonies is unlikely due to their brittleness, small fragments may remain or be dispersed.

Qu. 4.7a. How likely is the organism to spread in the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

Response: Ancestrula measure 350-400 x ~300 μm (Ryland et al 2014) and at this stage are extremely difficult to detect. A single ancestrula can develop and reproduce asexually to form colonies of hermaphroditic, reproductive individuals. Developed colonies are easier to detect measuring several centimetres across and being bright orange. However, confusions over identification and the large number of taxonomically similar native species reduce the likelihood that the species will be identified and intercepted except by experts. The use of regular eDNA monitoring in marinas and harbours could improve early detection, however to-date, the method does not appear to have been trialled for this particular species and it is impossible at present to provide the environmental conditions and population density that would be required at a site in order for this to be effective.

Qu. 4.8a How likely is the organism to be able to transfer from the pathway to a suitable habitat or host during spread? (including, where possible, details about the specific origins and end points of the pathway)

RESPONSE very likely CONFIDENCE high

Response: Non-feeding ciliated larvae are brooded and released from ovicells, these larvae persist for only a few hours (Loxton et al 2017) and Maximum 24 hours (Treibergs 2012), but during this time are able to transfer from their host to an adjacent surface. Multiple hard substrates have proved a suitable habitat for settlement and growth, including equipment and structures associated with aquaculture and natural hard substrates, such as shell, rock and boulders (see review in Loxton et al 2017), which are all likely to be found in the vicinity of ports, harbours and marinas.

Qu. 4.9a. Estimate the overall potential rate of spread within the Union based on this pathway? (please provide quantitative data where possible).

RESPONSE moderately CONFIDENCE medium

Response: Following the introduction of S. japonica in the UK in or not long before 2009, the species has spread widely throughout the UK and into Ireland. The discontinuous nature of the current known range coupled with its presence in locations associated with recreational sailing (Loxton et al 2017), suggests that this vector has been used effectively to spread within the area rapidly, expanding its range by more than 900miles in 10 years. It is not unreasonable to suppose that this rate of spread could continue throughout the RAA. It is also important to consider that populations may already exist in the RAA or on vessels moving within the RAA, undetected or misidentified, due to the cryptic nature of the species and therefore, rate of spread may be higher than anticipated.

Pathway name: Transport: Stowaway Machinery/ Equipment (Movement of equipment associated with aquaculture and renewable energy structures)

Qu. 4.3b. Is spread along this pathway intentional or unintentional (e.g. the organism is a contaminant of translocated goods within the risk assessment area)?

RESPONSE unintentional CONFIDENCE high

Response: As the demand for renewable energy increases, there are increasing numbers of marine structures associated with the industry, particularly on the Scottish coast. Nall (2015) studied such structures and found that they provided an ideal habitat for colonization by S. japonica. It was also discovered that many structures associated with offshore renewables are stored for significant periods of time in ports known to hold populations of S. japonica before being transported elsewhere for deployment (Loxton et al 2017). Such practices present a clear potential vector for spreading fouling species such as S. japonica.

Qu. 4.4b. How likely is it that a number of individuals sufficient to originate a viable population will spread along this pathway from the point(s) of origin over the course of one year? including the following elements:  an indication of the propagule pressure (e.g. estimated volume or number of specimens, or frequency of passage through pathway), including the likelihood of reinvasion after eradication  if appropriate, indicate the rate of spread along this pathway  if appropriate, include an explanation of the relevance of the number of individuals for spread with regard to the biology of species (e.g. some species may not necessarily rely on large numbers of individuals).

RESPONSE very likely CONFIDENCE high

Response: Schizoporella japonica is known to attach to and colonize a range of man-made structures including structures associated with wind and wave power generation (Collin et al 2015; Ryland et al 2014; Bishop et al 2015), predominantly not coated in antifouling paints (Nall 2015). It is also known to colonize marina pontoons, fenders and other structures likely to occur in the vicinity of this gear when stored before being towed to a deployment site, from which further spread or natural settlement might occur.

The species is hermaphroditic and reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement (Ryland et al 2014), giving time for the ciliated larvae to move between structures and moored vessels. These traits make attachment to the hulls of vessels moored in close proximity to colonies of S. japonica likely. Once settlement takes place, individuals reproduce and spread by budding asexually to form sheets.

Qu. 4.5b. How likely is the organism to survive, reproduce, or increase during transport and storage along the pathway (excluding management practices that would kill the organism)?

RESPONSE likely CONFIDENCE high

Response: Based on previous introductions, S. japonica has a very high potential to survive transportation attached to equipment and machinery that remains in the sea (Ashton et al 2014; Loxton et al 2017). The survivable temperature range is high (-1.4 - 30oC) (Loxton et al 2017, CABI 2019). Reproduction through asexual budding and colony growth is likely provided conditions are favourable and sexual reproduction (which takes place year round) is also likely.

Qu. 4.6b. How likely is the organism to survive existing management practices during spread?

RESPONSE likely CONFIDENCE medium

Response: The authors were unable to find information about the ability of S. japonica to resist antifouling treatments, however it should be noted that in the congener S. errata, Cu (copper) based antifouling coatings on boat hulls can prevent growth of S. errata and stop its spread to new locations (Piola and Johnston 2006). Many marine renewable energy and aquaculture structures are not treated with antifouling paints (Nall 2015), however, treatments with biocidal compounds may prove an effective method of controlling fouling and reduce the likelihood of spread.

There are very limited management measures in place currently to reduce the spread of non-native species when moving previously deployed equipment within the RAA.

Qu. 4.7b. How likely is the organism to spread in the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

Response: Ancestrula measure 350-400 x ~300 μm (Ryland et al 2014) and at this stage are extremely difficult to detect. A single ancestrula can develop and reproduce asexually to form colonies of hermaphroditic, reproductive individuals. Developed colonies are easier to detect measuring several centimetres across and being bright orange. However, confusions over identification and the large number of taxonomically similar native species reduce the likelihood that the species will be identified and intercepted except by experts. The methods required to check equipment which remains submerged even when not in use, are costly (diving) or not necessarily able to observe sufficient detail 43

to identify bryozoans to species level (ROVs). The use of regular eDNA monitoring at relevant sites may improve detection, however to-date, the method does not appear to have been trialled for this particular species and it is impossible at present to provide the environmental conditions and population density that would be required at a site in order for this to be effective.

Qu. 4.8b. How likely is the organism to be able to transfer from the pathway to a suitable habitat or host during spread? (including, where possible, details about the specific origins and end points of the pathway)

RESPONSE likely CONFIDENCE medium

Response: Non-feeding ciliated larvae are brooded and released from ovicells, these larvae persist for only a few hours (Loxton et al 2017), with a maximum of 24 hours (Treibergs 2012), but during this time are able to transfer from their parent to an adjacent surface. Multiple hard substrates have proved a suitable habitat for settlement and growth, including equipment and structures associated with aquaculture and natural hard substrates, such as shell, rock and boulders (see review in Loxton et al 2017), which are all likely to be found in the vicinity of ports and harbours used to store equipment.

If equipment is to be deployed on the seabed, intertidally or in the vicinity of vessels or natural hard substrates, propagules should be able to colonize these neighbouring areas easily. However for equipment deployed further out at sea, off the seabed, transfer may be secondary via service vessels, debris and transfer to a suitable habitat may not occur directly.

Qu. 4.9b. Estimate the overall potential rate of spread within the Union based on this pathway? (please provide quantitative data where possible).

RESPONSE slowly CONFIDENCE medium

Response: There is very little information about the rate of species spread based on this particular vector, however, it is likely that spread will be sporadic as objects are transported to dock after long periods at sea and then redeployed. It is likely that the distance of travel will be relatively low and that rate of spread would be very much object specific.

Pathway name: Transport: Contaminant - Contaminant on animals (Transfer of live shellfish)

Qu. 4.3c. Is spread along this pathway intentional or unintentional (e.g. the organism is a contaminant of translocated goods within the risk assessment area)?

RESPONSE unintentional CONFIDENCE high

Response: The primary introduction of S. japonica outside its native range is believed to have been as a result of accidental transportation with the commercially grown oyster Magallana (was Crassostrea) gigas when the species was exported during the early twentieth century from Japan to the west coast of North America (Loxton et al 2017) . Records of S. unicornis (considered likely to be S. japonica) from Australia were reported following the introduction of Pacific oysters (Dick et al 2005). Although bivalve introductions are now carefully regulated to minimize the risk of importation of contaminated stock, introduction to member states via movements of shellfish between sites is possible. Additionally, introduction of contaminated stock to neighbouring countries with different levels of control in place is feasible.

Shellfish, such as oysters, mussels and scallops are grown in open systems and transported between sites for on-growing throughout the RAA Currently movement within and between states is possible in most cases and there is certainly potential for colonized shellfish to become a vector of spread for organisms like S. japonica. Many such operations notably take place on the coast of Scotland and North Wales.

Qu. 4.4c. How likely is it that a number of individuals sufficient to originate a viable population will spread along this pathway from the point(s) of origin over the course of one year? including the following elements:  an indication of the propagule pressure (e.g. estimated volume or number of specimens, or frequency of passage through pathway), including the likelihood of reinvasion after eradication  if appropriate, indicate the rate of spread along this pathway  if appropriate, include an explanation of the relevance of the number of individuals for spread with regard to the biology of species (e.g. some species may not necessarily rely on large numbers of individuals).

RESPONSE likely CONFIDENCE high

hermaphroditic and reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement (Ryland et al 2014). These traits make contamination of shellfish stored in close proximity to colonies of S. japonica likely. Once settlement takes place, individuals reproduce and spread by budding asexually to form sheets. Therefore, the successful settlement, development and growth of an individual on a transporting organism can result in a high level of propagule potential. The ability of the species to colonise intertidal hard substrate (Treibergs 2012; Macleod et al 2016)) suggests it would be well adapted to make use of oyster beds (naturalized and maintained), prevalent through much of the RAA but particularly the North Sea region. Any movement of these oysters might support this spread. Records from oysters in the Dutch Wadden Sea (Gittenberger et al., 2019) also support this theory.

Qu. 4.5c. How likely is the organism to survive, reproduce, or increase during transport and storage along the pathway (excluding management practices that would kill the organism)?

RESPONSE likely CONFIDENCE High

Qu. 4.6c. How likely is the organism to survive existing management practices during spread?

RESPONSE moderately likely CONFIDENCE medium

Response: EC regulation 708/2007 (EC 2007) aims to reduce the impact of introduced alien species ffrom aquaculture and requires processes to be undertaken to ameliorate the potential environmental damage caused by such introductions. This should theoretically include measures to reduce the potential for ‘hitchhiking’ species to be introduced and may require careful treatment, quarantine and other processes before stock can be released into the wild. It is however unlikely that such stringent measures will be applied to movements of stock within and between member states and where species, normally native to or established in a member state are introduced. Where this is the case, it is difficult to evaluate whether or not management practices will be utilized that would effectively reduce the likelihood of introduction.

Qu. 4.7c. How likely is the organism to spread in the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

Response: Ancestrula measure 350-400 x ~300 μm (Ryland et al 2014) and at this stage are extremely difficult to detect. A single ancestrula can develop and reproduce asexually to form colonies of hermaphroditic, reproductive individuals. Developed colonies are easier to detect measuring several centimetres across and being bright orange. However, confusions over identification and the large number of taxonomically similar native species reduce the likelihood that the species will be identified and intercepted except by experts. Regular eDNA monitoring of aquaculture sites has the potential to improve detection of the species and facilitate the control of spread. To-date however, the method does not appear to have been trialled for this particular species and it is impossible at present to provide the environmental conditions and population density that would be required at a site in order for this to be effective.

Qu. 4.8c. How likely is the organism to be able to transfer from the pathway to a suitable habitat or host during spread? (including, where possible, details about the specific origins and end points of the pathway)

RESPONSE likely CONFIDENCE high

Qu. 4.9c. Estimate the overall potential rate of spread within the Union based on this pathway? (please provide quantitative data where possible).

RESPONSE moderately CONFIDENCE medium

Response: Movement of shellfish is controlled and moderated between member states, however, practices such as the transfer of mussel seed to growing beds and the movement of oysters to optimize growing conditions, may result in the spread of S. japonica attached to equipment, bivalves and associated substrate. Mussel seed might be transported hundreds of kilometers and spread over a wide area, providing optimal conditions for S. japonica to grow and form large colonies resulting in natural

spread from multiple points. Such activity would be likely to spread S. japonica rapidly, but again sporadically and in a discontinuous fashion. The current status of populations in the USA, 40 years after introduction and spread via this vector, suggests that over time distribution will become less discontinuous as introduced populations spread naturally (albeit slowly) and connect.

Pathway name: Stowaway/ corridor: Attachment to floating anthropogenic debris

Qu. 4.3d. Is spread along this pathway intentional or unintentional (e.g. the organism is a contaminant of translocated goods within the risk assessment area)?

RESPONSE unintentional CONFIDENCE high

Response: Schizoporella japonica is known to attach to debris and flotsam and to travel long distances by this method,. For example following the Japanese Tsunami in 2011, colonies of living S. japonica (alive with embryos) were identified on objects originating in Japan and found on the Hawaiian Islands and North American coast after traversing the Pacific Ocean (and Carlton 2018). It is therefor possible that colonies may develop on drifting plastic, lost fishing equipment and other man- made objects, which may become flotsam, providing a pathway of spread within the RAA. With an increase in drifting marine litter, this potential vector is becoming increasingly prevalent. Whilst drifting litter is transported by natural forces, it is considered by the authors that the presence of anthropogenic marine litter is a human influence, without which, fouling species would not be able to make use of prevailing currents to spread rapidly.

Qu. 4.4d. How likely is it that a number of individuals sufficient to originate a viable population will spread along this pathway from the point(s) of origin over the course of one year? including the following elements:  an indication of the propagule pressure (e.g. estimated volume or number of specimens, or frequency of passage through pathway), including the likelihood of reinvasion after eradication  if appropriate, indicate the rate of spread along this pathway  if appropriate, include an explanation of the relevance of the number of individuals for spread with regard to the biology of species (e.g. some species may not necessarily rely on large numbers of individuals).

RESPONSE likely CONFIDENCE medium

Response: Schizoporella japonica is known to attach to a wide range of substrates (Collin et al 2015). And is known to attach to drifting debris and litter (McCuller & Carlton 2018) which is often found in and around heavily populated areas or sites with heavy use, including marinas and ports. These are also places where colonization of natural and man-made substrates by S. japonica is most likely to occur. The species is hermaphroditic and reproduction is likely to take place year-round. Larvae are brooded, with a short larval phase of a few hours before settlement (Ryland et al 2014). It is therefore likely that drifting debris, which comes into close contact with infested areas will be colonized before continuing to drift, potentially to new sites in the RAA. Propagules will be produced and released during the drift and potentially in more concentrated quantities if and when the object becomes stranded or sinks.

Qu. 4.5d. How likely is the organism to survive, reproduce, or increase during transport and storage along the pathway (excluding management practices that would kill the organism)?

RESPONSE likely CONFIDENCE medium

Response: Based on previous introductions, S. japonica has a very high potential to survive transportation attached to drifting debris (McCuller & Carlton 2018). The survivable temperature range is high (-1.4 - 30oC) (Loxton et al 2017, CABI 2019). Reproduction through asexual budding and colony growth is likely provided conditions are favourable and propagule production (which takes place year round) is also likely. In fact, colonies found on drifting debris in the Pacific have been found bearing live larvae (McCuller & Carlton 2018), demonstrating the potential for sexual reproduction to occur ‘in transit’.

Qu. 4.6d. How likely is the organism to survive existing management practices during spread?

RESPONSE moderately likely CONFIDENCE low

Response: Physical removal of all anthropogenic debris from the shore, may remove fouling colonies, especially if objects are sensibly disposed of at a land-based facility. However, debris removal is currently inadequate in most of the RAA (and certainly in the areas where is S. japonica currently found) to effectively remove all potential objects.

Qu. 4.7d. How likely is the organism to spread in the risk assessment area undetected?

RESPONSE very likely CONFIDENCE high

Qu. 4.8d. How likely is the organism to be able to transfer from the pathway to a suitable habitat or host during spread? (including, where possible, details about the specific origins and end points of the pathway)

RESPONSE moderately likely CONFIDENCE low

Response: Non-feeding ciliated larvae are brooded and released, these larvae persist for only a few hours (Loxton et al2017), but during this time are able to transfer from their host to an adjacent surface. Multiple hard substrates have proved a suitable habitat for settlement and growth, including equipment and structures associated with aquaculture and natural hard substrates, such as shell, rock and boulders (see review in Loxton et al 2017). It would be necessary for host debris to either snag and hold on a floating object with suitable substrate for settlement, or for the drift object to become beached in the proximity of suitable habitat, these are both events which are considered to be moderately likely.

Qu. 4.9d. Estimate the overall potential rate of spread within the Union based on this pathway? (please provide quantitative data where possible).

RESPONSE moderately CONFIDENCE medium

Response: Large quantities of anthropogenic flotsam drifts throughout the RAA and is transported large distances via currents. The potential for such spread has been demonstrated in Helgoland, when the invasive bryozoan Watersipora subatra was found attached to rafting seaweed, thought to have travelled 800km from the English Channel (Kuhlenkamp & Kind 2013). Evidence of S. japonica surviving far longer journeys across the Pacific Ocean (McCuller & Carlton 2018) suggests distances such as this would be easily achievable. Spread by this pathway would also likely be sporadic, but potentially over long distances. They would potentially have the additional feature of occurring in natural and less expected locations (i.e. harbours or marinas) thus be more likely to go undetected.

End of pathway assessment, repeat Qu. 4.3 to 4.9. as necessary using separate identifiers.

Qu. 4.10. Within the risk assessment area, how difficult would it be to contain the organism in relation to these pathways of spread?

RESPONSE very difficult CONFIDENCE high

Response: Due to the open nature of the marine environment in which the described pathways of spread occur, complete containment would be extremely difficult, costly and most likely impossible.

Qu. 4.11. Estimate the overall potential rate of spread in relevant biogeographical regions under current conditions for this organism in the risk assessment area (indicate any key issues and provide quantitative data where possible). Thorough assessment of the risk of spread in relevant biogeographical regions in current conditions, providing insight in the risk of spread into (new areas in) the Union.

RESPONSE rapidly CONFIDENCE medium

Response: Following the introduction of S. japonica in the UK in, or not long before 2009, the species has spread widely throughout the UK and into Ireland. The discontinuous nature of the current known range coupled with its presence in locations associated with recreational boating (Loxton et al 2017) suggests that this vector has been used effectively to spread S. japonica within the area rapidly, expanding its range by more than 900miles in 10 years. It is not unreasonable to suppose that this rate of spread could continue throughout the RAA. Movements of bivalves are also likely to result in sporadic, discontinuous spread, but will generally be restricted to movement within each member state due to restrictions on the movement of live bivalves between states. However, in the USA, over 40 years the wide range and distribution of S. japonica (Alaska to California) has primarily been attributed this vector. Other potential vectors of spread, include rafting on anthropogenic materials and movement with equipment associated with renewable energy and aquaculture, are far more difficult to predict However it is believed that such spread will also take place sporadically and over long distances, resulting in discontinuous populations.

Qu. 4.12. Estimate the overall potential rate of spread in relevant biogeographical regions in foreseeable climate change conditions (provide quantitative data where possible). Thorough assessment of the risk of spread in relevant biogeographical regions in foreseeable climate change conditions: explaining how foreseeable climate change conditions will influence this risk, specifically if rates of spread are likely slowed down or accelerated.

RESPONSE rapidly CONFIDENCE low

Response: Under future climate change scenarios, there is no evidence to suggest that any of the impacts summarized in 4.11 will change. However, increased storminess may result in increased levels of anthropogenic flotsam entering the sea, resulting in an increased likelihood of rafting as a pathway.

5 MAGNITUDE OF IMPACT Important instructions:  Questions 5.1-5.5 relate to biodiversity and ecosystem impacts, 5.6-5.8 to impacts on ecosystem services, 5.9-5.13 to economic impact, 5.14-5.15 to social and human health impact, and 5.16-5.18 to other impacts. These impacts can be interlinked, for example a disease may cause impacts on biodiversity and/or ecosystem functioning that leads to impacts on ecosystem services and finally economic impacts. In such cases the assessor should try to note the different impacts where most appropriate, cross-referencing between questions when needed.  Each set of questions starts with the impact elsewhere in the world, then considers impacts in the risk assessment area (=EU excluding outermost regions) separating known impacts to date (i.e. past and current impacts) from potential future impacts (including foreseeable climate change).  Only negative impacts are considered in this section (socio-economic benefits are considered in Qu. A.7)

Biodiversity and ecosystem impacts Qu. 5.1. How important is the impact of the organism on biodiversity at all levels of organisation caused by the organism in its non-native range excluding the risk assessment area? including the following elements:  Biodiversity means the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems  impacted chemical, physical or structural characteristics and functioning of ecosystems

RESPONSE moderate CONFIDENCE medium

Comment: S. japonica is a strong competitor for space, able to inhibit growth of adjacent species of bryozoa and mussels, sometimes causing mortality (Treibergs 2012; Macleod et al 2016). It has been reported that S. japonica may be less able to settle on space which is already occupied (Sutherland 1978), which suggests that otherwise healthy and un-impacted natural systems may be less at risk from the deleterious effects of invasion by the species.

It is most commonly associated with marinas and harbours, however it has been observed in the natural environment in Alaska and now in Scottish waters. In Alaska, S. japonica has been shown to outcompete native bryozoans (Dick et al 2005). Dick et al (2005) observe that the species remains a dominant feature of such communities, occupying several square metres and occupying large portions of the underside of boulders in sites along the west coast of North America at least 40 years subsequent to its first introduction. This suggests that these impacts may be long lasting and significant.

Although little species-specific information is available, there is evidence that S. japonica is able to colonies Zostera marina (sea grass) beds (Williams 2007). This is a particularly sensitive and biologically important habitat within the RAA and any potential loss or damage caused by incursions by invasive species could severely impact biodiversity. Similar fouling organisms are known to reduce growth and photosynthesis in sea grass, with heavy infestations leading to canopy collapse and clearance of beds (Williams 2007).

Qu. 5.2. How important is the current known impact of the organism on biodiversity at all levels of organisation (e.g. decline in native species, changes in native species communities, hybridisation) in the risk assessment area (include any past impact in your response)?

Discuss impacts that are currently occurring or are likely occurring or have occurred in the past in the risk assessment area. Where there is no direct evidence of impact in the risk assessment area (for example no studies have been conducted), evidence from outside of the risk assessment area can be used to infer impacts within the risk assessment area.

RESPONSE Minor CONFIDENCE low

Comment: Due to the relatively recent incursion of the species into Europe (Ryland et al 2014), there is little evidence of impacts on biodiversity from the area. In the few sites currently occupied the level of establishment varies from occasional, sparse colonies on man-made structures in two out of three marinas in South-West England (personal observation by author), to well established colonies on man- made and natural substrate in Scotland (Loxton et al 2017). Schizoporella japonica is able to colonize newly cleared areas and competitively exclude other species as demonstrated by the colonization of a marina in North Wales following clearance to control another invasive fouling species (Ryland et al. 2014). Studies from outside the risk assessment area suggest that this exclusion may continue into further stages of succession, lasting for a significant period, however the extend to which this exclusion is likely to persist through succesionary stages in the North Wales and other sites within the RAA is uncertain.

The authors could find no studies specifically quantifying the impact of S. japonica on biodiversity, however its ability to overgrow and outcompete native species (Treibergs 2012; Macleod et al 2016)

S. japonica is known to overgrow and smother bivalves, including the mussel Mytilus edulis often smothering and causing mortality (Treibergs 2012; Macleod et al 2016). Loxton et al (2017) identified that the biological communities most at risk of impact through competition for space are mussel beds and boulder communities, both of which are UK priority habitats (Macleod et al 2016). Bivalves such as mussels create biologically diverse habitat and loss of this habitat which may be caused by overgrowing by S. japonica has the potential to reduce biodiversity, although, again no studies have been conducted to support this theory or quantify the extent to which a reduction in biodiversity may or may not result. The findings of Dick et al (2005) suggest that any impacts may be long lasting (more than 40 years) and significant.

The authors could find no evidence to suggest that hybridization with native species is likely to cause negative impacts on native biodiversity, however with the uncertainties around taxonomy of the genus (Loxton et al 2017), it should not be entirely discounted as a potential impact.

Qu. 5.3. How important is the potential future impact of the organism on biodiversity at all levels of organisation likely to be in the risk assessment area? See comment above. The potential future impact shall be assessed only for the risk assessment area.

RESPONSE moderate CONFIDENCE low

Comment: The authors could find no studies specifically quantifying the impact of S. japonica on biodiversity. In particular, none could be found to suggest how this impact might be influenced by change in environmental conditions such as warming. However the species’ ability to overgrow and outcompete native species (Treibergs 2012; Macleod et al 2016) and to competitively exclude other species (Ryland et al 2014) suggests a potential to impact benthic and under boulder communities intertidally and in the shallow subtidal. Dick et al (2005) observe that the species remains a dominant feature of such communities, occupying several square metres and occupying large portions of the underside of boulders in sites along the west coast of North America at least 40 years subsequent to its first introduction suggest that these impacts may be long lasting and significant.

S. japonica is known to overgrow and smother bivalves, including the mussel Mytilus edulis often smothering and causing mortality (Treibergs 2012; Macleod et al 2016). Bivalves such as mussels create biologically diverse habitat and loss of this habitat which may be caused by overgrowing by S. japonica has the potential to reduce biodiversity, although, again no studies have been conducted to support this theory or quantify the extent to which a reduction in biodiversity may or may not result. Studies by Powell (1970) observed that whilst S. japonica settles and grows on live bivalves, colonies seemed to develop more readily on empty shells, suggesting that impacts on live bivalves may be lower than anticipated.

The authors could find no evidence to suggest that hybridization with native species is likely to cause negative impacts on native biodiversity, however with the uncertainties around taxonomy of the genus (Dick et al 2005; Ryland et al. 2014), it should not be entirely discounted as a potential impact.

Changing conditions in some parts of the RAA are likely to fall outside optimal conditions and may impair (e.g. excess temperatures in the Mediterranean or decreasing salinity in Baltic and Black Sea) growth rate and reproduction in S. japonica reducing its ability to out compete other fouling organisms.

Qu. 5.4. How important is decline in conservation value with regard to European and national nature conservation legislation caused by the organism currently in the risk assessment area? Including the following elements:  Native species impacted, including red list species, endemic species and species listed in the Birds and Habitats directives  Protected sites impacted, in particular Natura 2000  Habitats impacted, in particular habitats listed in the Habitats Directive, or red list habitats  The ecological status of water bodies according to the Water Framework Directive and environmental status of the marine environment according to the Marine Strategy Framework Directive

RESPONSE Moderate CONFIDENCE Low

Comment: The current sites where the species has been identified as present or invasive sit within or in close proximity to a number of sites protected under the habitats directive. At particular risk of impairment are ‘Reefs’, which include bivalve beds as well as a range of subtidal and intertidal hard substrates, which are all suitable habitat for S. japonica to colonize. In these habitats, S. japonica has the potential to dominate and alter substrate and to competitively dominate native species (see5.2 & 5.3 for details), potentially reducing the condition of the interest feature.

As a species recognized as having the potential to impact natural systems and species, its presence and spread within member states could lead to a reduced environmental status under the Marine Strategy Framework Directive (EU Directive 2008/56/EC). In the UK, S. japonica has been added to a list of species, which will be monitored to ensure GES (Good Environmental Status) for Descriptor 2.

Qu. 5.5. How important is decline in conservation value with regard to European and national nature conservation legislation caused by the organism likely to be in the future in the risk assessment area? including the following elements:  native species impacted, including red list species and species listed in the Birds and Habitats directives  protected sites impacted, in particular Natura 2000  habitats impacted, in particular habitats listed in the Habitats Directive, or red list habitats  the ecological status of water bodies according to the Water Framework Directive and environmental status of the marine environment according to the Marine Strategy Framework Directive

RESPONSE Moderate CONFIDENCE Low

Comment: ‘Reefs’ as designated for protection under the Habitats Directive include bivalve beds as well as a range of subtidal and intertidal hard substrates which are all suitable habitat for S. japonica to colonizes. In these habitats, S. japonica has the potential to dominate and alter substrate and to 56

competitively dominate native species (see5.2 & 5.3 for details), potentially reducing the condition of the interest feature.

Is known to overgrow and smother bivalves, including the mussel Mytilus edulis often smothering and causing mortality (Treibergs 2012; Macleod et al 2016). Mussel beds are listed as features of interest and protected in several member states, due to their commercial importance, but also because they create biologically diverse habitat, which is often associated with protected birds. Such habitat is, for example essential for the survival of the common eider Somateria mollissima which is included in the European Red List for Birds as ‘vulnerable’. No studies have been conducted to support this theory or quantify the extent to which a loss of habitat may or may not result.

S. japonica is able to colonize Zostera marina (sea grass) beds (Williams 2007), which are a feature of conservation importance in many member states and are included as features of ‘Sandbanks, which are slightly covered by sea water all the time’. Similar fouling organisms are known to reduce growth and photosynthesis in sea grass, with heavy infestations leading to canopy collapse and clearance of beds (Williams 2007).

Ecosystem Services impacts Qu. 5.6. How important is the impact of the organism on provisioning, regulating, and cultural services in its non-native range excluding the risk assessment area?  For a list of relevant services use the CICES classification V5.1 provided as an annex.  Impacts on ecosystem services build on the observed impacts on biodiversity (habitat, species, genetic, functional) but focus exclusively on reflecting these changes in relation to their links with socio-economic well-being.  Quantitative data should be provided whenever available and references duly reported.  In absence of specific studies or other direct evidences this should be clearly stated by using the standard answer “No information has been found on the issue”. This is necessary to avoid confusion between “no information found” and “no impact found”.

RESPONSE Major CONFIDENCE Low

Comment: Provisioning – Biomass – Reared Aquatic Animals/ Provisioning – Biomass –Wild Animals

No information has been found on this issue, although S. japonica is known to overgrow and smother bivalves, including the commercially important mussel Mytilus edulis often smothering and causing mortality (Treibergs 2012; Macleod et al 2016). It is also know that S. japonica fouls oysters, likely impairing their potential market value, by reducing product quality and increasing the cost associated

with preparation and packaging, problems common to a number of fouling organisms (Watson et al 2009).

Qu. 5.7. How important is the impact of the organism on provisioning, regulating, and cultural services currently in the different biogeographic regions or marine sub-regions where the species has established in the risk assessment area (include any past impact in your response)?  See guidance to Qu. 5.6.

RESPONSE Minimal CONFIDENCE Medium

Comment:

Provisioning – Biomass – Reared Aquatic Animals/ Provisioning – Biomass –Wild Animals

No information has been found on the issue, although is known to overgrow and smother bivalves, including the mussel Mytilus edulis (an important food resource with cultural significance in many parts of the RAA) often smothering and causing mortality (Treibergs 2012, Macleod et al 2016).

Qu. 5.8. How important is the impact of the organism on provisioning, regulating, and cultural services likely to be in the different biogeographic regions or marine sub-regions where the species can establish in the risk assessment area in the future?  See guidance to Qu. 5.6.

RESPONSE major CONFIDENCE Low

Comment:

Provisioning – Biomass – Reared Aquatic Animals/ Provisioning – Biomass –Wild Animals

No information has been found on this issue, although is known to overgrow and smother bivalves, including the commercially important mussel Mytilus edulis often smothering and causing mortality (Treibergs 2012; Macleod et al 2016). It is also know that S. japonica fouls oysters, likely impairing their potential market value, by reducing product quality and increasing the cost associated with preparation and packaging, problems common to a number of fouling organisms (Watson et al 2009).

Throughout the Celtic Seas, Greater North Sea and northern Bay of Biscay regions, shellfisheries are commercially and culturally important. Mussel and oyster growing in open systems are the most important in terms of output and cultural significance. France (Mytilus edulis) and Spain (Mytilus galloprovincialis) produce 280 thousand tonnes of mussels per year (FAO 2019), around two thirds of European mussel production. UK and Ireland also produce significant quantities of mussels, often exported to Belgium and the Netherlands where they constitute an important element of traditional cuisine and are culturally important. It is unlikely that infestation of mussel and oyster operations will 58

be destroyed by S. japonica alone, however cumulative impacts with other invasive and native fouling organisms may cause widespread problems. Impacts on bivalve health, quality and productivity (as described by Watson et al 2009), may increase costs, and reduce competitiveness with alternative, global providers of bivalve product, resulting in loss of revenue and in the most extreme cases loss of culturally significant activities.

Economic impacts Qu. 5.9. How great is the overall economic cost caused by the organism within its current area of distribution (excluding the risk assessment area), including both costs of / loss due to damage and the cost of current management.

 Where economic costs of / loss due to the organism have been quantified for a species anywhere in the world these should be reported here. The assessment of the potential costs of / loss due to damage shall describe those costs quantitatively and/or qualitatively depending on what information is available. Cost of / loss due to damage within different economic sectors can be a direct or indirect consequence of the earlier-noted impacts on ecosystem services. In such case, please provide an indication of the interlinkage.

RESPONSE Moderate CONFIDENCE Low

Comment: We could find no evidence of economic loss caused specifically by S. japonica. However, associated costs are likely to be similar to those incurred due to other similar fouling organisms and fouling communities with which S. japonica might be associated. This would include the culture and harvest of shellfish and the fouling of commercial and recreational vessels. S. japonica is found in association with a range of structures and gear associated with commercial activities (Dick et al 2005; Ryland et al 2014; Loxton at al 2017) It is therefore likely that costs will have been incurred by commercial and recreational boat owners and marina operators as a result of having to clean and maintain vessels and equipment more often.

Qu. 5.10. How great is the economic cost of / loss due to damage (excluding costs of management) of the organism currently in the risk assessment area (include any past costs in your response)?

 Where economic costs of / loss due to the organism have been quantified for a species anywhere in the EU these should be reported here. Assessment of the potential costs of damage on human health, safety, and the economy, including the cost of non-action. A full economic assessment at EU scale might not be possible, but qualitative data or different case studies from across the EU (or third countries if relevant) may provide useful information to inform decision making. In absence of specific studies or other direct evidences this should be clearly stated by using the standard answer “No information has been found on the issue”. This is necessary to avoid confusion between “no information found” and “no impact found”. Cost of / loss due to damage within different economic sectors can be a direct or indirect consequence of the earlier-noted impacts on ecosystem services. In such case, please provide an indication of the interlinkage.

RESPONSE Minor CONFIDENCE Low

Comments: We could find no evidence of economic loss caused specifically by S. japonica , anywhere in the EU, however arrival in the RAA is potentially too recent and current range too small for any such costs to have been incurred.

Qu. 5.11. How great is the economic cost of / loss due to damage (excluding costs of management) of the organism likely to be in the future in the risk assessment area?  See guidance to Qu. 5.10.

RESPONSE Major CONFIDENCE Low

Comments: We could find no evidence of economic loss caused specifically by S. japonica, however associated costs are likely to be similar to those incurred due to other similar fouling organisms and fouling communities with which S. japonica might be associatedh. Although not possible to quantify direct costs, it is likely that the main areas affected might be:

Culture and harvest of shellfish: Quality and volume of product likely to be impaired if heavy fouling occurs (Watson et al 2009). It is possible that areas with known populations of S. japonica may be closed for export of live mussel seed and other bivalves within the European Union and indeed with each individual state. Restrictions on the movement of mussels from Morecombe Bay (UK) have been imposed for the past year due to the presence of Chinese mitten crabs, impacting the region’s largest fishery. Similar measures may be required should S. japonica arrive in the area, to prevent further spread.

Fouling of commercial and recreational vessels: S. japonica is found in association with a range of structures and gear associated with commercial activities (Loxton at al 2017). It is therefore likely that costs will be incurred by commercial and recreational boat owners due to: an increased requirement for fuel due to drag; increased maintenance and repair due to fouling of pipes and moving parts, increased cleaning and maintenance of vessels and equipment.

Qu. 5.12. How great are the economic costs / losses associated with managing this organism currently in the risk assessment area (include any past costs in your response)?  In absence of specific studies or other direct evidences this should be clearly stated by using the standard answer “No information has been found on the issue”. This is necessary to avoid confusion between “no information found” and “no impact found”.

RESPONSE Moderate CONFIDENCE Low

Comments: No information has been found on the issue directly relating to S. japonica however, the species is one of many fast growing, encrusting invasive species for which regular hull cleaning and maintenance has become a necessary requirement. This activity varies in cost depending on vessel size and location and between member states.

Qu. 5.13. How great are the economic costs / losses associated with managing this organism likely to be in the future in the risk assessment area?

 See guidance to Qu. 5.12.

RESPONSE Moderate CONFIDENCE Low

Comments: No information has been found, however restrictions on movement of vessels and shellfish, which could be implemented (as in the Morecombe Bay, UK mussel seed fishery for Eriocheir sinensis) to prevent spread may result in loss of earnings in the fishing industry or for marina owners and commercial shipping companies.

Additional costs may be incurred should S. japonica move into areas where shellfishing or shellfish culturing takes place, around the coasts of the UK, Ireland, France, Belgium, Netherlands, Denmark, Spain, Portugal and Germany. Incursion may result in loss or deterioration of product and/ or increased processing time, but should be considered along with costs already associated with removal of native and non-native fouling organisms.

Social and human health impacts Qu. 5.14. How important is social, human health or other impact (not directly included in any earlier categories) caused by the organism for the risk assessment area and for third countries, if relevant (e.g. with similar eco-climatic conditions). The description of the known impact and the assessment of potential future impact on human health, safety and the economy, shall, if relevant, include information on  illnesses, allergies or other affections to humans that may derive directly or indirectly from a species;  damages provoked directly or indirectly by a species with consequences for the safety of people, property or infrastructure;  direct or indirect disruption of, or other consequences for, an economic or social activity due to the presence of a species. Social and human health impacts can be a direct or indirect consequence of the earlier-noted impacts on ecosystem services. In such case, please provide an indication of the interlinkage.

RESPONSE Minimal CONFIDENCE low

Comments: The authors could find no evidence to suggest that S. japonica might directly impact human health. The ability for the species to grow on ropes and equipment associated with maritime industries and recreational boating (Loxton et al 2017) may make gear heavier and increase the risk of back injury or falling in when trying to retrieve lines, ropes and other gear. However, there is no reason to suppose that such an impact would be any worse that caused by other fouling organisms (native and non-native). S. japonica may in fact competitively exclude larger organisms such as solitary and colonial ascidians and macro algae, which would otherwise increase the mass of rope fouling.

Qu. 5.15. How important is social, human health or other impact (not directly included in any earlier categories) caused by the organism in the future for the risk assessment area.  In absence of specific studies or other direct evidence this should be clearly stated by using the standard answer “No information has been found on the issue”. This is necessary to avoid confusion between “no information found” and “no impact found”.

RESPONSE Minimal CONFIDENCE Low

Comments: No additional impacts could be found.

Other impacts Qu. 5.16. How important is the impact of the organism as food, a host, a symbiont or a vector for other damaging organisms (e.g. diseases)?

RESPONSE Minor CONFIDENCE Low

Comments: No additional impacts could be found for S. japonica specifically, however it is possible that the provision of additional hard substrate of calcareous biogenic structures created by S. japonica might provide additional settlement space and refuge for additional non-native species on what might otherwise be an inhospitable or homogenous substrate. The congeneric species S. errata is known to have had such an effect on mudflats in San Francisco Bay (Zabin et al 2010). Studies showed that 74% of the species of known origin colonizing the new ‘bryolyths’ were non-native.

Qu. 5.17. How important might other impacts not already covered by previous questions be resulting from introduction of the organism?

RESPONSE Moderate CONFIDENCE Low

Comments: No additional impacts could be identified, but this does not mean that none are possible. Alteration of habitat, indirect impacts on predators and wider ecosystem impacts may occur.

Qu. 5.18. How important are the expected impacts of the organism despite any natural control by other organisms, such as predators, parasites or pathogens that may already be present in the risk assessment area?

RESPONSE Moderate CONFIDENCE Low

Comments: No information could be found about impacts of predators, parasites or pathogens on the successful establishment and impacts of S. japonica. Predation on newly settled propagules by grazing mulloscs, flatworms and other invertebrates is likely, although the extent to which this will impair the establishment and subsequent impact of the species is not known. Based on the spread and current distribution of the species on the west coast of the USA (Dick et al 2005), where similar predator and pathogen assemblages can be found, it is not considered likely that this will be an important factor inhibiting impacts caused.

Qu. 5.19. Estimate the overall impact in the risk assessment area under current climate conditions. In addition, details of overall impact in relevant biogeographical regions should be provided. Thorough assessment of the overall impact on biodiversity and ecosystem services, with impacts on economy as well as social and human health as aggravating factors, in current conditions.

RESPONSE Moderate CONFIDENCE Medium

Comments: Although very little information exists, which can be used to quantify past or current impacts of S. japonica, a number of potential impacts have been considered based on best judgment and supported by published observations and lessons learned from similar and in particular congeneric species.

The ability of S. japonica to overgrow and outcompete native species (Treibergs 2012; Macleod et al 2016) and to competitively exclude other species (Ryland et al 2014), suggests a potential to impact benthic and under boulder communities intertidally and in the shallow subtidal. Such impacts may be long lasting. S. japonica is also known to overgrow and smother bivalves, including the mussel Mytilus edulis often smothering and causing mortality (Treibergs 2012; Macleod et al 2016). Bivalves such as mussels create biologically diverse habitat and loss of this habitat, which may be caused by overgrowing by S. japonica, has the potential to reduce biodiversity.

The potential to overgrow bivalves has additional potential impacts, including economic and social/ cultural and is likely to impede the functioning of ecosystem services as described in 5.10. Any such

impacts are likely to be long lasting, but should be considered alongside the impacts of other fouling organisms.

The ability of S. japonica to colonies a range of man-made structures, suggests that costs will be incurred in order to keep gear clean and in working order, and to maintain the efficiency of vessels. Again, the costs of these activities should be considered alongside the existing cost of antifouling and hull and equipment cleaning as is likely to replace existing fouling species, some of which are larger and bulkier and likely to generate more drag and additional weight.

It is possible that S. japonica, as with S. errata (Zabin et al 2010), will create new habitat, suitable for settlement by new non-native species and this might result in indirect impacts resulting from incursions of other non-native, invasive species.

The areas within the RAA most likely to be impacted are considered to be the Celtic Seas, Greater North Sea and the Bay of Biscay, with the northern Iberian coast above Portugal also likely to be impacted. Due to the primarily northern distribution and the apparently more rapid colonization by the species in colder conditions (Loxton et al 2017), it is considered that growth and spread may be faster in the northern parts of the UK, Scandinavia and Ireland than along the coast of France, Spain, Belgium, Netherlands and Germany. Resulting in higher levels of impact in these areas.

Qu. 5.20. Estimate the overall impact in the risk assessment area in foreseeable climate change conditions. In addition, details of overall impact in relevant biogeographical regions should be provided. Thorough assessment of the overall impact on biodiversity and ecosystem services, with impacts on economy as well as social and human health as aggravating factors, under future conditions.

RESPONSE Moderate CONFIDENCE Low

Comments: Under future climate change scenarios as discussed previously, there is no evidence to suggest that any of the impacts summarized in 5.19 will change.

RISK SUMMARIES RESPONSE CONFIDENCE COMMENT Summarise Very likely High It is considered that, given the proximity of Introduction* known populations to the RAA ([n particular Norway) and presence of established populations within the RAA (UK) it is very likely that S. japonica will be introduced unintentionally to new member states within the RAA. Populations exist in densities and locations that make attachment to vessel hulls, equipment, debris, and commercially harvested and transported bivalves very likely. It is considered by the authors that there are currently insufficient measures in place to control fouling organisms, on recreational vessels to reduce this potential source of introduction. Additionally, there is a constant flow of vessels between the sites currently hosting the species and uninfected sites within the RAA.

Summarise Very likely High (Northern) Due to the sessile nature of S. japonica entry Entry* (Northern) would mainly be due to release of propagules Medium from reproductively viable introduced or passing Moderately (Mediterranean populations. Reproduction is by the release of likely (Black and Black Sea) relatively large, brooded ciliated larvae, which Sea) settle and metamorphose within hours of release. They are capable of selecting optimal attachment Unlikely locations and once settled, a single propagule is (Southern able to reproduce asexually, forming an extensive Iberian colony of hermaphroditic zooids, with a high coast, fecundity. Production and release of propagules Mediterrane is constant and continues throughout the year, an) increasing the chance of spread from sources of introduction. Propagules, newly settled individuals and small colonies are difficult, if not impossible to detect without very close and detailed inspection and even large, conspicuous colonies may be overlooked due to difficulties with identification and recognition. Provided conditions are suitable for reproduction to occur and colonies to survive, it is therefore considered that there is a very high likelihood of entry into the RAA. These conditions exist in the entire Celtic Seas, Greater North Sea regions, Bay of Biscay and the Iberian Coast north of Bilbao, Spain. Conditions are considered unsuitable due to salinity levels falling outside the known tolerable range of the species on the Iberian coast south of Bilbao, and the Mediterranean (too high) and the Baltic (too low). Future predicted salinity decreases in the Iberian coast region might make this area habitable in the next 50 years. Whilst 65

salinity in the Black Sea may be suitable, it is unclear whether passage through the Mediterranean would result in reproductively viable colonies, therefore unless transported by another route, entry may be impaired. Summarise Very likely High S. japonica has demonstrated the ability to grown Establishment* fast and spread rapidly under a range of environmental conditions. It is capable of establishing large, long-lasting populations with low genetic diversity and a single successfully settling propagule is capable of growing into a large, reproducing colony. It is capable of overgrowing and competitively excluding existing fouling communities (possibly due to its ability to reproduce constantly and throughout the year) and to rapidly colonize newly available substrate, excluding competing organisms. Available habitat is ubiquitous throughout the RAA, with S. japonica capable of settling and growing on a range of natural and man-made substrates. Establishment is considered unlikely on the Iberian coast south of Bilbao, and in the Mediterranean (salinity too high) and the Baltic (salinity too low). Summarise Rapidly Medium Due to the short-lived nature of propagules and Spread* limited dispersal range, natural, self-initiated spread is likely to be slow from introduced populations; however, local, dense populations are likely. S. japonica has however demonstrated traits, which allow it to spread effectively by other means. Spread by transport with vessels, is likely to be over long distances, but resulting in discontinuous populations, but with regular vessel movements between member states and the life history traits discussed spread is likely to be rapid. Movement of bivalves is very likely to facilitate spread within member states, including between sea regions (e.g. Atlantic to Mediterranean oyster transplantations) due to limited regulation regarding the internal transfer of bivalves. Bivalve movement may also result in spread between states, although this will vary due to restrictions on bivalve movements in some states. Some natural spread by rafting of natural objects (seaweed), but perhaps more so anthropogenic flotsam may result in long-range, sporadic, disjointed introductions throughout the RAA.

Summarise Moderate Medium S. japonica is able to overgrow and outcompete Impact* native species and continue to dominate systems for in excess of 40 years. Few studies have been undertaken to quantify impacts of this species,

however information about similar species and impacts of dominating encrusting invasive species suggests a likelihood that this will result in loss of biodiversity and habitat alteration. An ability to overgrow and cause mortality of bivalves has implications for the environmental status of protected biogenic ‘reefs’, but also loss of food provision in the form of bivalve culture and resulting economic impacts. Bivalve fisheries and aquaculture (particularly mussels and oysters) have important economic and cultural significance through out the potentially affected areas of the RAA. Economic impacts on these activities may result from increased processing time, reduced product quality and quantity and ultimately loss of customers in a globally competitive market. Impacts on recreational and commercial shipping operations include increased cleaning and maintenance costs and higher fuel costs due to fouling. The ability of the species to colonize a range of man-made equipment, gear and vessels implies potential costs for the aquaculture industry, fishing industry and renewable marine energy companies. Costs may be incurred as a result of increased maintenance requirements, damage caused by increased drag and weight of gear or health issues caused by lifting and moving heavily fouled gear. However, these costs should be considered alongside the cost of dealing with existing fouling communities native and non- native (including some larger, faster growing organisms), which occurs throughout the RAA and which may be competitively excluded by S. japonica. Conclusion of High Medium Based on current conditions within the RAA, The the risk score applies to: The Celtic Seas, Greater North assessment Sea, Bay of Biscay and Iberian Coast north of (overall risk) Bilbao Spain. It is considered that conditions within these areas are suitable for the establishment of S. japonica where habitat is suitable and the life history traits make association with potential vectors of introduction and spread very likely. Populations capable of seeding new populations are already present in the RAA (UK) and in Norway, which is in close proximity to the RAA and shares many transport links suitable for transporting the species. Once arrived, the ability of the species to grow fast from a limited propagule bank and competitively exclude native species makes it likely that impacts on the environment and economic interests will occur and that these will be widespread or locally severe. Limited 67

information exists about the specific impacts of the species and the taxonomic uncertainty regarding the species means that some information may be difficult to locate and possibly unreliable. This means that some of the scores and predictions may require revision, as more is understood about the nature of the species in the future. It is however considered by the authors that information about the species alongside information about similar species and fouling communities makes it possible to make the predictions here with some confidence. A final point to note is that S.japonica exists alongside a large number of other fouling species (native and non-native), many of which will interact in as-yet unknown ways. Consideration of impacts and other factors, as well as management should be undertaken with this in mind. *In current climate conditions and in foreseeable future climate conditions

Appendix 1: Climatic variables maps

June 2019 Salinity analysis data from Global Ocean- Real time in-situ observations objective analysis. Black areas signify regions outside the known tolerable salinity levels for S. japonica. Future Predicted changes: Baltic likely to reduce by 50-80% due to ice melt (EEA 2017) from http://marine.copernicus.eu

Sea Temperature Maps From: http://marine.copernicus.eu/services-portfolio/access-to- products/?option=com_csw&view=details&product_id=INSITU_GLO_TS_OA_NRT_OBSERVATIONS_0 13_002_a

Average Sea Temperature: Feb 2019 – Min – max Average Sea Temperature: Aug 2019 – Min – max range known survival tolerances. Black areas range known survival tolerances. Black areas considered outside minimum or maximum considered outside minimum or maximum survivable survivable temperature range. temperature range.

Average Sea Temperature: Aug 2019 – Min – max range known survival tolerances reduced by 2.0°C to represent RCP 4.5 possible increase by 2065 Black areas considered outside minimum or maximum survivable temperature range.

References

Ashton, G., Davidson, I., Ruiz, G. (2014). Transient small boats as a long-distance coastal vector for dispersal of biofouling organisms. Estuar Coasts 37(6):1572–1581.

Bishop, J.D.D., Wood, C.A., Yunnie, A.L.E., Griffiths, C.A. (2015). Unheralded arrivals: non-native sessile invertebrates in marinas on the English coast. Aquat Invasions 10(3):249–264.

Bock, P. (2015). Schizoporella japonica. In: Bock, P., Gordon, D. (2015). World List of Bryozoa. Accessed through: World Register of Marine Species at: http://marinespecies.org/aphia.php?p=taxdetails&id=470388 in September 2015.

Bruno, J. F., Bates, A. E., Cacciapaglia, C., Pike, E. P., Amstrup, S. C., Van Hooidonk, R., et al. (2018). Climate change threatens the world’s marine protected areas. Nature Climate Change, 8, 499– 503.

CABI (2019). Data Sheet, Schizoporella japonica (orange ripple bryozoan). Invasive Species Compendium at: https://www.cabi.org/isc/datasheet/116955

Collin, S.B., Tweddle, J.F., Shucksmith, R.J. (2015). Rapid assessment of marine non-native species in the Shetland Islands, Scotland. BioInvasions Rec 4(3):147–155.

Dick, M. H., Grischenko, A. V., & Mawatari, S. F. (2005). Intertidal Bryozoa (Cheilostomata) of Ketchikan, Alaska. [Review]. Journal of Natural History, 39(43)

EC (2007) Council Regulation (EC) No 708/2007 of 11 June 2007 concerning use of alien and locally absent species in aquaculture

FAO (2019). GLOBEFISH - Information and Analysis on World Fish Trade http://www.fao.org/in- action/globefish/fishery-information/resource-detail/en/c/338588/

Gittenberger, A., Rensing, M., Veer, , H.W. van der, Philippart, C.J.M., Hoorn, B. van der, D’Hont, A., Wesdorp , K.H., Schrieken, N., Klunder, L., Kleine-Schaars, L., Holthuijsen, S. & H. Stegenga, 2019. Native and non-native species of the Dutch Wadden Sea in 2018. Commissioned by Office for Risk Assessment and Research, The Netherlands Food and Customer Product Safety Authority of the Ministry of Agriculture, Nature and Food Quality. GiMaRIS rapport 2019_09: 123 pp. (A copy of this report could not be obtained by authors and was therefore not reviewed. Information referenced is based on personal communication from an a reviewer February 2020)

Gordon, D.P. (1972), Biological relationships of an Intertidal Bryozoan population. J. Nat. Hist., 6, 503-514.

Hayward, P.J. & Ryland, J.S. (eds), The marine fauna of the British Isles and north-west Europe, 794/838. Oxford. The Clarendon Press.

IUCN/SSC Invasive Species Specialist Group (ISSG). (2019). CABI Invasive Species Compendium: Schizoporella errata (branching bryozoan). https://www.cabi.org/isc/datasheet/109921. Sept 2019

Jordà, G., Menéndez, M., Aznar, R. and Sánchez-Arcilla, A. (2017). Regional marine climate projections over Spain. In: Special Issue on climate over the Iberian Peninsula: an overview of

CLIVAR-Spain coordinated science. Casanueva, A., Manzanas, R., Fernández, J., Gutiérrez, J.M., Herrera, S. (eds).

Kuhlenkamp, R., & Kind, B. (2013). Arrival of the invasive Watersipora subtorquata (Bryozoa) at Helgoland (Germany, North Sea) on floating macroalgae (Himanthalia). Marine Biodiversity Records.

Loxton, J.. (2014.) Investigations into the Skeletal Mineralogy of Temperate and Polar Bryozoans. PhD Dissertation, Heriot Watt University, UK

Loxton, J., Wood, C. A., Bishop, J. D. D., Porter, J. S., Jones, M. S., Nall, C. R. (2017). Distribution of the invasive bryozoan Schizoporella japonica in Great Britain and Ireland and a review of its European distribution. Biological Invasions, 19(8)

Macleod, A., Cook, E.J., Hughes, D., Allen, C. (2016). Investigating the impacts of marine invasive non-native species. A report by Scottish Association for Marine Science Research Services Ltd for Natural England & Natural Resources Wales, p 59. Natural England Commissioned Reports, number 223

McCuller, M. & Carlton, J. (2018). Transoceanic rafting of Bryozoa (Cyclostomata, Cheilostomata, and Ctenostomata) across the North Pacific Ocean on Japanese tsunami marine debris. Aquatic Invasions. 13. 137-162. 10.3391/ai.2018.13.1.11.

Miller, A.W., Ruiz, G.M. (2014). Arctic shipping and marine invaders. Nat Clim Change 4(6):413– 416

Nall, C.R. (2015). Marine non-native species in northern Scotland and the implications for the marine renewable energy industry. PhD Dissertation, University of Aberdeen, UK

Nall, C.R., Guerin, A.J., Cook, E.J. (2015) Rapid assessment of marine non-native species in northern Scotland and a synthesis of existing Scottish records. Aquat Invasions 10(1):107–121. doi:10.3391/ai.2015.10.1.11

Oug, E., Gulliksen, B., Jelmert, A., Sundet, J. & Falkenhaug, T. (2019, February 5). Schizoporella japonica, assessment of ecological risk. Foreign species list 2018. The species database. Retrieved (2019, October 30) from https://artsdatabanken.no/Fab2018/N/3077

Piola, R.F. and Johnston, E.L. (2006). Differential resistance to extended copper exposure in four introduced bryozoans, Marine Ecology Progress Series 311: 103-114.

Porter, J. S. (2012). Seasearch Guide to Bryozoans and Hydroids of Britain and Ireland. Ross on Wye: Marine Conservation Society.

Porter, J.S., Spencer Jones, M.E., Kuklinsk,i P.& Rouse, S. (2015). First records of marine invasive non-native Bryozoa in Norwegian coastal waters from Bergen to Trondheim. Bioinvasions Rec 4(3):157–169

Powell, N. A. (1970). Schizoporella unicornis — An Alien Bryozoan introduced into the Strait of Georgia. Journal of the Fisheries Research Board of Canada, 27(10), 1847-1853. doi: 10.1139/f70-201

Pushpadas, D., Schrum, C., and Daewel, U. (2015). Projected climate change impacts on North Sea and Baltic Sea: CMIP3 and CMIP5 model based scenarios. Biogeosciences Discussions, 12, 12229– 12279.

Ryland, J.S., Holt, R., Loxton, J., Spencer Jones, M.E. & Porter, J.S. (2014). First occurrence of the non-native bryozoan Schizoporella japonica Ortmann (1890) in Western Europe. Zootaxa, 3780(3), 481-502

Schrum, C., Lowe, J., Meier, H. E. M., Grabemann, I., Holt, J., Mathis, M., et al. (2016). Projected Change—North Sea. In: M. Quante and F. Colijn (eds.), North Sea Region Climate Change Assessment, Regional Climate Studies.

Sutherland, J. P. (1978). Functional Roles of Schizoporella and Styela in the Fouling Community at Beaufort, North Carolina. Ecology, 59(2), 257-264

Taylor, P.D., Tan, S.H.A. (2015). Cheilostome Bryozoa from Penang and Langkawi,Malaysia. Eur J Taxon 149(1):1–34.

Thiébault, S., and Moatti, J.-P. (2016). The Mediterranean region under climate change: a scientific update. Available at: http://www.editions.ird.fr/produit/433/9782709922197/The Mediterranean Region under Climate Change.

Treibergs, K. (2012). Settlement and growth of the marine Bryozoan Schizoporella japonica, and Epifaunal Development in the South Slough Estuary. MSc Dissertation, University of Oregon, USA

Watson, D.I. & Shumway, Sandra & R.B., Whitlatch. (2009). Biofouling and the Shellfish Industry. 10.1533/9781845695576.2.317.

Watts P.C. & Thorpe J.P. (2006). Influence of contrasting larval developmental types upon the population-genetic structure of cheilostome bryozoans. Mar. Biol., 149: 1093-1101.

Williams, S.L. (2007). Introduced species in seagrass ecosystems: Status and concerns. J Exp Mar Biol Ecol 350:89–110.

Zabin, C. J., Obernolte, R., Mackie, J. A., Gentry, J., Harris, L., & Geller, J. (2010). A non-native bryozoan creates novel substrate on the mudflats in San Francisco Bay. Marine Ecology Progress Series, 412, 129-139. doi:10.3354/meps08664

Distribution Summary Please answer as follows: Yes if recorded, established or invasive – if not recorded, established or invasive ? Unknown; data deficient

The columns refer to the answers to Questions A5 to A12 under Section A. For data on marine species at the Member State level, delete Member States that have no marine borders. In all other cases, provide answers for all columns.

EU Member States and the United Kingdom

Recorded Established Possible Possible Invasive (currently) establishment establishment (currently) (under current (under climate) foreseeable climate) Austria - - - - - Belgium - - yes yes - Bulgaria - - yes yes - Croatia - - ? - - Cyprus - - - - - Czech Republic - - - - - Denmark - - yes yes - Estonia - - - - - Finland - - - - - France - - yes yes - Germany - - yes yes - Greece - - - - - Hungary - - - - - Ireland yes yes yes yes yes Italy - - ? - - Latvia - - - - - Lithuania - - - - - Luxembourg - - - - - Malta - - - - - Netherlands - - yes yes - Poland - - - - - Portugal - - ? yes - Romania - - yes yes - Slovakia - - - - - Slovenia - - - - - Spain - - yes yes - Sweden - - yes yes - United Kingdom yes yes yes yes yes

Biogeographical regions of the risk assessment area

Recorded Established Possible Possible Invasive (currently) establishment establishment (currently) (under current (under climate) foreseeable climate) Alpine - - - - - Atlantic yes yes yes yes yes Black Sea - - yes yes - Boreal - - - - - Continental - - - - - Mediterranean - - ? - - Pannonian - - - - - Steppic - - - - -

Marine regions and subregions of the risk assessment area

Recorded Established Possible Possible Invasive (currently) establishment establishment (currently) (under current (under climate) foreseeable climate) Baltic Sea - - - - - Black Sea - - yes yes - North-east Atlantic yes yes yes yes yes Ocean Bay of Biscay - - Yes Yes - and the Iberian Coast Celtic Sea yes yes yes yes yes Greater North yes yes yes yes yes Sea Mediterranean Sea - - - - - Adriatic Sea - - ? - - Aegean------Levantine Sea Ionian Sea and - - - - - the Central Mediterranean Sea Western - - - - - Mediterranean Sea

ANNEX I Scoring of Likelihoods of Events (taken from UK Non-native Organism Risk Assessment Scheme User Manual, Version 3.3, 28.02.2005)

Score Description Frequency Very unlikely This sort of event is theoretically possible, but is never 1 in 10,000 years known to have occurred and is not expected to occur Unlikely This sort of event has not occurred anywhere in living 1 in 1,000 years memory Possible This sort of event has occurred somewhere at least once in 1 in 100 years recent years, but not locally Likely This sort of event has happened on several occasions 1 in 10 years elsewhere, or on at least one occasion locally in recent years Very likely This sort of event happens continually and would be Once a year expected to occur

ANNEX II Scoring of Magnitude of Impacts (modified from UK Non-native Organism Risk Assessment Scheme User Manual, Version 3.3, 28.02.2005)

Score Biodiversity Ecosystem Economic impact Social and human and ecosystem Services impact (Monetary loss and health impact, and impact response costs per other impacts year) Question 5.1-5 Question 5.6-8 Question 5.9-13 Question 5.14-18 Minimal Local, short-term No services Up to 10,000 Euro No social disruption. population loss, affected6 Local, mild, short- no significant term reversible ecosystem effect effects to individuals. Minor Some ecosystem Local and 10,000-100,000 Significant concern impact, temporary, Euro expressed at local reversible reversible effects to level. Mild short- changes, one or few services term reversible localised effects to identifiable groups, localised. Moderate Measureable Measureable, 100,000-1,000,000 Temporary changes long-term temporary, local Euro to normal activities damage to and reversible at local level. Minor populations and effects on one or irreversible effects ecosystem, but several services and/or larger reversible; little numbers covered by spread, no reversible effects, extinction localised. Major Long-term Local and 1,000,000- Some permanent irreversible irreversible or 10,000,000 Euro change of activity ecosystem widespread and locally, concern change, reversible effects expressed over wider spreading on one / several area. Significant beyond local services irreversible effects area locally or reversible effects over large area. Massive Widespread, Widespread and Above 10,000,000 Long-term social long-term irreversible effects Euro change, significant population loss on one / several loss of employment, or extinction, services migration from affecting several affected area. species with Widespread, severe, serious long-term, ecosystem irreversible health effects effects.

6 Not to be confused with “no impact”. 77

ANNEX III Scoring of Confidence Levels (modified from Bacher et al. 2017)

Each answer provided in the risk assessment must include an assessment of the level of confidence attached to that answer, reflecting the possibility that information needed for the answer is not available or is insufficient or available but conflicting.

The responses in the risk assessment should clearly support the choice of the confidence level.

Confidence Description level Low There is no direct observational evidence to support the assessment, e.g. only inferred data have been used as supporting evidence and/or Impacts are recorded at a spatial scale which is unlikely to be relevant to the assessment area and/or Evidence is poor and difficult to interpret, e.g. because it is strongly ambiguous and/or The information sources are considered to be of low quality or contain information that is unreliable. Medium There is some direct observational evidence to support the assessment, but some information is inferred and/or Impacts are recorded at a small spatial scale, but rescaling of the data to relevant scales of the assessment area is considered reliable, or to embrace little uncertainty and/or The interpretation of the data is to some extent ambiguous or contradictory. High There is direct relevant observational evidence to support the assessment (including causality) and Impacts are recorded at a comparable scale and/or There are reliable/good quality data sources on impacts of the taxa and The interpretation of data/information is straightforward and/or Data/information are not controversial or contradictory.

ANNEX IV Ecosystem services classification (CICES V5.1, simplified) and examples For the purposes of this risk assessment, please feel free to use what seems as the most appropriate category / level / combination of impact (Section – Division – Group), reflecting information available.

Section Division Group Examples (i.e. relevant CICES “classes”) Provisioning Biomass Cultivated terrestrial Cultivated terrestrial plants (including fungi, algae) grown for plants nutritional purposes; Fibres and other materials from cultivated plants, fungi, algae and bacteria for direct use or processing (excluding genetic materials); Cultivated plants (including fungi, algae) grown as a source of energy

Example: negative impacts of non-native organisms to crops, orchards, timber etc. Cultivated aquatic Plants cultivated by in- situ aquaculture grown for nutritional plants purposes; Fibres and other materials from in-situ aquaculture for direct use or processing (excluding genetic materials); Plants cultivated by in- situ aquaculture grown as an energy source.

Example: negative impacts of non-native organisms to aquatic plants cultivated for nutrition, gardening etc. purposes. Reared animals Animals reared for nutritional purposes; Fibres and other materials from reared animals for direct use or processing (excluding genetic materials); Animals reared to provide energy (including mechanical)

Example: negative impacts of non-native organisms to livestock Reared aquatic Animals reared by in-situ aquaculture for nutritional animals purposes; Fibres and other materials from animals grown by in-situ aquaculture for direct use or processing (excluding genetic materials); Animals reared by in-situ aquaculture as an energy source

Example: negative impacts of non-native organisms to fish farming Wild plants Wild plants (terrestrial and aquatic, including fungi, algae) (terrestrial and used for nutrition; aquatic) Fibres and other materials from wild plants for direct use or processing (excluding genetic materials); Wild plants (terrestrial and aquatic, including fungi, algae) used as a source of energy Example: reduction in the availability of wild plants (e.g. wild berries, ornamentals) due to non-native organisms (competition, spread of disease etc.) Wild animals Wild animals (terrestrial and aquatic) used for nutritional (terrestrial and purposes; aquatic) Fibres and other materials from wild animals for direct use or processing (excluding genetic materials); Wild animals (terrestrial and aquatic) used as a source of energy

Example: reduction in the availability of wild animals (e.g. fish stocks, game) due to non-native organisms (competition, predations, spread of disease etc.) 79

Genetic material Genetic material Seeds, spores and other plant materials collected for from all biota from plants, algae or maintaining or establishing a population; fungi Higher and lower plants (whole organisms) used to breed new strains or varieties; Individual genes extracted from higher and lower plants for the design and construction of new biological entities

Example: negative impacts of non-native organisms due to interbreeding Genetic material Animal material collected for the purposes of maintaining or from animals establishing a population; Wild animals (whole organisms) used to breed new strains or varieties; Individual genes extracted from organisms for the design and construction of new biological entities

Example: negative impacts of non-native organisms due to interbreeding Water7 Surface water used Surface water for drinking; for nutrition, Surface water used as a material (non-drinking purposes); materials or energy Freshwater surface water, coastal and marine water used as an energy source

Example: loss of access to surface water due to spread of non-native organisms Ground water for Ground (and subsurface) water for drinking; used for nutrition, Ground water (and subsurface) used as a material (non- materials or energy drinking purposes); Ground water (and subsurface) used as an energy source

Example: reduced availability of ground water due to spread of non-native organisms and associated increase of ground water consumption by vegetation. Regulation Transformation Mediation of wastes Bio-remediation by micro-organisms, algae, plants, and & of biochemical or or toxic substances animals; Filtration/sequestration/storage/accumulation by Maintenance physical inputs to of anthropogenic micro-organisms, algae, plants, and animals ecosystems origin by living processes Example: changes caused by non-native organisms to ecosystem functioning and ability to filtrate etc. waste or toxics Mediation of Smell reduction; noise attenuation; visual screening (e.g. by nuisances of means of green infrastructure) anthropogenic origin Example: changes caused by non-native organisms to ecosystem structure, leading to reduced ability to mediate nuisances. Regulation of Baseline flows and Control of erosion rates; physical, extreme event Buffering and attenuation of mass movement; chemical, regulation Hydrological cycle and water flow regulation (Including biological flood control, and coastal protection); conditions Wind protection; Fire protection

Example: changes caused by non-native organisms to ecosystem functioning or structure leading to, for example, destabilisation of soil, increased risk or intensity of wild fires etc. Lifecycle Pollination (or 'gamete' dispersal in a marine context); maintenance, habitat Seed dispersal; and gene pool Maintaining nursery populations and habitats (Including gene protection pool protection)

7 Note: in the CICES classification provisioning of water is considered as an abiotic service whereas the rest of ecosystem services listed here are considered biotic. 80

Example: changes caused by non-native organisms to the abundance and/or distribution of wild pollinators; changes to the availability / quality of nursery habitats for fisheries Pest and disease Pest control; control Disease control

Example: changes caused by non-native organisms to the abundance and/or distribution of pests Soil quality Weathering processes and their effect on soil quality; regulation Decomposition and fixing processes and their effect on soil quality

Example: changes caused by non-native organisms to vegetation structure and/or soil fauna leading to reduced soil quality Water conditions Regulation of the chemical condition of freshwaters by living processes; Regulation of the chemical condition of salt waters by living processes

Example: changes caused by non-native organisms to buffer strips along water courses that remove nutrients in runoff and/or fish communities that regulate the resilience and resistance of water bodies to eutrophication Atmospheric Regulation of chemical composition of atmosphere and composition and oceans; conditions Regulation of temperature and humidity, including ventilation and transpiration

Example: changes caused by non-native organisms to ecosystems’ ability to sequester carbon and/or evaporative cooling (e.g. by urban trees) Cultural Direct, in-situ Physical and Characteristics of living systems that that enable activities and outdoor experiential promoting health, recuperation or enjoyment through active interactions with interactions with or immersive interactions; living systems natural environment Characteristics of living systems that enable activities that depend on promoting health, recuperation or enjoyment through passive presence in the or observational interactions environmental setting Example: changes caused by non-native organisms to the qualities of ecosystems (structure, species composition etc.) that make it attractive for recreation, wild life watching etc. Intellectual and Characteristics of living systems that enable scientific representative investigation or the creation of traditional ecological interactions with knowledge; natural environment Characteristics of living systems that enable education and training; Characteristics of living systems that are resonant in terms of culture or heritage; Characteristics of living systems that enable aesthetic experiences

Example: changes caused by non-native organisms to the qualities of ecosystems (structure, species composition etc.) that have cultural importance Indirect, remote, Spiritual, symbolic Elements of living systems that have symbolic meaning; often indoor and other interactions Elements of living systems that have sacred or religious interactions with with natural meaning; living systems environment Elements of living systems used for entertainment or that do not require representation presence in the environmental Example: changes caused by non-native organisms to the setting qualities of ecosystems (structure, species composition etc.) that have sacred or religious meaning

Other biotic Characteristics or features of living systems that have an characteristics that existence value; have a non-use value Characteristics or features of living systems that have an option or bequest value

Example: changes caused by non-native organisms to ecosystems designated as wilderness areas, habitats of endangered species etc.

ANNEX V EU Biogeographic Regions and MSFD Subregions See https://www.eea.europa.eu/data-and-maps/figures/biogeographical-regions-in-europe-2 , http://ec.europa.eu/environment/nature/natura2000/biogeog_regions/ and https://www.eea.europa.eu/data-and-maps/data/msfd-regions-and-subregions-1/technical- document/pdf

ANNEX VI Delegated Regulation (EU) 2018/968 of 30 April 2018 see https://eur-lex.europa.eu/legal-content/en/TXT/?uri=CELEX%3A32018R0968