Risk Assessment of Aquatic Invasive Species’ Introductions via European Inland Waterways

VADIM E. PANOV, BORIS ALEXANDROV, KESTUTIS ARBACIAUSKAS, ROSA BINIMELIS, GORDON H. COPP, MICHAL GRABOWSKI, FRANCES LUCY, ROB S.E.W. LEUVEN, STEFAN NEHRING, MOMIR PAUNOVIĆ, VITALIY SEMENCHENKO & MIKHAIL O. SON

Introduction changes. The future developments of Responses European inland waterways have provid- the European network of inland water- (measures within RBMP) ed opportunities for the spread of inva- ways will highly facilitate the transfer of sive alien aquatic (IAS) species for many IAS across European inland waters and Aquatic RAT centuries. Over the past century, the coastal ecosystems. Appropriate risk (risk-based DSS) potential for species to expand their assessment-based management options Driving forces range has been enhanced both as a result are required to address risks posed by Environmental indicators: of the construction of new canals and human-mediated introductions of these Impacts 1. List of Extreme Risk due to increased trade. At present, the species (Panov et al. 2007). pathways Environmental indicators: complex European network of inland Considering the current gap in 2. List of High Risk pathways 1. Species-specific Biopollution waterways is made up of > 28,000 km addressing invasive alien species in 3. List of High Risk donor Risk index (SBPR index) areas 2. Integrated Biopollution Risk of navigable rivers and canals, connect- European river basin management, our Pressures index (IBPR index) ing 37 countries in Europe and beyond goal was to develop relevant risk assess- 3. Grey, White and Black list of (Figure 1). This aquatic network con- Environmental indicators: alien species ment protocols and water quality indica- 1. Biological Contamination Rate (BCR) State nects the previously isolated catchments tors on IAS for possible consideration in 2. Pathway-specific Biological Environmental indicators: Contamination Rate (PBCR) 1. Biological Contamination Level (BCL) White 2. Site-specific Biological Contamination index (SBC index) Sea 3. Integrated Biological Contamination index (IBC index)

Trunk waterways " 3 " Other main waterways Figure 2. Environmental indicators and Risk Assessment Toolkit (RAT) for introductions of aquatic invasive species

in the DPSIR framework (after Panov et al. 2009, modified). RBMP – River Basin Management Plans, DSS – Decision

" Important shipping canals " " 2 Support System on aquatic invasive species (for description of specific environmental indicators see text). " Northern corridor Main watersheds Volga Neva Conceptual model of risk assess- early warning service for reporting Baltic ment of IAS introductions via Sea of environmental indicators and European inland waterways recommendations for risk manage- North Sea Owing to the high degree of scientif- ment to stakeholders – DPSIR Central corridor ic uncertainty when dealing with such “Responses”.

15

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6 " " as large-scale intercontinental and For the purpose of testing this

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9 4 Dnieper " Oder intra-continental introductions of model, we selected a 10-year obser- El be Don Caspian IAS, the qualitative model of risk vation period (1997-2007) for analy-

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14 assessment of IAS introductions via propagule pressure within the select- "

"13 " " " European inland waterways (Panov et ed ecosystems (Assessment Unit), Loire " 11 12 al. 2007, 2009). The present variant and an observation period of time Danube Black Sea e Western of this qualitative model of risk since 1900 for the assessment of bio- Rhôn corridor assessment of IAS introductions via logical contamination level of the Southern corridor navigable waterways includes six main ecosystem. components: ◙ Identification of main invasion Identification of main invasion gateways, routes and corridors in gateways, routes and corridors Europe, and selection of ecosys- in Europe tems as assessment and manage- There are four principal invasion corri- Mediterranean Sea ment units (AUs) within invasions dors in Europe (Figure 1): Figure 1. Important European waterways and invasion corridors for the spread of aquatic species (after Galil corridors/invasion network. ◙ The Northern corridor: linking et al. 2007, modified). Main canal number: 1 – Volga-Don Canal, 2 – Volga-Baltic Canal, 3 – White Sea – Baltic ◙ Identification and analysis of path- the Black and Azov seas with the Sea Canal, 4 – Bug-Pripyat Canal, 5 – Vistula-Oder Canal, 6 – Havel-Oder Canal, 7 – Mittelland Canal, 8 – Dortmund-Ems Canal, 9 – Rhine-Herne Canal, 10 – Ludwig Canal and Main-Danube Canal, 11 – Rhine-Rhône ways of IAS introductions within Caspian Sea via the Azov – Caspian Canal, 12 – Canal du Centre, 13 – Canal de Briar, 14 – Rhine-Marne Canal, 15 – Kiel Canal. Solid red arrows the ecosystem – “Driving forces” waterway including the Volga-Don indicate the Southern meridian invasion corridor and the Northern meridian invasion corridor. according to the DPSIR framework. Canal, and with the Baltic and ◙ Assessment of inoculation rates White seas via the Volga-Baltic of the southern European seas the Common Implementation Strategy (propagule pressure) within the waterway including the Volga-Baltic (Caspian, Azov, Black, Mediterranean) of the EC Water Framework Directive ecosystem– DPSIR “Pressures”; Canal, and the White Sea – Baltic and the northern European seas (Baltic, and as part of a holistic (cumulative) risk- ◙ Assessment of biological contami- Sea waterway, including the White North, Wadden, White), to provide cor- based management of European river nation level of the ecosystem – Sea – Baltic Sea Canal. ridors for IAS. In Europe, there are thir- basins. The European Environmental DPSIR “State”. ◙ The Central corridor: connecting ty main canals with >100 branch canals Agency (EEA) ‘Typology of indicators’ ◙ Assessment of invasiveness of alien the Black Sea with the Baltic Sea and > 350 ports (Galil et al. 2007). and the Driving forces–Pressures–State– species, established in the ecosys- region via Dnieper and Bug-Pripyat There are plans to deepen many of Impact–Response (DPSIR) framework tem (potential biopollution risk) – Canal, with Nemunas River branch these canals to accommodate larger ves- was used to structure developed environ- DPSIR “Impacts”. connected to Pripyat and Bug by sels and to prepare for the lower antici- mental indicators in the socio-economic ◙ Development of an online Risk Oginsky and Augustov canals, cor- pated water levels arising from climate context (Figure 2). Assessment Toolkit (RAT) with respondingly.

140 ATLAS OF BIODIVERSITY RISK CHAPTER 6 ◙ The Southern corridor: linking the Black Sea basin with the North Sea basin via the Danube-Main- Rhine waterway including the Main- Danube Canal. NC6 BCR = 6 ◙ The Western corridor: linking the BCL = 13 Mediterranean with the North Sea IBPR = 3 via the River Rhône and the Rhine- NC4 BCR = 2 Rhône Canal. BCL = 4 IBC = 4 These principal corridors are inter- IBPR = 4 linked via two additional invasion cor- NC5 ridors: the Southern meridian corri- BCR = 1 BCL = 8 dor linking the Northern, Central and IBC = 4 Southern corridors on the south, and IBPR = 4 the Northern meridian corridor, CC12 BCR = 1 CC10 linking the Northern, Central, BCL = 8 IBC = 4 BCR = 2 Southern and Western on the north IBPR = 4 BCL = 12 IBC = 2 (Figure 1). This complex system of IBPR = 4 navigable waterways and invasion cor- CC16 CC9 BCR = 7 BCR = 5 ridors can be considered as an BCL = 27 BCL = 16 European inland water invasion SC8 IBC = 4 IBC = 2 IBPR = 4 IBPR = 4 NC3 BCR = 12 network (Figure 1), with estuaries of BCL = 59 BCR = 2 IBC = 4 CC14 BCL = 82 large European rivers (Don, Danube, IBPR = 4 BCR = 6 IBPR = 4 SC4 BCL = 24 Dnieper, Neva, Odra, Rhine) and IBC = 2 BCR = 10 IBPR = 4 lagoons (Curonian, Vistula) serving as BCL = 73 IBC = 4 entries to the main invasion corridors IBPR = 4 and considered as “invasion gate- SC3 SC2 ways” (Panov et al. 2009). In our NC1 BCR = 14 BCR = 11 study, we selected assessment units BCL = 38 BCL = 24 BCR = 7 IBC = 4 IBC = 4 BCL = 41 within three main invasion corridors IBPR = 4 IBPR = 4 IBPR = 4 (Northern, Central and Southern) in order to consider an ecosystem approach to the management of IAS using river basins as the main man- NC2 BCR = 12 agement units (Figure 3). BCL = 47 IBPR = 4 Identification and analysis of pathways of IAS introductions within the ecosystem Pathways involved in the introduc- Figure 3. Assessment units selected within the Northern, Central and Southern inland water invasion corridors (NC, CC and SC, respectively): NC1 – River Don and Azov Sea, NC2 – lower part of River Volga and Caspian Sea, NC3 – upper and middle parts of River Volga, NC4 – Lake Ladoga, NC5 – River Neva estuary, NC6 – tions of IAS can be considered as River Severnaya Dvina, CC9 – middle part of River Pripyat, CC10 – Dnieper-Bug canal, CC 12 – lower part of River Nemunas, CC14 – River Vistula, CC16 – River “Driving forces” according DPSIR Oder, SC2 – lower part of River Danube, SC3 – middle part of River Danube, SC4 – upper part of River Danube, SC8 – lower part of River Rhine. The Integrated bio- framework (Figure 2). Principal path- logical pollution risk (IBPR) is indicated both by numbers and colours of area boundaries (High biopollution risk and Very high biopollution risk are in orange and red, respectively). ways of aquatic IAS spread in Europe and qualitative descriptors of princi- pal human activities involved in the be attributed with some level of units for last reporting period (1997- ture of the ecosystem can be assessed spread of IAS have been identified certainty to the specific pathway), it 2007 in the present study) are provid- via estimation of the number of estab- (see in Panov et al. 2009). For the can be defined as “Extreme Risk ed in Figure 3. lished alien species and their relative purpose of the present qualitative risk (ER) pathway”. The Pathway-specific Biological roles in the structural organization of assessment of IAS introductions via Contamination Rate (PBCR) reflects plant and animal communities. For the inland waterways, these principal Assessment of inoculation rates the inoculation rate in AU by specific purposes of our study, BCL is estimat- human activities were considered as within the ecosystem pathways and can be estimated by the ed as the number of established alien potential pathways for any selected In the present study we suggest number of recorded alien species in species in AU since 1900 (BCL esti- ecosystem (assessment unit – AU). assessing inoculation rate indirectly AU by specific pathway during the mates for selected assessment units are Pathways are defined according to via the Biological Contamination Rate reporting period. PBCR can be used as provided in Figure 3). BCL can be three classifications: (BCR). “Biological contamination” a DPSIR Environmental indicator for used as a DPSIR Environmental indi- ◙ A pathway with low certainty of of the ecosystem means the introduc- “Pressures”. Where PBCR = 0, there is cator of “State”. the existence of a specific pathway tion of alien species regardless of no biological contamination by existing The Site-specific Biological for a specific AU, can be defined as their abilities to cause negative eco- pathway, whereas if PBCR > 0, then Contamination (SBC) index has “Low Risk (LR) pathway”. logical and/or socio-economic the Extreme Risk pathway (ER path- been elaborated to assess biological ◙ A pathway with a high level of cer- impacts; in a case where impacts of way) can be distinguished. contamination of the specific sam- tainty of its existence in the AU, introduced alien species are measur- pling site within AU with respect to but with no evidence existing of able, the “biological pollution” of Assessment of biological “taxonomic” and “abundance” con- the introduction of alien species in the ecosystem should be evaluated contamination level of the tamination (Arbačiauskas et al. 2008). AU by this pathway during the past (see in Panov et al. 2009). ecosystem For ranking of SBC index see 10 years, can be defined as “High The Biological Contamination Biological contamination level Table 1; an example of assessment Risk (HR) pathway”. Rate (BCR) of the ecosystem or any (BCL) of the AU (ecosystem) reflects of SBC indices for macrozoobenthic ◙ Where the operating pathway can assessment unit (AU) can be estimated the invasibility of the ecosystem (prob- communities and the corresponding be defined as responsible for an as the number of recorded alien spe- ability of establishment of alien spe- ecological quality for 13 locations in introduction of specific alien spe- cies in AU per observation/reporting cies as a complex function of abiotic three assessment units of River cies into a AU during the past 10 period (e.g., total number of recorded and biotic resistance of the ecosystem Pripyat are provided in Figure 5. years (even if only one record of alien species per year or per 10 years). to biological invasions under a specific The Integrated Biological alien species within this period can BCR values for selected assessment level of propagule pressure). This fea- Contamination (IBC) index for the

RISK ASSESSMENT OF AQUATIC INVASIVE SPECIES’ INTRODUCTIONS VIA EUROPEAN INLAND WATERWAYS 141 Table 1. Scoring of Site-specific and Integrated Biological Contamination indices (SBC and IBC) with respect to abundance contamination index (ACI) and taxonomic contamination index (TCI). SBC or IBC ranks: 0 (high status, no biological contamination (BC), blue cell), 1 (good status, low BC, green cell), 2 (moderate status, No No No moderate BC, yellow cells), 3 (low status, high BC, orange cells), 4 (bad status, very high BC, red cells) (after HPS HPE HPI Grey list Arbaˇciauskas et al. 2008).

ACI TCI none 0.01 – 0.10 0.11 – 0.20 0.21 – 0.50 >0.50 Ye s none none 0.01 – 0.10 1 2 3 4 No Ye s 0.11 – 0.20 2 2 3 4 HPE White list 0.21 – 0.50 3 3 3 4 >0.50 4 4 4 4 Ye s

AU can be estimated by averaging “tax- framework. For this purpose we have No onomic” and “abundance” contamina- developed a Species-specific Ye s tion of study sites (within AU), and Biopollution Risk (SBPR) index, HPI Black list can be ranked in the same way as SBC which is based on the general assess- index (see Table 1 and example for ment of the level of invasiveness of macrozoobenthos of Pripyet River in the specific alien species according to 5 Figure 4. Procedure for listing alien species according their potential invasiveness (after Panov et al. 2009, Figure ). The IBC index can be used the estimates of three such descrip- modified). “Yes” in this scheme means that information on potential invasiveness of the species is available, both as DPSIR Environmental indica- tors of the species as High risk for “No” means “Unknown”, or information is not available (HRD – High risk of dispersal, HRE – High risk for tor of “State” (Figure 2) and for dispersal (HRD), High risk for estab- establishment in new environment, HRI – High risk to cause ecological and negative socio-economic impacts). assessment of ecological status of the lishment in a new environment whole AU (aquatic ecosystem) (HRE), and High risk to cause eco- cific locations of the AU can be fur- “White” lists corresponds to IBPR = (Figure 5). IBC indices for selected logical and negative socio-economic ther used for estimation of the 2 (Moderate biopollution risk: assessment units are provided in impacts (HRI). The knowledge on Integrated Biopollution Risk “Moderate” ecological status). Where Figure 3. HRD, HRE and HRI of the alien (IBPR) index. Where no alien species alien species from the “Black list” are species is generally available from sci- are present in the AU, IBPR = 0 (No present in the community, the IBPR Assessment of invasiveness of entific reports and publications asso- biopollution risk: reference condi- can be estimated as 3 in a situation alien species (potential ciated with a particular species intro- tions, or “High” ecological status sensu with relatively low abundance of these biopollution risk) duction (Panov et al. 2009). This the Common Implementation Strategy species (High biopollution risk: Estimations of actual impacts of approach to the risk-based assess- of the EC Water Framework “Poor” ecological status), or 4 in a sit- alien species in specific aquatic eco- ment of invasiveness of the alien Directive). If alien species from uation with relatively high abundance systems (e.g., AUs) are not always species, established in the aquatic “Grey” or “White” lists are present in of “Black list” species (Very high bio- possible and usually require costly ecosystem (AU), was further used in relatively low abundances (less than pollution risk: “Bad” ecological status) long-term research efforts in the spe- the formal procedure of listing of 20 % of total abundance of alien and with the same 20 % threshold for cific water body. In this regard, a risk- alien species into the Grey, White and native species in the community), then “low” and “high” relative abundances based assessment of invasiveness of Black Lists (Figure 4). IBPR = 1 (Low biopollution risk: this (see Figures 3 and 5 for examples). the established alien species can be This ranking of alien species may correspond to “Good” ecological Grey, White and Black Lists of considered the most cost-effective according their invasiveness along status of a water body). Relatively IAS, SBPR and IBPR indices can be way for developing practicable indica- with information on relative abun- high abundance of alien species used as DPSIR Environmental indica- tors for “Impacts” in the DPSIR dance of invasive alien species in spe- (exceeding 20 %) from “Grey” or tors of “Impacts” (Figure 2). Also, the Black List can be used as the EEA SEBI 2010 indicator “Invasive alien species in Europe”, element ‘Worst invasive alien species threaten- SBC, IBC, Ecological ing biodiversity in Europe’’ IBPR scoring status (European Environment Agency 2007). In addition, the IBPR index 0 High Belarus can be recommended for the risk- 1 Good based estimation of ecological status 2 Moderate of water bodies considering alien spe- 3 Poor cies introductions as a specific pres- 4 Bad CC10 CC9 CC8 sure (Panov et al. 2009). Development of an online risk IBPR assessment toolkit with an early warning service for reporting of IBC environmental indicators and recommendations for risk management to stakeholders The aquatic component of the online Risk Assessment Toolkit (RAT) includes risk assessment protocols for IAS introductions via European inland SBC (!7 waterways, supporting database and 1 (!2 (!3 !8 (!11 (! (!4 (!5 ( (!9 (!10 (!12 (!6 electronic journal “Aquatic Invasions” (!13 (Figure 6). The latter serves as an instrument to protect authors’ rights on IAS information stored in the data- base and as an early warning tool (Panov et al. 2008, see also Figures 6 Figure 5. Assessment of ecological status of three assessments units and specific locations in the River Pripyat basin based on estimations of Site-specific biological and 7). The aquatic part of RAT will contamination (SBC), Integrated biological contamination (IBC) and Integrated biological pollution risk (IBPR) indices (after Panov et al. 2009, modified). also serve as the decision-support sys-

142 ATLAS OF BIODIVERSITY RISK CHAPTER 6 GALIL BS, NEHRING S, PANOV VE (2007) tem (DSS), the online transmitter of Waterways as invasion highways – Impact essential information needed for deci- of climate change and globalization. – In: Decision-makers, managers, general public and other interested stakeholders sion-making (Figure 2, Panov et al. Nentwig W, editor. Biological Invasions. (EC, EEA, OSPAR, ICES, CIESM, HELCOM) 2008), and will provide links to other Ecological Studies Nr. 193. Berlin, IAS risk assessment protocols (http:// Germany: Springer, 59-74. PANOV V, D GEBUADZE Y, S HIGANOVA T, www.reabic.net and http://www.cefas. FILIPPOV A, MINCHIN D (2007) A risk co.uk/4200.aspx). assessment of biological invasions: inland waterways of Europe – the northern inva- Conclusions sion corridor case study. – In: Gherardi F, RAT information The developed DPSIR environmental editor. Biological Invaders in Inland Waters: Profiles, Distribution and Threats. Invading transmitter indicators for alien species (“Drivers” Nature – Springer Series in Invasion system – List of Extreme Risk pathways for Ecology, Vol. 2. Heidelberg, Germany: AUs, List of High Risk pathways for Springer, 639-656. AUs, List of High Risk Donor Areas PANOV VE, GOLLASCH S, ALEXANDROV B, Online risk assessment E-jornal for AUs; “Pressures” – Biological ARBACIAUSKAS K, GRABOWSKI M, LUCY F, protocols and supporting Aquatic Invasions MINCHIN D, OLENIN S, PAUNOVIĆ M, SON (protection of author's rights information systems Contamination Rate (BCR), Pathway- M (2008) New electronic journal “Aquatic on primary data and early specific Biological Contamination Rate Invasions”: an important part of the devel- (Cefas and REABIC) warning) (PBCR); “State” – Biological oping European early warning system on Contamination Level (BCL), Site- aquatic invasive species. Deliverable D 5.1.7 specific Biological Contamination (The second volume of “Aquatic Invasions”) to the EC FP6 Integrated (SBC) index, Integrated Biological Project ALARM, 8 p. Available online at Information on records of alien species from monitoring and biological surveys, Contamination (IBC) index; http://ec.europa.eu/environment/nature/ alien species checklists and biology research “Impacts” – Species-specific invasivealien/docs/alarm_deliverable.pdf Biopollution Risk (SBPR) index, Grey, PANOV VE, ALEXANDROV B, ARBACIAUSKAS K, BINIMELIS R, COPP GH, GRABOWSKI M, White and Black lists of alien species Figure 6. Conceptual structure of the online Risk Assessment Toolkit (RAT) for aquatic alien species with LUCY F, L EUVEN RSEW, NEHRING S, early warning functions (after Panov et al. 2009, modified). EC – European Commission (http://ec.europa.eu/), and Integrated Biopollution Risk PAUNOVIĆ M, SEMENCHENKO V, S ON MO (IBPR) index, Figure 2) can be useful EEA – European Environment Agency (http://www.eea.europa.eu/), CIESM – International Commission for the (2009) Assessing the risks of aquatic species Scientific Exploration of the Mediterranean Sea (http://www.ciesm.org), OSPAR – OSPAR Commission for the for risk management at the local, river invasions via European inland waterways: Protection of the Marine Environment of the North-East Atlantic (http://www.ospar.org), HELCOM – Baltic basin, national and regional levels. from concepts to environmental indicators. Marine Environment Protection Commission (http://www.helcom.fi), Cefas – Cefas Risks and impacts of non- Management measures for the Integrated Environmental Assessment and native species Decision support tools (http://www.cefas.co.uk/4200.aspx), REABIC – Regional Euro-Asian Management 5: 110-126. Biological Invasions Centre information system (http://www.reabic.net). DPSIR “Driving forces” and “Pressures” may include preventive actions toward management of 1, 2 345 Extreme Risk and High Risk path- ways. Biological Contamination Rate (BCR) and Pathway-specific Biological Contamination Rate (PBCR) can be used as indicators of the effectiveness of preventive management. In con- 6 11, 12 trast, the management actions for “State” and “Impacts” may involve the control and eradication of estab- lished species from Black List

(according to CBD provisions), and 7 Site-specific and Integrated Biological 21 1 Contamination indices. Along with 12 20 3 the Integrated Biopollution Risk 15 19 index, these can be used as compara- tively simple indicators of the effec- 11 14 8 tiveness of these measures. 16 17 18 Three environmental indicators 14 2 4 from this list can be recommended as cost-effective “Quality Elements” 13 (QEs) according to the Common 10 9, 10 Implementation Strategy of the Water 9 Framework Directive for assessment 7 of ecological status of aquatic ecosys- 8 15-21 tems: Site-specific Biological Contamination (SBC) index, Integrated Biological Contamination (IBC) index 13 and, specifically, based on precaution- 6 ary approach, the Integrated 5 Biopollution Risk (IBPR) index.

Figure 7. Selected new geo-referenced records of invasive alien species in European coastal and inland waters in 2007, published in the second volume of Aquatic References Invasions (2007): 1 – the tubenose goby Proterorhinus marmoratus from the River Neva estuary, Russia (Antsulevich 2007), 2 – the tubenose goby Proterorhinus marmora- ARBAČIAUSKAS K, SEMENCHENKO V, G RABOWSKI tus from the Pripyat River, Belarus (Rizevsky et al. 2007), 3 – the Chinese mitten crab, Eriocheir sinensis from the River Volga, Russia (Shakirova et al. 2007), 4 – the M, LEUVEN RSEW, PAUNOVIĆ M, SON MO, Ponto-Caspian mysid Limnomysis benedeni from the River Pripyat, Belarus (Semenchenko et al. 2007), 5 – the Indo-Pacific humpnose big-eye bream, Monotaxis grandoculis CSÁNYI B, GUMULIAUSKAITĖ S, KONOPACKA in the Mediterranean Sea (Bilecenoglu 2007), 6 – the Red Sea mussel Brachidontes pharaonis from the Turkish coasts (Doˇgan et al. 2007), 7 – the Asian clam Sinanodonta woodiana from Eastern Romania (Popa et al. 2007), 8 – the Ponto-Caspian amphipod Dikerogammarus villosus (“killer shrimp”) in Lac du Bourget, France (Grabowski et A, VAN DER VELDE G, VEZHNOVETZ V, al. 2007), 9 – the Quagga mussels Dreissena bugensis in Ukraine (Son 2007), 10 – the Quagga mussels Dreissena bugensis in the River Main, Germany (van der Velde and PANOV VE (2008) Assessment of biological Platvoet 2007), 11-12 – the Asian amphipod Caprella mutica in coastal waters of UK and Norway (Cook et al. 2007), 13 – the American oyster drill, Urosalpinx cinerea in contamination of benthic macroinvertebrate The Netherlands (Faasse and Ligthart 2007), 14 – the Asian tunicate Styela clava from the central German Bight (Krone et al. 2007), 15-21 – the North-American communities in European inland waterways. ctenophore Mnemiopsis leidyi in the Oslofjorden, Norway (Oliveira 2007), in Danish waters (Tendal et al. 2007), in south-western Baltic Sea (Kube et al. 2007), in the Aquatic Invasions 3: 206-224. Gulf of Gda´nsk, southern Baltic Sea (Janas & Zgrundo 2007), in the central Baltic, Gulf of Bothnia and Gulf of Finland, respectively (Lehtiniemi et al. 2007).

RISK ASSESSMENT OF AQUATIC INVASIVE SPECIES’ INTRODUCTIONS VIA EUROPEAN INLAND WATERWAYS 143