Status and Trends in the Rate of Introduction of Marine Non-Indigenous Species in European Seas

Abstract

Invasive alien species are a major worldwide driver of biodiversity change. The current study lists verified records of non-indigenous species (NIS) in European marine waters until 2020, with the purpose of establishing a baseline, assessing trends, and discussing appropriate threshold values for good environmental status (GES) according to the relevant European legislation. All NIS records were verified by national experts and trends are presented in six-year assessment periods from 1970 to 2020 according to the European Union Marine Strategy Framework Directive. Altogether, 874 NIS have been introduced to European marine waters until 2020 with the Mediterranean Sea and North-East Atlantic Ocean hosting most of the introductions. Overall, the number of new introductions has steadily increased since 2000. The annual rate of new introductions reached 21 new NIS in European seas within the last six-year assessment period (2012–2017). This increase is likely due to increased human activities and research efforts that have intensified during the early 21st century within European Seas. As Europe seas are not environmentally, nor geographically homogenous, the setting of threshold values for assessing GES requires regional expertise. Further, once management measures are operational, pathway-specific threshold values would enable assessing the effectiveness of such measures.

1. Introduction

The introduction of marine Non-Indigenous Species (NIS) is widely perceived as one of the main threats to biological diversity next to habitat destruction at a global scale [1,2]. Invasive Alien Species (IAS) are a subset of NIS, which are of particular concern due to their ability to naturally reproduce in the recipient areas, spread rapidly, and threaten biological diversity in various ways, from reducing genetic variation and modifying gene pools, displacing, hybridizing or competing with local endemic or native species to altering habitat and ecosystem functioning [3,4,5,6,7]. It is essential to note that the term “invasive” may have various implications depending on the context. From a scientific perspective, “invasive” refers to the ability of the species to survive, reproduce and spread in the invaded region [8], whereas political frameworks, such as the EU Regulation (No 1143/2014) on the prevention and management of the introduction and spread of invasive alien species (IAS Regulation) often connect invasiveness to impact.

Marine NIS, and IAS in particular, are addressed by European Union (EU) policies, such as the EU Biodiversity Strategy 2020 (COM (2011) 244) target 5; the European Water Framework Directive (WFD) (2000/60/EC); the EU Marine Strategy Framework Directive (MSFD) (2008/56/EC) with a dedicated descriptor (D2 “Non-indigenous species introduced by human activities are at levels that do not adversely alter the ecosystems”) and the IAS Regulation (No 1143/2014). Non-indigenous species is one of the 11 descriptors in the MSFD that refer to anthropogenic pressures on the marine environment of the EU [9]. In the latest MSFD update [9] among the criteria for assessing descriptor D2 on marine NIS, primary criterion D2C1 concerning new NIS introductions states that: “The number of non-indigenous species which are newly introduced via human activity into the wild, per assessment period (6 years), measured from the reference year (2011) as reported for initial assessment under Article 8(1) of Directive 2008/56/EC, is minimised and where possible reduced to zero”. Efforts to make this target more quantitative are ongoing [10,11,12], further encouraged by Target 6 of the first draft of the Convention on Biological Diversity (CBD) Post-2020 Global Biodiversity Framework, which stipulates at least a 50% reduction in the rate of new introductions [13]. However, to date, only the Baltic Marine Environment Protection Commission (Helsinki Convention, HELCOM) has set a numerical threshold of zero new NIS introductions through anthropogenic activities in the Baltic Sea [10]. At the EU level, Tsiamis et al. [14] suggested that the most suitable approach for setting the Good Environmental Status (GES) thresholds for criterion D2C1 would be a percentage reduction of new NIS introductions for an assessment period compared to the previous six-year assessment period (baseline). Preferably, the more previous six-year cycles that are included in the assessment, the better (e.g., starting from the 1970s) since the inclusion of earlier assessment periods enables tracking down how management measures have changed the result of the assessment over time. Thus, as qualitative GES descriptions turn into quantitative targets, it is now more imperative than ever that information on NIS in European seas is as accurate and complete as possible to provide a sound baseline for future management.

The first compilation of marine NIS inventory in Europe was conducted by Streftaris et al. [15] and followed by an update in 2009 toward the SEBI2010 report [16]. In the same period, comprehensive data collection from a wide range of taxonomic groups through the EU-funded project Delivering Alien Species Inventories for Europe resulted in a European database [17]. The DAISIE database, which included recorded information on the impacts, pathways of introduction, and associated references, was integrated into the information system on Aquatic Non-Indigenous and Cryptogenic Species (AquaNIS) [18]. In parallel, the European Alien Species Information Network (EASIN) [19] has been developed by the European Commission’s Joint Research Centre (JRC) aiming to facilitate the exploration of existing alien species information from a variety of distributed information sources through freely available tools and interoperable web services, compliant with internationally recognized standards. Updated information on NIS is provided by data partners and the editorial board of EASIN [20]. AquaNIS stores and disseminates information on NIS introduction histories, recipient regions, taxonomy, biological traits, impacts, and other relevant documented data. The system is continuously updated with new NIS records provided by registered data providers.

With the digital infrastructure in place and prompted by the increased demands placed by legislation, there is an increasing availability of national (e.g., Portugal) [21] and regional inventories of NIS (e.g., Baltic [22], Mediterranean [23], Black Sea [24]), which have been instrumental for analyzing trends and pathways of NIS introductions at national (e.g., Italy [25], Greece [26], Denmark [27], Belgium [28]), subregional (Macaronesia [29]), regional (Mediterranean [30], Baltic [22]), and global scales [31]. All these assessments have the shared ambition to assess the most updated status of NIS and provide a robust baseline for understanding trends in new NIS arrivals and pathways. Such knowledge is essential for the optimal implementation of existing policies and for evaluating policy effectiveness. Furthermore, knowledge is important to evaluate the need for new policies and management strategies. Updated and validated NIS inventories constitute a milestone for the implementation of the MSFD D2. Based on refined baseline inventories of NIS set by each EU Member State (MS), in the context of the MSFD and the updated data of EASIN, Tsiamis et al. [32] estimated that 787 non-indigenous taxa were found in EU marine and partially transitional waters (including Macaronesia) by the end of 2011. Further, Tsiamis et al. [14] updated the EASIN marine data at the national and MSFD subregional levels up to 31 December 2017. In the period of 2018–2020, not only have new NIS been identified in the European seas, but also new information has emerged on the taxonomic identity (e.g., as a consequence of recent taxonomic revision efforts), biogeographic origin, and distribution of NIS records, resulting in significant changes in both the status and distribution of several species. Now more than ever, it is crucial to reassess, revise and update the NIS inventories at all spatial assessment levels. In this context, the present work presents the most updated list of marine NIS introduced in the EU and surrounding waters validated by national experts and examines trends in these NIS introductions at European, regional, and subregional levels paving the way for the setting of threshold values for new NIS introductions in the context of the MSFD, and particularly of the primary criterion D2C1.

2. Methodology

The national inventories of EU countries submitted to JRC for the purposes of the 2012–2017 assessment cycle [33] formed the starting point for the revision process. They were updated with published data from biodiversity and hot-spot campaigns, academic surveys, and citizen science project observations until December 2020 (reported until June 2022). For Norway, Albania, and Montenegro, local experts were invited. The subsequent validation of the revised lists with the contribution of national experts included several rounds of communication whereby many discrepancies were resolved, and several controversial species were agreed upon. Subsequently, the national data were aggregated at subregional, regional, and Pan-European levels. The species list includes every first novel report of species introduction, irrespective of the establishment status. In our analysis, we only considered the first new record of a NIS within a region/subregion. Duplicate records for any given species were removed to avoid overestimating new NIS records at all spatial levels. The number of species detected/observed per six-year cycles since 1970 was analyzed from these datasets.

2.1. Geographic Coverage

The study area included European marine waters surrounding EU countries, EU candidate countries (Albania, Montenegro), and Norway a country of the European Economic Area (EEA) all divided into regions and subregions (Figure 1,

Table 1. Geographic coverage of new NIS introductions in the present study at regional and subregional levels. Abbreviation: ABI = Bay of Biscay and the Iberian Coast, ACS = Celtic Seas, ANS = Greater North Sea, AMA = Macaronesia, MWE = Western Mediterranean Sea, MIC = Ionian Sea and the Central Mediterranean Sea, MAD = Adriatic Sea, MAL = Aegean-Levantine Sea (Eastern Mediterranean Sea).

Regional Level	Subregional Level
Baltic Sea (BAL)	BAL Denmark (In the Sound area of the Kattegat, the border follows the Øresund/Öresund bridge between Denmark and Sweden and in Copenhagen harbor, the border is defined by a lock just north of the bridge. On the west side of Sjælland, the border follows the OSPAR Convention boundary connecting Gniben Point on Sjællands Odde with Hasenore Head on the coast of Jutland), Estonia, Finland, Germany (Baltic Sea-side), Latvia, Lithuania, Poland, Sweden (Baltic Sea-side)
North-East Atlantic Ocean (NEA)	ANS France (including Eastern English Channel, and a small area of the Western English Channel), Belgium, Netherlands, Germany, Denmark, Sweden, Norway up to 62° N (EEA country).	ACS Ireland and France (Western English Channel)	ABI Spain (mainland), Portugal (mainland), and France.	AMA Portugal (Azores, and Madeira) Spain (Canary Islands)
Mediterranean Sea (MED)	WME Spain, France, and Western Italy	MIC Western Greece (Ionian Sea), Ionian coasts of Italy, and Malta	MAD Adriatic coasts of Italy, Slovenia, Croatia, and Albania and Montenegro (EU candidates)	MAL Cyprus and Eastern Greece
Black Sea (BLK)	BLKBulgaria and Romania

) as per the MSFD delineation [33]. Marine waters of the United Kingdom (UK), Turkey, and Russian Federation were not considered in this work, meaning that NIS records from these countries are not included.

The Baltic Sea (BAL) is here regarded as both a region and a subregion according to the MSFD delineation, and the same applies to the Black Sea (BLK). The North-East Atlantic (NEA) comprises four MSFD subregions, namely: (a) Greater North Sea (ANS) (b) Celtic Seas (ACS), (c) the Bay of Biscay and the Iberian Coast (ABI), and (d) Macaronesia (AMA). The ANS spans the Kattegat, the eastern English Channel, and a small part of the Western English Channel. It covers NIS in coastal and estuarine waters from seven countries including Norway (an EEA country). The Celtic Seas (ACS) are represented only by Ireland and the western English Channel waters of France. Macaronesia (AMA) is a complex of oceanic islands located in the NEA. The region comprises the archipelagos of the Azores (Portugal), Madeira (Portugal), Canary Islands (Spain), and Cabo Verde. For the present paper exclusively European Macaronesia (i.e., the Azores, Madeira, and Canary Islands), which.h is the European marine ecoregion within the Lusitanian province following the proposed classification in [35], was considered. The Mediterranean Sea (MED) includes four MSFD subregions: (a) the Western Mediterranean Sea (MWE); (b) the Ionian Sea and the Central Mediterranean Sea (MIC); (c) the Adriatic Sea (MAD); and (d) the Eastern Mediterranean Sea (MAL), encompassing the Aegean and Levantine basins.

2.2. Data Included

The most recent MSFD D2 evaluation recommendations [13] were largely followed for the inclusion of marine NIS in the present analyses. Accordingly, cryptogenic, and crypto-expanding species for the regions considered were removed from NIS lists and subsequent analyses. The terms cryptogenic and crypto expanding refer to uncertainties in the status of a species in relation to either their true native range [36] or true dispersion pathway (i.e., natural range expansion vs. human-mediated expansion) [14].

Species with insufficient information or new records unverified by experts or NIS with unresolved taxonomic status [32] were included in this study only after detailed scrutiny by different experts and a general agreement that there is a strong indication that their presence and distribution pattern implies an introduction event. It is worth mentioning the case of the annelid Laonome xeprovala, by Bick and Bastrop in Bick et al., 2018, a species described from the Netherlands and subsequently found in other Dutch rivers, canals, and estuaries [37], as well as in the eastern part of the Baltic Sea, and identified originally as Laonome calida Capa, 2007 [38]. Previous literature suggests that North America’s eastern coast is a potential native origin for Laonome xeprovala, although further clarification is still required [39].

It has been heavily debated in recent years whether parasitic NIS and pathogens (including disease agents) should be omitted from MSFD D2 since they are managed under the Aquatic Animal Health Directive (2006/88/EC) [32]. Overall, the JRC group agreed that these NIS should be reported in D2 criteria, but not considered when assessing against a GES threshold [14]. Aiming to produce results that are as representative and comparable as possible with future GES assessments, parasites and pathogens are listed in Table 2 but were not considered in the D2 trend and status analyses.

There are contrasting opinions among national NIS experts with regard to microscopic algae (phytoplankton) and to their native, cryptogenic, or NIS status, which is reflected in the literature [40] but also in the information systems of EASIN and AquaNIS. However, due to the high reproductive potential of phytoplankton and thus the high potential of spreading, it is important to have a gauge on phytoplankton expansion. The JRC invited the D2 NIS experts’ network to contact phytoplankton experts across Europe, to set up a working group that could deliver a consolidated revision of phytoplankton NIS in European seas [14]. Given that further clarification is yet to be provided regarding the status of microalgae in Europe, they are listed in Table 2 but were not considered in the D2 trend and status analyses.

Oligohaline species are included if such species were found in estuarine or coastal systems of the marine region.

NIS spreading from one region/subregion to another through natural dispersal mechanisms (secondary introduction) is included in our analyses. Their introduction pathway was classified as UNAIDED. Such is the case of many Red Sea species that have invaded the eastern Mediterranean (known as Lessepsian immigrants) and are progressively moving to the central and western Mediterranean as well as to the Adriatic Sea. However, species that have undergone tropicalization processes (i.e., shifts in range distribution induced by climate change) [41] were not included as NIS, and thus not considered in these analyses.

With regards to partly native and partly cryptogenic species, here defined as species that are native or cryptogenic in one EU region while they are non-indigenous (i.e., introduced by humans), in another EU region, they were included in the analyses at regional and/or subregional level but not at the pan-European level. Such NIS notably include Mediterranean molluscan transported with shellfish movements to the North-East Atlantic and vice versa, as well as also sessile biota, such as tunicates. Species native within a subregion (e.g., North Sea) that have been anthropogenically transferred to another country within the same subregion, were not included in the subregional analysis, although they are regarded as NIS in the countries they have invaded. This also applies to countries with coastal areas in more than one regional sea (Denmark, France, Germany, Spain, and Sweden).

2.3. Detection Year

The year of introduction was based on the reported date of the first collection/detection. However, it is important to point out that this date does not necessarily reflect the actual year of introduction which may have occurred years or even decades earlier since most species are often overlooked in the early stages of the invasion process, e.g., the green alga Codium fragile that has spread rapidly throughout the globe from its native range in Japan and the North Pacific was first detected in Europe c. 1900 in the Netherlands but reported in 1955 [42]. In addition, the date of first detection/collection is not always documented. In such cases, the publication date was accepted as the first record date. Moreover, in cases where only a time range has been supplied (e.g., 1986–1994), or the first record refers to a decade (e.g., the 1970s), the introduction date was set approximately as the average year for that given period (1990 and 1975, respectively).

3. Results

In total, 874 NIS were identified across European seas by December 2020 including 22 species of parasites and pathogens, and 50 species of microalgae (Table 2, Figure 2a). Of these 80% (701 taxa) were first reported in 1970. The vast majority of NIS are invertebrates (59%), followed by primary producers (algae and plants) (25%) and vertebrates (16%). Dissimilar proportions of all mentioned groups were evidenced across regions and subregions (Figure 3). While invertebrates dominate at all regional seas, the contribution of vertebrates (fishes) at the pan-European level is largely driven by the high contribution of Red Sea fish species in the Mediterranean Sea (Lessepsian immigrants) as opposed to their low presence in the NEA and Black Sea. Primary producers have a higher share in the NEA (29%) than the other regional seas (14–22%).

Table 2. List of NIS and their first year of detection at pan-European and regional levels. Group: VER = vertebrate, INV = invertebrate, PP = primary producer, INV/par = parasite, PP/micro = microalgae. BAL = Baltic Sea, NEA = North-East Atlantic Sea, MED = Mediterranean Sea, BLK = Black Sea. In bold, species detected since 1970. Asterisk denotes freshwater species detected in marine/estuarine environments.

Group	Species	Pan-European	BAL	NEA	MED	BLK
VER	Ablennes hians (Valenciennes, 1846)	2018			2018
VER	Abudefduf sexfasciatus (Lacepède, 1801)	2017			2017
VER	Abudefduf vaigiensis (Quoy & Gaimard, 1825)	2005			2005
VER	Abudefduf hoefleri (Steindachner, 1881)	2014			2014
INV	Acanthaster planci (Linnaeus, 1758)	2006			2006
VER	Acanthopagrus bifasciatus (Forsskål, 1775)	2019			2019
PP	Acanthosiphonia echinata (Harvey) A.M.Savoie & G.W.Saunders	2018			2018
VER	Acanthurus bahianus Castelnau, 1855	2013		2013
VER	Acanthurus cfr gahhm (Forsskål, 1775)	2019			2019
VER	Acanthurus coeruleus Bloch & Schneider, 1801	2011		2013	2011
VER	Acanthurus sohal (Forsskål, 1775)	2017			2017
VER	Acanthurus chirurgus (Bloch, 1787)	2012		2013	2012
INV	Acartia (Acanthacartia) tonsa Dana, 1849	1921	1921	1921	1986	1976
INV	Acartia (Acartiura) omorii Bradford, 1976	2004		2004
INV	Achelia sawayai Marcus, 1940	2016			2016
VER	Acipenser baerii Brandt, 1869	1960	1960	1985
VER	Acipenser gueldenstaedtii Brandt & Ratzeburg, 1833*	1962	1962	2010
VER	Acipenser ruthenus Linnaeus, 1758*	1887	1887
VER	Acipenser stellatus Pallas, 1771	1999	1999
VER	Acipenser transmontanus Richardson, 1836	1999		1999
PP	Acrochaetium catenulatum M.A.Howe	1967		1967
PP	Acrothamnion preissii (Sonder) E.M.Wollaston	1968		2009	1968
INV	Actaeodes tomentosus (H. Milne Edwards, 1834)	2013			2013
INV	Acteocina mucronata (Philippi, 1849)	1991			1991
INV	Actumnus globulus Heller, 1861	1978			1978
PP	Adelosina carinatastriata (Wiesner)	2004		2004
Pathogen	Aerococcus viridans Williams, Hirch & Cowan	1961		1961
PP	Agardhiella subulata (C.Agardh) Kraft & M.J.Wynne	1984		1989	1984
PP	Agarophyton vermiculophyllum (Ohmi) Gurgel, J.N.Norris & Fredericq	1989	2003	1989	2008
PP	Aglaothamnion halliae (Collins) Aponte, D.L.Ballantine & J.N.Norris	1960		1960	2016
VER	Agonus cataphractus (Linnaeus, 1758)	2005			2005
PP	Ahnfeltiopsis flabelliformis (Harvey) Masuda, 1993	1994			1994
PP/micro	Akashiwo sanguinea (K.Hirasaka) G.Hansen & Ø.Moestrup	1982		1982
VER	Alepes djedaba (Forsskål, 1775)	1960			1960
PP/micro	Alexandrium ostenfeldii (Paulsen) Balech & Tangen	1986		1986
PP/micro	Alexandrium affine (H.Inoue & Y.Fukuyo) Balech	1987		1987
PP/micro	Alexandrium leei Balech	1991		1991
PP/micro	Alexandrium margalefii Balech	2006		2006
PP/micro	Alexandrium taylori Balech	1994			1994
INV	Aliculastrum cylindricum (Helbling, 1779)	2020			2020
INV/par	Allolepidapedon fistulariae Yamaguti, 1940	2005			2005
INV	Alpheus rapacida de Man, 1908	1998			1998
INV	Amathina tricarinata (Linnaeus, 1767)	2012			2012
INV	Ammothea hilgendorfi (Böhm, 1879)	1979		2013	1979
INV	Ampelisca cavicoxa Reid, 1951	2005		2005
INV	Ampelisca heterodactyla Schellenberg, 1925	1986		1986
INV	Amphibalanus eburneus (Gould, 1841)	1818		1872	1818	1933
INV	Amphibalanus reticulatus (Utinomi, 1967)	1977		1997	1977
INV	Amphibalanus variegatus (Darwin, 1854)	1997		1997
INV	Amphinome rostrata (Pallas, 1766)	1900		1900
PP	Amphistegina cf. papillosa Said, 1949	2005			2005
PP	Amphistegina lessonii d’Orbigny in Guérin-Méneville, 1832	2001			2001
PP	Amphistegina lobifera Larsen, 1976	1959			1959
INV	Ampithoe valida Smith, 1873	1985		1985	2000
INV	Anadara kagoshimensis (Tokunaga, 1906)	1966		1993	1966	1981
INV	Anadara transversa (Say, 1822)	1975		2016	1975
INV/par	Anguillicola crassus (Kuwahara, Niimi & Itagaki, 1974)	1980	1988	1982	1980
INV	Anomia chinensis Philippi, 1849	1974		1974
INV	Anoplodactylus californicus Hall, 1912	1965			1965
PP	Anotrichium furcellatum (J.Agardh) Baldock	1950		1950
PP	Antithamnion densum (Suhr) M.Howe	1964		1964
PP	Antithamnion diminuatum Wollaston	1989		1989
PP	Antithamnion hubbsii E.Y.Dawson	1987		1989	1987
PP	Antithamnion amphigeneum A.J.K.Millar	1992		1995	1992
PP	Antithamnionella ternifolia (Hooker fil. & Harvey) Lyle	1910	2014	1910	1981
INV	Aoroides curvipes Ariyama, 2004	2009		2009
INV	Aoroides semicurvatus Ariyama, 2004	2009		2009
INV	Aoroides longimerus Ren & Zheng, 1996	2013		2013	2015
INV	Apanthura addui Wägele, 1981	1998			1998
INV	Aplidium antillense (Gravier, 1955)	2004		2004
INV	Aplidium accarense (Millar, 1953)	2012			2012
VER	Apogonichthyoides pharaonis (Bellotti, 1874)	1964			1964
INV	Aquilonastra burtoni (Gray, 1840)	2003			2003
INV	Arachnidium lacourti d’Hondt & Faasse, 2006	1999	2015	1999
INV	Arachnoidella protecta Harmer, 1915	1992			1992
INV	Arbopercula tenella (Hincks, 1880)	1990			1990
INV	Arctapodema australis (Vanhöffen, 1912)	1967			1967
INV	Arcuatula senhousia (Benson, 1842)	1982		2002	1982	2002
INV	Argopecten gibbus (Linnaeus, 1758)	2016		2016
INV	Arhynchite arhynchite (Ikeda, 1924)	2001			2001
INV	Arietellus pavoninus Sars G.O., 1905	1967			1967
VER	Arothron hispidus (Linnaeus, 1758)	2018			2018
INV	Artemia monica Verrill, 1869	1972		1987	1972
INV	Ascidia curvata (Traustedt, 1882)	2014		2014
INV	Ascidia interrupta Heller, 1878	1990		1990
INV	Asclerocheilus ashworthi Blake, 1981	2005		2005
PP	Ascophyllum nodosum (Linnaeus) Le Jolis	2009			2009
PP	Asparagopsis taxiformis (Delile) Trevisan de Saint-Léon (lineage 2)	1928		1928	1992
PP	Asparagopsis armata Harvey	1880		1922	1880
INV	Asterocarpa humilis (Heller, 1878)	2005		2005
PP/micro	Asteromphalus sarcophagus Wallich, 1860	1993		1993
INV	Atactodea striata (Gmelin, 1791)	1977			1977
INV	Atergatis roseus (Rüppell, 1830)	2009			2009
VER	Atherinomorus forskalii (Rüppell, 1838)	1929			1929
INV	Atys angustatus E. A. Smith, 1872	2017			2017
INV	Atys ehrenbergi (Issel, 1869)	2016			2016
INV	Aurelia coerulea von Lendenfeld, 1884	2002			2002
INV	Aurelia solida Browne, 1905	2000			2000
INV	Austrominius modestus (Darwin, 1854)	1944		1944	1990
INV	Axionice medusa (Savigny in Lamarck, 1818)	1976			1976
INV	Baeolidia moebii Bergh, 1888	2017			2017
INV	Balanus glandula Darwin, 1854	2015		2015
INV	Balanus trigonus Darwin, 1854	1887		1887	1927
VER	Balistoides conspicillum (Bloch & Schneider, 1801)	2012			2012
INV	Bankia fimbriatula Moll & Roch, 1931	1847		1847
INV	Barentsia ramosa (Robertson, 1900)	1962		1962
PP	Batophora occidentalis var. largoensis (Harvey) S.Berger & Kaever ex M.J.Wynne	2020			2020
INV	Beania maxilladentata Ramalho, Muricy & Taylor, 2010	2013		2013
INV	Bemlos leptocheirus (Walker, 1909)	2015			2015
INV	Beroe ovata Bruguière, 1789	1997	2011	2013	2004	1997
INV	Berthellina citrina (Rüppell & Leuckart, 1828)	2019			2019
PP/micro	Biddulphia rhombus (Ehrenberg) W.Smith	1983		1983
PP/micro	Biddulphia sinensis Greville	1903	1904	1903
INV	Biflustra grandicella (Canu & Bassler, 1929)	2016		2016
INV	Bispira polyomma Giangrande & Faasse, 2012	2010		2010	2014
INV	Biuve fulvipunctata (Baba, 1938)	1993			1993
INV	Boccardia proboscidea Hartman, 1940	1996		1996	2014
INV	Boccardia semibranchiata Guérin, 1990	1999		1999
INV	Boccardiella hamata (Webster, 1879)	2001		2001
Pathogen	Bonamia exitiosa Hine, Cochennac & Berthe	2006		2006	2007
Pathogen	Bonamia ostreae Pichot, Comps, Tigé, Grizel & Rabouin	1978		1978	1990
PP	Bonnemaisonia hamifera Hariot	1898	1900	1898	1932
INV	Bostrycapulus odites Collin, 2005	1973			1973
INV	Botrylloides diegensis Ritter & Forsyth, 1917	1999		1999	2004
INV	Botrylloides giganteum (Pérès, 1949)	2003			2003
INV	Botrylloides niger Herdman, 1886	2013		2013	2014
INV	Botrylloides violaceus Oka, 1927	1991		1999	1991
PP	Botryocladia wrightii (Harvey) W.E.Schmidt, D.L.Ballantine & Fredericq	1978		2005	1978
PP	Botryocladia madagascariensis G.Feldmann	1978			1978
PP	Botrytella parva (Takamatsu) H.S.Kim	1996			1996
INV	Bougainvillia macloviana Lesson, 1830	1895		1895
INV	Brachidontes exustus (Linnaeus, 1758)	1977		1977
INV	Brachidontes pharaonis (P. Fischer, 1870)	1960			1960
INV	Branchiomma bairdi (McIntsosh, 1885)	1998		2012	1998
INV	Branchiomma boholense (Grube, 1878)	2004			2004
INV	Branchiomma luctuosum (Grube, 1870)	1978		2015	1978
VER	Bregmaceros nectabanus Whitley, 1941	2014			2014
INV	Bugulina simplex (Hincks, 1886)	1982		1982
INV	Bugulina stolonifera (Ryland, 1960)	1976		1976
INV	Bulla arabica Malaquias & Reid, 2008	1998			1998
INV	Bursatella leachii Blainville, 1817	1969			1969
INV	Calanopia elliptica (Dana, 1849)	1891			1891
INV	Callinectes danae Smith, 1869	1981			1981
INV	Callinectes pallidus (de Rochebrune, 1883)	2013		2013
INV	Callinectes sapidus Rathbun, 1896	1901	1951	1901	1947	1967
VER	Callionymus filamentosus Valenciennes, 1837	2003			2003
INV	Calyptospadix cerulea Clarke, 1882	1940	2014		1978	1940
VER	Cantherhines pullus (Ranzani, 1842)	2015		2015
INV	Caprella mutica Schurin, 1935	1985	2017	1985
INV	Caprella scaura Templeton, 1836	1985		1985	1994
VER	Carassius auratus (Linnaeus, 1758)	2012		2012
VER	Carassius gibelio (Bloch, 1782)*	1800	1800
INV	Carijoa riisei (Duchassaing & Michelotti, 1860)	2016		2016
INV	Carupa tenuipes Dana, 1852	2009			2009
INV	Cassiopea andromeda (Forsskål, 1775)	1903			1903
PP	Caulacanthus okamurae Yamada	1999		1999	2002
PP	Caulerpa cylindracea Sonder	1991		1997	1991
PP	Caulerpa lamourouxii (Turner) C.Agardh	1956			1956
PP	Caulerpa taxifolia (M.Vahl) C.Agardh	1984			1984
PP	Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procaccini	2007			2007
PP	Caulerpa webbiana Montagne	2002		2002
INV	Caulibugula zanzibariensis (Waters, 1913)	2003		2003
INV	Cellana rota (Gmelin, 1791)	2007			2007
INV	Celleporaria inaudita Tilbrook, Hayward & Gordon, 2001	2007		2007
INV	Celleporaria aperta (Hincks, 1882)	1975			1975
INV	Celleporaria brunnea (Hincks, 1884)	2007		2007	2010
INV	Celleporaria vermiformis (Waters, 1909)	2015			2015
INV	Celleporella carolinensis Ryland, 1979	1993			1993
INV	Celtodoryx ciocalyptoides (Burton, 1935)	1996		1996
INV	Centropages furcatus (Dana, 1849)	1988			1988
VER	Cephalopholis hemistiktos (Rüppell, 1830)	2009			2009
VER	Cephalopholis taeniops (Valenciennes, 1828)	2009		2009
VER	Cephalopholis nigri (Günther, 1859)	2016			2016
INV	Cephalothrix simula Iwata, 1952	2012		2012
PP	Ceramium atrorubescens Kylin	1988		1988
PP	Ceramium sungminbooi Hughey & Boo	2018		2018
PP	Ceramium tenuicorne (Kützing) Waern	2011		2011
PP	Ceramium bisporum D.L.Ballantine	1980			1980
PP	Ceramium strobiliforme G.W.Lawson & D.M.John	1991			1991
INV	Ceratonereis mirabilis Kinberg, 1865	1997			1997
INV	Cerithidium perparvulum (Watson, 1886)	1995			1995
INV	Cerithiopsis pulvis (Issel, 1869)	1985			1985
INV	Cerithiopsis tenthrenois (Melvill, 1896)	1985			1985
INV	Cerithium scabridum Philippi, 1848	1972			1972
PP/micro	Chaetoceros peruvianus Brightwell	1981		1981
PP/micro	Chaetoceros rostratus Ralfs	2003		2003
PP/micro	Chaetoceros bacteriastroides G.H.H.Karsten	1996			1996
PP/micro	Chaetoceros concavicornis Mangin	2011		2011
PP/micro	Chaetoceros pseudosymmetricus Nielsen	2015			2015
VER	Chaetodipterus faber (Broussonet, 1782)	2019			2019
VER	Chaetodon sanctaehelenae Günther, 1868	1993		1993
VER	Chaetodon auriga Forsskål, 1775	2015			2015
VER	Chaetodontoplus septentrionalis (Temminck & Schlegel, 1844)	2015		2015
INV	Chaetopleura angulata (Spengler, 1797)	1850		1850
INV	Chaetozone corona Berkeley & Berkeley, 1941	1982		1996	1982
INV	Chama asperella Lamarck, 1819	2007			2007
INV	Chama pacifica Broderip, 1835	1998			1998
VER	Champsodon nudivittis (Ogilby, 1895)	2012			2012
INV	Charybdis (Charybdis) japonica (A. Milne-Edwards, 1861)	2006			2006
INV	Charybdis (Charybdis) feriata (Linnaeus, 1758)	2004			2004
INV	Charybdis (Charybdis) hellerii (A. Milne-Edwards, 1867)	1998			1998
INV	Charybdis (Charybdis) lucifera (Fabricius, 1798)	2006			2006
INV	Charybdis (Goniohellenus) longicollis Leene, 1938	1969			1969
PP/micro	Chattonella marina (Subrahmanyan) Hara & Chihara	1974		1974
VER	Cheilodipterus novemstriatus (Rüppell, 1838)	2015			2015
INV	Chelicorophium robustum (G.O. Sars, 1895)	2018	2018
INV	Chelicorophium curvispinum (G.O. Sars, 1895)	1912	1921	1912
VER	Chlorurus rhakoura Randall & Anderson, 1997	2017			2017
PP	Chondria pygmaea Garbary & Vandermeulen	1974			1974
PP	Chondria curvilineata F.S.Collins & Hervey	1981			1981
PP	Chondrus giganteus f. flabellatus Mikami	1994			1994
VER	Chromis multilineata (Guichenot, 1853)	2015		2015
INV	Chromodoris quadricolor (Rüppell & Leuckart, 1830)	1982			1982
INV	Chrysaora achlyos Martin, Gershwin, Burnett, Cargo & Bloom, 1997	2018			2018
VER	Chrysiptera cyanea (Quoy & Gaimard, 1825)	2013			2013
VER	Chrysiptera hemicyanea (Weber, 1913)	2017			2017
PP	Chrysonephos lewisii (W.R.Taylor) W.R.Taylor	1988			1988
INV	Cingulina isseli (Tryon, 1886)	1998			1998
INV	Ciona robusta Hoshino & Tokioka, 1967	1901		2007	1901
VER	Cirrhitus atlanticus Osório, 1893	2018		2018
PP	Cladophora patentiramea (Montagne) Kützing	1991			1991
INV	Clavelina oblonga Herdman, 1880	1929		1971	1929
Pathogen	Claviceps purpurea (Fr.:Fr.)Tul.	1960		1960
PP	Clavulina cf. multicamerata Chapman, 1907	2012			2012
INV	Clementia papyracea (Gmelin, 1791)	1985			1985
INV	Clymenella torquata (Leidy, 1855)	1977		1977
INV	Clytia gregaria (Agassiz, 1862)	2017		2017
INV	Clytia hummelincki (Leloup, 1935)	1996			1996
INV	Clytia linearis (Thorneley, 1900)	1951		1983	1951
PP	Codium arabicum Kützing	2006		2006
PP	Codium fragile subsp. fragile (Suringar) Hariot	1895	1919	1895	1946
PP	Colaconema codicola (Børgesen) H.Stegenga, J.J. Bolton & R.J.Anderson	1926		1926	1952
PP	Colaconema dasyae (F.S.Collins) Stegenga, I.Mol, Prud’homme van Reine & Lokhorst	1951		1951
INV	Coleusia signata (Paul’son, 1875)	2005			2005
PP	Colpomenia peregrina Sauvageau	1905		1905	1918
INV	Conomurex persicus (Swainson, 1821)	1983			1983
INV	Corambe obscura (A.E. Verrill, 1870)	1879		1879		1986
INV	Corbicula fluminea (O. F. Müller, 1774)	1978		1978
INV	Corella eumyota Traustedt, 1882	2002		2002
PP/micro	Corymbellus aureus J.C.Green	1992		1992
PP	Corynomorpha prismatica (J.Agardh) J.Agardh	1990		1990
PP	Corynophlaea verruculiformis (Y.-P.Lee & I.K.Lee) Y.-P.Lee	1994		1994
INV	Coryphellina rubrolineata O’Donoghue, 1929	2008			2008
INV	Crassostrea rhizophorae (Guilding, 1828)	1976		1976
INV	Crassostrea virginica (Gmelin, 1791)	1861		1861		1974
INV	Crepidacantha poissonii (Audouin, 1826)	1982			1982
INV	Crepidula fornicata (Linnaeus, 1758)	1902		1902	1957
INV	Crepipatella dilatata (Lamarck, 1822)	2005		2005	2014
INV	Crisularia plumosa (Pallas, 1766)	1937		1937
INV	Crisularia serrata (Lamarck, 1816)	1902			1902
PP	Cryptonemia hibernica Guiry & L.M.Irvine	1911		1911
PP	Cushmanina striatopunctata (Parker & Jones, 1865)	1913			1913
INV	Cuthona perca (Er. Marcus, 1958)	1976			1976
INV	Cycloscala hyalina (G. B. Sowerby II, 1844)	1992			1992
INV	Cymodoce fuscina Schotte & Kensley, 2005	2015			2015
VER	Cynoscion regalis (Bloch & Schneider, 1801)	2009		2009
VER	Cyprinus carpio (Linnaeus, 1758)*	1200	1200	1879
PP	Dasya sessilis Yamada	1984		1989	1984
PP	Dasysiphonia japonica (Yendo) H.-S.Kim	1984		1984	1998
INV	Dendostrea frons (Linnaeus, 1758)	1983		1983
INV	Dendostrea folium (Linnaeus, 1758)	2005			2005
PP	Derbesia rhizophora Yamada	1984			1984
INV	Desdemona ornata Banse, 1957	1983		1993	1983
INV	Diadema setosum (Leske, 1778)	2010			2010
INV	Diadumene lineata (Verrill, 1869)	1925	2011	1963	1925	1945
PP/micro	Dicroerisma psilonereiella F.J.R.Taylor & S.A. Cattell	1998		1998
PP	Dictyota cyanoloma Tronholm, De Clerck, A.Gómez-Garreta & Rull Lluch in Tronholm et al.	1935		2006	1935
INV	Didemnum perlucidum Monniot F., 1983	2006		2006
INV	Didemnum vexillum Kott, 2002	1968		1968	2007
INV	Dikerogammarus villosus (Sowinsky, 1894)	2015	2015
INV	Dikoleps micalii Agamennone, Sbrana, Nardi, Siragusa & Germanà, 2020	2016			2016
PP/micro	Dinophysis sacculus Stein	2004		2004
INV	Diodora funiculata (Reeve, 1850)	2013			2013
INV	Diplosoma listerianum (Milne Edwards, 1841)	1877			1877
INV	Dipolydora quadrilobata (Jacobi, 1883)	2003				2003
INV	Dipolydora socialis (Schmarda, 1861)	2006		2006
INV	Dipolydora tentaculata (Blake & Kudenov, 1978)	2005		2005
PP	Dipterosiphonia dendritica (C.Agardh) F.Schmitz	1961		1961
INV	Dispio magna (Day, 1955)	1982			1982
PP/micro	Dissodinium pseudocalani (Gonnert) Drebes ex Elbrachter & Drebes	2003		2003
INV	Distaplia magnilarva (Della Valle, 1881)	1929		1929
INV	Distaplia bermudensis Van Name, 1902	1953		2006	1953
INV	Distaplia corolla Monniot F., 1974	1971		1971
INV	Dodecaceria capensis Day, 1961	1976			1976
INV	Dorvillea similis (Crossland, 1924)	2014			2014
INV	Dreissena rostriformis bugensis (Andrusov, 1897)	2014	2014
VER	Dussumieria elopsoides Bleeker, 1849	2005			2005
INV	Dyspanopeus texanus (Stimpson, 1859)	2015		2015
INV	Dyspanopeus sayi (Smith, 1869)	1992		2007	1992
INV	Echinogammarus trichiatus (Martynov, 1932)	2014	2014
INV	Ecteinascidia styeloides (Traustedt, 1882)	1983			1983
INV	Ectopleura crocea (Agassiz, 1862)	1895		1989	1895
INV	Edwardsiella lineata (Verrill in Baird, 1873)	2010		2010
PP	Elachista spp mentioned as E. flaccida	1993		1993
VER	Elates ransonnettii (Steindachner, 1876)	2005			2005
PP	Elodea canadensis Michx.*	1873	1873
PP	Elodea nuttallii (Planch.) H.St.John	1991	1991	2006
PP	Elphidium striatopunctatum (Fichtel & Moll, 1798)	1911			1911
INV	Elysia nealae (Ostergaard, 1955)	2018			2018
PP/micro	Emiliania huxleyi (Lohmann) W.W.Hay & H.P.Mohler	1989		1989
INV	Endeis biseriata Stock, 1968	1979			1979
INV	Ensis leei M. Huber, 2015	1978	1991	1978
INV	Eocuma dimorphum Fage, 1928	1992		1992
INV	Eocuma sarsii (Kossmann), 1880	1901			1901
VER	Epinephelus fasciatus (Forsskål, 1775)	2018		2018
VER	Epinephelus coioides (Hamilton, 1822)	1998			1998
VER	Epinephelus malabaricus (Bloch & Schneider, 1801)	2011			2011
VER	Epinephelus merra Bloch, 1793	2004			2004
VER	Equulites klunzingeri (Steindachner, 1898)	1955			1955
INV	Ergalatax junionae Houart, 2008	1993			1993
INV	Eriocheir sinensis H. Milne Edwards, 1853*	1912	1921	1912	1959	1997
INV	Erugosquilla massavensis (Kossmann, 1880)	1956			1956
PP/micro	Ethmodiscus punctiger Castracane	1800	1979	1800
VER	Etrumeus golanii DiBattista, Randall & Bowen, 2012	1999			1999
INV	Euchaeta concinna Dana, 1849	1987			1987
INV	Eucheilota paradoxica Mayer, 1900	1967			1967
INV	Euchone limnicola Reish, 1959	2015		2015
INV	Eucidaris tribuloides (Lamarck, 1816)	1998			1998
INV	Eudendrium carneum Clarke, 1882	1950			1950
INV	Eudendrium merulum Watson, 1985	1969			1969
INV	Eunaticina papilla (Gmelin, 1791)	2020			2020
INV	Euplana gracilis Girard, 1853	2002		2002
INV	Euplokamis dunlapae Mills, 1987	2011		2011
PP/micro	Eupyxidicula turris (Greville) S.Blanco & C.E. Wetzel	1983		1983
INV	Eurypanopeus depressus (Smith, 1869)	2009				2009
INV	Eurytemora americana Williams, 1906	1938		1938
INV	Eurytemora carolleeae Alekseev & Souissi, 2011	2011	2012	2011
INV	Eurytemora pacifica Sato, 1913	2014		2014
INV	Eurythoe laevisetis Fauvel, 1914	2011			2011
INV	Eusarsiella zostericola (Cushman, 1906)	2012		2012
INV	Eusyllis kupfferi Langerhans, 1879	1998			1998
INV	Euthymella colzumensis (Jousseaume, 1898)	2017			2017
PP/micro	Eutintinnus lusus-undae (Entz)	2001				2001
INV	Fauveliopsis glabra (Hartman, 1960)	2007			2007
INV	Favorinus ghanensis Edmunds, 1968	2020			2020
INV	Faxonius limosus (Rafinesque, 1817)	2015	2015
INV	Fenestrulina malusii (Audouin, 1826)	2011		2011
INV	Fenestrulina delicia Winston, Hayward & Craig, 2000	2002		2002
INV	Ferosagitta galerita (Dallot, 1971)	2011			2011
PP/micro	Fibrocapsa japonica S.Toriumi & H.Takano	1924		1924
INV	Ficopomatus enigmaticus (Fauvel, 1923)	1919	1939	1921	1919	1935
INV	Finella pupoides A. Adams, 1860	1996			1996
VER	Fistularia petimba Lacepède, 1803	2018			2018
VER	Fistularia commersonii Rüppell, 1838	1999			1999
INV	Fistulobalanus albicostatus (Pilsbry, 1916)	1973		1973
INV	Fulvia fragilis (Forsskål in Niebuhr, 1775)	1983			1983
VER	Fundulus heteroclitus heteroclitus (Linnaeus, 1766)	1970		1970	2005
INV	Gafrarium savignyi (Jonas, 1846)	2005			2005
INV	Gammarus tigrinus Sexton, 1939	1931	1975	1931
PP	Gelidium microdonticum W.R.Taylor	2017		2017
PP	Gelidium vagum Okamura	2010		2010
VER	Genyatremus cavifrons (Cuvier, 1830)	2015		2015
INV	Glabropilumnus laevis (Dana, 1852)	1956			1956
INV	Glycinde bonhourei Gravier, 1904	2007			2007
VER	Gobiosoma bosc (Lacepède, 1800)	2009		2009
INV	Godiva quadricolor (Barnard, 1927)	1985			1985
INV	Goniadella gracilis (Verrill, 1873)	1968		1968
INV	Goniobranchus annulatus (Eliot, 1904)	2004			2004
INV	Goniobranchus obsoletus (Rüppell & Leuckart, 1830)	2018			2018
INV	Gonioinfradens giardi (Nobili, 1905)	2010			2010
INV	Gonionemus vertens A. Agassiz, 1862	1700		1700	1918
PP	Goniotrichopsis sublittoralis G.M.Smith	1975		1975	1989
PP	Gracilariopsis chorda (Holmes) Ohmi	2010		2010
INV	Grandidierella japonica Stephensen, 1938	2010	2010	2010	2013
PP	Grateloupia imbricata Holmes	2005		2005
PP	Grateloupia asiatica S.Kawaguchi & H.W.Wang	1984			1984
PP	Grateloupia patens (Okamura) S.Kawaguchi & H.W.Wang	1994			1994
PP	Grateloupia subpectinata Holmes	1978		1978	1990
PP	Grateloupia turuturu Yamada	1982		1989	1982
PP	Grateloupia yinggehaiensis H.W.Wang & R.X.Luan	2008			2008
INV	Guinearma alberti (Rathbun, 1921)	2016		2016
VER	Gymnomuraena zebra (Shaw, 1797)	2002		2002
PP	Gymnophycus hapsiphorus Huisman & Kraft	2011		2011
INV/par	Gyrodactylus salaris Malmberg, 1957	1975		1975
PP/micro	Gyrodinium corallinum Kofoid & Swezy	2001		2001
INV	Halgerda willeyi Eliot, 1904	1988			1988
INV	Haliclona (Halichoclona) vansoesti de Weerdt, de Kluijver & Gómez, 1999	2019			2019
INV	Haliclystus tenuis Kishinouye, 1910	2010		2010
PP	Halimeda incrassata (J.Ellis) J.V.Lamouroux	2011			2011
INV	Haliotis discus hannai Ino, 1953	1985		1985
INV	Haloa japonica (Pilsbry, 1895)	1992		1992	1992
PP	Halophila stipulacea (Forsskål) Ascherson	1894			1894
INV	Haminella solitaria (Say, 1822)	2016	2016	2020
Pathogen	Haplosporidium nelsoni Haskin, Stauber & Mackin	1975		1975
INV	Heleobia charruana (d’Orbigny, 1841)	2014		2014
INV	Heliacus implexus (Mighels, 1845)	2019			2019
INV	Hemigrapsus sanguineus (De Haan, 1835)	1999		1999	1999	2008
INV	Hemigrapsus takanoi Asakura & Watanabe, 2005	1993	2014	1993
INV	Hemimysis anomala G.O. Sars, 1907*	1962	1962	1999	2007
VER	Hemiramphus far (Forsskål, 1775)	1943			1943
VER	Heniochus acuminatus (Linnaeus, 1758)	2014		2014
VER	Heniochus intermedius Steindachner, 1893	2013		2013	2014
INV	Herbstia nitida Manning & Holthuis, 1981	2002			2002
INV	Herdmania momus (Savigny, 1816)	1998			1998
PP	Herposiphonia parca Setchell	1997		2006	1997
INV	Hesperibalanus fallax (Broch, 1927)	1976		1976	1976
PP	Heterostegina depressa d’Orbigny, 1826	1988			1988
INV	Heterotentacula mirabilis (Kramp, 1957)	1997			1997
PP	Hildenbrandia occidentalis Setch.	2011		2011
VER	Hippocampus kuda Bleeker, 1852	2014			2014
INV	Hippopodina feegeensis (Busk, 1884)	1996			1996
VER	Holacanthus africanus Cadenat, 1951	2017		2018	2017
VER	Holacanthus ciliaris (Linnaeus, 1758)	2011			2011
VER	Holocentrus adscensionis (Osbeck, 1765)	2016			2016
INV	Homarus americanus H. Milne Edwards, 1837	1961	2007	1961	2018
VER	Huso huso (Linnaeus, 1758)*	1962	1962
PP	Hydroclathrus tilesii (Endlicher) Santiañez & M.J.Wynne	2006		2006
INV	Hydroides brachyacantha Rioja, 1941	2015			2015
INV	Hydroides dirampha Mörch, 1863	1981		1982	1981
INV	Hydroides elegans (Haswell, 1883)	1868		1973	1868
INV	Hydroides ezoensis Okuda, 1934	1968		1968
INV	Hydroides heterocera (Grube, 1868)	1998			1998
INV	Hymeniacidon gracilis (Hentschel, 1912)	2017		2017
INV	Hypania invalida (Grube, 1860)	1995		1995
INV	Hypereteone heteropoda (Hartman, 1951)	2017		2017
PP	Hypnea musciformis (Wulfen) J.V.Lamouroux	2005		2005
PP	Hypnea anastomosans Papenfuss, Lipkin & P.C.Silva	2008			2008
PP	Hypnea cervicornis J.Agardh	2009			2009
PP	Hypnea cornuta (Kützing) J.Agardh	1894			1894
PP	Hypnea spinella (C.Agardh) Kützing	1977			1977
PP	Hypnea valentiae (Turner) Montagne	1996		2006	1996
INV	Hypselodoris infucata (Rüppell & Leuckart, 1830)	2002			2002
INV	Ianiropsis serricaudis Gurjanova, 1936	2000		2000	2012
INV	Incisocalliope aestuarius (Watling & Maurer, 1973)	1975		1975
INV	Indothais lacera (Born, 1778)	1983			1983
INV	Isognomon aff. australicus (Reeve, 1858)	2016			2016
INV	Isognomon legumen (Gmelin, 1791)	2016			2016
INV	Isognomon radiatus (Anton, 1838)	1996		1996
INV	Isolda pulchella Müller in Grube, 1858	1994		1994
INV	Ixa monodi Holthuis & Gottlieb, 1956	1999			1999
INV	Jasus lalandii (H. Milne Edwards, 1837)	1980		1980
PP	Kapraunia schneideri (Stuercke & Freshwater) A.M.Savoie & G.W.Saunders	2010		2010	2016
PP/micro	Karenia longicanalis Z.B.Yang, I.J.Hodgkiss & Gerd Hansen	2008		2008
PP/micro	Karenia mikimotoi (Miyake & Kominami ex Oda) Gert Hansen & Ø.Moestrup	1968	1980	1968
PP/micro	Karenia papilionacea A.J.Haywood & K.A.Steidinger	1994		1994
INV	Koinostylochus ostreophagus (Hyman, 1955)	1970		1970
Pathogen	Labyrinthula zosterae D. Porter & Muehlst. in Muehlstein & Short	1930		1930
VER	Lactophrys triqueter (Linnaeus, 1758)	1909			1909
VER	Lagocephalus guentheri Miranda Ribeiro, 1915	1952			1952
VER	Lagocephalus sceleratus (Gmelin, 1789)	2004			2004
VER	Lagocephalus suezensis Clark & Gohar, 1953	2003			2003
INV	Lamprohaminoea ovalis (Pease, 1868)	2001			2001
INV	Laonome xeprovala Bick & Bastrop, in Bick et al., 2018	2012	2012	2016		2018
INV	Latopilumnus malardi (De Man, 1914)	1910		1910
PP/micro	Lauderia pumila Castracane	1995				1995
PP	Laurencia brongniartii J.Agardh	1989		1989
PP	Laurencia caduciramulosa Masuda & Kawaguchi	1991			1991
PP	Laurencia okamurae Yamada	1984			1984
PP	Leathesia marina (Lyngbye) Decaisne	1905			1905
INV	Leiocapitellides analis Hartmann-Schröder, 1960	2000			2000
INV	Leiochrides australis Augener, 1914	2002			2002
PP/micro	Lennoxia faveolata H.A.Thomsen & K.R.Buck	2007	2007
INV	Leonnates persicus Wesenberg-Lund, 1949	2013			2013
INV	Lepidonotus tenuisetosus (Gravier, 1902)	2007			2007
INV	Lepidonotus carinulatus (Grube, 1870)	1984			1984
INV	Leucotina natalensis E. A. Smith, 1910	1996			1996
INV	Limnodrilus profundicola (Verrill, 1871)	2014	2014
INV	Limulus polyphemus (Linnaeus, 1758)	1866		1866
INV	Linguimaera caesaris Krapp-Schickel, 2003	1997			1997
INV	Linopherus canariensis Langerhans, 1881	1997			1997
INV	Lioberus ligneus (Reeve, 1858)	2019			2019
PP	Lithophyllum yessoense Foslie	1994			1994
PP	Lomentaria flaccida Tanaka	2002			2002
PP	Lomentaria hakodatensis Yendo	1978		1984	1978
PP	Lophocladia lallemandii (Montagne) F.Schmitz	1908			1908
INV	Lottia sp.	2015			2015
INV	Lovenella assimilis (Browne, 1905)	2007		2007
INV	Lumbrinerides crassicephala (Hartman, 1965)	1994		1994
INV	Lumbrinerides neogesae Miura, 1981	2002			2002
INV	Lumbrineris perkinsi Carrera-Parra, 2001	1973			1973
VER	Lutjanus argentimaculatus (Forsskål, 1775)	2019			2019
VER	Lutjanus griseus (Linnaeus, 1758)	2018		2018
VER	Lutjanus jocu (Bloch & Schneider, 1801)	2005			2005
VER	Lutjanus sebae (Cuvier, 1816)	2010			2010
VER	Lutjanus fulviflamma (Forsskål, 1775)	2013			2013
INV	Lysidice collaris Grube, 1870	1961			1961
PP	Macrocystis pyrifera (Linnaeus) C.Agardh	1972		1972
INV	Macromedaeus voeltzkowi (Lenz, 1905)	1910		1910
INV	Macrophthalmus (Macrophthalmus) indicus Davie, 2012	2009			2009
INV	Macrorhynchia philippina Kirchenpauer, 1872	1982		1982
INV	Magallana angulata (Lamarck, 1819)	1700		1700
INV	Magallana gigas (Thunberg, 1793)	1700	2019	1700	1850	2010
INV	Magallana rivularis (Gould, 1861)	1994		1994
INV	Magallana sikamea (Amemiya, 1928)	1994		1994
INV	Malleus regula (Forsskål in Niebuhr, 1775)	1970			1970
INV	Marenzelleria arctia (Chamberlin, 1920)	2004	2004
INV	Marenzelleria neglecta Sikorski & Bick, 2004	1983	1983	1985
INV	Marenzelleria viridis (Verrill, 1873)	1983	1985	1983
INV	Marginella glabella (Linnaeus, 1758)	2009			2009
INV	Maritigrella fuscopunctata (Prudhoe, 1978)	2014			2014
INV	Marivagia stellata Galil & Gershwin, 2010	2019			2019
INV	Marphysa victori Lavesque, Daffe, Bonifácio & Hutchings, 2017	1975		1975
Pathogen	Marteilia refringens Grizel, Comps, Bonami, Cousserans, Duthoit & Le Pennec	1975		1975	1992
INV	Matuta victor (J.C. Fabricius, 1781)	2018			2018
PP/micro	Mediopyxis helysia Kühn, Hargreaves & Halliger	2003		2003
INV	Megabalanus tintinnabulum (Linnaeus, 1758)	1764		1764	1971
INV	Megabalanus coccopoma (Darwin, 1854)	1851		1851
INV	Melanella orientalis Agamennone, Micali & Siragusa, 2020	2016			2016
PP	Melanothamnus flavimarinus (M.-S.Kim & I.K.Lee) Díaz-Tapia & Maggs	2010		2010
PP	Melanothamnus harveyi (Bailey) Díaz-Tapia & Maggs	1958	1982	2015	1958
PP	Melanothamnus japonicus (Harvey) Díaz-Tapia & Maggs	2016			2016
INV	Melibe viridis (Kelaart, 1858)	1970			1970
INV	Melita nitida S.I. Smith in Verrill, 1873	1996	2010	1996
INV	Menaethius monoceros (Latreille, 1825)	1978			1978
INV	Mercenaria mercenaria (Linnaeus, 1758)	1861		1861	1964
INV	Mesanthura cfr. romulea Poore & Lew Ton, 1986	2000			2000
INV	Metacalanus acutioperculum Ohtsuka, 1984	1995			1995
INV	Metacirolana rotunda (Bruce & Jones, 1978)	1998			1998
INV	Metapenaeopsis aegyptia Galil & Golani, 1990	1996			1996
INV	Metapenaeopsis mogiensis consobrina (Nobili, 1904)	1995			1995
INV	Metapenaeus monoceros (Fabricius, 1798)	1961			1961
INV	Metaxia bacillum (Issel, 1869)	1995			1995
INV	Microcosmus anchylodeirus Traustedt, 1883	1980			1980
INV	Microcosmus squamiger Michaelsen, 1927	1971		1992	1971
INV	Microcosmus exasperatus Heller, 1878	2005		2005	2014
VER	Micropogonias undulatus (Linnaeus, 1766)	1998		1998
PP	Miliolinella fichteliana (d’Orbigny, 1839)	1911			1911
INV	Millepora alcicornis Linnaeus, 1758	2004		2004
PP	Mimosina affinis Millett, 1900	2012			2012
INV	Mitrella psilla (Duclos, 1846)	2016			2016
INV	Mizuhopecten yessoensis (Jay, 1857)	1979		1979
INV	Mnemiopsis leidyi A. Agassiz, 1865	1986	2006	2001	1990	1986
INV	Mnestia girardi (Audouin, 1826)	1990			1990
INV	Moerisia inkermanica Paltschikowa-Ostroumowa	1959	2018	1959
INV	Molgula occidentalis Traustedt, 1883	2010		2010
INV	Monocorophium uenoi (Stephensen, 1932)	2007		2007
VER	Morone saxatilis x Morone chrysops	2019			2019
INV	Mulinia lateralis (Say, 1822)	2017		2017
INV	Murchisonellidae T. L. Casey, 1904	2013	2013
INV	Mycale (Carmia) senegalensis Lévi, 1952	2002		2002
VER	Mycteroperca tigris (Valenciennes, 1833)	2018		2018
INV/par	Myicola ostreae Hoshina & Sugiura, 1953	1972		1972	1972
INV	Myra subgranulata Kossmann, 1877	2004			2004
INV/par	Mytilicola orientalis Mori, 1935	1977	2018	1977	1977
INV	Mytilopsis leucophaeata (Conrad, 1831)	1835	1928	1835
INV	Naineris setosa (Verrill, 1900)	2010			2010
INV	Namanereis littoralis (Grube, 1872)	1991		1991
INV	Neanthes agulhana (Day, 1963)	2007			2007
PP	Nemalion vermiculare Suringar	2005			2005
VER	Nemipterus randalli Russell, 1986	2014			2014
INV	Nemopsis bachei L. Agassiz, 1849	1905		1905
INV	Neodexiospira brasiliensis (Grube, 1872)	1982		1982
PP	Neogastroclonium subarticulatum (Turner) L.Le Gall, Dalen & G.W.Saunders	2017		2017
VER	Neogobius melanostomus (Pallas, 1814)	1990	1990	2004
PP	Neoizziella divaricata (C.K.Tseng) S.-M.Lin, S.-Y.Yang & Huisman	1989		1989
INV	Neomysis americana (S.I. Smith, 1873)	2010		2010
INV	Nereis jacksoni Kinberg, 1865	1964			1964
INV	Nerita sanguinolenta Menke, 1829	1969			1969
INV	Nippoleucon hinumensis (Gamô, 1967)	2019	2019
PP	Nitophyllum stellato-corticatum Okamura	1984			1984
PP	Nonionella sp. T1/Nonionella stella	2012		2012
INV	Notocochlis gualtieriana (Récluz, 1844)	1978			1978
INV	Notomastus aberans Day, 1957	1964			1964
INV	Notomastus mossambicus (Thomassin, 1970)	1997			1997
INV	Novafabricia infratorquata (Fitzhugh, 1973)	1985		2013	1985
INV/par	Nybelinia africana Dollfus, 1960	2005			2005
INV	Obesogammarus crassus (Sars G.O., 1894)*	1962	1962	2016
INV	Ocinebrellus inornatus (Récluz, 1851)	1993		1993
INV	Odontodactylus scyllarus (Linnaeus, 1758)	2009		2009
INV	Oithona davisae Ferrari F.D. & Orsi, 1984	2000		2002	2000	2009
VER	Oncorhynchus gorbuscha (Walbaum, 1792)	1958	1958	1958
VER	Oncorhynchus kisutch (Walbaum, 1792)*	1905	1984	1905
VER	Oncorhynchus mykiss (Walbaum, 1792)*	1882	1882	1899
PP	Operculina ammonoides (Gronovius, 1781)	1911			1911
INV	Ophiactis macrolepidota Marktanner-Turneretscher, 1887	1998			1998
INV	Ophiactis savignyi (Müller & Troschel, 1842)	1968			1968
VER	Ophioblennius atlanticus (Valenciennes, 1836)	2017			2017
INV	Ophryotrocha japonica Paxton & Åkesson, 2010	1999			1999
INV	Ophryotrocha diadema Åkesson, 1976	2006			2006
VER	Oplegnathus fasciatus (Temminck & Schlegel, 1844)	2009			2009
VER	Orthopristis chrysoptera (Linnaeus, 1766)	2020			2020
INV	Oscilla galilae Bogi, Karhan & Yokeş, 2012	2016			2016
VER	Ostorhinchus fasciatus (White, 1790)	2014			2014
Pathogen	Ostracoblabe implexa Born & Flahault	1951		1951
INV	Ostraea angasi G. B. Sowerby II, 1871	1985		1985
INV	Ostrea equestris Say, 1834	1995		1995
INV	Ostrea denselamellosa Lischke, 1869	1982		1982
INV	Ostrea puelchana d’Orbigny, 1842	1989		1989
INV	Oulastrea crispata (Lamarck, 1816)	2012			2012
INV	Oxydromus humesi (Pettibone, 1961)	2009		2009
PP/micro	Oxytoxum criophilum Balech	2003		2003
VER	Oxyurichthys papuensis (Valenciennes, 1837)	2010			2010
INV	Pachygrapsus gracilis (de Saussure, 1857)	2013		2013
PP	Pachymeniopsis gargiuli S.Y.Kim, Manghisi, Morabito & S.M.Boo	1968		2001	1968
PP	Pachymeniopsis lanceolata (K.Okamura) Y.Yamada ex S.Kawabata	1982		2006	1982
INV	Pacifastacus leniusculus (Dana, 1852)	2014	2014
INV	Pacificincola perforata (Okada & Mawatari, 1937)	2001		2001
PP	Padina boergesenii Allender & Kraft	1965			1965
VER	Pagrus major (Temminck & Schlegel, 1843)	2004			2004
INV	Pagurus longicarpus (Say, 1817)	2020		2020
INV	Palaemon macrodactylus Rathbun, 1902	1998	2014	1998	2005	2002
INV	Palola valida (Gravier, 1900)	2014			2014
VER	Pampus argenteus (Euphrasen, 1788)	1896			1896
INV	Panopeus occidentalis Saussure, 1857	2015		2015
PP	Papenfussiella kuromo (Yendo) Inagaki	1990		1990
INV	Paracalanus quasimodo Bowman, 1971	2017		2017
INV	Paracaprella pusilla Mayer, 1890	2010		2010	2011
INV	Paracerceis sculpta (Holmes, 1904)	1981		1988	1981
INV	Paradella dianae (Menzies, 1962)	1985		1988	1985
INV	Paradyte cf. crinoidicola (Potts, 1910)	1968			1968
INV	Paraleucilla magna Klautau, Monteiro & Borojevic, 2004	2000		2006	2000
INV	Paralithodes camtschaticus (Tilesius, 1815)	2008			2008
INV	Parametopella cypris Holmes, 1905	2014			2014
INV	Paramysis (Mesomysis) intermedia (Czerniavsky, 1882)	2008	2008
INV	Paramysis (Serrapalpisis) lacustris (Czerniavsky, 1882)	1962	1962
INV	Paranais frici Hrabĕ, 1941	1970	1970
VER	Paranthias furcifer (Valenciennes, 1828)	2011		2014	2011
INV	Paranthura japonica Richardson, 1909	2005		2007	2005
INV	Parasmittina alba Ramalho, Muricy & Taylor, 2011	2014		2014
INV	Parasmittina multiaviculata Souto, Ramalhosa & Canning-Clode, 2016	2016		2016
INV	Parasmittina egyptiaca (Waters, 1909)	2016			2016
PP	Parasorites orbitolitoides Hofker, 1930	2016			2016
INV	Paratapes textilis (Gmelin, 1791)	2004			2004
INV/par	Paratenuisentis ambiguus (Van Cleave, 1921)	2001	2001
VER	Parexocoetus mento (Valenciennes, 1847)	1955			1955
VER	Parupeneus forsskali (Fourmanoir & Guézé, 1976)	2014			2014
INV	Parvocalanus crassirostris (Dahl F., 1894)	2009			2009
PP	Pegidia lacunata McCulloch, 1977	2010			2010
VER	Pempheris rhomboidea Kossmann & Räuber, 1877	1983			1983
INV	Penaeus aztecus Ives, 1891	2012		2018	2012
INV	Penaeus hathor (Burkenroad, 1959)	2012			2012
INV	Penaeus monodon Fabricius, 1798	2011		2011
INV	Penaeus japonicus Spence Bate, 1888	1972		1980	1972
INV	Penaeus pulchricaudatus Stebbing, 1914	1961		1982	1961
INV	Penaeus semisulcatus De Haan, 1844 [in De Haan, 1833–1850]	2016		2016
PP/micro	Peridiniella catenata (Levander) Balech	1987	1987
PP/micro	Peridiniella danica (Paulsen) Y.B.Okolodkov & J.D.Dodge	1901		1901
PP/micro	Peridinium quadridentatum (F.Stein) Gert Hansen	2005	2008	2005
INV	Perinereis linea (Treadwell, 1936)	2012			2012
Pathogen	Perkinsus chesapeaki McLaughlin, Tall, Shaheen, El Sayed & Faisal	1992		1992	1992
Pathogen	Perkinsus olsenii R.J.G.Lester & G.H.G.Davis	1983		1983
INV	Perophora multiclathrata (Sluiter, 1904)	1983			1983
INV	Perophora viridis Verrill, 1871	1971		1971
INV	Perophora japonica Oka, 1927	1982		1982
PP	Petalonia binghamiseae (J.Agardh) K.L.Vinogradova	1985		1985
INV	Petricolaria pholadiformis (Lamarck, 1818)	1896	1927	1896	1985
VER	Petroscirtes ancylodon Rüppell, 1835	2004			2004
INV	Phallusia nigra Savigny, 1816	2008			2008
INV	Phascolion convestitum Sluiter, 1902	1977			1977
INV	Phascolosoma (Phascolosoma) scolops (Selenka & de Man, 1883)	1975			1975
INV	Photis lamellifera Schellenberg, 1928	1990			1990
Pathogen	Photobacterium damsela Love, Teebken-Fisher, Hose, Farmer III, Hickman & Fanning	1992			1992
PP	Phrix spatulata (E.Y.Dawson) M.J.Wynne, M.Kamiya & J.A.West	1992			1992
INV	Phyllorhiza punctata Lendenfeld, 1884	2005		2018	2005
VER	Piaractus brachypomus (Cuvier, 1818)	2013		2013
PP	Pikea californica Harvey	1991		1991
INV	Pileolaria berkeleyana (Rioja, 1942)	1977		2007	1977
INV	Pilumnopeus africanus (de Man, 1902)	2013		2013
INV	Pilumnopeus vauquelini (Audouin, 1826)	1963			1963
INV	Pilumnus minutus De Haan, 1835 [in De Haan, 1833–1850]	2017			2017
INV	Pinctada fucata (A. Gould, 1850)	2018			2018
INV	Pinctada radiata (Leach, 1814)	1899		1998	1899
VER	Pinguipes brasilianus Cuvier, 1829	1990			1990
INV/par	Piscicola pojmanskae Bielecki, 1994	2008	2008
INV	Pista unibranchia Day, 1963	1997		2005	1997
INV	Plagusia squamosa (Herbst, 1790)	1906			1906
VER	Planiliza haematocheila (Temminck & Schlegel, 1845)	1972			1995	1972
PP	Planispirinella exigua (Brady, 1879)	1910			1910
PP	Planogypsina acervalis (Brady, 1884)	1909			1909
VER	Platycephalus indicus (Linnaeus, 1758)	1978			1978
PP	Plocamium secundatum (Kützing) Kützing	1991			1991
INV	Plocamopherus ocellatus Rüppell & Leuckart, 1828	2015			2015
VER	Poecilopsetta beanii (Goode, 1881)	1995		1995
INV	Polyandrocarpa zorritensis (Van Name, 1931)	1974			1974
INV	Polycera hedgpethi Er. Marcus, 1964	1986		2001	1986
INV	Polycerella emertoni A. E. Verrill, 1880	1964		1981	1964
INV	Polycirrus twisti Potts, 1928	1983			1983
INV	Polyclinum constellatum Savigny, 1816	2014			2014
INV	Polydora colonia Moore, 1907	1983		2018	1983
INV	Polydora triglanda Radashevsky & Hsieh, 2000	2014		2014
INV	Polydora websteri Hartman in Loosanoff & Engle, 1943	2014		2014
PP	Polyopes lancifolius (Harvey) Kawaguchi & Wang	2008		2008
PP	Polysiphonia paniculata Montagne	1967			1967
PP	Polysiphonia forfex Harvey	2011		2011
PP	Polysiphonia morrowii Harvey	1975		1975	1997
PP	Polysiphonia senticulosa Harvey	1993		1993
VER	Pomacanthus imperator (Bloch, 1787)	2016			2016
VER	Pomacanthus paru (Bloch, 1787)	2015		2015
VER	Pomacanthus maculosus (Forsskål, 1775)	1994		1994	2012
VER	Pomadasys stridens (Forsskål, 1775)	1968			1968
INV	Pontogammarus robustoides (Sars, 1894)*	1962	1962
PP	Porphyra umbilicalis Kützing	1989	1989
INV	Portunus segnis (Forskål, 1775)	1958			1958
INV	Potamocorbula amurensis (Schrenck, 1862)	2018		2018
INV	Potamopyrgus antipodarum (Gray, 1843)*	1801	1801	1887
INV	Potamothrix moldaviensis Vejdovský & Mrázek, 1903	2008	2008
INV	Potamothrix bavaricus (Oschmann, 1913)	2015	2015
INV	Potamothrix bedoti (Piguet, 1913)	1915	1915
INV	Potamothrix heuscheri (Bretscher, 1900)*	1960	1960
INV	Potamothrix vejdovskyi (Hrabĕ, 1941)*	1967	1967
inv	Prionospio aluta Maciolek, 1985	1994		1994
INV	Prionospio depauperata Imajima, 1990	2018			2018
INV	Prionospio pulchra Imajima, 1990	1989		1989	1991
INV	Proasellus coxalis (Dollfus, 1892)	2011	2011
INV	Procambarus clarkii (Girard, 1852)*	2000			2000
INV	Prokelisia marginata (Van Duzee, 1897)	2011		2011
PP/micro	Prorocentrum gracile Schütt	1989		1989
INV	Prosphaerosyllis longipapillata (Hartmann-Schröder, 1979)	1997			1997
VER	Proterorhinus nasalis (De Filippi, 1863)	2020	2020
INV	Protodorvillea biarticulata Day, 1963	1975			1975
INV	Protoreaster nodosus (Linnaeus, 1758)	1981			1981
INV	Psammacoma gubernaculum (Hanley, 1844)	2009			2009
PP/micro	Pseudochattonella farcimen (Riisberg I.)	1998	2001	1998
PP/micro	Pseudochattonella verruculosa (Y.Hara & M.Chihara) S.Tanabe-Hosoi, D.Honda, S.Fukaya, Y.Inagaki & Y.Sako	1998	2015	1998
INV/par	Pseudodactylogyrus anguillae (Yin & Sproston, 1948)	1982	1985	1982
INV/par	Pseudodactylogyrus bini (Kikuchi, 1929)	1985	1985	1997
INV	Pseudodiaptomus marinus Sato, 1913	2007		2010	2007
INV	Pseudonereis anomala Gravier, 1899	1969			1969
PP/micro	Pseudo-nitzschia australis Frenguelli	1995		1995	2000
PP/micro	Pseudo-nitzschia multistriata (Takano) Takano	1985		1985
INV	Pseudopolydora paucibranchiata (Okuda, 1937)	1977		1982	1977
VER	Pteragogus trispilus Randall, 2013	1992			1992
VER	Pterois miles (Bennett, 1828)	2009			2009
INV	Ptilohyale littoralis (Stimpson, 1853)	2009		2009
INV	Purpuradusta gracilis notata (Gill, 1858)	1988			1988
INV	Pyrgulina pupaeformis (Souverbie, 1865)	1995			1995
INV	Pyromaia tuberculata (Lockington, 1877)	2016		2016
PP	Pyropia yezoensis (Ueda) M.S.Hwang & H.G.Choi	1975		1984	1975
PP	Pyropia suborbiculata (Kjellman) J.E.Sutherland, H.G.Choi, M.S.Hwang & W.A.Nelson	2010		2010	2014
INV	Pyrunculus fourierii (Audouin, 1826)	1995			1995
INV	Rangia cuneata (G. B. Sowerby I, 1832)	1997	2011	1997
INV	Rapana venosa (Valenciennes, 1846)	1956		1997	1973	1956
VER	Rastrelliger kanagurta (Cuvier, 1816)	2018			2018
INV	Rhinoclavis kochi (Philippi, 1848)	1976			1976
INV	Rhithropanopeus harrisii (Gould, 1841)	1936	1936	1950	1994	1948
PP/micro	Rhizosolenia calcar-avis Schultze	2009		2009
INV	Rhopilema nomadica Galil, 1990	1995			1995
INV	Ringicula minuta H. Adams, 1872	2019			2019
INV	Rissoina bertholleti Issel, 1869	1985			1985
INV	Ruditapes philippinarum (Adams & Reeve, 1850)	1973		1973	1980
PP	Rugulopteryx okamurae (E.Y.Dawson) I.K.Hwang, W.J.Lee & H.S.Kim	2002		2015	2002
PP	Saccharina japonica (J.E. Areschoug) C.E.Lane, C.Mayes, Druehl & G.W.Saunders	1976		1980	1976
INV	Saccostrea cuccullata (Born, 1778)	2007		2007
INV	Saccostrea glomerata (Gould, 1850)	1984			1984
VER	Salvelinus fontinalis (Mitchill, 1814)*	1916		1916
PP	Sarconema filiforme (Sonder) Kylin	1990			1990
PP	Sarconema scinaioides Børgesen	1980			1980
PP	Sargassum muticum (Yendo) Fensholt	1972		1972	1980
VER	Sargocentron rubrum (Forsskål, 1775)	1943			1943
VER	Saurida lessepsianus Russell, Golani & Tikochinski, 2015	1960			1960
PP	Scageliopsis patens Wollaston	1989		1989
VER	Scarus ghobban Forsskål, 1775	2010			2010
VER	Scatophagus argus (Linnaeus, 1766)	2007			2007
INV	Schizoporella japonica Ortmann, 1890	1976		1976
INV	Schizoporella pungens Canu & Bassler, 1928	2010		2010
VER	Sciaenops ocellatus (Linnaeus, 1766)	2016			2016
INV	Scolelepis (Parascolelepis) gilchristi (Day, 1961)	1977			1977
INV	Scolelepis korsuni Sikorski, 1994	1994		1994
INV	Scolionema suvaense (Agassiz & Mayer, 1899)	1950			1950
VER	Scomberomorus commerson (Lacepède, 1800)	2008			2008
INV	Scyllarus caparti Holthuis, 1952	1977			1977
PP	Scytosiphon dotyi M.J.Wynne	1968		1991	1968
VER	Sebastes schlegelii Hilgendorf, 1880	2008		2008
INV	Sebastiscus marmoratus (Cuvier, 1829)	2016		2016
INV	Sepioteuthis lessoniana Férussac [in Lesson], 1831	2009			2009
INV	Septifer cumingii Récluz, 1848	2005			2005
VER	Siganus fuscescens (Houttuyn, 1782)	2020			2020
VER	Siganus virgatus (Valenciennes, 1835)	1975			1975
VER	Siganus luridus (Rüppell, 1829)	1964			1964
VER	Siganus rivulatus Forsskål & Niebuhr, 1775	1925			1925
PP	Sigmamiliolinella australis (Parr, 1932)	2001			2001
VER	Sillago suezensis Golani, Fricke & Tikochinski, 2013	2009			2009
INV	Sinelobus vanhaareni Bamber, 2014	2006	2010	2006
INV	Sinezona plicata (Hedley, 1899)	2019			2019
INV	Smaragdia souverbiana (Montrouzier in Souverbie & Montrouzier, 1863)	1993			1993
INV	Smittina nitidissima (Hincks, 1880)	2014			2014
INV	Smittoidea prolifica Osburn, 1952	1995		1995
PP	Solieria filiformis (Kützing) P.W.Gabrielson	1922			1922
PP	Sorites variabilis Lacroix, 1941	1996			1996
PP	Spartina anglica C.E. Hubbard	1924		1924
PP	Spartina densiflora Brongn.	1986		1986
PP	Spartina patens (Aiton) Muhl.	1986		1986
PP	Spartina alterniflora Loisel	1806		1806
PP	Spermothamnion cymosum (Harvey) De Toni	2010			2010
INV	Sphaeroma walkeri Stebbing, 1905	1977		2015	1977	2004
PP	Sphaerotrichia firma (E.S.Gepp) A.D.Zinova	1981			1981
INV	Sphaerozius nitidus Stimpson, 1858	2013			2013
VER	Sphyraena chrysotaenia Klunzinger, 1884	1964			1964
VER	Sphyraena flavicauda Rüppell, 1838	2003			2003
INV	Spirobranchus tetraceros (Schmarda, 1861)	1970			1970
PP	Spiroloculina angulata Cushman, 1917	1996			1996
PP	Spiroloculina antillarum d’Orbigny, 1839	1911			1911
INV	Spirorbis (Spirorbis) marioni Caullery & Mesnil, 1897	1974		1974	1977
INV	Spondylus spinosus Schreibers, 1793	2001			2001
PP	Spongoclonium caribaeum (Børgesen) M.J.Wynne	1967		1967	1974
VER	Spratelloides delicatulus (Bennett, 1832)	2014			2014
VER	Stegastes variabilis (Castelnau, 1855)	2014			2014
INV	Stenothoe georgiana Bynum & Fox, 1977	2010		2011	2010
VER	Stephanolepis diaspros Fraser-Brunner, 1940	1935			1935
INV	Sternodromia spinirostris (Miers, 1881)	1969			1969
INV	Sticteulima lentiginosa (A. Adams, 1861)	1995			1995
INV	Stomatella sp.	2011			2011
INV	Streblospio gynobranchiata Rice & Levin, 1998	2011				2011
INV	Streblospio benedicti Webster, 1879	1982		1982
INV	Styela plicata (Lesueur, 1823)	1877		1989	1877
INV	Styela canopus (Savigny, 1816)	2006		2006
INV	Styela clava Herdman, 1881	1968	2017	1968	2005	2002
PP	Stypopodium schimperi (Kützing) M.Verlaque & Boudouresque	1990			1990
INV	Syllis hyllebergi (Licher, 1999)	1972			1972
INV	Syllis pectinans Haswell, 1920	1982		1982	2013
PP	Symphyocladia marchantioides (Harvey) Falkenberg	1971		1971	1984
PP	Symphyocladiella dendroidea (Montagne) D.Bustamante, B.Y.Won, S.C.Lindstrom & T.O.Cho	1993		2005	1993
INV	Symplegma rubra Monniot C., 1972	2014		2014
INV	Symplegma brakenhielmi (Michaelsen, 1904)	2003			2003
VER	Synagrops japonicus (Döderlein, 1883)	1987			1987
INV	Synaptula reciprocans (Forsskål, 1775)	1967			1967
VER	Synchiropus sechellensis Regan, 1908	2014			2014
INV	Synidotea laticauda Benedict, 1897	1975		1975
INV	Syphonota geographica (A. Adams & Reeve, 1850)	1999			1999
INV	Syrnola fasciata Jickeli, 1882	1995			1995
INV/par	Taeniastrotos sp.	1993		1993
PP/micro	Takayama tasmanica de Salas, Bolch & Hallegraeff	2008		2008
INV	Telmatogeton japonicus Tokunaga, 1933	1962	1962	1979
INV	Tenellia adspersa (Nordmann, 1845)	2001		2001
VER	Terapon theraps (Cuvier, 1829)	2007			2007
INV	Terebella ehrenbergi Gravier, 1906	1952			1952
INV	Teredo bartschi Clapp, 1923	2003		2003	2007
INV	Thalamita gloriensis Crosnier, 1962	1977			1977
INV	Thalamita poissonii (Audouin, 1826)	1969			1969
PP/micro	Thalassiosira nordenskioeldii Cleve	1967				1967
PP/micro	Thalassiosira hendeyi Hasle & G.Fryxell	1978		1978
PP/micro	Thalassiosira tealata Takano	1968		1968
PP/micro	Thecadinium yashimaense S.Yoshimatsu, S.Toriumi & J.D.Dodge	2002		2002
INV	Thelepus japonicus Marenzeller, 1884	2017		2017
INV	Theora lubrica Gould, 1861	2001		2010	2001
INV	Timarete punctata (Grube, 1859)	2006			2006
INV	Tonicia atrata (G.B. Sowerby II, 1840)	1978		1978
VER	Torquigener flavimaculosus Hardy & Randall, 1983	2006			2006
INV	Trachysalambria palaestinensis (Steinitz, 1932)	1995			1995
INV	Tremoctopus gracilis (Souleyet, 1852)	1937			1937
INV	Tricellaria inopinata d’Hondt & Occhipinti Ambrogi, 1985	1982		1996	1982
INV	Triconia rufa (Boxshall & Böttger, 1987)	2004			2004
INV	Triconia umerus (Böttger-Schnack & Boxshall, 1990)	2004			2004
INV	Tridentata marginata (Kirchenpauer, 1864)	1980		1980	1990
VER	Tridentiger barbatus (Günther, 1861)	2016		2016
PP/micro	Trieres mobiliensis (J.W.Bailey) Ashworth & Theriot	1983		1983
PP/micro	Trieres regia (M.Schultze) M.P.Ashworth & E.C.Theriot	1989		1989
VER	Trinectes maculatus (Bloch & Schneider, 1801)	1984		1984
PP/micro	Tripos arietinus (Cleve) F.Gómez	1992		1992
PP/micro	Tripos macroceros (Ehrenberg) F.Gómez	1983		1983
INV	Trochus erithreus Brocchi, 1821	1985			1985
INV	Tubastraea tagusensis Wells, 1982	2017		2017
INV	Turbonilla edgarii (Melvill, 1896)	1996			1996
VER	Tylerius spinosissimus (Regan, 1908)	2004			2004
VER	Tylosurus crocodilus crocodilus (Péron & Lesueur, 1821)	2003			2003
PP	Ulva australis Areschoug	1984		1990	1984
PP	Ulva californica Wille	2006		2006	2011
PP	Ulva gigantea (Kützing) Bliding	2015		2015
PP	Ulva ohnoi M.Hiraoka & S.Shimada	2011		2015	2011
PP	Ulvaria obscura (Kützing) P.Gayral ex C.Bliding	1985			1985
PP	Umbraulva dangeardii M.J.Wynne & G.Furnari	2014		2014
PP	Undaria pinnatifida (Harvey) Suringar	1971		1975	1971
PP	Undella hadai Balech	2004			2004
VER	Upeneus moluccensis (Bleeker, 1855)	1947			1947
VER	Upeneus pori Ben-Tuvia & Golani, 1989	2003			2003
INV	Urocaridella pulchella Yokes & Galil, 2006	2018			2018
PP	Uronema marinum Womersley	1989			1989
INV	Urosalpinx cinerea (Say, 1822)	1960		1960
INV	Vallicula multiformis Rankin, 1956	1998		1998
VER	Vanderhorstia mertensi Klausewitz, 1974	2019			2019
VER	Variola louti (Forsskål, 1775)	2018			2018
PP	Vaucheria longicaulis Hoppaugh	2020		2020
INV	Viriola sp.[cf. bayani] Jousseaume, 1884	2016			2016
INV	Watersipora aterrima (Ortmann, 1890)	1983		1983
INV	Watersipora subatra (Ortmann, 1890)	1987		1987
INV	Watersipora arcuata Banta, 1969	1990		1990	2013
PP	Womersleyella setacea (Hollenberg) R.E.Norris	1986			1986
INV	Xanthias lamarckii (H. Milne Edwards, 1834)	2013			2013
INV	Xenostrobus securis (Lamarck, 1819)	1991		2005	1991
INV	Yoldia limatula (Say, 1831)	2019		2019
INV	Zafra savignyi (Moazzo, 1939)	1995			1995
INV	Zafra selasphora (Melvill & Standen, 1901)	1995			1995
VER	Zebrasoma flavescens (Bennett, 1828)	2008			2008
VER	Zebrasoma xanthurum (Blyth, 1852)	2015			2015

Table 2. List of NIS and their first year of detection at pan-European and regional levels. Group: VER = vertebrate, INV = invertebrate, PP = primary producer, INV/par = parasite, PP/micro = microalgae. BAL = Baltic Sea, NEA = North-East Atlantic Sea, MED = Mediterranean Sea, BLK = Black Sea. In bold, species detected since 1970. Asterisk denotes freshwater species detected in marine/estuarine environments.

Group	Species	Pan-European	BAL	NEA	MED	BLK
VER	Ablennes hians (Valenciennes, 1846)	2018			2018
VER	Abudefduf sexfasciatus (Lacepède, 1801)	2017			2017
VER	Abudefduf vaigiensis (Quoy & Gaimard, 1825)	2005			2005
VER	Abudefduf hoefleri (Steindachner, 1881)	2014			2014
INV	Acanthaster planci (Linnaeus, 1758)	2006			2006
VER	Acanthopagrus bifasciatus (Forsskål, 1775)	2019			2019
PP	Acanthosiphonia echinata (Harvey) A.M.Savoie & G.W.Saunders	2018			2018
VER	Acanthurus bahianus Castelnau, 1855	2013		2013
VER	Acanthurus cfr gahhm (Forsskål, 1775)	2019			2019
VER	Acanthurus coeruleus Bloch & Schneider, 1801	2011		2013	2011
VER	Acanthurus sohal (Forsskål, 1775)	2017			2017
VER	Acanthurus chirurgus (Bloch, 1787)	2012		2013	2012
INV	Acartia (Acanthacartia) tonsa Dana, 1849	1921	1921	1921	1986	1976
INV	Acartia (Acartiura) omorii Bradford, 1976	2004		2004
INV	Achelia sawayai Marcus, 1940	2016			2016
VER	Acipenser baerii Brandt, 1869	1960	1960	1985
VER	Acipenser gueldenstaedtii Brandt & Ratzeburg, 1833*	1962	1962	2010
VER	Acipenser ruthenus Linnaeus, 1758*	1887	1887
VER	Acipenser stellatus Pallas, 1771	1999	1999
VER	Acipenser transmontanus Richardson, 1836	1999		1999
PP	Acrochaetium catenulatum M.A.Howe	1967		1967
PP	Acrothamnion preissii (Sonder) E.M.Wollaston	1968		2009	1968
INV	Actaeodes tomentosus (H. Milne Edwards, 1834)	2013			2013
INV	Acteocina mucronata (Philippi, 1849)	1991			1991
INV	Actumnus globulus Heller, 1861	1978			1978
PP	Adelosina carinatastriata (Wiesner)	2004		2004
Pathogen	Aerococcus viridans Williams, Hirch & Cowan	1961		1961
PP	Agardhiella subulata (C.Agardh) Kraft & M.J.Wynne	1984		1989	1984
PP	Agarophyton vermiculophyllum (Ohmi) Gurgel, J.N.Norris & Fredericq	1989	2003	1989	2008
PP	Aglaothamnion halliae (Collins) Aponte, D.L.Ballantine & J.N.Norris	1960		1960	2016
VER	Agonus cataphractus (Linnaeus, 1758)	2005			2005
PP	Ahnfeltiopsis flabelliformis (Harvey) Masuda, 1993	1994			1994
PP/micro	Akashiwo sanguinea (K.Hirasaka) G.Hansen & Ø.Moestrup	1982		1982
VER	Alepes djedaba (Forsskål, 1775)	1960			1960
PP/micro	Alexandrium ostenfeldii (Paulsen) Balech & Tangen	1986		1986
PP/micro	Alexandrium affine (H.Inoue & Y.Fukuyo) Balech	1987		1987
PP/micro	Alexandrium leei Balech	1991		1991
PP/micro	Alexandrium margalefii Balech	2006		2006
PP/micro	Alexandrium taylori Balech	1994			1994
INV	Aliculastrum cylindricum (Helbling, 1779)	2020			2020
INV/par	Allolepidapedon fistulariae Yamaguti, 1940	2005			2005
INV	Alpheus rapacida de Man, 1908	1998			1998
INV	Amathina tricarinata (Linnaeus, 1767)	2012			2012
INV	Ammothea hilgendorfi (Böhm, 1879)	1979		2013	1979
INV	Ampelisca cavicoxa Reid, 1951	2005		2005
INV	Ampelisca heterodactyla Schellenberg, 1925	1986		1986
INV	Amphibalanus eburneus (Gould, 1841)	1818		1872	1818	1933
INV	Amphibalanus reticulatus (Utinomi, 1967)	1977		1997	1977
INV	Amphibalanus variegatus (Darwin, 1854)	1997		1997
INV	Amphinome rostrata (Pallas, 1766)	1900		1900
PP	Amphistegina cf. papillosa Said, 1949	2005			2005
PP	Amphistegina lessonii d’Orbigny in Guérin-Méneville, 1832	2001			2001
PP	Amphistegina lobifera Larsen, 1976	1959			1959
INV	Ampithoe valida Smith, 1873	1985		1985	2000
INV	Anadara kagoshimensis (Tokunaga, 1906)	1966		1993	1966	1981
INV	Anadara transversa (Say, 1822)	1975		2016	1975
INV/par	Anguillicola crassus (Kuwahara, Niimi & Itagaki, 1974)	1980	1988	1982	1980
INV	Anomia chinensis Philippi, 1849	1974		1974
INV	Anoplodactylus californicus Hall, 1912	1965			1965
PP	Anotrichium furcellatum (J.Agardh) Baldock	1950		1950
PP	Antithamnion densum (Suhr) M.Howe	1964		1964
PP	Antithamnion diminuatum Wollaston	1989		1989
PP	Antithamnion hubbsii E.Y.Dawson	1987		1989	1987
PP	Antithamnion amphigeneum A.J.K.Millar	1992		1995	1992
PP	Antithamnionella ternifolia (Hooker fil. & Harvey) Lyle	1910	2014	1910	1981
INV	Aoroides curvipes Ariyama, 2004	2009		2009
INV	Aoroides semicurvatus Ariyama, 2004	2009		2009
INV	Aoroides longimerus Ren & Zheng, 1996	2013		2013	2015
INV	Apanthura addui Wägele, 1981	1998			1998
INV	Aplidium antillense (Gravier, 1955)	2004		2004
INV	Aplidium accarense (Millar, 1953)	2012			2012
VER	Apogonichthyoides pharaonis (Bellotti, 1874)	1964			1964
INV	Aquilonastra burtoni (Gray, 1840)	2003			2003
INV	Arachnidium lacourti d’Hondt & Faasse, 2006	1999	2015	1999
INV	Arachnoidella protecta Harmer, 1915	1992			1992
INV	Arbopercula tenella (Hincks, 1880)	1990			1990
INV	Arctapodema australis (Vanhöffen, 1912)	1967			1967
INV	Arcuatula senhousia (Benson, 1842)	1982		2002	1982	2002
INV	Argopecten gibbus (Linnaeus, 1758)	2016		2016
INV	Arhynchite arhynchite (Ikeda, 1924)	2001			2001
INV	Arietellus pavoninus Sars G.O., 1905	1967			1967
VER	Arothron hispidus (Linnaeus, 1758)	2018			2018
INV	Artemia monica Verrill, 1869	1972		1987	1972
INV	Ascidia curvata (Traustedt, 1882)	2014		2014
INV	Ascidia interrupta Heller, 1878	1990		1990
INV	Asclerocheilus ashworthi Blake, 1981	2005		2005
PP	Ascophyllum nodosum (Linnaeus) Le Jolis	2009			2009
PP	Asparagopsis taxiformis (Delile) Trevisan de Saint-Léon (lineage 2)	1928		1928	1992
PP	Asparagopsis armata Harvey	1880		1922	1880
INV	Asterocarpa humilis (Heller, 1878)	2005		2005
PP/micro	Asteromphalus sarcophagus Wallich, 1860	1993		1993
INV	Atactodea striata (Gmelin, 1791)	1977			1977
INV	Atergatis roseus (Rüppell, 1830)	2009			2009
VER	Atherinomorus forskalii (Rüppell, 1838)	1929			1929
INV	Atys angustatus E. A. Smith, 1872	2017			2017
INV	Atys ehrenbergi (Issel, 1869)	2016			2016
INV	Aurelia coerulea von Lendenfeld, 1884	2002			2002
INV	Aurelia solida Browne, 1905	2000			2000
INV	Austrominius modestus (Darwin, 1854)	1944		1944	1990
INV	Axionice medusa (Savigny in Lamarck, 1818)	1976			1976
INV	Baeolidia moebii Bergh, 1888	2017			2017
INV	Balanus glandula Darwin, 1854	2015		2015
INV	Balanus trigonus Darwin, 1854	1887		1887	1927
VER	Balistoides conspicillum (Bloch & Schneider, 1801)	2012			2012
INV	Bankia fimbriatula Moll & Roch, 1931	1847		1847
INV	Barentsia ramosa (Robertson, 1900)	1962		1962
PP	Batophora occidentalis var. largoensis (Harvey) S.Berger & Kaever ex M.J.Wynne	2020			2020
INV	Beania maxilladentata Ramalho, Muricy & Taylor, 2010	2013		2013
INV	Bemlos leptocheirus (Walker, 1909)	2015			2015
INV	Beroe ovata Bruguière, 1789	1997	2011	2013	2004	1997
INV	Berthellina citrina (Rüppell & Leuckart, 1828)	2019			2019
PP/micro	Biddulphia rhombus (Ehrenberg) W.Smith	1983		1983
PP/micro	Biddulphia sinensis Greville	1903	1904	1903
INV	Biflustra grandicella (Canu & Bassler, 1929)	2016		2016
INV	Bispira polyomma Giangrande & Faasse, 2012	2010		2010	2014
INV	Biuve fulvipunctata (Baba, 1938)	1993			1993
INV	Boccardia proboscidea Hartman, 1940	1996		1996	2014
INV	Boccardia semibranchiata Guérin, 1990	1999		1999
INV	Boccardiella hamata (Webster, 1879)	2001		2001
Pathogen	Bonamia exitiosa Hine, Cochennac & Berthe	2006		2006	2007
Pathogen	Bonamia ostreae Pichot, Comps, Tigé, Grizel & Rabouin	1978		1978	1990
PP	Bonnemaisonia hamifera Hariot	1898	1900	1898	1932
INV	Bostrycapulus odites Collin, 2005	1973			1973
INV	Botrylloides diegensis Ritter & Forsyth, 1917	1999		1999	2004
INV	Botrylloides giganteum (Pérès, 1949)	2003			2003
INV	Botrylloides niger Herdman, 1886	2013		2013	2014
INV	Botrylloides violaceus Oka, 1927	1991		1999	1991
PP	Botryocladia wrightii (Harvey) W.E.Schmidt, D.L.Ballantine & Fredericq	1978		2005	1978
PP	Botryocladia madagascariensis G.Feldmann	1978			1978
PP	Botrytella parva (Takamatsu) H.S.Kim	1996			1996
INV	Bougainvillia macloviana Lesson, 1830	1895		1895
INV	Brachidontes exustus (Linnaeus, 1758)	1977		1977
INV	Brachidontes pharaonis (P. Fischer, 1870)	1960			1960
INV	Branchiomma bairdi (McIntsosh, 1885)	1998		2012	1998
INV	Branchiomma boholense (Grube, 1878)	2004			2004
INV	Branchiomma luctuosum (Grube, 1870)	1978		2015	1978
VER	Bregmaceros nectabanus Whitley, 1941	2014			2014
INV	Bugulina simplex (Hincks, 1886)	1982		1982
INV	Bugulina stolonifera (Ryland, 1960)	1976		1976
INV	Bulla arabica Malaquias & Reid, 2008	1998			1998
INV	Bursatella leachii Blainville, 1817	1969			1969
INV	Calanopia elliptica (Dana, 1849)	1891			1891
INV	Callinectes danae Smith, 1869	1981			1981
INV	Callinectes pallidus (de Rochebrune, 1883)	2013		2013
INV	Callinectes sapidus Rathbun, 1896	1901	1951	1901	1947	1967
VER	Callionymus filamentosus Valenciennes, 1837	2003			2003
INV	Calyptospadix cerulea Clarke, 1882	1940	2014		1978	1940
VER	Cantherhines pullus (Ranzani, 1842)	2015		2015
INV	Caprella mutica Schurin, 1935	1985	2017	1985
INV	Caprella scaura Templeton, 1836	1985		1985	1994
VER	Carassius auratus (Linnaeus, 1758)	2012		2012
VER	Carassius gibelio (Bloch, 1782)*	1800	1800
INV	Carijoa riisei (Duchassaing & Michelotti, 1860)	2016		2016
INV	Carupa tenuipes Dana, 1852	2009			2009
INV	Cassiopea andromeda (Forsskål, 1775)	1903			1903
PP	Caulacanthus okamurae Yamada	1999		1999	2002
PP	Caulerpa cylindracea Sonder	1991		1997	1991
PP	Caulerpa lamourouxii (Turner) C.Agardh	1956			1956
PP	Caulerpa taxifolia (M.Vahl) C.Agardh	1984			1984
PP	Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procaccini	2007			2007
PP	Caulerpa webbiana Montagne	2002		2002
INV	Caulibugula zanzibariensis (Waters, 1913)	2003		2003
INV	Cellana rota (Gmelin, 1791)	2007			2007
INV	Celleporaria inaudita Tilbrook, Hayward & Gordon, 2001	2007		2007
INV	Celleporaria aperta (Hincks, 1882)	1975			1975
INV	Celleporaria brunnea (Hincks, 1884)	2007		2007	2010
INV	Celleporaria vermiformis (Waters, 1909)	2015			2015
INV	Celleporella carolinensis Ryland, 1979	1993			1993
INV	Celtodoryx ciocalyptoides (Burton, 1935)	1996		1996
INV	Centropages furcatus (Dana, 1849)	1988			1988
VER	Cephalopholis hemistiktos (Rüppell, 1830)	2009			2009
VER	Cephalopholis taeniops (Valenciennes, 1828)	2009		2009
VER	Cephalopholis nigri (Günther, 1859)	2016			2016
INV	Cephalothrix simula Iwata, 1952	2012		2012
PP	Ceramium atrorubescens Kylin	1988		1988
PP	Ceramium sungminbooi Hughey & Boo	2018		2018
PP	Ceramium tenuicorne (Kützing) Waern	2011		2011
PP	Ceramium bisporum D.L.Ballantine	1980			1980
PP	Ceramium strobiliforme G.W.Lawson & D.M.John	1991			1991
INV	Ceratonereis mirabilis Kinberg, 1865	1997			1997
INV	Cerithidium perparvulum (Watson, 1886)	1995			1995
INV	Cerithiopsis pulvis (Issel, 1869)	1985			1985
INV	Cerithiopsis tenthrenois (Melvill, 1896)	1985			1985
INV	Cerithium scabridum Philippi, 1848	1972			1972
PP/micro	Chaetoceros peruvianus Brightwell	1981		1981
PP/micro	Chaetoceros rostratus Ralfs	2003		2003
PP/micro	Chaetoceros bacteriastroides G.H.H.Karsten	1996			1996
PP/micro	Chaetoceros concavicornis Mangin	2011		2011
PP/micro	Chaetoceros pseudosymmetricus Nielsen	2015			2015
VER	Chaetodipterus faber (Broussonet, 1782)	2019			2019
VER	Chaetodon sanctaehelenae Günther, 1868	1993		1993
VER	Chaetodon auriga Forsskål, 1775	2015			2015
VER	Chaetodontoplus septentrionalis (Temminck & Schlegel, 1844)	2015		2015
INV	Chaetopleura angulata (Spengler, 1797)	1850		1850
INV	Chaetozone corona Berkeley & Berkeley, 1941	1982		1996	1982
INV	Chama asperella Lamarck, 1819	2007			2007
INV	Chama pacifica Broderip, 1835	1998			1998
VER	Champsodon nudivittis (Ogilby, 1895)	2012			2012
INV	Charybdis (Charybdis) japonica (A. Milne-Edwards, 1861)	2006			2006
INV	Charybdis (Charybdis) feriata (Linnaeus, 1758)	2004			2004
INV	Charybdis (Charybdis) hellerii (A. Milne-Edwards, 1867)	1998			1998
INV	Charybdis (Charybdis) lucifera (Fabricius, 1798)	2006			2006
INV	Charybdis (Goniohellenus) longicollis Leene, 1938	1969			1969
PP/micro	Chattonella marina (Subrahmanyan) Hara & Chihara	1974		1974
VER	Cheilodipterus novemstriatus (Rüppell, 1838)	2015			2015
INV	Chelicorophium robustum (G.O. Sars, 1895)	2018	2018
INV	Chelicorophium curvispinum (G.O. Sars, 1895)	1912	1921	1912
VER	Chlorurus rhakoura Randall & Anderson, 1997	2017			2017
PP	Chondria pygmaea Garbary & Vandermeulen	1974			1974
PP	Chondria curvilineata F.S.Collins & Hervey	1981			1981
PP	Chondrus giganteus f. flabellatus Mikami	1994			1994
VER	Chromis multilineata (Guichenot, 1853)	2015		2015
INV	Chromodoris quadricolor (Rüppell & Leuckart, 1830)	1982			1982
INV	Chrysaora achlyos Martin, Gershwin, Burnett, Cargo & Bloom, 1997	2018			2018
VER	Chrysiptera cyanea (Quoy & Gaimard, 1825)	2013			2013
VER	Chrysiptera hemicyanea (Weber, 1913)	2017			2017
PP	Chrysonephos lewisii (W.R.Taylor) W.R.Taylor	1988			1988
INV	Cingulina isseli (Tryon, 1886)	1998			1998
INV	Ciona robusta Hoshino & Tokioka, 1967	1901		2007	1901
VER	Cirrhitus atlanticus Osório, 1893	2018		2018
PP	Cladophora patentiramea (Montagne) Kützing	1991			1991
INV	Clavelina oblonga Herdman, 1880	1929		1971	1929
Pathogen	Claviceps purpurea (Fr.:Fr.)Tul.	1960		1960
PP	Clavulina cf. multicamerata Chapman, 1907	2012			2012
INV	Clementia papyracea (Gmelin, 1791)	1985			1985
INV	Clymenella torquata (Leidy, 1855)	1977		1977
INV	Clytia gregaria (Agassiz, 1862)	2017		2017
INV	Clytia hummelincki (Leloup, 1935)	1996			1996
INV	Clytia linearis (Thorneley, 1900)	1951		1983	1951
PP	Codium arabicum Kützing	2006		2006
PP	Codium fragile subsp. fragile (Suringar) Hariot	1895	1919	1895	1946
PP	Colaconema codicola (Børgesen) H.Stegenga, J.J. Bolton & R.J.Anderson	1926		1926	1952
PP	Colaconema dasyae (F.S.Collins) Stegenga, I.Mol, Prud’homme van Reine & Lokhorst	1951		1951
INV	Coleusia signata (Paul’son, 1875)	2005			2005
PP	Colpomenia peregrina Sauvageau	1905		1905	1918
INV	Conomurex persicus (Swainson, 1821)	1983			1983
INV	Corambe obscura (A.E. Verrill, 1870)	1879		1879		1986
INV	Corbicula fluminea (O. F. Müller, 1774)	1978		1978
INV	Corella eumyota Traustedt, 1882	2002		2002
PP/micro	Corymbellus aureus J.C.Green	1992		1992
PP	Corynomorpha prismatica (J.Agardh) J.Agardh	1990		1990
PP	Corynophlaea verruculiformis (Y.-P.Lee & I.K.Lee) Y.-P.Lee	1994		1994
INV	Coryphellina rubrolineata O’Donoghue, 1929	2008			2008
INV	Crassostrea rhizophorae (Guilding, 1828)	1976		1976
INV	Crassostrea virginica (Gmelin, 1791)	1861		1861		1974
INV	Crepidacantha poissonii (Audouin, 1826)	1982			1982
INV	Crepidula fornicata (Linnaeus, 1758)	1902		1902	1957
INV	Crepipatella dilatata (Lamarck, 1822)	2005		2005	2014
INV	Crisularia plumosa (Pallas, 1766)	1937		1937
INV	Crisularia serrata (Lamarck, 1816)	1902			1902
PP	Cryptonemia hibernica Guiry & L.M.Irvine	1911		1911
PP	Cushmanina striatopunctata (Parker & Jones, 1865)	1913			1913
INV	Cuthona perca (Er. Marcus, 1958)	1976			1976
INV	Cycloscala hyalina (G. B. Sowerby II, 1844)	1992			1992
INV	Cymodoce fuscina Schotte & Kensley, 2005	2015			2015
VER	Cynoscion regalis (Bloch & Schneider, 1801)	2009		2009
VER	Cyprinus carpio (Linnaeus, 1758)*	1200	1200	1879
PP	Dasya sessilis Yamada	1984		1989	1984
PP	Dasysiphonia japonica (Yendo) H.-S.Kim	1984		1984	1998
INV	Dendostrea frons (Linnaeus, 1758)	1983		1983
INV	Dendostrea folium (Linnaeus, 1758)	2005			2005
PP	Derbesia rhizophora Yamada	1984			1984
INV	Desdemona ornata Banse, 1957	1983		1993	1983
INV	Diadema setosum (Leske, 1778)	2010			2010
INV	Diadumene lineata (Verrill, 1869)	1925	2011	1963	1925	1945
PP/micro	Dicroerisma psilonereiella F.J.R.Taylor & S.A. Cattell	1998		1998
PP	Dictyota cyanoloma Tronholm, De Clerck, A.Gómez-Garreta & Rull Lluch in Tronholm et al.	1935		2006	1935
INV	Didemnum perlucidum Monniot F., 1983	2006		2006
INV	Didemnum vexillum Kott, 2002	1968		1968	2007
INV	Dikerogammarus villosus (Sowinsky, 1894)	2015	2015
INV	Dikoleps micalii Agamennone, Sbrana, Nardi, Siragusa & Germanà, 2020	2016			2016
PP/micro	Dinophysis sacculus Stein	2004		2004
INV	Diodora funiculata (Reeve, 1850)	2013			2013
INV	Diplosoma listerianum (Milne Edwards, 1841)	1877			1877
INV	Dipolydora quadrilobata (Jacobi, 1883)	2003				2003
INV	Dipolydora socialis (Schmarda, 1861)	2006		2006
INV	Dipolydora tentaculata (Blake & Kudenov, 1978)	2005		2005
PP	Dipterosiphonia dendritica (C.Agardh) F.Schmitz	1961		1961
INV	Dispio magna (Day, 1955)	1982			1982
PP/micro	Dissodinium pseudocalani (Gonnert) Drebes ex Elbrachter & Drebes	2003		2003
INV	Distaplia magnilarva (Della Valle, 1881)	1929		1929
INV	Distaplia bermudensis Van Name, 1902	1953		2006	1953
INV	Distaplia corolla Monniot F., 1974	1971		1971
INV	Dodecaceria capensis Day, 1961	1976			1976
INV	Dorvillea similis (Crossland, 1924)	2014			2014
INV	Dreissena rostriformis bugensis (Andrusov, 1897)	2014	2014
VER	Dussumieria elopsoides Bleeker, 1849	2005			2005
INV	Dyspanopeus texanus (Stimpson, 1859)	2015		2015
INV	Dyspanopeus sayi (Smith, 1869)	1992		2007	1992
INV	Echinogammarus trichiatus (Martynov, 1932)	2014	2014
INV	Ecteinascidia styeloides (Traustedt, 1882)	1983			1983
INV	Ectopleura crocea (Agassiz, 1862)	1895		1989	1895
INV	Edwardsiella lineata (Verrill in Baird, 1873)	2010		2010
PP	Elachista spp mentioned as E. flaccida	1993		1993
VER	Elates ransonnettii (Steindachner, 1876)	2005			2005
PP	Elodea canadensis Michx.*	1873	1873
PP	Elodea nuttallii (Planch.) H.St.John	1991	1991	2006
PP	Elphidium striatopunctatum (Fichtel & Moll, 1798)	1911			1911
INV	Elysia nealae (Ostergaard, 1955)	2018			2018
PP/micro	Emiliania huxleyi (Lohmann) W.W.Hay & H.P.Mohler	1989		1989
INV	Endeis biseriata Stock, 1968	1979			1979
INV	Ensis leei M. Huber, 2015	1978	1991	1978
INV	Eocuma dimorphum Fage, 1928	1992		1992
INV	Eocuma sarsii (Kossmann), 1880	1901			1901
VER	Epinephelus fasciatus (Forsskål, 1775)	2018		2018
VER	Epinephelus coioides (Hamilton, 1822)	1998			1998
VER	Epinephelus malabaricus (Bloch & Schneider, 1801)	2011			2011
VER	Epinephelus merra Bloch, 1793	2004			2004
VER	Equulites klunzingeri (Steindachner, 1898)	1955			1955
INV	Ergalatax junionae Houart, 2008	1993			1993
INV	Eriocheir sinensis H. Milne Edwards, 1853*	1912	1921	1912	1959	1997
INV	Erugosquilla massavensis (Kossmann, 1880)	1956			1956
PP/micro	Ethmodiscus punctiger Castracane	1800	1979	1800
VER	Etrumeus golanii DiBattista, Randall & Bowen, 2012	1999			1999
INV	Euchaeta concinna Dana, 1849	1987			1987
INV	Eucheilota paradoxica Mayer, 1900	1967			1967
INV	Euchone limnicola Reish, 1959	2015		2015
INV	Eucidaris tribuloides (Lamarck, 1816)	1998			1998
INV	Eudendrium carneum Clarke, 1882	1950			1950
INV	Eudendrium merulum Watson, 1985	1969			1969
INV	Eunaticina papilla (Gmelin, 1791)	2020			2020
INV	Euplana gracilis Girard, 1853	2002		2002
INV	Euplokamis dunlapae Mills, 1987	2011		2011
PP/micro	Eupyxidicula turris (Greville) S.Blanco & C.E. Wetzel	1983		1983
INV	Eurypanopeus depressus (Smith, 1869)	2009				2009
INV	Eurytemora americana Williams, 1906	1938		1938
INV	Eurytemora carolleeae Alekseev & Souissi, 2011	2011	2012	2011
INV	Eurytemora pacifica Sato, 1913	2014		2014
INV	Eurythoe laevisetis Fauvel, 1914	2011			2011
INV	Eusarsiella zostericola (Cushman, 1906)	2012		2012
INV	Eusyllis kupfferi Langerhans, 1879	1998			1998
INV	Euthymella colzumensis (Jousseaume, 1898)	2017			2017
PP/micro	Eutintinnus lusus-undae (Entz)	2001				2001
INV	Fauveliopsis glabra (Hartman, 1960)	2007			2007
INV	Favorinus ghanensis Edmunds, 1968	2020			2020
INV	Faxonius limosus (Rafinesque, 1817)	2015	2015
INV	Fenestrulina malusii (Audouin, 1826)	2011		2011
INV	Fenestrulina delicia Winston, Hayward & Craig, 2000	2002		2002
INV	Ferosagitta galerita (Dallot, 1971)	2011			2011
PP/micro	Fibrocapsa japonica S.Toriumi & H.Takano	1924		1924
INV	Ficopomatus enigmaticus (Fauvel, 1923)	1919	1939	1921	1919	1935
INV	Finella pupoides A. Adams, 1860	1996			1996
VER	Fistularia petimba Lacepède, 1803	2018			2018
VER	Fistularia commersonii Rüppell, 1838	1999			1999
INV	Fistulobalanus albicostatus (Pilsbry, 1916)	1973		1973
INV	Fulvia fragilis (Forsskål in Niebuhr, 1775)	1983			1983
VER	Fundulus heteroclitus heteroclitus (Linnaeus, 1766)	1970		1970	2005
INV	Gafrarium savignyi (Jonas, 1846)	2005			2005
INV	Gammarus tigrinus Sexton, 1939	1931	1975	1931
PP	Gelidium microdonticum W.R.Taylor	2017		2017
PP	Gelidium vagum Okamura	2010		2010
VER	Genyatremus cavifrons (Cuvier, 1830)	2015		2015
INV	Glabropilumnus laevis (Dana, 1852)	1956			1956
INV	Glycinde bonhourei Gravier, 1904	2007			2007
VER	Gobiosoma bosc (Lacepède, 1800)	2009		2009
INV	Godiva quadricolor (Barnard, 1927)	1985			1985
INV	Goniadella gracilis (Verrill, 1873)	1968		1968
INV	Goniobranchus annulatus (Eliot, 1904)	2004			2004
INV	Goniobranchus obsoletus (Rüppell & Leuckart, 1830)	2018			2018
INV	Gonioinfradens giardi (Nobili, 1905)	2010			2010
INV	Gonionemus vertens A. Agassiz, 1862	1700		1700	1918
PP	Goniotrichopsis sublittoralis G.M.Smith	1975		1975	1989
PP	Gracilariopsis chorda (Holmes) Ohmi	2010		2010
INV	Grandidierella japonica Stephensen, 1938	2010	2010	2010	2013
PP	Grateloupia imbricata Holmes	2005		2005
PP	Grateloupia asiatica S.Kawaguchi & H.W.Wang	1984			1984
PP	Grateloupia patens (Okamura) S.Kawaguchi & H.W.Wang	1994			1994
PP	Grateloupia subpectinata Holmes	1978		1978	1990
PP	Grateloupia turuturu Yamada	1982		1989	1982
PP	Grateloupia yinggehaiensis H.W.Wang & R.X.Luan	2008			2008
INV	Guinearma alberti (Rathbun, 1921)	2016		2016
VER	Gymnomuraena zebra (Shaw, 1797)	2002		2002
PP	Gymnophycus hapsiphorus Huisman & Kraft	2011		2011
INV/par	Gyrodactylus salaris Malmberg, 1957	1975		1975
PP/micro	Gyrodinium corallinum Kofoid & Swezy	2001		2001
INV	Halgerda willeyi Eliot, 1904	1988			1988
INV	Haliclona (Halichoclona) vansoesti de Weerdt, de Kluijver & Gómez, 1999	2019			2019
INV	Haliclystus tenuis Kishinouye, 1910	2010		2010
PP	Halimeda incrassata (J.Ellis) J.V.Lamouroux	2011			2011
INV	Haliotis discus hannai Ino, 1953	1985		1985
INV	Haloa japonica (Pilsbry, 1895)	1992		1992	1992
PP	Halophila stipulacea (Forsskål) Ascherson	1894			1894
INV	Haminella solitaria (Say, 1822)	2016	2016	2020
Pathogen	Haplosporidium nelsoni Haskin, Stauber & Mackin	1975		1975
INV	Heleobia charruana (d’Orbigny, 1841)	2014		2014
INV	Heliacus implexus (Mighels, 1845)	2019			2019
INV	Hemigrapsus sanguineus (De Haan, 1835)	1999		1999	1999	2008
INV	Hemigrapsus takanoi Asakura & Watanabe, 2005	1993	2014	1993
INV	Hemimysis anomala G.O. Sars, 1907*	1962	1962	1999	2007
VER	Hemiramphus far (Forsskål, 1775)	1943			1943
VER	Heniochus acuminatus (Linnaeus, 1758)	2014		2014
VER	Heniochus intermedius Steindachner, 1893	2013		2013	2014
INV	Herbstia nitida Manning & Holthuis, 1981	2002			2002
INV	Herdmania momus (Savigny, 1816)	1998			1998
PP	Herposiphonia parca Setchell	1997		2006	1997
INV	Hesperibalanus fallax (Broch, 1927)	1976		1976	1976
PP	Heterostegina depressa d’Orbigny, 1826	1988			1988
INV	Heterotentacula mirabilis (Kramp, 1957)	1997			1997
PP	Hildenbrandia occidentalis Setch.	2011		2011
VER	Hippocampus kuda Bleeker, 1852	2014			2014
INV	Hippopodina feegeensis (Busk, 1884)	1996			1996
VER	Holacanthus africanus Cadenat, 1951	2017		2018	2017
VER	Holacanthus ciliaris (Linnaeus, 1758)	2011			2011
VER	Holocentrus adscensionis (Osbeck, 1765)	2016			2016
INV	Homarus americanus H. Milne Edwards, 1837	1961	2007	1961	2018
VER	Huso huso (Linnaeus, 1758)*	1962	1962
PP	Hydroclathrus tilesii (Endlicher) Santiañez & M.J.Wynne	2006		2006
INV	Hydroides brachyacantha Rioja, 1941	2015			2015
INV	Hydroides dirampha Mörch, 1863	1981		1982	1981
INV	Hydroides elegans (Haswell, 1883)	1868		1973	1868
INV	Hydroides ezoensis Okuda, 1934	1968		1968
INV	Hydroides heterocera (Grube, 1868)	1998			1998
INV	Hymeniacidon gracilis (Hentschel, 1912)	2017		2017
INV	Hypania invalida (Grube, 1860)	1995		1995
INV	Hypereteone heteropoda (Hartman, 1951)	2017		2017
PP	Hypnea musciformis (Wulfen) J.V.Lamouroux	2005		2005
PP	Hypnea anastomosans Papenfuss, Lipkin & P.C.Silva	2008			2008
PP	Hypnea cervicornis J.Agardh	2009			2009
PP	Hypnea cornuta (Kützing) J.Agardh	1894			1894
PP	Hypnea spinella (C.Agardh) Kützing	1977			1977
PP	Hypnea valentiae (Turner) Montagne	1996		2006	1996
INV	Hypselodoris infucata (Rüppell & Leuckart, 1830)	2002			2002
INV	Ianiropsis serricaudis Gurjanova, 1936	2000		2000	2012
INV	Incisocalliope aestuarius (Watling & Maurer, 1973)	1975		1975
INV	Indothais lacera (Born, 1778)	1983			1983
INV	Isognomon aff. australicus (Reeve, 1858)	2016			2016
INV	Isognomon legumen (Gmelin, 1791)	2016			2016
INV	Isognomon radiatus (Anton, 1838)	1996		1996
INV	Isolda pulchella Müller in Grube, 1858	1994		1994
INV	Ixa monodi Holthuis & Gottlieb, 1956	1999			1999
INV	Jasus lalandii (H. Milne Edwards, 1837)	1980		1980
PP	Kapraunia schneideri (Stuercke & Freshwater) A.M.Savoie & G.W.Saunders	2010		2010	2016
PP/micro	Karenia longicanalis Z.B.Yang, I.J.Hodgkiss & Gerd Hansen	2008		2008
PP/micro	Karenia mikimotoi (Miyake & Kominami ex Oda) Gert Hansen & Ø.Moestrup	1968	1980	1968
PP/micro	Karenia papilionacea A.J.Haywood & K.A.Steidinger	1994		1994
INV	Koinostylochus ostreophagus (Hyman, 1955)	1970		1970
Pathogen	Labyrinthula zosterae D. Porter & Muehlst. in Muehlstein & Short	1930		1930
VER	Lactophrys triqueter (Linnaeus, 1758)	1909			1909
VER	Lagocephalus guentheri Miranda Ribeiro, 1915	1952			1952
VER	Lagocephalus sceleratus (Gmelin, 1789)	2004			2004
VER	Lagocephalus suezensis Clark & Gohar, 1953	2003			2003
INV	Lamprohaminoea ovalis (Pease, 1868)	2001			2001
INV	Laonome xeprovala Bick & Bastrop, in Bick et al., 2018	2012	2012	2016		2018
INV	Latopilumnus malardi (De Man, 1914)	1910		1910
PP/micro	Lauderia pumila Castracane	1995				1995
PP	Laurencia brongniartii J.Agardh	1989		1989
PP	Laurencia caduciramulosa Masuda & Kawaguchi	1991			1991
PP	Laurencia okamurae Yamada	1984			1984
PP	Leathesia marina (Lyngbye) Decaisne	1905			1905
INV	Leiocapitellides analis Hartmann-Schröder, 1960	2000			2000
INV	Leiochrides australis Augener, 1914	2002			2002
PP/micro	Lennoxia faveolata H.A.Thomsen & K.R.Buck	2007	2007
INV	Leonnates persicus Wesenberg-Lund, 1949	2013			2013
INV	Lepidonotus tenuisetosus (Gravier, 1902)	2007			2007
INV	Lepidonotus carinulatus (Grube, 1870)	1984			1984
INV	Leucotina natalensis E. A. Smith, 1910	1996			1996
INV	Limnodrilus profundicola (Verrill, 1871)	2014	2014
INV	Limulus polyphemus (Linnaeus, 1758)	1866		1866
INV	Linguimaera caesaris Krapp-Schickel, 2003	1997			1997
INV	Linopherus canariensis Langerhans, 1881	1997			1997
INV	Lioberus ligneus (Reeve, 1858)	2019			2019
PP	Lithophyllum yessoense Foslie	1994			1994
PP	Lomentaria flaccida Tanaka	2002			2002
PP	Lomentaria hakodatensis Yendo	1978		1984	1978
PP	Lophocladia lallemandii (Montagne) F.Schmitz	1908			1908
INV	Lottia sp.	2015			2015
INV	Lovenella assimilis (Browne, 1905)	2007		2007
INV	Lumbrinerides crassicephala (Hartman, 1965)	1994		1994
INV	Lumbrinerides neogesae Miura, 1981	2002			2002
INV	Lumbrineris perkinsi Carrera-Parra, 2001	1973			1973
VER	Lutjanus argentimaculatus (Forsskål, 1775)	2019			2019
VER	Lutjanus griseus (Linnaeus, 1758)	2018		2018
VER	Lutjanus jocu (Bloch & Schneider, 1801)	2005			2005
VER	Lutjanus sebae (Cuvier, 1816)	2010			2010
VER	Lutjanus fulviflamma (Forsskål, 1775)	2013			2013
INV	Lysidice collaris Grube, 1870	1961			1961
PP	Macrocystis pyrifera (Linnaeus) C.Agardh	1972		1972
INV	Macromedaeus voeltzkowi (Lenz, 1905)	1910		1910
INV	Macrophthalmus (Macrophthalmus) indicus Davie, 2012	2009			2009
INV	Macrorhynchia philippina Kirchenpauer, 1872	1982		1982
INV	Magallana angulata (Lamarck, 1819)	1700		1700
INV	Magallana gigas (Thunberg, 1793)	1700	2019	1700	1850	2010
INV	Magallana rivularis (Gould, 1861)	1994		1994
INV	Magallana sikamea (Amemiya, 1928)	1994		1994
INV	Malleus regula (Forsskål in Niebuhr, 1775)	1970			1970
INV	Marenzelleria arctia (Chamberlin, 1920)	2004	2004
INV	Marenzelleria neglecta Sikorski & Bick, 2004	1983	1983	1985
INV	Marenzelleria viridis (Verrill, 1873)	1983	1985	1983
INV	Marginella glabella (Linnaeus, 1758)	2009			2009
INV	Maritigrella fuscopunctata (Prudhoe, 1978)	2014			2014
INV	Marivagia stellata Galil & Gershwin, 2010	2019			2019
INV	Marphysa victori Lavesque, Daffe, Bonifácio & Hutchings, 2017	1975		1975
Pathogen	Marteilia refringens Grizel, Comps, Bonami, Cousserans, Duthoit & Le Pennec	1975		1975	1992
INV	Matuta victor (J.C. Fabricius, 1781)	2018			2018
PP/micro	Mediopyxis helysia Kühn, Hargreaves & Halliger	2003		2003
INV	Megabalanus tintinnabulum (Linnaeus, 1758)	1764		1764	1971
INV	Megabalanus coccopoma (Darwin, 1854)	1851		1851
INV	Melanella orientalis Agamennone, Micali & Siragusa, 2020	2016			2016
PP	Melanothamnus flavimarinus (M.-S.Kim & I.K.Lee) Díaz-Tapia & Maggs	2010		2010
PP	Melanothamnus harveyi (Bailey) Díaz-Tapia & Maggs	1958	1982	2015	1958
PP	Melanothamnus japonicus (Harvey) Díaz-Tapia & Maggs	2016			2016
INV	Melibe viridis (Kelaart, 1858)	1970			1970
INV	Melita nitida S.I. Smith in Verrill, 1873	1996	2010	1996
INV	Menaethius monoceros (Latreille, 1825)	1978			1978
INV	Mercenaria mercenaria (Linnaeus, 1758)	1861		1861	1964
INV	Mesanthura cfr. romulea Poore & Lew Ton, 1986	2000			2000
INV	Metacalanus acutioperculum Ohtsuka, 1984	1995			1995
INV	Metacirolana rotunda (Bruce & Jones, 1978)	1998			1998
INV	Metapenaeopsis aegyptia Galil & Golani, 1990	1996			1996
INV	Metapenaeopsis mogiensis consobrina (Nobili, 1904)	1995			1995
INV	Metapenaeus monoceros (Fabricius, 1798)	1961			1961
INV	Metaxia bacillum (Issel, 1869)	1995			1995
INV	Microcosmus anchylodeirus Traustedt, 1883	1980			1980
INV	Microcosmus squamiger Michaelsen, 1927	1971		1992	1971
INV	Microcosmus exasperatus Heller, 1878	2005		2005	2014
VER	Micropogonias undulatus (Linnaeus, 1766)	1998		1998
PP	Miliolinella fichteliana (d’Orbigny, 1839)	1911			1911
INV	Millepora alcicornis Linnaeus, 1758	2004		2004
PP	Mimosina affinis Millett, 1900	2012			2012
INV	Mitrella psilla (Duclos, 1846)	2016			2016
INV	Mizuhopecten yessoensis (Jay, 1857)	1979		1979
INV	Mnemiopsis leidyi A. Agassiz, 1865	1986	2006	2001	1990	1986
INV	Mnestia girardi (Audouin, 1826)	1990			1990
INV	Moerisia inkermanica Paltschikowa-Ostroumowa	1959	2018	1959
INV	Molgula occidentalis Traustedt, 1883	2010		2010
INV	Monocorophium uenoi (Stephensen, 1932)	2007		2007
VER	Morone saxatilis x Morone chrysops	2019			2019
INV	Mulinia lateralis (Say, 1822)	2017		2017
INV	Murchisonellidae T. L. Casey, 1904	2013	2013
INV	Mycale (Carmia) senegalensis Lévi, 1952	2002		2002
VER	Mycteroperca tigris (Valenciennes, 1833)	2018		2018
INV/par	Myicola ostreae Hoshina & Sugiura, 1953	1972		1972	1972
INV	Myra subgranulata Kossmann, 1877	2004			2004
INV/par	Mytilicola orientalis Mori, 1935	1977	2018	1977	1977
INV	Mytilopsis leucophaeata (Conrad, 1831)	1835	1928	1835
INV	Naineris setosa (Verrill, 1900)	2010			2010
INV	Namanereis littoralis (Grube, 1872)	1991		1991
INV	Neanthes agulhana (Day, 1963)	2007			2007
PP	Nemalion vermiculare Suringar	2005			2005
VER	Nemipterus randalli Russell, 1986	2014			2014
INV	Nemopsis bachei L. Agassiz, 1849	1905		1905
INV	Neodexiospira brasiliensis (Grube, 1872)	1982		1982
PP	Neogastroclonium subarticulatum (Turner) L.Le Gall, Dalen & G.W.Saunders	2017		2017
VER	Neogobius melanostomus (Pallas, 1814)	1990	1990	2004
PP	Neoizziella divaricata (C.K.Tseng) S.-M.Lin, S.-Y.Yang & Huisman	1989		1989
INV	Neomysis americana (S.I. Smith, 1873)	2010		2010
INV	Nereis jacksoni Kinberg, 1865	1964			1964
INV	Nerita sanguinolenta Menke, 1829	1969			1969
INV	Nippoleucon hinumensis (Gamô, 1967)	2019	2019
PP	Nitophyllum stellato-corticatum Okamura	1984			1984
PP	Nonionella sp. T1/Nonionella stella	2012		2012
INV	Notocochlis gualtieriana (Récluz, 1844)	1978			1978
INV	Notomastus aberans Day, 1957	1964			1964
INV	Notomastus mossambicus (Thomassin, 1970)	1997			1997
INV	Novafabricia infratorquata (Fitzhugh, 1973)	1985		2013	1985
INV/par	Nybelinia africana Dollfus, 1960	2005			2005
INV	Obesogammarus crassus (Sars G.O., 1894)*	1962	1962	2016
INV	Ocinebrellus inornatus (Récluz, 1851)	1993		1993
INV	Odontodactylus scyllarus (Linnaeus, 1758)	2009		2009
INV	Oithona davisae Ferrari F.D. & Orsi, 1984	2000		2002	2000	2009
VER	Oncorhynchus gorbuscha (Walbaum, 1792)	1958	1958	1958
VER	Oncorhynchus kisutch (Walbaum, 1792)*	1905	1984	1905
VER	Oncorhynchus mykiss (Walbaum, 1792)*	1882	1882	1899
PP	Operculina ammonoides (Gronovius, 1781)	1911			1911
INV	Ophiactis macrolepidota Marktanner-Turneretscher, 1887	1998			1998
INV	Ophiactis savignyi (Müller & Troschel, 1842)	1968			1968
VER	Ophioblennius atlanticus (Valenciennes, 1836)	2017			2017
INV	Ophryotrocha japonica Paxton & Åkesson, 2010	1999			1999
INV	Ophryotrocha diadema Åkesson, 1976	2006			2006
VER	Oplegnathus fasciatus (Temminck & Schlegel, 1844)	2009			2009
VER	Orthopristis chrysoptera (Linnaeus, 1766)	2020			2020
INV	Oscilla galilae Bogi, Karhan & Yokeş, 2012	2016			2016
VER	Ostorhinchus fasciatus (White, 1790)	2014			2014
Pathogen	Ostracoblabe implexa Born & Flahault	1951		1951
INV	Ostraea angasi G. B. Sowerby II, 1871	1985		1985
INV	Ostrea equestris Say, 1834	1995		1995
INV	Ostrea denselamellosa Lischke, 1869	1982		1982
INV	Ostrea puelchana d’Orbigny, 1842	1989		1989
INV	Oulastrea crispata (Lamarck, 1816)	2012			2012
INV	Oxydromus humesi (Pettibone, 1961)	2009		2009
PP/micro	Oxytoxum criophilum Balech	2003		2003
VER	Oxyurichthys papuensis (Valenciennes, 1837)	2010			2010
INV	Pachygrapsus gracilis (de Saussure, 1857)	2013		2013
PP	Pachymeniopsis gargiuli S.Y.Kim, Manghisi, Morabito & S.M.Boo	1968		2001	1968
PP	Pachymeniopsis lanceolata (K.Okamura) Y.Yamada ex S.Kawabata	1982		2006	1982
INV	Pacifastacus leniusculus (Dana, 1852)	2014	2014
INV	Pacificincola perforata (Okada & Mawatari, 1937)	2001		2001
PP	Padina boergesenii Allender & Kraft	1965			1965
VER	Pagrus major (Temminck & Schlegel, 1843)	2004			2004
INV	Pagurus longicarpus (Say, 1817)	2020		2020
INV	Palaemon macrodactylus Rathbun, 1902	1998	2014	1998	2005	2002
INV	Palola valida (Gravier, 1900)	2014			2014
VER	Pampus argenteus (Euphrasen, 1788)	1896			1896
INV	Panopeus occidentalis Saussure, 1857	2015		2015
PP	Papenfussiella kuromo (Yendo) Inagaki	1990		1990
INV	Paracalanus quasimodo Bowman, 1971	2017		2017
INV	Paracaprella pusilla Mayer, 1890	2010		2010	2011
INV	Paracerceis sculpta (Holmes, 1904)	1981		1988	1981
INV	Paradella dianae (Menzies, 1962)	1985		1988	1985
INV	Paradyte cf. crinoidicola (Potts, 1910)	1968			1968
INV	Paraleucilla magna Klautau, Monteiro & Borojevic, 2004	2000		2006	2000
INV	Paralithodes camtschaticus (Tilesius, 1815)	2008			2008
INV	Parametopella cypris Holmes, 1905	2014			2014
INV	Paramysis (Mesomysis) intermedia (Czerniavsky, 1882)	2008	2008
INV	Paramysis (Serrapalpisis) lacustris (Czerniavsky, 1882)	1962	1962
INV	Paranais frici Hrabĕ, 1941	1970	1970
VER	Paranthias furcifer (Valenciennes, 1828)	2011		2014	2011
INV	Paranthura japonica Richardson, 1909	2005		2007	2005
INV	Parasmittina alba Ramalho, Muricy & Taylor, 2011	2014		2014
INV	Parasmittina multiaviculata Souto, Ramalhosa & Canning-Clode, 2016	2016		2016
INV	Parasmittina egyptiaca (Waters, 1909)	2016			2016
PP	Parasorites orbitolitoides Hofker, 1930	2016			2016
INV	Paratapes textilis (Gmelin, 1791)	2004			2004
INV/par	Paratenuisentis ambiguus (Van Cleave, 1921)	2001	2001
VER	Parexocoetus mento (Valenciennes, 1847)	1955			1955
VER	Parupeneus forsskali (Fourmanoir & Guézé, 1976)	2014			2014
INV	Parvocalanus crassirostris (Dahl F., 1894)	2009			2009
PP	Pegidia lacunata McCulloch, 1977	2010			2010
VER	Pempheris rhomboidea Kossmann & Räuber, 1877	1983			1983
INV	Penaeus aztecus Ives, 1891	2012		2018	2012
INV	Penaeus hathor (Burkenroad, 1959)	2012			2012
INV	Penaeus monodon Fabricius, 1798	2011		2011
INV	Penaeus japonicus Spence Bate, 1888	1972		1980	1972
INV	Penaeus pulchricaudatus Stebbing, 1914	1961		1982	1961
INV	Penaeus semisulcatus De Haan, 1844 [in De Haan, 1833–1850]	2016		2016
PP/micro	Peridiniella catenata (Levander) Balech	1987	1987
PP/micro	Peridiniella danica (Paulsen) Y.B.Okolodkov & J.D.Dodge	1901		1901
PP/micro	Peridinium quadridentatum (F.Stein) Gert Hansen	2005	2008	2005
INV	Perinereis linea (Treadwell, 1936)	2012			2012
Pathogen	Perkinsus chesapeaki McLaughlin, Tall, Shaheen, El Sayed & Faisal	1992		1992	1992
Pathogen	Perkinsus olsenii R.J.G.Lester & G.H.G.Davis	1983		1983
INV	Perophora multiclathrata (Sluiter, 1904)	1983			1983
INV	Perophora viridis Verrill, 1871	1971		1971
INV	Perophora japonica Oka, 1927	1982		1982
PP	Petalonia binghamiseae (J.Agardh) K.L.Vinogradova	1985		1985
INV	Petricolaria pholadiformis (Lamarck, 1818)	1896	1927	1896	1985
VER	Petroscirtes ancylodon Rüppell, 1835	2004			2004
INV	Phallusia nigra Savigny, 1816	2008			2008
INV	Phascolion convestitum Sluiter, 1902	1977			1977
INV	Phascolosoma (Phascolosoma) scolops (Selenka & de Man, 1883)	1975			1975
INV	Photis lamellifera Schellenberg, 1928	1990			1990
Pathogen	Photobacterium damsela Love, Teebken-Fisher, Hose, Farmer III, Hickman & Fanning	1992			1992
PP	Phrix spatulata (E.Y.Dawson) M.J.Wynne, M.Kamiya & J.A.West	1992			1992
INV	Phyllorhiza punctata Lendenfeld, 1884	2005		2018	2005
VER	Piaractus brachypomus (Cuvier, 1818)	2013		2013
PP	Pikea californica Harvey	1991		1991
INV	Pileolaria berkeleyana (Rioja, 1942)	1977		2007	1977
INV	Pilumnopeus africanus (de Man, 1902)	2013		2013
INV	Pilumnopeus vauquelini (Audouin, 1826)	1963			1963
INV	Pilumnus minutus De Haan, 1835 [in De Haan, 1833–1850]	2017			2017
INV	Pinctada fucata (A. Gould, 1850)	2018			2018
INV	Pinctada radiata (Leach, 1814)	1899		1998	1899
VER	Pinguipes brasilianus Cuvier, 1829	1990			1990
INV/par	Piscicola pojmanskae Bielecki, 1994	2008	2008
INV	Pista unibranchia Day, 1963	1997		2005	1997
INV	Plagusia squamosa (Herbst, 1790)	1906			1906
VER	Planiliza haematocheila (Temminck & Schlegel, 1845)	1972			1995	1972
PP	Planispirinella exigua (Brady, 1879)	1910			1910
PP	Planogypsina acervalis (Brady, 1884)	1909			1909
VER	Platycephalus indicus (Linnaeus, 1758)	1978			1978
PP	Plocamium secundatum (Kützing) Kützing	1991			1991
INV	Plocamopherus ocellatus Rüppell & Leuckart, 1828	2015			2015
VER	Poecilopsetta beanii (Goode, 1881)	1995		1995
INV	Polyandrocarpa zorritensis (Van Name, 1931)	1974			1974
INV	Polycera hedgpethi Er. Marcus, 1964	1986		2001	1986
INV	Polycerella emertoni A. E. Verrill, 1880	1964		1981	1964
INV	Polycirrus twisti Potts, 1928	1983			1983
INV	Polyclinum constellatum Savigny, 1816	2014			2014
INV	Polydora colonia Moore, 1907	1983		2018	1983
INV	Polydora triglanda Radashevsky & Hsieh, 2000	2014		2014
INV	Polydora websteri Hartman in Loosanoff & Engle, 1943	2014		2014
PP	Polyopes lancifolius (Harvey) Kawaguchi & Wang	2008		2008
PP	Polysiphonia paniculata Montagne	1967			1967
PP	Polysiphonia forfex Harvey	2011		2011
PP	Polysiphonia morrowii Harvey	1975		1975	1997
PP	Polysiphonia senticulosa Harvey	1993		1993
VER	Pomacanthus imperator (Bloch, 1787)	2016			2016
VER	Pomacanthus paru (Bloch, 1787)	2015		2015
VER	Pomacanthus maculosus (Forsskål, 1775)	1994		1994	2012
VER	Pomadasys stridens (Forsskål, 1775)	1968			1968
INV	Pontogammarus robustoides (Sars, 1894)*	1962	1962
PP	Porphyra umbilicalis Kützing	1989	1989
INV	Portunus segnis (Forskål, 1775)	1958			1958
INV	Potamocorbula amurensis (Schrenck, 1862)	2018		2018
INV	Potamopyrgus antipodarum (Gray, 1843)*	1801	1801	1887
INV	Potamothrix moldaviensis Vejdovský & Mrázek, 1903	2008	2008
INV	Potamothrix bavaricus (Oschmann, 1913)	2015	2015
INV	Potamothrix bedoti (Piguet, 1913)	1915	1915
INV	Potamothrix heuscheri (Bretscher, 1900)*	1960	1960
INV	Potamothrix vejdovskyi (Hrabĕ, 1941)*	1967	1967
inv	Prionospio aluta Maciolek, 1985	1994		1994
INV	Prionospio depauperata Imajima, 1990	2018			2018
INV	Prionospio pulchra Imajima, 1990	1989		1989	1991
INV	Proasellus coxalis (Dollfus, 1892)	2011	2011
INV	Procambarus clarkii (Girard, 1852)*	2000			2000
INV	Prokelisia marginata (Van Duzee, 1897)	2011		2011
PP/micro	Prorocentrum gracile Schütt	1989		1989
INV	Prosphaerosyllis longipapillata (Hartmann-Schröder, 1979)	1997			1997
VER	Proterorhinus nasalis (De Filippi, 1863)	2020	2020
INV	Protodorvillea biarticulata Day, 1963	1975			1975
INV	Protoreaster nodosus (Linnaeus, 1758)	1981			1981
INV	Psammacoma gubernaculum (Hanley, 1844)	2009			2009
PP/micro	Pseudochattonella farcimen (Riisberg I.)	1998	2001	1998
PP/micro	Pseudochattonella verruculosa (Y.Hara & M.Chihara) S.Tanabe-Hosoi, D.Honda, S.Fukaya, Y.Inagaki & Y.Sako	1998	2015	1998
INV/par	Pseudodactylogyrus anguillae (Yin & Sproston, 1948)	1982	1985	1982
INV/par	Pseudodactylogyrus bini (Kikuchi, 1929)	1985	1985	1997
INV	Pseudodiaptomus marinus Sato, 1913	2007		2010	2007
INV	Pseudonereis anomala Gravier, 1899	1969			1969
PP/micro	Pseudo-nitzschia australis Frenguelli	1995		1995	2000
PP/micro	Pseudo-nitzschia multistriata (Takano) Takano	1985		1985
INV	Pseudopolydora paucibranchiata (Okuda, 1937)	1977		1982	1977
VER	Pteragogus trispilus Randall, 2013	1992			1992
VER	Pterois miles (Bennett, 1828)	2009			2009
INV	Ptilohyale littoralis (Stimpson, 1853)	2009		2009
INV	Purpuradusta gracilis notata (Gill, 1858)	1988			1988
INV	Pyrgulina pupaeformis (Souverbie, 1865)	1995			1995
INV	Pyromaia tuberculata (Lockington, 1877)	2016		2016
PP	Pyropia yezoensis (Ueda) M.S.Hwang & H.G.Choi	1975		1984	1975
PP	Pyropia suborbiculata (Kjellman) J.E.Sutherland, H.G.Choi, M.S.Hwang & W.A.Nelson	2010		2010	2014
INV	Pyrunculus fourierii (Audouin, 1826)	1995			1995
INV	Rangia cuneata (G. B. Sowerby I, 1832)	1997	2011	1997
INV	Rapana venosa (Valenciennes, 1846)	1956		1997	1973	1956
VER	Rastrelliger kanagurta (Cuvier, 1816)	2018			2018
INV	Rhinoclavis kochi (Philippi, 1848)	1976			1976
INV	Rhithropanopeus harrisii (Gould, 1841)	1936	1936	1950	1994	1948
PP/micro	Rhizosolenia calcar-avis Schultze	2009		2009
INV	Rhopilema nomadica Galil, 1990	1995			1995
INV	Ringicula minuta H. Adams, 1872	2019			2019
INV	Rissoina bertholleti Issel, 1869	1985			1985
INV	Ruditapes philippinarum (Adams & Reeve, 1850)	1973		1973	1980
PP	Rugulopteryx okamurae (E.Y.Dawson) I.K.Hwang, W.J.Lee & H.S.Kim	2002		2015	2002
PP	Saccharina japonica (J.E. Areschoug) C.E.Lane, C.Mayes, Druehl & G.W.Saunders	1976		1980	1976
INV	Saccostrea cuccullata (Born, 1778)	2007		2007
INV	Saccostrea glomerata (Gould, 1850)	1984			1984
VER	Salvelinus fontinalis (Mitchill, 1814)*	1916		1916
PP	Sarconema filiforme (Sonder) Kylin	1990			1990
PP	Sarconema scinaioides Børgesen	1980			1980
PP	Sargassum muticum (Yendo) Fensholt	1972		1972	1980
VER	Sargocentron rubrum (Forsskål, 1775)	1943			1943
VER	Saurida lessepsianus Russell, Golani & Tikochinski, 2015	1960			1960
PP	Scageliopsis patens Wollaston	1989		1989
VER	Scarus ghobban Forsskål, 1775	2010			2010
VER	Scatophagus argus (Linnaeus, 1766)	2007			2007
INV	Schizoporella japonica Ortmann, 1890	1976		1976
INV	Schizoporella pungens Canu & Bassler, 1928	2010		2010
VER	Sciaenops ocellatus (Linnaeus, 1766)	2016			2016
INV	Scolelepis (Parascolelepis) gilchristi (Day, 1961)	1977			1977
INV	Scolelepis korsuni Sikorski, 1994	1994		1994
INV	Scolionema suvaense (Agassiz & Mayer, 1899)	1950			1950
VER	Scomberomorus commerson (Lacepède, 1800)	2008			2008
INV	Scyllarus caparti Holthuis, 1952	1977			1977
PP	Scytosiphon dotyi M.J.Wynne	1968		1991	1968
VER	Sebastes schlegelii Hilgendorf, 1880	2008		2008
INV	Sebastiscus marmoratus (Cuvier, 1829)	2016		2016
INV	Sepioteuthis lessoniana Férussac [in Lesson], 1831	2009			2009
INV	Septifer cumingii Récluz, 1848	2005			2005
VER	Siganus fuscescens (Houttuyn, 1782)	2020			2020
VER	Siganus virgatus (Valenciennes, 1835)	1975			1975
VER	Siganus luridus (Rüppell, 1829)	1964			1964
VER	Siganus rivulatus Forsskål & Niebuhr, 1775	1925			1925
PP	Sigmamiliolinella australis (Parr, 1932)	2001			2001
VER	Sillago suezensis Golani, Fricke & Tikochinski, 2013	2009			2009
INV	Sinelobus vanhaareni Bamber, 2014	2006	2010	2006
INV	Sinezona plicata (Hedley, 1899)	2019			2019
INV	Smaragdia souverbiana (Montrouzier in Souverbie & Montrouzier, 1863)	1993			1993
INV	Smittina nitidissima (Hincks, 1880)	2014			2014
INV	Smittoidea prolifica Osburn, 1952	1995		1995
PP	Solieria filiformis (Kützing) P.W.Gabrielson	1922			1922
PP	Sorites variabilis Lacroix, 1941	1996			1996
PP	Spartina anglica C.E. Hubbard	1924		1924
PP	Spartina densiflora Brongn.	1986		1986
PP	Spartina patens (Aiton) Muhl.	1986		1986
PP	Spartina alterniflora Loisel	1806		1806
PP	Spermothamnion cymosum (Harvey) De Toni	2010			2010
INV	Sphaeroma walkeri Stebbing, 1905	1977		2015	1977	2004
PP	Sphaerotrichia firma (E.S.Gepp) A.D.Zinova	1981			1981
INV	Sphaerozius nitidus Stimpson, 1858	2013			2013
VER	Sphyraena chrysotaenia Klunzinger, 1884	1964			1964
VER	Sphyraena flavicauda Rüppell, 1838	2003			2003
INV	Spirobranchus tetraceros (Schmarda, 1861)	1970			1970
PP	Spiroloculina angulata Cushman, 1917	1996			1996
PP	Spiroloculina antillarum d’Orbigny, 1839	1911			1911
INV	Spirorbis (Spirorbis) marioni Caullery & Mesnil, 1897	1974		1974	1977
INV	Spondylus spinosus Schreibers, 1793	2001			2001
PP	Spongoclonium caribaeum (Børgesen) M.J.Wynne	1967		1967	1974
VER	Spratelloides delicatulus (Bennett, 1832)	2014			2014
VER	Stegastes variabilis (Castelnau, 1855)	2014			2014
INV	Stenothoe georgiana Bynum & Fox, 1977	2010		2011	2010
VER	Stephanolepis diaspros Fraser-Brunner, 1940	1935			1935
INV	Sternodromia spinirostris (Miers, 1881)	1969			1969
INV	Sticteulima lentiginosa (A. Adams, 1861)	1995			1995
INV	Stomatella sp.	2011			2011
INV	Streblospio gynobranchiata Rice & Levin, 1998	2011				2011
INV	Streblospio benedicti Webster, 1879	1982		1982
INV	Styela plicata (Lesueur, 1823)	1877		1989	1877
INV	Styela canopus (Savigny, 1816)	2006		2006
INV	Styela clava Herdman, 1881	1968	2017	1968	2005	2002
PP	Stypopodium schimperi (Kützing) M.Verlaque & Boudouresque	1990			1990
INV	Syllis hyllebergi (Licher, 1999)	1972			1972
INV	Syllis pectinans Haswell, 1920	1982		1982	2013
PP	Symphyocladia marchantioides (Harvey) Falkenberg	1971		1971	1984
PP	Symphyocladiella dendroidea (Montagne) D.Bustamante, B.Y.Won, S.C.Lindstrom & T.O.Cho	1993		2005	1993
INV	Symplegma rubra Monniot C., 1972	2014		2014
INV	Symplegma brakenhielmi (Michaelsen, 1904)	2003			2003
VER	Synagrops japonicus (Döderlein, 1883)	1987			1987
INV	Synaptula reciprocans (Forsskål, 1775)	1967			1967
VER	Synchiropus sechellensis Regan, 1908	2014			2014
INV	Synidotea laticauda Benedict, 1897	1975		1975
INV	Syphonota geographica (A. Adams & Reeve, 1850)	1999			1999
INV	Syrnola fasciata Jickeli, 1882	1995			1995
INV/par	Taeniastrotos sp.	1993		1993
PP/micro	Takayama tasmanica de Salas, Bolch & Hallegraeff	2008		2008
INV	Telmatogeton japonicus Tokunaga, 1933	1962	1962	1979
INV	Tenellia adspersa (Nordmann, 1845)	2001		2001
VER	Terapon theraps (Cuvier, 1829)	2007			2007
INV	Terebella ehrenbergi Gravier, 1906	1952			1952
INV	Teredo bartschi Clapp, 1923	2003		2003	2007
INV	Thalamita gloriensis Crosnier, 1962	1977			1977
INV	Thalamita poissonii (Audouin, 1826)	1969			1969
PP/micro	Thalassiosira nordenskioeldii Cleve	1967				1967
PP/micro	Thalassiosira hendeyi Hasle & G.Fryxell	1978		1978
PP/micro	Thalassiosira tealata Takano	1968		1968
PP/micro	Thecadinium yashimaense S.Yoshimatsu, S.Toriumi & J.D.Dodge	2002		2002
INV	Thelepus japonicus Marenzeller, 1884	2017		2017
INV	Theora lubrica Gould, 1861	2001		2010	2001
INV	Timarete punctata (Grube, 1859)	2006			2006
INV	Tonicia atrata (G.B. Sowerby II, 1840)	1978		1978
VER	Torquigener flavimaculosus Hardy & Randall, 1983	2006			2006
INV	Trachysalambria palaestinensis (Steinitz, 1932)	1995			1995
INV	Tremoctopus gracilis (Souleyet, 1852)	1937			1937
INV	Tricellaria inopinata d’Hondt & Occhipinti Ambrogi, 1985	1982		1996	1982
INV	Triconia rufa (Boxshall & Böttger, 1987)	2004			2004
INV	Triconia umerus (Böttger-Schnack & Boxshall, 1990)	2004			2004
INV	Tridentata marginata (Kirchenpauer, 1864)	1980		1980	1990
VER	Tridentiger barbatus (Günther, 1861)	2016		2016
PP/micro	Trieres mobiliensis (J.W.Bailey) Ashworth & Theriot	1983		1983
PP/micro	Trieres regia (M.Schultze) M.P.Ashworth & E.C.Theriot	1989		1989
VER	Trinectes maculatus (Bloch & Schneider, 1801)	1984		1984
PP/micro	Tripos arietinus (Cleve) F.Gómez	1992		1992
PP/micro	Tripos macroceros (Ehrenberg) F.Gómez	1983		1983
INV	Trochus erithreus Brocchi, 1821	1985			1985
INV	Tubastraea tagusensis Wells, 1982	2017		2017
INV	Turbonilla edgarii (Melvill, 1896)	1996			1996
VER	Tylerius spinosissimus (Regan, 1908)	2004			2004
VER	Tylosurus crocodilus crocodilus (Péron & Lesueur, 1821)	2003			2003
PP	Ulva australis Areschoug	1984		1990	1984
PP	Ulva californica Wille	2006		2006	2011
PP	Ulva gigantea (Kützing) Bliding	2015		2015
PP	Ulva ohnoi M.Hiraoka & S.Shimada	2011		2015	2011
PP	Ulvaria obscura (Kützing) P.Gayral ex C.Bliding	1985			1985
PP	Umbraulva dangeardii M.J.Wynne & G.Furnari	2014		2014
PP	Undaria pinnatifida (Harvey) Suringar	1971		1975	1971
PP	Undella hadai Balech	2004			2004
VER	Upeneus moluccensis (Bleeker, 1855)	1947			1947
VER	Upeneus pori Ben-Tuvia & Golani, 1989	2003			2003
INV	Urocaridella pulchella Yokes & Galil, 2006	2018			2018
PP	Uronema marinum Womersley	1989			1989
INV	Urosalpinx cinerea (Say, 1822)	1960		1960
INV	Vallicula multiformis Rankin, 1956	1998		1998
VER	Vanderhorstia mertensi Klausewitz, 1974	2019			2019
VER	Variola louti (Forsskål, 1775)	2018			2018
PP	Vaucheria longicaulis Hoppaugh	2020		2020
INV	Viriola sp.[cf. bayani] Jousseaume, 1884	2016			2016
INV	Watersipora aterrima (Ortmann, 1890)	1983		1983
INV	Watersipora subatra (Ortmann, 1890)	1987		1987
INV	Watersipora arcuata Banta, 1969	1990		1990	2013
PP	Womersleyella setacea (Hollenberg) R.E.Norris	1986			1986
INV	Xanthias lamarckii (H. Milne Edwards, 1834)	2013			2013
INV	Xenostrobus securis (Lamarck, 1819)	1991		2005	1991
INV	Yoldia limatula (Say, 1831)	2019		2019
INV	Zafra savignyi (Moazzo, 1939)	1995			1995
INV	Zafra selasphora (Melvill & Standen, 1901)	1995			1995
VER	Zebrasoma flavescens (Bennett, 1828)	2008			2008
VER	Zebrasoma xanthurum (Blyth, 1852)	2015			2015

The Baltic Sea dataset encompasses 100 NIS introductions (including 6 parasites and 9 microalgae), 34 of which were introduced before 1970. The major proportion of the introductions since 1970 have been invertebrates (42 species, ~83%), followed by primary producers (5 species, ~10%), and vertebrates (4 species, ~8%). Invertebrates consist of a wide range of benthic crustaceans, as well as pelagic zooplanktonic taxa, whereas primary producers include both, phytoplankton, and phytobenthic species. Vertebrate species include Ponto-Caspian sturgeons and gobies, as well as cultured salmonids.

456 NIS are known from the North-East Atlantic (NEA), 372 of which have been detected since 1970 (81%). The Greater North Sea (ANS) hosts 260 NIS including parasites and pathogens (Figure 4b), 193 of which (74%) have been observed since 1970. The NIS biota is dominated by invertebrates (154 taxa = 59%) and primary producers (macroalgae, microalgae, pathogens) 88 taxa (34%). The proportion of vertebrates (fish) is low (18 taxa = 7%), and mostly related to freshwater NIS expanding their distribution into estuarine coastal waters.

The Celtic Seas (ACS) host 107 NIS including parasites and pathogens (Figure 4b), 72 of which (67%) have been detected since 1970. The vast majority (69 taxa = 64%) are invertebrates, followed by primary producers (35 taxa = 33%) while vertebrates are represented only by three freshwater fishes that have been observed in Irish estuarine waters.

The Bay of Biscay and Iberian Shelf (ABI) subregion hosts 250 NIS, 215 of which (86%) have been introduced since 1970. Most of them are invertebrates (180 taxa = 72%), followed by primary producers (68 taxa = 27%) and vertebrates (2 taxa = 1%).

The Macaronesia (AMA) hosts 121 species, 109 (90%) introduced since 1970. Invertebrates dominate (72 taxa = 59%), followed by primary producers (29 taxa = 24%) and vertebrates (20 taxa = 17%).

The Mediterranean NIS list includes 578 species (473 = 83% since 1970) dominated by invertebrates (59%) (Figure 4a). Primary producers follow with approximately 23% of species among which macroalgae and Rhodophyta prevail. Vertebrates (103 taxa = 18%) are dominated by Red Sea (Lessepsian) fishes. The contribution of NIS groups varies among the Mediterranean subregions (Figure 2c). Primary producers have their largest representation in MWE and MAD (31–32%), introduced as contaminants in shellfish consignments in the major shellfish culture areas of the northern Adriatic and the French coast. On the other hand, the percentage of vertebrates is higher in MAL where they mostly arrived through the Suez Canal, and in MIC which receives naturally dispersing fish from MAL than all other subregions.

The EU part of the Black Sea (Bulgaria and Romania) hosts only 38 validated NIS out of a total of more than 110 NIS reported for the whole Black Sea. These are mostly invertebrates (33 species) with crustacean and molluscan species dominating. Only 24 NIS have been reported since 1970 including two microalgae.

In addition to the 874 NIS in European waters, 57 NIS detected in one regional sea are native or cryptogenic in at least one other regional Sea (Supplementary Table S1). These include macroalgae (18 taxa), mollusks (13 taxa), crustaceans (11 taxa), cnidarian (5 taxa), polychaetes (5 taxa), tunicates (2 taxa), bryozoan (1 taxon), Fish (1 taxon), and microalgae (1 taxon). They have been transferred from the NEA to the MED and BLK Seas (more than 27 taxa), but also from the MED to the NEA (more than 22 taxa). Finally, six species have been transferred from the EU BLK waters to the BAL.

Species classified as NIS in a country but partly native or cryptogenic within the subregion/region of the country were not included in the analyses, with some examples provided in

Table 3. Examples of partly native/cryptogenic species within the same region/subregion excluded from the analyses. For regions/subregions’ abbreviations see Table 1.

Group	Species	Region/Subregion Native	Country/Region Introduced
Dinoflagellates	Prorocentrum lima (Ehrenberg) F.Stein, 1878	NEA	Denmark/NEA
Macroalgae	Asperococcus scaber Kuckuck, 1899	NEA/ANS	Netherlands
Macroalgae	Fucus distichus subsp. evanescens (C.Agardh) H.T.Powell	NEA/ANS CRY in Norway	Sweden/NEA
Crustacea	Necora puber (Linnaeus, 1767)	NEA, MED	Sweden/NEA
Crustacea	Pseudomyicola spinosus spinosus (Raffaele & Monticelli, 1885)	NEA, MED	France/NEA
Crustacea	Pilumnus spinifer H. Milne Edwards, 1834	NEA, MED	Sweden/NEA
Mollusca	Calliostoma zizyphinum (Linnaeus, 1758)	NEA, MED	Netherlands
Mollusca	Cymbium olla (Linnaeus, 1758)	NEA/ABI	Spain/MED
Mollusca	Tritia corniculum (Olivi, 1792)	NEA, MED	Spain/NEA
Mollusca	Tritia neritea (Linnaeus, 1758)	MED, partly in ABI	France/NEA
Cnidaria	Cereus pedunculatus (Pennant, 1777)	NEA/ANS	Denmark/NEA
Porifera	Suberites massa Nardo, 1847	NEA/ANS	Netherlands
Porifera	Haliclona (Haliclona) urceolus (Rathke & Vahl, 1806)	NEA/ANS	Netherlands
Porifera	Haliclona (Reniera) cinerea (Grant, 1826)	NEA/ANS	Netherlands
Bryozoa	Reptadeonella violacea (Johnston, 1847)	NEA	Portugal

. In contrast, species native in one subregion, but NIS in another subregion within the same MSFD region were not listed in Table 2 but are considered as NIS at the subregional level (Supplementary Table S2). They are mostly widespread native or cryptogenic species in the MED and NEA that have been classified as NIS in Macaronesia.

The trend in new NIS introductions per 6 year assessment periods varies among groups and regional seas (Figure 3). The upward trend observed for invertebrates at the pan-European level is evident in the BAL, NEA, and MED Seas but not in the BLK Sea.

Overall, the rate of new NIS introductions (excluding parasites, pathogens, and microalgae) at the Pan-European level has increased at what appears to be a linear trend since 1970 from six to 21 NIS per year (Figure 4a). While evident in most regional seas, the increase also obscures large regional differences such as the steep increase from the early 2000s to 2017 in the Baltic Sea (Figure 4b) and a decreasing trend in the Black Sea (Figure 4b) and the Celtic Seas (Figure 4c). Comparison with the latest assessment period (2018–2020) shows a decline in the annual average rate of new NIS introductions compared to the preceding trends in many regional seas. Thus, while the annual rate of NIS in the North-East Atlantic steadily increased since 1970, although with subregional differences, reaching 11 new NIS per year in the 2012–2017 period, the latest assessment period (2018–2020) indicated a decline to an average of five NIS per year (Figure 4b). The annual rate of new NIS in the Greater North Sea (ANS) increased rapidly in the 1994–1999 period and maintained the upward trend in the last assessment period reaching six new NIS per year (Figure 4c). In the Bay of Biscay and Iberian Shelf (ABI), a steady upward trend was observed until 2005, followed by a sharp increase in the following periods, reaching seven new NIS per year in the 2012–2017 period. A similar pattern to that of ABI was observed in Macaronesia where the annual rate reached five NIS/per year in the 2012–2017 period. The highest number of new NIS introductions in the Celtic Seas occurred in the assessment period 1994–2005 with two new NIS per year. A declining trend was observed in the last assessment periods. Only five invertebrates were detected in the 2012–2017 period, and none since 2017.

All analyses in the Mediterranean Sea are based on 460 NIS taxa observed for the first time since 1970. On an annual basis, the number of newly introduced NIS has increased in the Mediterranean since the late 1990′s reaching 14 species per year in the period 2012–2017 (Figure 4b). This increasing trend is also observed at a subregional level for all regions but the MWE. Specifically, the annual new NIS rate calculated in the assessment period (2012–2017) reached 11 new NIS per year in the MIC, followed by nine in the MAL, seven in the MWE and six in the MAD (Figure 4d). In the MWE, the annual rate of NIS introductions fluctuates between two and seven species per year without any pronounced peaks or temporal trends. In contrast, a slight leveling off in the introductions rate appears in the MAD, while the rate of new NIS introductions presents a steeper increase in the MAL and MIC after the mid-2000s.

The rate of introductions in the BLK peaked in the 1994–2006 period reaching one new NIS per year but dropped in the following periods (Figure 4b). As many as six species (18%) have expanded the geographic range from neighboring areas surrounding the Black Sea where they first invaded, while the presence of two NIS namely the oysters Crassostrea virginica and Magallana gigas is attributed to escape from confinement (oyster culture facilities).

4. Discussion

With the current work, we aimed at establishing an updated status of NIS in European waters to provide a robust baseline for understanding trends in new NIS arrivals. The presented analyses documented an increasing trend in the annual rate of new NIS at all spatial levels until 2017 while highlighting some major regional differences both in the composition of xenodiversity and the temporal evolution of new NIS introductions at the subregional level, that can prove useful in further steps of setting thresholds for NIS trends indicators. Our findings are discussed in the context of spatial, temporal, species-specific and effort-related sources of uncertainty (Figure 5), which are primarily epistemic in nature (sensu [43,44]) i.e., they relate to measurement or systematic error, be it in species taxonomy, identification, and origin, in the spatial aspects of inventories or the temporal uncertainties associated with trends estimation. Subjective judgment may introduce additional uncertainty in determining species to include/exclude from management actions, such as cryptogenic species or functional groups addressed with different policy instruments. Finally, we provided an explicit account of partly native species in different management units, helping to resolve linguistic uncertainties stemming from a context-dependent definition of the terms alien/native.

4.1. Validation of European NIS: A Challenging and Dynamic Task

One of the main challenges in establishing a robust and accurate baseline is addressing taxonomic or biogeographic uncertainties and incorporating new taxonomic information. To maintain a conservative viewpoint and avoid potential false positives, the authors agreed to exclude species that have raised uncertainties regarding (i) the known existence of cryptic species, (ii) recent taxonomic revisions, (iii) suspicions of possible errors for taxa belonging to species complex, and/or (iv) species that are possibly non-native but only recently described and thus requiring further clarification about their status. Issues arising from cryptic species, taxonomic revision, and occurrence of species complexes were noticed in the NEA for the ascidians Botrylloides schlosseri, Ciona intestinalis, and the mussels Mytilus galloprovincialis and Mytilus trossulus.

Botrylloides schlosseri is an example of the problems associated with the identification of cryptic species complexes, which are common among widely distributed marine taxa [45]. An extensive study by Bock et al. [46] showed that several cryptic species of B. schlosseri coexist at a regional scale in northwestern Europe. Some are probably native (e.g., clade E in Brittany, France) while others are likely to be introduced, considering their near-global distribution (e.g., clade A in Brittany, France). The specimens of B. schlosseri, reported in the North-East Atlantic, could thus be either NIS or native species. Thus, overall, it seems more reasonable to assign B. schlosseri a cryptogenic status.

In the case of Ciona intestinalis, uncertainties stem from a recent extensive taxonomic revision [47]. Based on a series of morphological and molecular investigations (references in 47), this species name was shown to bring together two distinct species, namely Ciona intestinalis and Ciona robusta, which had previously been described as two distinct species but unfortunately synonymized in 1985. Until a recent taxonomic revision, C. robusta was known as C. intestinalis type A and C. intestinalis as C. intestinalis type B although the type was not always reported. Furthermore, since the taxonomic revision was announced in 2017, the use of the correct species name is questionable for our dataset ending in 2020. C. robusta, native to Asia, is the only Ciona species introduced, so far, to the North-East Atlantic (in the early 2000s) [48,49]. We, therefore, excluded records of C. intestinalis and retained only records of C. robusta or C. intestinalis type A, as the use of these names refers to the Pacific-origin species.

The situation is even more complicated with the Mytilus edulis species complex, which obscures three European accepted species M. edulis, M. galloprovincialis and M. trossulus that still hybridize and exchange genes at contact zones. In our list, we have two species reported as introduced in the North-East Atlantic, for which reports are questionable: M.e galloprovincialis and M. trossulus. The use of the species name M. galloprovincialis is insufficient to determine native vs. introduced status, as it covers two distinct lineages, one present in the Mediterranean Sea, and the other in the Atlantic [50]. As with C. intestinalis prior to its taxonomic revision, the name M. galloprovincialis does not allow us to determine the native or introduced status of specimens reported from the North-East Atlantic. In addition, the natural presence of the Atlantic lineage as enclosed population patches in Brittany, Wales, Scotland, and Northern Ireland is not always recognized by some specialists and is debated. In the case of M. trossulus, identification has most often been established using barcoding or metabarcoding based on the COI mitochondrial marker. However, in the absence of details regarding the reference sequence that was used for the taxonomic assignment, we face another problem here. Some of the reference data available in public databases are indeed from specimens collected in the Baltic Sea, where the mitochondrial genome of M. trossulus has been extensively introgressed (i.e., replaced) by that of M. edulis, which may lead to a false taxonomic assignment of a M. edulis specimen to M. trossulus [51]. In addition, recent work has shown that M. edulis carries a transmissible cancer of M. trossulus origin. Thus, molecular-based identification may lead to the assignment of M. trossulus or edulis-trossulus hybrids for M. edulis specimens with this cancer [52,53]. The so-called “Baltic Mytilus trossulus” actually differs distinctly in morphology, ecology and genetic characters from M. trossulus, i.e., a species described from the NE Pacific [54]. To resolve this, Mytilus edulis balthicus by Gittenberger and Gittenberger, 2021, has recently been described. In addition, to further the nomenclatorial stability within the M. edulis complex, the locus typicus restrictus of the nominal taxon M. edulis has been restricted to the North Sea off the Dutch coast [54].

The improvement of molecular methods in ecological studies has helped to shed some light on species’ origins and their actual distribution, (see for instance the case of Tritia neritea detailed in the next Section). However, at the same time, this may give rise to some controversies until further studies finally provide unequivocal confirmation of status with more data. This is the case, for example, of the oyster Ostrea stentina, which was recently found to encompass two different genotypes, one of them belonging to the newly described Ostrea neostentina with type locality in Hong Kong [55]. A new distribution map of this genus has thus been constructed, with O. stentina present in both the MED and NEA regions, and O. neostentina only in the MED. New studies are taking place to confirm the native range, but, so far, regarding the present knowledge of historical records and taxonomical studies, the population of O. stentina present in the ABI subregion is considered introduced.

In addition, systematics is a dynamic field of research, as novel species are continuously being described; some of them possibly being novel introduced species. However, in the absence of further verification regarding their status, we did not include some of these species in our list. A case in point is that of the spaghetti worm Terebella banksyi nov. sp [56] newly described following its collection in 2017 in Arcachon Bay and found in farms or reefs of the Pacific oyster Magallana gigas. Similar uncertainty is occurring for the newly described colonial tunicate Didemnum pseudovexillum nov. sp [57], distinctive from the well-known invader D. vexillum by morphological traits and genetic characteristics and found only in marinas in the Celtic Seas (Brittany, France) and NW Mediterranean Sea (Spain). Considering the habitats (farms, marinas) and extensive range of D. pseudovexillum nov., it is likely that it had been introduced. However, further clarification would be needed to ascertain its introduced or cryptogenic status.

We included in the list of accepted species that arose following hybridization between a NIS and a native species. Hybridization between native and introduced species is very common in plants [58,59]. It has also been documented in marine species although being still poorly examined, and yet an important issue to consider for marine NIS management [6]. In coastal systems, this process is well-illustrated by cordgrass species from the Spartina genus [60,61]. For instance, S. alterniflora hybridized with the native species S. maritima after its introduction in the United Kingdom. This hybridization gave rise to S. townsendii, a sterile species, which then gave rise through polyploidization to S. anglica. The latter species is highly successful, displacing the native S. maritima, and is present in most of the ANS and locally in the western BAL. Thus, S. anglica is not per se introduced but is included in our list, because it would have never existed without the introduction of S. alterniflora in Europe.

Another cordgrass species, Spartina versicolor Fabre, has also a controversial taxonomic status. Although it was recorded as NIS in several European countries in the 19th and 20th centuries, it was considered synonymous with Spartina patens, due to morphological similarities [62,63] sampled several populations of S. versicolor in the Mediterranean, Atlantic, and North Africa saltmarshes and conducted cytogenetic and molecular analysis (microsatellite, nuclear and chloroplast DNA sequences) and compared it to North American Spartina species. Their results supported the hypothesis that all European and African populations of S. versicolor are, in fact, North American S. patens, introduced before or at the beginning of the nineteenth century. Due to potential hybridization within Spartina species, further investigations are needed to clarify any potential hybridizations between introduced species with the native ones (e.g., S. maritima).

4.2. Issues with Assessing the Spatial Distribution of NIS in Europe’s Seas

The NIS data-gathering process is not standardized (there is no consistent methodology) among EU Member States, which is a drawback and likely to generate bias and uncertainty in the assessment itself. In addition, biases may arise from the lack of dedicated surveillance programs. Not only studies focused on NIS introduction hot spots, such as ports and marinas or aquaculture facilities, but also the increment of monitoring programs to give responses to other MSFD descriptors increased the probability of finding newly introduced NIS during the surveys. However, it must be highlighted that several new records are introductions that most probably either went unnoticed in previous surveys or from areas that were never previously investigated. Monitoring programs are also not equally implemented in all subregions, and only a few have specifically focused on NIS and cryptogenic species detection [14].

Therefore, data need to be updated continuously from other monitoring programs or scientific literature reporting NIS. For example, in the NEA region, subregions such as ANS or ACS have historically received more attention than ABI [64]. In several countries such as Spain, Portugal, and Denmark, there were no baseline studies for NIS until very recently and the list included in the last assessment period (2012–2017), can therefore be considered as a baseline for some countries.

Boundaries between sub-regions established for MSFD reports are also challenging. In particular, the ABI subregion boundaries, as the boundaries between ANS and ACS, very often raise questions when establishing the status of some species because the natural borders between water masses are not static at these human-established borders (Figure 1). The same holds for the MWE subregion. Its western limit finishes a few kilometers after the strait of Gibraltar making it difficult to establish proper frontiers between Mediterranean and Atlantic waters since the Mediterranean shows a high influence even until central Atlantic waters [65]. In this sense in the southern extension of the ABI subregion, being highly influenced by Mediterranean waters, some species whose native range extends in both NEA and MED regions can be found, giving them the category of partly native species in a subregion, but being NIS in a country of this same subregion (Table 3) or in another subregion of the same region. This is the case, for example, of the gastropod Cymbium olla, whose native range includes Algarve (southern Portugal) and the Gulf of Cadiz (southern Spain—Atlantic coast), which are part of the ABI subregion, but also Cadiz in the Alboran Sea site, which is in the MWE subregion. Therefore, Cymbium olla, which is partly native in the MWE subregion even in some other localities in the MWE, might be locally classified as NIS [66].

Species distribution and their possible expansion, are never contained within any human delineation of marine borders, making it difficult to categorize their status when it comes to classification at any bordering level (subregion, region, or Pan-European). This issue is particularly important for species spreading gradually, which might be considered either as a natural expansion or introduced by human activities. For example, the nassariid gastropod Tritia neritea’s native range includes the Mediterranean and the Black Sea, as well as all around the Iberian Peninsula (Hidalgo [67] as Cyclops neriteum), but since the 1970s, this gastropod has been extending its range along the coast of Frances since its first record in 1976 in Arcachon Bay [68]. Its presence almost exclusively in oyster farming areas and the genetic characteristics of the French populations (e.g., admixture of lineages found in different locations of the Mediterranean Sea that indicated multiple introductions [69]) finally concur to report this nassariid gastropod as a NIS, probably introduced by oyster cultures in France [70]. Therefore, it is considered partly native to the ABI subregion because of its native range in Portugal and Spain, and its later introduction in France (Table 3). Some cases such as Tritia neritea, exemplify the difficulty of sometimes categorizing species as either NIS, cryptogenic or native because of their life history, migratory and demographic history, influenced by paleoclimatic events in a longer time scale and more recently by human activities [69,71]. These processes determine the species’ contemporary distribution, showing a patched map of native and introduced localities, even at local small scales [72].

Another example of a partly native species is that of the amphipod Ericthonius didymus (Krapp-Schickel, 2013), which was described in the Adriatic Sea from the Venice Lagoon (Italy). This recent description was rapidly followed by new records in Europe both in the Mediterranean and the Atlantic between 2013 and 2017 [73]. These observations, some of which date back to the year of description of the species, do not allow an unequivocal designation of the species as non-indigenous in the Bay of Biscay. However, the species is considered NIS in the ANS and the AMA, due to its presence in anthropogenically stressed sites, such as harbors/marinas and shellfish grounds [73].

4.3. Trends Indicator

Across all taxonomic groups, the rate of new NIS introductions in EU waters has increased gradually since 1970 and reached an average of 21 NIS per year in the period 2012–2017. The same upward trend was noticed for the Baltic, North-East Atlantic, and the Mediterranean Sea, but was more evident in the Mediterranean and Baltic Seas. In contrast, a decreasing trend was seen in the Black Sea with only one new species detected in the last assessment periods (0.2–0.3 NIS per year). Low figures noticed in the periods of 1988–1993 and 2000–2005 are likely an artifact of varying monitoring and reporting efforts between the regions over these periods.

The high rate of annual Introductions from 2000–2005 was very likely associated with a growing research interest in NIS, rather than discrete episodic events leading to high levels of new introductions during these years. Indeed, the development of several dedicated projects (AquaNIS, DAISIE, EASIN) produced outputs with updates on the list of NIS.

The decreased annual rate of new NIS introductions in the period 2018–2020 at almost all geographic levels examined has recently been attributed to time lags in reporting [74] rather than a result of NIS intervention programs. Also, there are fewer sampling years in this last interval analyzed, which might entail larger variability in the annual rate. This provisional reduction of new NIS registered is furthermore not likely to be associated with the implementation of measures since no new programs of measures have been implemented yet (e.g., only three marine NIS, the fish Plotosus lineatus, the seaweed Rugulopteryx okamurae, and the crab Eriocheir sinensis (only partly marine), are in the EU list of Invasive Alien Species of Union concern) and the implementation of the Ballast Water Management Convention at the European level is still in progress [75]. The only exception is the Council Regulation (EC) No 708/2007 of 11 June 2007 concerning the use of alien and locally absent species in aquaculture that may have decreased the risk of novel species introduced for cultivation purposes, although not preventing transfer within each EU country’s borders. A decrease in new NIS records in the last assessment period (2018–2020) for most regions might furthermore be explained by the homogeneity of marine NIS fauna since more and more species previously found exclusively in one of the countries are now found in more countries. Probably many species are expanding naturally from previously invaded countries.

The present upward trend in new NIS introductions to the Baltic Sea contradicts the previous D2C1 assessment, which indicated that the trend was decreasing since 2011 [76]. The discrepancy is very likely due to updated NIS records from several countries around the Baltic Sea. The latest assessment period in the present study covered only three years (2018–2020), but already five new NIS were recorded from the EU marine waters of the Baltic Sea during this time, suggesting that the ultimate HELCOM goal of zero new NIS introductions will not be reached, even though the rate of new NIS introductions has dropped to less than two new NIS per year. Overall, the current Baltic Sea analysis indicated that the number of new introductions has had a steep increase from the early 2000s to 2017. The increase may be due to growing scientific interest and promotion of citizen science projects [77], but it is evident that anthropogenic pressure through intensified shipping has steadily increased toward the marine environment of the Baltic Sea [78].

The NEA region encompasses several ecoregions, 4 sub-regions, and 10 different countries, making this region a very complex one for analyzing trends because of the heterogeneity in surveys and ecosystems. It is thus not surprising that quite a large number of species are reported as NIS within the region, and subregions (Figure 4b,c). Altogether the number of novel NIS has always been increasing, at least for invertebrates that are the most numerous NIS in this region (Figure 3). This is likely attributed to the continued increased maritime traffic in the region. Indeed, overall shipping density increased across the North-East Atlantic by 33.6% between 2013 and 2017 [79].

In comparison to the previous assessment [3,15,32], this work does not consider data from the UK waters. This leads to differences not only in the total number of NIS but also in the trends indicator as first detection dates may be years earlier in neighboring non-EU countries.

An earlier assessment (over the period of 2003–2014) of NIS in the ANS, ACS, and the ABI subregions showed that the number of newly recorded NIS varied by year and region showing a relatively constant linear increase in the ANS only, but not so in the ACS and ABI [80]. In this study, an increasing trend was observed in all subregions but the ACS. The high number of NIS in the ABI in the 2012–2017 period (7 NIS/year) is partly attributed to intensive studies in port areas and marinas [81,82,83] in the framework of the implementation of the MSFD descriptor 2 or research projects dedicated to NIS surveys. Furthermore, the increase of studies based on genetic analyses within this last decade has helped to rapidly and accurately detect newly introduced species reassess some species that have been misidentified, and elaborate an updated checklist of NIS [84,85,86]. In addition to traditional genetic approaches, in recent years metabarcoding of environmental DNA had been proposed and is increasingly used as a new tool to improve NIS detection [87]. The approach is promising and effective although it needs to be used cautiously to avoid both false negatives (i.e., present, but undetected NIS) and false positives (i.e., NIS erroneously detected) [51]. NIS detection by these methods requires fit-to-purpose protocols and should not be based on molecular data obtained for general biodiversity assessments [88]. Either way, the data show that the increase seems to be stabilizing, indicating that it is a good time to set the baseline.

The increasing trend in introductions in ANS, which culminated in the 2012–2017 period with six NIS per year, appears to be slowing down in the last assessment period (2018–2020) with four new NIS per year, although future publications are expected to bring to light more NIS. During the period 2018–2020, in France, the number of records increased. However, this is the only French subregion with such an increase, thanks to dedicated surveys programs carried out in the Normandy region [86]; these reports are not new either for France or for ANS [89] (and references therein), suggesting a decrease of new species but an important dispersal between subregions.

In the ACS, the decrease is even more pronounced than in the ANS, with no novel NIS reported after 2017. As for the ANS, the difference from the previous assessment can be partly attributed to the geographic areas involved. In the previous assessment [76] the NIS of the United Kingdom in ACS were included in the analysis. Moreover, pathogens were also included. Additionally, in the Western English Channel (French and UK coastline), a research project (Interreg Marinexus project) dedicated to rapid assessment surveys of NIS in marinas, well-known introduction hotspots, was carried out over 2010–2017 [78], and provided novel reports for European waters (e.g., the ascidian Asterocarpa humilis [90]).

The AMA NIS list presented here represents an updated version of the list reported by Castro et al. [29] following similar criteria. As opposed to the current study, species that underwent tropicalization processes (see 29, 41) were considered one of the criteria for NIS attributes in Castro et al. [29] inventory. Most changes were made on macroalgae records for the Azores as more information on records, taxonomy, and distributional updates have been gathered and led to some changes. In addition, a few new records have been added as [29] included records only until 2020 whereas the present account includes records reported until summer 2022.

Comparisons with the full NIS inventory of the MED are somewhat hampered by the geographic coverage of the current study, which is limited to the EU waters of the Mediterranean (plus Albania and Montenegro). As a result, total numbers of new NIS, as well as annual introduction rates, appear to be reduced in comparison to, e.g., [30], especially for the eastern Mediterranean, as primary Lessepsian introductions restricted to the Levantine were outside the spatial scope of this study. Indicatively, the whole Mediterranean Sea hosts upward of 1000 validated NIS, 786 of which are in the MAL [12,23,91], compared with the 579 NIS present in the EU parts of these waters. As such, it is not surprising that the annual introduction rate in the central Mediterranean in the 2012–2017 period exceeds that of the eastern Mediterranean, as the accelerated sea warming rates favor the spread of Indo-Pacific species already present in the Levantine [92]. On the other hand, the reduction in Transport-Contaminant species [76], which are more prevalent in the Adriatic and the western Mediterranean, may have contributed to the observed leveling off or decreasing NIS trends in these two subregions. For the Mediterranean Sea as a whole, there appear to be two “stepwise” increases in new NIS introductions, the first one in the late 1990′s, mostly driven by introductions in the MAL and likely related to sea surface warming [30,93], and the second in the 2012–2017 period. This last peak could partly reflect intensified research efforts, which the whole basin has undoubtedly experienced in the last decade [94] as already suggested for other regions and subregions of the NEA, and in line with comments by Bailey et al. [31]. In Slovenia, for example, the number of detected NIS has increased from 17 in 2012 to 57 in 2021, which is due to increased targeted research, mainly founded by the Ministry of Agriculture, Forestry and Food for the implementation of D2 in the country [95]. It also coincides with a sharp increase in the introduction rate of fouling species, notably in marinas and on leisure boats, at least in their detection and reporting [96,97]. Hence it is difficult to really evaluate the significance of these trends without considering a measure of “effort”, which again starkly exemplifies the need for standardized monitoring for any assessments to be meaningful.

Some of the earlier invading NIS in the BLK such as the blue crab Callinectes sapidus (Rathbun, 1896) appear to be established and spreading in the area over the years. Callinectes sapidus was first found on the Bulgarian coast of the Black Sea in 1967 [98], most likely transferred in ballast water but could have been spreading via the Marmara Sea from an invasive population in the northern Aegean. Six new records of the blue crab have been documented near the Bulgarian Black Sea coast since 2010. This is evidence of a recent expansion of the species in this part of the Black Sea. This expansion could be explained by the existence of an established population in the area and is confirmed by the capturing of an egg-bearing female in Varna Bay in 2005 [99]. It is anticipated that in the face of climate change the number of NIS in the EU areas of the BLK will increase in the near future due to the spreading (Unaided pathway) of NIS from the North Aegean Sea that has already invaded the BLK via the Sea of Marmara such as the marbled pine foot Siganus rivulatus [100,101]. Moreover, NIS recently introduced via vessels in the northeastern and southern Black Sea could spread unaided in the study area [102,103]. Such is the case of the polychaetes Laonome xeprovala that spread in the Danube Delta–Black Sea Ecosystem and Marenzelleria neglecta that was detected in 2021 in the same area [103].

4.4. Uncertainties in Trends

Uncertainties in trends first rely on the uncertainty of the first date of the report (if not consistent across periods). The true introduction year of NIS may be different from the detection year. As an example, the Terebellid polychaete Marphysa victori was detected in 2016 and described in 2017 from French waters in the Arcachon Bay, with doubts already surrounding its true origin due to its presence in and close to oyster farms where Magallana gigas is cultivated [104]. This possibility was verified several years later. Marphysa victori is native to the Northwest Pacific [105], and it has undoubtedly been introduced as a contaminant with oyster transfers. However, it remains unproven if its introduction is a consequence of oyster importation from Japan. Between 1971 and 1975, about 1200 t of Magallana gigas spat collected from Sendai Bay (Japan) were introduced into Arcachon Bay. Marphysa victori has a substantial economic value as bait and is widely collected by recreational and professional fishermen. The number of worms collected in the lagoon (13 companies) could reach 1 million per year [104]. Reaching such densities within a year would be impossible. Thus 1975 was set as the most plausible year of its introduction.

Other examples include Mollusca species observations in EU waters around 80 years after their first detection in neighboring non-EU waters. Such are the cases of the gastropod Berthellina citrina (Rüppell & Leuckart, 1828), which was first reported in the MED from the Gaza Strip in 1940 [106], but only in 2019 in EU Mediterranean waters: Cyprus [107] or of the bivalve Gafrarium savignyi (Jonas, 1846) with a first Mediterranean record in 1905 from Egypt [108] but an EU record in 2005 from Cyprus [109].

Various policy measures relevant to the Baltic Sea countries can result in uncertainties regarding the emergent reports of new NIS introductions. Trend analyses on new NIS introductions to the Baltic Sea, such as [22,27,110] may differ mainly due to the applied assessment principles, e.g., area of interest, and species included in the analyses. Baltic Sea delineation determined according to the EU MSFD differs from HELCOM delineation, and this often leads to NIS being reported, for example, from the Kattegat area, which is BAL according to the HELCOM delineation, but at the same time a part of the ANS according to the EU MSFD delineation. In addition, Russian coastal waters outside of St. Petersburg and Kaliningrad are obviously part of the Baltic Sea but are not included in assessments that refer to the marine waters of the EU.

Even more, pronounced discrepancies may be observed with pan-Mediterranean assessments due to the exclusion of non-EU Mediterranean countries in this study (see above). Regardless of administrative boundaries for EU policies, it is crucial that the marine environment is managed with sufficient harmonization between regional policies. Toward that end, the Contracting Parties to the Barcelona Convention—21 Mediterranean countries and the European Union—have recently developed and adopted the Integrated Monitoring and Assessment Programme for the Mediterranean region (IMAP) [111]. Within its framework and in accordance with the MSFD [9], GES for NIS in the Mediterranean was defined as the minimization of the introduction and spread of NIS linked to human activities, in particular for potential IAS, with the reduction in human-mediated introductions as the proposed State Target [112], a target that clearly needs to be further refined but seems far from achieved based on our latest data.

4.5. Threshold Values

Qualitative GES assessments to date have been based on directional trends and, despite ongoing efforts [110], threshold values for the NIS trend indicator have not been set yet and neither have more specific recommendations been made for the magnitude of this reduction or the number of reporting cycles that will define the reference conditions [113].

Waiting for a value of the percentage reduction to be established at a European level, as suggested by [14], the French decree relating to the definition of GES states that GES is achieved if there is a significant decrease in the number of new NIS over two cycles at minimum. As visible in this work, the number of new NIS increased in all French marine subregions during the previous cycle (2012–2017), and the goal has therefore not been reached to date.

The identification and comprehension of impact thresholds on ABI marine native communities is required. ABI countries must collaborate more closely to implement common methodologies for MSFD implementation, particularly regarding non-indigenous species (D2) [114]. Furthermore, good coordination is required for the creation of an effective alert system. It is worth mentioning the risk-based approaches to good environmental status (RAGES) project, which attempted to establish reproducible, transparent, and standardized risk management decision procedures based on international best practices. The increase in the number of new NIS introductions in the period 2006–2017 seems to be stabilizing, indicating that it is a good time to set the baseline. This decrease in new NIS records might be explained by a biotic homogenization of the ABI marine NIS fauna since more and more species previously found exclusively in one of the countries are now found in all three ABI countries. Probably many species are expanding naturally from previously invaded countries.

In the Mediterranean Sea, preliminary analyses [12] indicated that threshold values should be established separately for each subregion and should be sought by examining the data of the last two decades, if not an even more recent period. Further work by Galanidi and Zenetos [30], based on breakpoint analysis of 1970–2017 NIS data, corroborated the validity of a subregional approach, demonstrating different temporal breakpoints in the rate of NIS introductions per subregion, ranging from 1997 in the MAL, to 2000 in the MAD, 2003 in the MWE and 2012 in the MIC. They suggest that the mean introduction rate of these periods can be used to define threshold values but stress that GES target refinement and percentage reduction cannot proceed without careful consideration of management objectives and pathway pressure, as also pointed out in Tsiamis et al. [14].

Trends in the arrival of new NIS is a core indicator of the Baltic Marine Environment Protection Commission (Helsinki Convention, HELCOM), and the primary criterion D2C1 was assessed for the first time for a six-year assessment period (2011–2016) in 2018 [10]. The report listed new NIS and cryptogenic species for BAL over the assessment period. Contracting Parties of HELCOM have set a precautionary threshold to assess GES in relation to NIS. Zero new NIS introductions through anthropogenic activities to the Baltic Sea per six-year assessment period has been defined as the GES for NIS [10], and therefore one or more introductions to BAL would result in GES not being reached. Furthermore, it has been argued whether a reduction in new NIS introductions could be set as an intermediate objective if the goal of no new introductions cannot be reached. Even though a proportional reduction of new NIS introductions between the assessment periods would indicate temporary improvement of GES, the “zero tolerance policy” was chosen as the GES threshold to the BAL, because it is pragmatic, independent of earlier assessment periods, applicable even with uncertainties in relation to taxonomy and introduction pathways, and efficiently reflecting management measures [10,110].

4.6. Concluding Remarks—The Way forward

Considering how dynamic biological invasions are, NIS inventories should be curated regularly, especially when used to inform policy, in order to minimize errors and avoid over- or under-estimating the state of invasions in a region [44]. While the validation process in this work explicitly addressed many of the taxonomic and spatial components of uncertainty in the EU NIS baseline, other issues remain unresolved, among which the lack of standardized monitoring needs to be urgently rectified both for the meaningful interpretation of results and for the refinement of the relevant indicators.

Regional and sub-regional analyses revealed that there are relatively strong variations in the number of new NIS introductions between the European seas, as well as among the subregions within the same region. Hence, it is natural that GES threshold values for the primary criterion D2C1 are discussed and decided under regional cooperation, as some regions have preferable conditions for a wider variety of species and thus tend to suffer from a higher number of introductions. In addition, NIS pathways are region-specific (e.g., the Suez Canal in the MED, shipping in the NEA). Shipping was found to be a likely vector for over half of NIS in European waters both through biofouling and ballast discharges [2], while biofouling, particularly of recreational vessels, appears to be an important driver for the homogenization of the alien biota in the Mediterranean. As such, a more detailed focus on quantitative measures of pathway pressure would help better elucidate the observed NIS patterns, inform target setting and evaluate GES achievement in relation to management. Considering that currently only aquaculture-related introductions are addressed with EU-wide legislation and that the BWMC is not expected to be fully implemented until 2024 at the earliest, expectations for percentage reduction should have a realistic temporal horizon and, if possible, promote management implementation for the remaining major introduction pathways. More specific national or local measures may be put in place to protect sectors or sensitive habitats, e.g., see [115] for additional measures related to shellfish culture in the Wadden Sea), pathways of species introductions however operate globally and should be managed at appropriate scales.