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Indicator Assessment
Since 1949, 1 039 non-indigenous species have been introduced into European seas.
The largest proportion of NIS introductions into European seas are associated with the shipping (49.1%) and corridor pathway (33 %: Suez Canal, inland canals). These are followed by unintentional movement of live organisms as contaminants (11 %) and escapees from aquaria, aquaculture and mariculture (5.1 %). Intentional releases in nature account for 1.7 % of NIS.
Main vectors for transfer of NIS by vessels are ballast waters (346 species) and boat hull fouling (287).
Shipping is the major pathway for introductions in all regional seas. Specifically, 45% of NIS introductions into Eastern Mediterranean and 82% in the Black Sea are associated with the shipping pathway.
Corridors are the main pathway in the Eastern Mediterranean, where more than 46 % of NIS was introduced via the Suez Canal. 14.5 % of NIC was introduced via inland canals in the Baltic Sea.
Transport contaminants (directly related to oyster aquaculture) are responsible for more than 30 % of introductions in the North-East Atlantic (Celtic, Iberian, Icelandic and North Seas).
While NIS introductions still occur, the rate of NIS introductions decreases in the time period 2006-2017 in all regional seas. The decreasing trend can be assigned to polices effectiveness as well as to other reasons, such as decreasing pool of potential NIS species, variations in sampling effort or available expertise.
In some of EU Member States, the number of new marine species introduced via human activity has already been reduced to zero.
Monitoring is not considered to sufficiently cover all the hot spot areas for new introductions. Identification of the areas that are most at risk of becoming invaded, as early detection mechanism will increase chances of eradication of invasive species.
Pathways into European Seas
Since 1949, the main pathway of introduction of non-indigenous species (NIS) into European is shipping (i.e. transport stowaway), contributing 49.1 % to NIS introductions by moving live organisms attached to ships (hull fouling) or in ballast water and sediments. Second main pathway are corridors (33 %, e.g. Suez Canal and inland canals). Other important pathways are: unintentional movements of live organisms as contaminants (11 %), escapees from aquaria, aquaculture and mariculture (5.1% ) and intentional releases to nature (1.7 %) (Figure 1).
However, these figures are a best estimate because the introduction pathway is often uncertain. Among NIS transferred by vessels, most appear to have been come from ballast waters (346 species) and boat hull fouling (287).
The rate of introduction, which peaked between 2000 and 2005, has since shown a declining trend in all regional seas, as reflected at Pan-European level (see Figures 2 and 3).
Previous studies have shown that the most prominent invasion pathways are shipping and aquaculture activities (Streftaris et al., 2005; Katsanevakis et al., 2013). An exception to this general trend can be found in the Mediterranean Sea, where the dominant invasion pathway (sometimes referred to as 'vector') is the Suez Canal, which enables Red Sea species to migrate into the south-eastern Mediterranean Sea and vice-versa. This phenomenon is also known as Lessepsian migration. Hull fouling is thought to have been the vector of introduction for many macro-algal species (Mineur et al., 2007).
Monitoring is not considered to sufficiently cover all the hot spot areas for new introductions. Identification of the areas that are most at risk of becoming invaded, as early detection mechanism will increase chances of eradication of invasive species.
Pathways at (sub)regional level
Shipping (i.e. transport stowaway), is the main vector into the Black Sea, the Icelandic Shelf and the Baltic Sea, mainly transferred via ballast waters (Figure 2). The contribution of ship hull fouling is also high in the Mediterranean sub-regions, and the Iberian and Celtic Seas (Figure 3). Introductions via corridor (i.e. the Suez Canal, Lessepsian immigrants) peak in the eastern Mediterranean and decline towards the western Mediterranean.
Unintentional contamination via transport is the second most important pathway (Figure 3). While the number of NIS intentionally imported for aquaculture has dropped dramatically, the number transferred from one Regional Sea to another via secondary or accidental introduction has increased.
Effectiveness of policies addressing ship transferred non-indigenous species
An assessment of all available pan-European data on ship transferred NIS after 1970 shows that species introduced via ballast water (27.9 %) seem to dominate those associated with hull fouling (22 %). Despite initiatives to control ballast water transfers, shippings remains the main pathway for non-indigenous species introduction. A total of 63 species are estimated to have entered Europe’s seas in the 20th Century on ship hulls compared with 61 species in the 1990s (Katsanevakis et al, 2013).
The International Maritime Organization (IMO) promoted the Ballast Water Management Convention (BWMC), which was adopted in 2004 (www.imo.org) and came into force on 8 September 2017. If the BWMC is adequately implemented, the number of ballast-transported alien species will likely be reduced.
Besides international shipping, recreational vessels can pose a significant risk of primary or secondary introductions of alien species, especially in the light of the increase in yachting activities (Ferrario et al, 2017; Cole et al., 2018). The risks of transferring NIS may, however, be minimised by preventing fouling on hulls and by taking action against neglected boats before they can act as vectors.
A ‘European code of conduct on recreational boating and invasive alien species’ was recently presented to the Council of Europe (https://rm.coe.int/1680746815). A new global project to help protect marine ecosystems from the negative effects of invasive aquatic species introduced via ship hulls has been given the go-ahead. The GloFouling Partnerships project — a collaboration between the Global Environment Facility (GEF), the United Nations Development Programme (UNDP) and the IMO — will address the transfer of aquatic species through bio-fouling (http://www.imo.org/en/mediacentre/pressbriefings/pages/20-biofouling.aspx).
Corridors
Inland canals: Canals connecting rivers over watersheds or seas across narrow land bridges 'dissolve' natural barriers to the dispersal of aquatic organisms, thereby furnishing these with many opportunities for natural dispersal as well as for shipping-mediated transport. The precise number of aquatic species that benefited from the network of inland canals is as yet unknown, but it was estimated that 65 species may have spread throughout European waterways (Galil et al., 2007). The vast majority of them are freshwater species, but 24 species extended their distribution in marine and estuarine waters of the Baltic and North Sea.
The Suez Canal: Approximately 350 NIS are estimated to have entered the Mediterranean via the Suez Canal after 1970, of which were 280 Lessepsian immigrants and approximately 70 entered by ship via the Suez Canal. The pace of Lessepsian migration has been decreasing, particularly in the last decade (Figure 3), despite the expansion of the Canal (Zenetos, 2017).
Of the 280 Lessepsian immigrants, approximately 200 species are established, but only 50 are invasive and spreading across the Mediterranean. The rest are locally established and their distribution is limited to the eastern Mediterranean. One of the latest invasive Lessepsian species is the lion fish (Pterois miles), which, within 6 years of its establishment (2012-2017), spread to the central Mediterranean (ESENIAS: Karachle et al., 2017).
The past two decades have seen a decrease in Indo-Pacific NIS and in increase in invasion rates of Ponto-Caspian species. Compared with the 20 known Ponto-Caspian alien species that entered before 2000 via the canal system, there has been a slight increase over the last decade. The latest introduction is that of the Ponto-Caspian amphipod Echinogammarus trichiatus, which was detected in 2014 in the Baltic Sea catchment area (Zettler, 2015).
Given that it is impossible to eradicate widely-spread species, their interception or the closure of new pathways are probably the only effective strategies for reducing future impacts of new introductions (Carlton and Ruiz, 2005).
Effectiveness of policies addressing non-indigenous species in aquaculture (releases, transport contaminant, escape from contaminant)
The crisis in wild fisheries and the globalisation of the market (Casal, 2006) have led to an increase in human-mediated movements of aquatic species. Commensal species are also often introduced as contaminants, such seaweeds and crustaceans attached to oysters traded for mariculture (Wolff & Reise, 2002; Savini et al, 2010).
As seen in Figures 2 and 3, a decline in aquaculture related species is evident: only 6 new NIS were accidentally transferred as contaminants in the 2012-2017 period compared with 21 recorded in the 2005-2011 period. This testifies that policies (e.g. Regulation (EC) 708/2007) have been effective in regulating the number of new imported and accidentally introduced species. However, the translocation of shellfish from an area in Europe where the species is already established to another involves the risk of transfer of accidentally introduced species with it.
The ICES Code of Practice on the Introductions and Transfers of Marine Organisms (ICES, 2005) recommends the procedure for introduced or transferred species, which are part of current commercial practice. The procedure states clearly: a) all products should originate from sources in areas that meet current codes, such as the World Organisation for Animal Health (OIE) International Aquatic Animal Health Code or equivalent EU directives; and b) if required, there should be inspection, disinfection, quarantine or destruction of the introduced organisms and transfer material (e.g., transport water, packing material and containers) based on OIE or EU directives.
Effectiveness of policies related to aquaria/trade
Although ballast water has received much attention as a source of aquatic invasive species, aquaria and trade in aquarium and ornamental species are emerging as another important source for species likely to invade aquatic habitats (Padilla & Williams, 2004). The aquarium trade has a long history of transporting and introducing fish, plants and snails into regions where they are not native (Duggan, 2010).
Enforcing the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) legislation on importing ornamental species has led some European traders to concentrate on local species (Calado, 2006). However, this does not prevent movement of marine species from one regional sea to another. Restrictions on possession and trade in known or potential NIS do not exist in all Member States (Miller et al., 2006)
The rate of aquaria species released to the wild (pathway classification 'escape from confinement' has tripled over the last decade (Figure 3)). These are mostly fish purchased in aquaria but also macroalgae, and mollusca. The most well-known case is that of the 'killer algae', Caulerpa taxifolia, one of the 100 top invasive species worldwide, that was released/escaped from the Monaco Aquarium. The phenomenon is particularly worrying in the Mediterranean, where more than 20 fish species among those imported and kept in domestic aquaria have been detected in the wild (Zenetos et al., 2016; Deidun et al., 2017; Insacco & Zava, 2017; Deidun et al., 2018)
There are no current management practices that can affect the species’ survival during its passage through the aquarium trade. Improved bio-security measures in public and research aquaria would address a potential pathway for a range of species, providing value beyond management
The EU Trade control and Expert System (TRACES) could be adjusted to gather compulsory information on the intra-EU trade of alien taxa as research organisms. This system can currently be used to track imports of the species from third countries.
Despite the existence of strict European legislation on the regulation of food fisheries, the capture and trade of ornamental species in European Seas has never been addressed. This leads to the spread of traded species throughout the world in a generally unregulated industry.
The risk posed to the aquarium trade could be reduced by enforcing similar regulations and procedures as those applied to aquaculture (see above) and by educating the public about the dangers of releasing aquarium species to the sea or improperly disposing of aquarium water, rocks and sediment. An extreme solution would be to ban the collection of ornamental species completely. A feasible solution would be to use alien species thriving in the wild in invaded areas for marine aquaria, turning the threat to a profit. Such a case has been demonstrated for the grapsoid crab, Percnon gibbesi, which has invaded the Mediterranean Sea (Calado, 2012). It has been suggested that the use of this species could replace those species being collected in the species' home range in order to supply the European marine aquarium trade. Although a selective fishery on young recruits and female crabs of this species will not eradicate or even stop the dispersal of this highly successful invader, it will certainly generate a new income source for local fishermen and probably help to alleviate the fishing pressure on potentially over-harvested stocks of Percnon gibbesi in its home range (Calado, 2012).
At the national level, the number of marine species introduced via human activity has been reduced to zero in some countries. Good examples are Lithuania, Finland, Poland, Sweden, Estonia, Latvia, United Kingdom, Ireland, Denmark, Belgium, Norway, Netherlands, Spain, Germany (ICES, 2018).
References in key assessment text
https://www.ices.dk/community/groups/Pages/WGITMO.aspx
This indicator describes the processes (pathways) that result in the transfer of alien species from one location to another. The identification and categorisation of pathways follows the Convention on Biological Diversity (CBD) classification as interpreted by the IUCN (2017).
A hierarchical approach has been adopted to describe the pathways, based on the framework developed by Hulme et al. (2008). The main pathways shown above, in which a NIS arrive, can be subdivided into the following categories: importation of a commodity; arrival of a transport vector; or spread from a neighbouring region. The principal pathways were identified under the CBD process (UNEP, 2014) as quoted below.
Pathways:
The secondary natural dispersal of invasive alien species that have been introduced by various pathways is unaided. Information on the mechanisms of the secondary spread of invasive alien species, after their introduction is not considered in this analysis.
Trends in primary pathways over 6 year periods should tell a story when combined with management policies applied/implemented over the last decades. In reality, there could be other factors involved, for example: the decrease could be partly explained by the decreasing pool of potential NIS species not yet arrived in Europe; another factor could be variations in sampling effort, available expertise; the decrease may also be a temporal phenomenon etc.. These aspects are no yet considered in this analysis.
The units used in this indicator are:
Invasive species are addressed in European and global legislation.
The MSFD (Directive 2008/56/EC amended by 2017/845/EC), which is the environmental pillar of the EU Integrated Maritime Policy, sets an overall objective to reach or maintain 'Good Environmental Status' (GES) in European marine waters, by 2020. One of the objectives addresses ‘Non-indigenous species introduced by human activities, that shall be at levels that do not adversely alter the ecosystems’. The MSFD aims to set up an effective management system to prevent further introductions and limit the impacts of NIS already introduced (EU, 2017) and addresses:
- newly-introduced non-indigenous species;
- established non-indigenous species, particularly invasive non-indigenous species; and
- species groups and broad habitat types that are at risk from non-indigenous species.
Overall, policies are split per pathway, but you could add somewhere that the measures established under the MSFD (D2) are expected to have some effect on the reduction of introductions and impact of NIS in the marine environment.
The EU Regulation (EU, 2014) addresses exclusively invasive alien species (IAS) and aims to increase coordination among existing legal instruments. It includes innovative pathway-related measures, aiming to provide a holistic framework for the assessment, management and prevention of NIS.
Other legislation relevant for management of NIS includes: Regulation (708/2007/EC) on the use of alien and locally absent species in aquaculture; Regulation (338/97/EC) on the protection of species of wild fauna and flora by regulating trade; Directive (2000/29/EC) on protective measures against the introduction of organisms harmful to plants or plant products; and Water Framework Directive (2000/60/EC) in the filed water policy.
A number of International policies are in place. The Convention on Biological Diversity (CBD, 2014), adopted in the EU by the Biodiversity Strategy (COM(2011) 244 final) has the overall objective of halting biodiversity loss and also addresses the reduction in the impacts of alien species. The EU Biodiversity Strategy 2020 Target 5, states that 'By 2020, IAS and their pathways are identified and prioritised, priority species are controlled or eradicated and pathways are managed to prevent the introduction and establishment of new IAS' (EC, 2011).
Shipping is an important vector for NIS introduction, addressed by the ballast waters convention implementation (IMP, 2017; IUCN, 2017) The convention entered into force in 2017, meaning that ships must manage their ballast water so that aquatic organisms and pathogens are removed or rendered harmless before the ballast water is released to a new location. This will help prevent the spread of invasive species as well as potentially harmful pathogens (International Maritime Organization (IMO)).
Regional Seas Conventions contribute to implementing this through supporting the ratification and implementation of IMO conventions.
The number of alien species is highest in the Mediterranean, where countries agreed on the Action Plan concerning Species Introductions and Invasive Species (UNEP MAP, 2017), because of the Suez Canal and Lessepsian migration from the Red Sea (Fox, 1924), in conjunction with the Aswan Dam construction in the 1960s. This construction removed the protection zone for the spread of IAS throughout Suez, represented by the freshwater buffer in the Nile River (Zakaria, 2015). Until the construction of the dam, this water was a relatively effective control of NIS.
The Baltic Sea coastal countries cooperate within HELCOM (Helsinki Commission). One of their activities was to work toward harmonized implementation of the 2004 Ballast Water Management Convention of the International Maritime Organisation (IMO, 2004) in the Baltic Sea area (HELCOM, 2014).
The list of species used for the analysis is the same as that considered for the trends in the introduction analysis (EEA indicator MAR002 https://www.eea.europa.eu/data-and-maps/indicators/trends-in-marine-alien-species-mas-2/assessment) and stored in the HCMR/EEA database. It includes both alien and cryptogenic species. The information on the country, year of first introduction of each species and pathway/vector is publicly available through the species search widgets in EASIN, updated on 27/3/2018, Version: 7.1 (https://easin.jrc.ec.europa.eu/easin) see Tsiamis et al. (2017). The HCMR/EEA database is in full agreement with the pathway classification given in EASIN, and updated for new species to May 2018.
The following European alien species data bases have been used for defining possible pathways:
Trends in introduction per pathway were calculated on a 6-year basis, considering the very first sighting/collection of the species in European Waters/regional Sea/MSFD area. In the absence of exact collection dates, the date of publication was used as the best available information. All alien species — invasive, established and casual — were taken into account.
The primary pathway/vector was filled in as far as possible. Marine and estuarine species are those aquatic species that do not complete their entire life cycle in freshwater (modified after ICES, 2005). Cryptogenic, range expanding and vagrant species are not considered in the analysis. Thus, the primary pathway was calculated for 876 species that were introduced since 1970. However, on calculating the trends at regional/MSFD level, the secondary pathway was also considered in cases where a species spread unintentionally or by another mode of introduction than the original one in the first recipient EU area.
To categorise pathways of primary introduction of alien species into a new region, we have followed the framework proposed by CBD (2014), as described in the 'Indicator definition' section .
Unless species are found when deliberately moved, evidence of their actual transmission is seldom known.
Information on vectors is mostly derived from expert judgement on an extensive review of the referred databases, since specific research projects aimed at identifying vectors and occurrences are complicated and demand large resources. The only exception is published reports issued on maritime traffic worldwide (BWM, 2005). In a large number of cases, likely pathways are merely inferred, for example, taking into account the most common activity occurring in a specific location (shipping, aquaculture), but no scientific evidence is provided.
Vertebrate pathways tend to be characterised as deliberate releases. With the exception of the Lessepsian immigrants that arrived unintentionally via the Suez Canal, invertebrates were introduced mostly as contaminants and plants as escapees. Pathogenic microorganisms and fungi are generally introduced as contaminants of their hosts.
No methodology references available.
In many cases, it is impossible to identify the introduction vector. Thus, the pathway of 32 species is assigned as ‘unknown’. In bivalves, for example, introductions may be attributed to larval transport in ballast water releases, adults in hull fouling of ships or imports of stock for aquaculture purposes, or for direct human consumption but released into the environment
For species that are most frequently associated with hull fouling, this form of transport was assumed to be the responsible vector. For planktonic taxa and microscopic resting stages, we have deemed ballast water to be the most likely vector since such species that are associated with hull fouling might be expected to become flushed away during ship journeys at sea. Human activities near to the site of the first records are generally assumed to be responsible for an introduction event. However, such deductions are not always secure and for this reason we have calculated more than one vector where the likely vector remains unclear.
Where more than one pathway of introduction is suspected/documented, the analysis has considered both modes of introduction. Thus, the resulting percentage of contribution per pathway amounts to more than 100 %.
See rationale uncertainty
Different levels of certainty are associated with alien species that areintroduced. A scheme proposed by Minchin (2007) and adopted by Katsanevakis et al. (2013), provides a basis for an improved quality of information for pathways and vectors.
(1) There is direct information of a pathway/vector: the species was clearly associated with a specific vector(s) of a pathway at the time of introduction to a particular locality. This is the case in intentional introductions (i.e. aquaculture/commodity) and in many cases of Lessepsian immigrants (when there was direct evidence of a gradual expansion along the Suez Canal and then in the localities around the exit of the Canal into the Mediterranean).
(2) A most likely pathway/vector can be inferred: the species appears for the first time in a locality where a single pathway/vector is known to operate and there is no other rational explanation for its presence except by this pathway/vector. This applies to many species introduced by shipping or aquarium trade or as aquaculture contaminants. In some cases, a specific vector could not be inferred, e.g. some species probably introduced by shipping could not be further linked to ballasts or hull fouling and were classified as ‘shipping/unknown’. In many cases, inference is based on known examples of introductions elsewhere for the same or similar species, the biology and ecology of the species, the habitats and locales it occupies in both the native and introduced range, and its pattern of dispersal (if known), e.g. for a fouling species frequently recorded in ports, shipping has been assumed to be the most probable vector.
(3) One or more possible pathways/vectors can be inferred: the species cannot be convincingly ascribed to a single pathway/vector. Inference is based on the activities in the locality where the species was found and may include evidence on similarly behaving species reported elsewhere.
(4) Unknown: where there is doubt as to any specific pathway explaining an arrival. The pathway of 32 species has been assigned as ‘unknown’.
(5) Uncertainty in year of introduction: the year of introduction is based on reported first collection dates but does not necessarily imply the true year of introduction, which may be years earlier.
http://www.sciencedirect.com/science/article/pii/S0964569113000562
For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/trends-in-marine-alien-species-1/assessment or scan the QR code.
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