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Indicator Specification
Non-indigenous species (NIS) are alien plants, animals or other organisms, introduced as a consequence of human activities outside their native range. NIS have been systematically observed since the early 1990s, and their introduction into Europe’s seas has happened at unprecedented rates (Hulme et al., 2008).
NIS may arrive and enter a new region through various pathways: arrival of a transport vector (mostly shipping), import of a commodity (e.g. aquaculture), and/or natural spread from a neighbouring region where the species is itself alien. The introduction of species into habitats outside their native ranges is closely linked to the increasing globalisation of trade and travel (Mooney & Hobbs 2000). While there is a consensus that shipping, along with aquaculture, are the primary drivers for NIS introductions, and a key locus for preventive regulation, few policies have been evaluated by scientists for their effectiveness.
Historically, aquaculture and stock transfers of aquatic species resulted in a significant amount of taxa being transported worldwide (Nentwing, 2007). The speed and access of different transport modes in the spread of cultured species, their pests, parasites, diseases and associate species, have changed over this time. At one time shipping journeys would have taken some months but now aircraft can spread biota within a day or less over the same distances. Elton (1958) stated: 'the greatest agency of all that spreads marine animals to new quarters of the world must be the business of oyster culture'. He was unaware of the impact that shipping will already have had by that time and of the trade that was to follow.
Knowledge of the invasion process is essential for designing management plans to cope with the potential effects of invasive species, and to attempt to prevent their large-scale spread, underlines the importance of recognizing the hot spot areas for new introductions (e.g. ports and marinas) and covering these with the statutory monitoring.
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
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For references, please go to https://www.eea.europa.eu/data-and-maps/indicators/trends-in-marine-alien-species-1 or scan the QR code.
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