Non-indigenous species (NIS) are those species introduced outside their natural past or present range which might survive and reproduce. Some of the NIS can be harmless, with negligible impacts on native species. Other NIS can be invasive with potential to change native community composition and cause local population extinction with long lasting impacts which threaten biodiversity and ecosystem services. Those are addressed by the EU Regulation 1143/2014 on Invasive Alien Species which starts to include some marine species.

The MSFD requires to identify the newly-introduced NIS in the EU Member States waters, as well as to assess the abundance and spatial distribution of established NIS, as well as the adverse effects produced by them.

In relation to 'Non-indigenous species', the Marine Strategy Framework Directive considers that 'good environmental status' is achieved when 'Non-indigenous species introduced by human activities are at levels that do not adversely alter the ecosystems (EC, 2008, 2017)'.

1.223 NIS have been introduced in Europe’s Seas between 1949 and 2019 (Figure 1). The number of NIS is highest in the Mediterranean Sea, where 69 % of all NIS have been recorded. A total of 21% were recorded in the North-East Atlantic Ocean, 5 % in the Baltic Sea and 3 % in the Black Sea. More than 80 NIS were identified as 'invasive alien species' with a high potential to produce impacts on the biodiversity, as well as cause negative economic and social consequences. Currently, over 53% of Europe’s coastline is inhabited by invasive NIS. These invasive species have been known for typically impact several other species, ecosystem functions and the modification of natural habitats. The mean number of new recorded NIS introductions slowed down from 28 to 16 species per year in the period 2006 - 2017. In some of EU Member States, the number of new marine species introduced via human activity has already been reduced to zero as a result of successful management.

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Figure 1: Trends in introductions of marine non-indigenous species (vertebrates, invertebrates, primary producers) after 1949-2017 per 6-year periods in the Europe’s seas.(EEA, 2019a).

The introduction of NIS is closely linked to the increasing globalisation of trade and travel. Shipping (49%) and inland corridors (33%) are the main pathways for the introduction of NIS to Europe’s Seas. Other pathways include the unintentional movement of live organisms (11%), escapes from aquaria and aquaculture (5%) and intentional release (2%).

Corridors are the main pathway in the Eastern Mediterranean, where more than 46 % of NIS was introduced via the Suez Canal. 14% of NIS was introduced via inland canals in the Baltic Sea. In the North East Atlantic the oyster culture industry is responsible for more than 30% of marine NIS introductions.


Figure 2: Percentage of NIS introductions associated with each pathway in European Seas after 1949 (EEA, 2019b).

General outcomes of the  regional assessments 

Over 160 NIS have been identified in the OSPAR area. Some of the main routes for these unintended introductions are through the discharge of ballast water (and the sediments that it carries) and fouling on ships’ hulls. With increasing ship traffic there is a higher risk that new species will be introduced. Faster ships and shorter journey times mean that organisms have a greater chance of surviving the voyage (OSPAR Commission, 2017).

The introduction of NIS in the Baltic Sea has contributed to its degradation, however there has been a slight decrease in the number of new NIS detected in recent years. Over 170 NIS and cryptogenic species have been observed in the Baltic Sea. The pathways responsible for the currently established species (59% of all introduced species) are shipping and natural spread from neighbouring areas (Helsinki Commission, 2018).

263 NIS were registered by 2014 in the Black Sea basin. Over the last decades numerous alien invasive species, among which a mollusc species, Rapana venosa, bivalve species, Mya arenaria and Anadara inaequivalvis, as well as gelatinous carnivorous species, Mnemiopsis leidyi and Beroe ovata, have developed mass populations and caused severe impacts on the pelagic and/or benthic food webs of the Black Sea. Main vectors of NIS in the Black Sea are shipping activities, intentional or unintentional introduction by humans and migration of Mediterranean originated species to the Black Sea (BSC, 2019).

Corridors (mainly the Suez Canal) are the most important pathways of new introductions in the Mediterranean, followed by shipping and aquaculture. A considerable increase is noticeable in the trends of new non-indigenous species introduced to the Mediterranean Sea. Progress has been made in creating national and regional inventories of non-indigenous species and assessing their pathways and impacts. Evidence for most of the reported impacts of alien species is weak, mostly based on expert judgement, therefore a need for stronger inference is needed based on experiments or ecological modelling (UNEP MAP, 2017).

Outcomes from the MSFD assessments

In 2018, Member States had to update the Good Environmental Status (GES) assessments performed under Marine Strategy Framework Directive Article 8. The present dashboard displays the overall status reported by countries for the features, where the results show which is the percentage of assessments where GES has been achieved, not achieved or is unknown or not assessed.