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Onderdeel van Invasieve exoten


WaLTER surveys

As part of the WaLTER project, a comprehensive assessment of information and monitoring needs was carried out amongst stakeholders in the Wadden Sea region (Vugteveen et al. 2014). In this assessment, which included online surveys, the topic of alien species scored high (Vugteveen & Hanssen reports Natuur and Havens en Energie). Respondents specifically had an interest in learning more about the (long-term) effects of alien species on the Wadden Sea ecosystem, e.g. the effects of alien species on food webs, which in turn might be affecting bird populations. Other information needs concerned the vectors and spread of alien species and more specifically, ballast water as one such vector. The need for an inventory of the occurrence and distribution of alien species in the Wadden Sea was stated, as well as the need to carry out long-term, regular surveillance of the effects of alien species on the Wadden Sea ecosystem. However, current monitoring levels were considered inadequate for keeping track of introductions of new species (e.g. via mussel transports or shipping) and for finding out more about the effects of alien species on the Wadden Sea ecosystem. In summary, questions concerned the full scope of the invasion process, including questions about the origin and transfer of alien species, their dispersal, and their effects on the Wadden Sea ecosystem.

Policy-driven questions

In addition, there are policy-driven information needs resulting from the various European and global legal instruments that apply to the management of alien species in the trilateral Wadden Sea region (see subchapter ‘Overview of Regulations’ in chapter ‘Background’). These are listed chronologically below.

Water Framework Directive (2000/60/EC)
The Water Framework Directive (WFD) aims to achieve Good Ecological and Good Chemical Status. Although the text of the WFD does not explicitly mention alien species, the European Commission has come to accept that alien species are a pressure on water bodies and that they should be considered when implementing the Directive (e.g. IMPRESS 2002). It has been argued by many EU Member States ‘that no explicit assessment of IAS is required, assuming that significant IAS pressures will affect the WFD biological quality elements, and be detected by generic WFD status assessments’ (Vanderkerkhove et al. 2013, p.25). The ICES Benthos Ecology Working Group described the key principles of the WFD and the Marine Strategy Framework Directive (MSFD), and suggested that the way forward is to focus on the effect of alien species (function, niche) on the ecosystem, and to follow the precautionary principle by installing an early warning system (monitoring programme) at a national level (Van Hoey et al. 2010).

Council Regulation concerning use of alien and locally absent species in aquaculture (EC No 708/2007 of 11 June 2007)
The intentional import of alien species frequently leads to the import of other associated alien species. The Pacific oyster Crassostrea gigas and the Manila clam Ruditapes philippinarum for example, were found to be responsible for the introduction of a large number of alien algae and invertebrates into Europe via attachment to packaging material, shell fouling or parasitism (Savini et al. 2010). The Council Regulation concerning the use of alien and locally absent species in aquaculture ‘establishes a framework governing aquaculture practices in relation to alien and locally absent species to assess and minimise the possible impact of these and any associated non-target species on aquatic habitats and in this manner contribute to the sustainable development of the sector’ (Article 1). The implementation of these measures falls primarily under the responsibility of the Member States. The regulation specifies that alien species shall be monitored after their release into open aquaculture facilities for a period of two years or a full generation cycle, whichever is longer. Questions that the monitoring needs to answer are:

  • Have the impacts of the alien species in question been accurately predicted
  • Are there additional or different impacts
  • What is the level of spread or containment of these alien species

The advisory committee, after the evaluation of the monitoring programme, may ‘require longer monitoring periods to assess any possible long-term ecosystem effects’.

Marine Strategy Framework Directive (2008/56/EC)
The objective of the Marine Strategy Framework Directive (MSFD) is to achieve or maintain a ‘good environmental status’ (GES) in the marine environment by 2020 at the latest (Article 1). This should be done by developing and implementing marine strategies ‘in order to protect and preserve the marine environment, prevent its deterioration or, where practicable, restore marine ecosystems in areas where they have been negatively affected’. For descriptor 2 of the MSFD, non-indigenous (synonym: alien) species, the GES shall be met if  ‘non-indigenous species introduced by human activities are at levels that do not adversely alter the ecosystem’ (Annex I). The GES is determined at the level of marine (sub)regions. The Wadden Sea falls under the region ‘North-east Atlantic Ocean’, but Member States may implement the MSFD by reference to subdivisions in order to take into account the specificities of a particular area (Article 4(2)). In order to judge whether the GES of alien species, particularly invasive alien species, has been met, the following questions must be answered:

  • What are the trends in abundance of alien species in the Wadden Sea
  • What are the temporal occurrences of alien species in the Wadden Sea
  • What are the spatial distributions of alien species in the Wadden Sea

These should be investigated with special regard to risk areas, and in relation to the main vectors and pathways of the spreading of alien species. Furthermore, the environmental impact of invasive alien species was named as a criterion in the EU Commission Decision (2010/477/EU) (see also Bundesamt für Naturschutz & Bundesumweltamt 2011). Indicators for this criterion are the ‘ratio between invasive non-indigenous species and native species in some well-studied taxonomic groups that may provide a measure of change in species composition’ and ‘impacts of non-indigenous invasive species at the level of species, habitats and ecosystem, where feasible’.
In the case of the Dutch Wadden Sea, the ‘implementation of particular aspects of the environmental status not covered by the WFD or other EU legislation will be addressed within the framework of the Trilateral Wadden Sea Cooperation, not requiring the formal application of the MSFD to the Wadden Sea’ (Wadden Sea Board 2012, p.5). Examples of these aspects include litter and noise as well as alien species.

Joint HELCOM/OSPAR Guidelines on the granting of exemptions under the International Convention for the Control and Management of Ships’ Ballast Water and Sediments, Regulation A-4 (HELCOM 2013):
The Joint HELCOM/OSPAR Guidelines are voluntary guidelines which assist applicants and national authorities with the realisation of inventories of alien species in ports as part of a risk assessment undertaken in the application process for an exemption under the Ballast Water Management Convention. A minimum of three sites should be sampled twice a year (spring and late summer in order to identify species throughout all life-cycles) in each port, but more sampling sites may be required, depending on the size and type of port. All main substrate types are to be sampled for fouling organisms, benthic infauna, mobile epifauna and plankton. Thereby special attention must be given to high priority areas. The prescribed timing of surveys for maintaining an exemption is a minimum of every five years. Questions that need to be answered are:

  • Are the target species (HELCOM/OSPAR Guidelines, p.10) present in both ports
  • Are the target species equally common in both ports
  • Do ports have different/similar salinities, how much do they differ

Regulation of the European Parliament and of the Council on the Prevention and Management of the Introduction and Spread of Invasive Alien Species (EU No 1143/2014)
Since 2008, the EU has worked towards the development of a targeted, overarching Strategy on Invasive Alien Species for Europe, as the above policies only address alien and invasive alien species as a subtopic, or only consider single-vector bioinvasions. This EU development meets the concerns of Target 9 of the Aichi Biodiversity Targets of the Convention on Biological Diversity that ‘by 2020, invasive alien species and pathways are identified and prioritised, priority species are controlled or eradicated, and measures are in place to manage pathways to prevent their introduction and establishment’. In October 2014, the European Commission published the targeted Regulation on the Prevention and Management of the Introduction and Spread of Invasive Alien Species, which came into force on 1 January 2015. This new regulation seeks to address the problem of invasive alien species in terrestrial and aquatic environments in a comprehensive manner, in order to protect native biodiversity and ecosystem services, as well as to minimise and mitigate the social and economic impacts these species can have.

The proposal is for three types of intervention: prevention, early warning and rapid response, in addition to management. Member States must collaboratively draw up a list of invasive alien species of Union concern based on risk assessments and scientific evidence. In the interest of efficiency and cost-effectiveness, the regulation will be implemented by applying systems of border control, surveillance, and monitoring already established under Union legislation, e.g. via the assessments under the MSFD. Chapter IV of this Regulation addresses the management of invasive alien species that are widely spread. It states: ‘By 12 months of an invasive alien species being included on the list (…), Member States shall have in place management measures for those invasive alien species of Union concern which the Member States have found to be widely spread on their territory, so that their impacts on biodiversity and ecosystem services, (…) are minimised’ (Article 17). The effectiveness of management actions (eradication, population control or containment) in minimising the impacts on biodiversity and ecosystem services should be surveyed, making use of the same monitoring programme set up for the early detection of alien species on the list of Union concern.

Ballast Water Management Convention (IMO 2004)
In 2004, the International Maritime Organization (IMO) adopted the International Convention for the Control and Management of Ships’ Ballast Water and Sediments to reduce the risk of organism introductions. The Convention will enter into force 12 months after ratification by at least 30 IMO Member States, representing 35% of the world’s merchant shipping tonnage. As of March 2015, 44 States had ratified the Convention for a total tonnage of 32.86%.
Article 6 ‘Scientific and Technical Research and Monitoring’ of the BWMC calls for Parties to, individually or jointly, promote and facilitate scientific and technical research on ballast water management, and to monitor the effects of ballast water management in waters under their jurisdiction. Such research and monitoring activities should aim at finding out more about the effectiveness and adverse impacts of any technology or methodology as well as any adverse impacts caused by organisms and pathogens that have been introduced through ships‘ ballast water. The information gathered through research and monitoring should be made available to other interested Parties.
Article 9 of the BWMC further states that ‘a ship to which the Convention applies may, in any port or offshore terminal of another Party, be subject to inspection (…) for the purpose of determining whether the ship is in compliance with this Convention. Such an inspection is limited to, inter alia, a sampling of the ship’s ballast water, carried out in accordance with the guidelines to be developed…’. The Marine Environment Protection Committee (MEPC) adopted the ‘Guidelines for Ballast Water Sampling’ (G2) in its Resolution MEPC.173(58) to fulfil the needs of this Compliance Monitoring and Enforcement (CME). Contrary to the monitoring referred to in Article 6 which would need to take place on a larger scale, i.e. in parts or the whole of the Wadden Sea, compliance monitoring is done in ports and when necessary, i.e. when a ship is releasing ballast water from its tanks.

In summary, information needs and monitoring questions result from several European and global legal instruments. They concern trends in abundances, temporal occurrences, spatial distributions and impacts of invasive alien species.