Non-Indigenous Species Thematic Assessment

Impact of non-indigenous species on ecosystem services

The impact of the introduction of non-indigenous species (NIS) on ecosystem services in the Greater North Sea, Celtic Seas and Bay of Biscay and Iberian Coast has not been quantified in this assessment, as common indicators for NIS impact have not yet been developed and implemented.

Based on expert judgement, a few overall comments on NIS impact are provided:

• Impacts by a smaller group of invasive NIS are reported by Contracting Parties across the whole OSPAR Maritime Area. Several NIS however, have low or unknown impacts.
• The impacts include the out-competing of native species; increased disease spread; biodiversity loss / decline; and food web structure changes.
• Thematic assessment experts identified both negative and positive impacts by NIS on marine ecosystem services. The highest impact identified was on the provision of aquatic biomass.
• For several marine ecosystem services, the impact of NIS was defined as uncertain.
• While NIS are shown to have negative global impact on marine biodiversity, it is currently very difficult to provide a general assessment of the NIS impact on marine ecosystem services in the OSPAR Regions.
• A thorough assessment of NIS impact requires the development and implementation of NIS impact indicators.

Impacts on Ecosystem Services: Method for the development of the Schematic

This chapter evaluates the impact that changes in the state of NIS observed in the QSR thematic assessments have had on the ecosystem services that the North-East Atlantic provides. It was developed through literature review combined with expert judgement, using the same methodology across all Thematic Assessments. Several workshops involving experts on ecosystem services and NIS were held to discuss and agree on the results presented below.